Component feeder exchange cart, and mechanism and method for positioning component feeder

A cart comprises a base frame, driver for extending an operational stroke of a hydraulic jack and transferring this movement into an up and down motion, a pair of elevating rods simultaneously lifted of lowered by movement of the driver, a pair of supporting frames for operably supporting the elevating rods by virtue of guide rollers, and a holder fixed to the elevating rods for lifting and lowering the component supply unit, wherein a multi purpose space is formed surrounded by the driver, the elevating rods, and the holder. By using a positioning mechanism containing a structure where a positioning pin of a fixing device fits into a V-shaped slot formed on a component supply unit side, a component supply unit may be positioned in two different directions by pushing the component supply unit in a single direction.

This application is a National Stage of PCT/JP00/08640, filed Dec. 7, 2000.

FIELD OF THE INVENTION

The present invention relates to a cart for changing a component supply unit, which is used for installing the component supply unit onto a component mounting apparatus and removing the same from a component mounting apparatus. The present invention also relates to a component supply unit positioning mechanism for positioning a component supply unit relative to a component mounting apparatus, and a method of positioning a component supply unit.

BACKGROUND OF THE INVENTION

Recently, in the field of production of circuit formed materials, such as electronic circuit substrates, there has been a demand to reduce production cycle time and to improve operating efficiency of manufacturing facilities by reducing setup time when changing production models. In such setup time for a component mounting apparatus, it is important to fix a component supply unit so as to accurately position components at predetermined pick up locations of the component mounting apparatus. Especially, in order to respond to recent trends of miniaturization and weight reduction of electronic equipment, density of mounted components on a circuit formed material has increased. As a result, a component itself tends to be smaller, and hence even further accurate positioning of components at a setup time is required.

One known way to reduce setup time is simultaneous changing of supplying devices. When production of one specific model is completed, and a new model production is to be started, it is necessary to change a plurality of supplying devices, such as cassettes, for supplying a variety of components needed for production of the new model. Since numbers of different components are normally mounted on a single circuit formed material, it takes a considerably long time to change all of cassettes carrying these components. Simultaneous changing of a plurality of supplying devices, which may be conducted outside of the component mounting apparatus, has made it possible to complete these time consuming changes prior to a next setup timing. Consequently, setup may be performed in an efficient manner. In order to perform this simultaneous changing smoothly, a cart for changing component supply units (hereinafter, referred to as a “cart”) is used.

A component supply unit for holding a plurality of supplying devices as well as the cart for mounting and transporting the component supply unit are required to satisfy conditions such as accurate positioning capability, low cost, stability and easy handling. In the course of aforementioned trends of miniaturization of components and increasing of component mounting density, further improvement of accurate positioning for a purpose of repeated setup is required.

Now, a component mounting apparatus and a cart of prior art is described by referring to the appended drawings. In the following explanation, a substrate is used as a representative of circuit formed materials. In recent years, however, components may be mounted even on a casing of electronic equipment. Therefore, a term “substrate” used hereinafter includes all these kinds of materials in addition to an electronic circuit substrate.FIG. 17schematically illustrates an overall view of a conventional component mounting apparatus. Referring toFIG. 17, a transferring device101transfers a substrate102into and out of the component mounting apparatus, and holds the substrate at a predetermined position while a component103is being mounted on it. In order for a mounting head108to perform a series of operations, such as sucking a component103from a component supply unit106(tray type) or107(cassette type), and mounting the component103onto the substrate102, XY robot104transports the mounting head108toward these predetermined positions and holds it at the positions. Recognizing camera109images and recognizes a condition of sucked component103while the component103is being held by the mounting head108.

Next, an operation of the component mounting apparatus structured as above is described. The substrate102is transferred to a mounting position and firmly held by the transferring device101. The XY robot104transports the mounting head108to a position just above the component supply unit107, and each nozzle attached to the head108sucks a component103for picking up these components. A condition of the component103sucked by each nozzle is imaged by the recognizing camera109. Based on information recognized and obtained by the camera109, necessary adjustment of a position of the mounting head108and an angle of the components103is made, and then the mounting head108mounts the component103on a predetermined mounting position of the substrate102.

Next, the component supply unit107for holding a plurality of cassettes112, and a cart120used for simultaneous changing of a plurality of cassettes112are described. After a plurality of cassettes112are attached to the component supply unit107, the component supply unit107is installed on the component mounting apparatus and positioned by engaging with two positioning pins114provided at a fixing device113of the component mounting apparatus.FIG. 18shows a schematic perspective view of the cart120used for installing the component supply unit107onto the component mounting apparatus. Referring toFIG. 18, the cart120mainly comprises a base frame121, lifter122, holder123, and a handle124. The base frame121includes a movable and maneuverable trolley having four total wheels including two caster wheels. A lift pedal126is provided on the base frame121for operating a hydraulic jack to lift or lower the holder123.

The component supply unit107is mounted on a central portion of U-shaped holder123, which is supported by the lifter122. At both ends of the holder123in an X direction ofFIG. 18, positioning bars127having a pair of protrusions for each are provided for positioning the cart120in a Z direction of this figure. When the cart120is moved toward the component mounting apparatus in a Y direction for installing the component supply unit107onto the component mounting apparatus, the positioning bars127engage with corresponding guides provided on the component mounting apparatus. Each protruded end of the bar127has a tapered portion which makes engagement with the guide easier. The handle124, structured by a pair of bars, is used by an operator for maneuvering the cart120structured as above.

Now, a setup operation of the component supply unit107after completion of a production of one model and before starting production of another model is described. Referring back toFIG. 17, a cassette112carrying components needed for a model of completed production is still fixed to the component mounting apparatus at one of the fixing devices113. A vacant cart120is moved forward to the fixing device113. The component supply unit107is pulled back onto the holder123of that cart120, and then lift pedal126is operated for lifting holder123. By this operation, the component supply unit107installed on the component mounting apparatus is lifted from the component mounting apparatus and held by the holder123. When the cart120is moved backward together with the component supply unit107, all the cassettes112installed on the component supply unit107are removed from the component mounting apparatus at once by performing a single operation.

Next, a different component supply unit107holding a plurality of cassettes112for a next production model is mounted on the holder123of the cart120. The operator moves this cart120forward to the fixing device113of the component mounting apparatus. Then, the operator operates lift pedal126for lifting up holder123together with the component supply unit107. The cart120is then further moved forward, and after the operator confirms that U-shaped slots provided in the component supply unit107, which will be described in detail later, engage with locating pins114provided on the fixing device113, the operator again operates the lift pedal126for lowering the component supply unit107. The component supply unit107is now positioned firmly on the fixing device113of the component mounting apparatus. After the component supply unit107is installed, vacant cart120is pulled backward, and production resumes.

FIG. 19shows the component supply unit107viewed from its bottom, illustrating a positioning mechanism for fixing the unit107to the component mounting apparatus. When the component supply unit107is mounted on the component mounting apparatus, the component supply unit107is pushed forward to a base line of the component mounting apparatus shown by a double-dashed line A—A. In this figure, a bottom surface of the component supply unit107comprises base plate116. This base plate116functions as a reference plane for positioning the component supply unit onto the component mounting apparatus in a horizontal direction.

Extended portions117and118, are formed in the vicinity of both ends of the base plate116in an X direction, each of which has a U-shaped slot119facing the component mounting apparatus. By pushing both of the extended portions117and118firmly against the double-dashed line A—A, the component supply unit is positioned relative to the component mounting apparatus in a Y direction shown inFIG. 19. And when the positioning pins114located on the fixing device113of the component mounting apparatus fit into the U-shaped slots119formed at both extended portions117and118, the component supply unit is positioned firmly on the component mounting apparatus in the X direction. After the component supply unit is fixed in position, a clamp, not shown in this figure, is operated for fixing the component supply unit107to the component mounting apparatus, thereby readying the component mounting apparatus for resuming a component mounting operation.

InFIG. 19, the U-shaped slots119are formed at both extended portions117and118. It is known, however, that U-shaped slot119may be formed at only one of the extended portions117or118, and the other portion117or118may have a flat surface which contacts with the reference plane formed at a component mounting apparatus side. In either case, the positioning pins114and the U-shaped slot(s)119are to be tightly engaged with each other in order to position the component supply unit107on the component mounting apparatus. Therefore, the operator is required to perform a technique to properly move the cart120for achieving this tight engagement between the positioning pins114and the U-shaped slot(s).

SUMMARY OF THE INVENTION

According to the component supply unit of prior art structured as above, it is technically difficult to conduct simultaneous changing while achieving a high level of positioning accuracy. Because of recent requirements to achieve efficient utilization of manufacturing facilities, a large reel carrying a tape containing increased number of components are used on a cassette. Accordingly, a weight of a single cassette has increased to 3 kg or 5 kg. Furthermore, because of recent requirements of multi functioning of electronic products, a number of cassettes112to be installed on a component supply unit107has increased to 20 or 30. The component supply unit107used for simultaneous changing, therefore, should have sufficient rigidity to withstand such a heavy load weighing 50 kg to even 200 kg in total. As a result, the cart120is also required to have stronger structure, which leads to increased size and cost of the cart120. Also, careful handling is required to accurately position such a heavy item, and accordingly, present operability of the cart is not considered satisfactory.

Furthermore, lifter122of the cart120of the prior art may need to have a linear moving bearing or specially designed rail for lifting and lowering such a heavy item, which requires increased cost and larger space. Since the lifter122includes a hydraulic jack located just beneath the holder123for supplying a lifting force to the holder123, extra space may not be available in a central area of the cart120. Because of this space limitation, it is difficult to allocate a utility space in the cart120, which may be used for, for example, accommodating reels having components in a tape to be supplied by the cassette112, or may be used for collecting a supplying tape or its cover tape after it is used. If these spaces are prepared outside of the cart120, excessive floor space is necessary near the component mounting apparatus, which may create a further problem of operability of and accessibility to the component mounting apparatus.

Moreover, installing the component supply unit107onto the component mounting apparatus by using cart120of the prior art may not satisfy a recent requirement of reducing setup time, and may cause a problem for maintaining accuracy for repeated operations. The cart120itself has a problem of its high cost, and increased size.

Accordingly, an object of the present invention is to resolve the above-mentioned problems, and to provide a cart for changing a component supply unit, which may reduce setup time in a case producing a variety of substrates, achieve a high level of positioning accuracy, with increased safety, easier handling and low cost, and be capable of using a compact lifter. Also, it is an object of the present invention to provide a positioning mechanism and positioning method for achieving accurate and easy positioning of a component supply unit.

One aspect of the present invention relates to a cart for changing a component supply unit, which is connectible with and separable from a component mounting apparatus for a purpose of simultaneously changing a plurality of supplying devices attached to the component supply unit by installing the component supply unit onto the component mounting apparatus, or removing the same from the component mounting apparatus, wherein the cart has a multi purpose utility space beneath the component supply unit mounted on the cart. By utilizing such multi purpose space, operability of the cart is improved by lowering a center of gravity of the cart having the component supply unit, and by reducing an amount of extensions of the cart.

Another aspect of the present invention relates to a cart including: a base frame having wheels including caster wheels; a driver accommodated inside the base frame; a pair of lifters fixed to the base frame and to be driven simultaneously by the driver, and a holder fixed to a pair of the lifters for mounting the component supply unit, wherein a space is surrounded by the base frame and the pair of lifters.

Another aspect of the present invention relates to a cart in which a reel box and/or a collecting box is (are) provided in a space for accommodating a reel around which a supplying tape of the supplying device attached to a component supply unit is wound, and/or for collecting used supplying tapes or used cover tapes for covering the supplying tapes.

The driver mentioned above may include a hydraulic jack, and a lever mechanism for transferring extending and contracting movements of the hydraulic jack to the lifters simultaneously. Each of lifters mentioned above may include an elevating rod driven by the driver for lifting and lowering motions, and a supporting frame having a linear bearing structure for movably supporting the elevating rod in up and down directions. The linear bearing structure may include first engaging elements formed on an outer surface of the elevating rod along a first direction parallel to an up and down motion of the elevating rod, which engaging elements are formed on two sides of the outer surface opposing each other in a second direction perpendicular to the first direction, and second engaging elements formed on circumferences of at least three guide rollers rotatably fixed to each of supporting frames for holding the elevating rod from both sides of the second direction, wherein when the first engaging elements engage with the second engaging elements, the at least three guide rollers guide a movement of the elevating rod in the first direction while restricting movement of the elevating rod in the second direction as well as a third direction perpendicular to both the first and the second directions.

Yet another aspect of the present invention relates to a cart wherein a safety mechanism is provided for restricting movements of the driver depending on a distance between the cart and the component mounting apparatus when the cart is moved forward to or moved away from the component mounting apparatus. The safety mechanism is designed to be switched in three different stages including a first stage in which downward movement of the component supply unit is restricted while the cart is completely separated from the component mounting apparatus, a second stage in which both upward and downward movements of the component supply unit are allowed while the cart is in a predetermined range of a close distance from the component mounting apparatus, and a third stage in which upward movement of the component supply unit is restricted while the cart is fully pushed forward to the component mounting apparatus. More specifically, the safety mechanism controls movements of a release lever of a hydraulic jack, or a driving source, wherein in the first stage, movement of the release lever is restricted so as to not release hydraulic pressure for maintaining the hydraulic jack in an extended position; in the second stage, movement of the release lever is permitted so as to allow extending and contracting of the hydraulic jack, and in the third stage, movement of the release lever is restricted so as to release hydraulic pressure for maintaining the hydraulic jack in a contracted position.

Yet another aspect of the present invention relates to a cart in which a holder is equipped with a buffer type fixing mechanism for permitting separation of a component supply unit from the holder by a predetermined distance when the component supply unit is to be mounted on the holder for installing the component supply unit onto the component mounting apparatus. This mechanism is designed to mount the component supply unit safely on the holder of the cart and to position the component supply unit relative to the component mounting apparatus securely.

The buffer type fixing mechanism may include at least one bolt which is inserted into a through hole of a holding arm and fastened to a bottom surface of the component supply unit for holding the component supply unit onto the holder, and a spring which may be compressed and held between a bolt head of the bolt and the holding arm, wherein the buffer type fixing mechanism separably holds the component supply unit onto the holding arm by virtue of an elastic force of a spring at the place where the bolt is fastened.

Another aspect of the present invention relates to a cart which may be separated from the component mounting apparatus after a component supply unit is installed on the component mounting apparatus. The cart may be used for other purposes after it is separated from the component mounting apparatus.

Yet another aspect of the present invention relates to a mechanism for positioning a component supply unit, capable of holding a plurality of supplying devices, onto a fixing device provided on the component mounting apparatus when the component supply unit is to be installed on the component mounting apparatus, including: a first positioning mechanism for positioning the component supply unit onto a first plane in a substantially horizontal direction, and a second positioning mechanism for positioning the component supply unit onto a second plane which is substantially perpendicular to the first plane, wherein the second positioning mechanism further comprises a third positioning mechanism for restricting movement of the component supply unit in a direction parallel to a line defined by an intersection of the first and the second planes. By arranging the second positioning mechanism to function as a third positioning mechanism, operation of positioning may be performed quite easily with simple structures.

The first positioning mechanism may include: two horizontal guide planes, which are parallel to the first plane, provided on the fixing device, and two flat portions formed on a bottom surface of the component supply unit and facing the two horizontal planes, respectively, wherein when each of the flat portions is placed on each of the horizontal guide planes, respectively, the component supply unit may be positioned on the first plane.

The second positioning mechanism may include: two positioning elements attached to the fixing device forming a substantially vertical second plane perpendicular to the first plane, and two contact elements formed on the component supply unit, having a distance between each other and facing the two positioning elements, respectively, wherein, after the component supply unit is positioned on the first plane, the component supply unit is positioned on the second plane by pushing the component supply unit toward the component mounting apparatus so that the two contact elements may contact with the two positioning elements, respectively.

The third positioning mechanism is formed by a combination of one of the two positioning elements provided on the fixing device and one of the two contact elements provided on the component supply unit, wherein the component supply unit is positioned in a direction parallel to a line defined by an intersection of the first and the second planes by virtue of a pair of elemental forces generated at a pair of contact points between the contact element and the positioning element when the contact element of the component supply unit is pushed forward against the positioning element attached to the fixing device during positioning of the component supply unit on the second plane. Either one of the positioning element and the contact element may be in the form of a V-shaped slot, while the other may be in the form of a circular protrusion.

Another aspect of the present invention relates to a component supply unit positioning mechanism including: a first guide mechanism for once blocking forward movement of the component supply unit in a direction toward the component mounting apparatus; a second guide mechanism for guiding the component supply unit to lower and place the component supply unit onto a horizontal guide plane after forward movement of the component supply unit is once blocked at a predetermined position; a third guide mechanism for guiding further forward movement of the component supply unit mounted on the horizontal guide plane toward the component mounting apparatus so as to push two contact elements formed on the component supply unit against two positioning elements, respectively; a fourth guide mechanism for once blocking backward movement of the component supply unit in a direction moving away from the component mounting apparatus during a time of removing the component supply unit from the component mounting apparatus; and a fifth guide mechanism for guiding upward movement of the component supply unit so as to make it possible to remove the component supply unit from the component mounting apparatus after backward movement of the component supply unit is once blocked at a predetermined position.

The component supply unit may include a pair of stopper bolts attached to a pair of vertical surfaces located on both side ends perpendicular to a direction of forward movement of the component supply unit toward the component mounting apparatus, and the fixing device of the component mounting apparatus may include vertical stoppers, horizontal stoppers, and slots facing each of the vertical surfaces, wherein a pair of the stopper bolts and a pair of the vertical stoppers function as the first and fifth guide mechanisms; a pair of the stopper bolts and a pair of the horizontal stoppers function as the second and fourth guide mechanisms; and a pair of the stopper bolts and a pair of the slots function as the third guide mechanism.

Yet another aspect of the present invention relates to a method of positioning a component supply unit for installing the component supply unit onto a fixing device of a component mounting apparatus, including: a first positioning step for positioning the component supply unit onto a substantially horizontal first plane, including moving forward the component supply unit toward the fixing device, once blocking this forward movement at a predetermined position, and lowering and placing the component supply unit onto the fixing device; and a second positioning step for positioning the component supply unit on a substantially vertical second plane perpendicular to the first plane, including further moving forward the component supply unit placed and positioned on the first plane, and blocking this forward movement at a predetermined position, wherein during the second positioning step, the component supply unit is simultaneously positioned in a direction parallel to a line defined by an intersection of the first and the second planes. According to this method, the component supply unit may easily and securely be positioned with simple structures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of a cart for changing a component supply unit and a mechanism for positioning the component supply unit according to the present invention are described by referring to appended drawings.FIG. 1shows a component mounting apparatus1, a component supply unit2used for simultaneous changing of components, and a cart3for changing the component supply unit2(hereinafter, referred to as a “cart”) according to the present embodiment. Referring toFIG. 1, two fixing devices4are provided on the component mounting apparatus1for locating two component supply units2at one time. One of the fixing devices4on the left hand side of an X direction of this figure holds a component supply unit2aby using a cart3a. The fixing device4on the right hand side in the X direction of the figure is ready for receiving another component supply unit2held by another cart3. A clamp switch6is provided to operate a clamp mechanism for securely fixing the component supply unit2to the component mounting apparatus1. Other structures of the component mounting apparatus1are similar to those explained above in connection with the conventional component mounting apparatus.

Referring toFIG. 1, the component supply unit2holding a plurality of cassettes7(or supplying devices), is ready to be installed onto the component mounting apparatus1. Each cassette7shown in the figure is so designed that a reel portion8carrying a component supplying tape may be accommodated in a reel box9. Due to this cassette design, the cart3according to the present embodiment may reduce an extension amount of the cassette7when the cart3is attached to the component mounting apparatus1, and may keep its center of gravity at a low position, which makes handling of the cart3easier. A collecting box10, also provided at a central area of the cart3, may be used for collecting component supplying tapes, or cover tapes for protecting components contained in the component supplying tapes, after they are used.

InFIG. 1, component supply unit2ainstalled on the component mounting apparatus1is shown in a condition that the cart3ais still attached to the component supply unit2a. According to this condition, the reel box9and/or the collecting box10provided on the cart3may be fully utilized for accommodating reels and/or collecting used tapes. The cart3, however, may alternatively be designed to be separable from the component mounting apparatus1during operation, rather than being attached to the component mounting apparatus1, if required. This will be further described later.

FIG. 2shows the component supply unit2according to the present embodiment. Referring toFIG. 2, the component supply unit2mainly comprises a base plate11, holder plate12fixed on the base plate11, and a guide plate13attached vertically to the holder plate12. A stopper bolt16is provided on each of a pair of vertical surfaces14located at both ends of the base plate11in an X direction of this figure. The stopper bolts16are used as guides when installing the component supply unit2onto the component mounting apparatus1. A plurality of undercut slots17are formed in the holder plate12for holding a plurality of cassettes. Each cassette7is slid into each undercut slot17for attachment. Broken lines show one cassette7abeing attached to one of the undercut slots17a. The cassettes7attached may be as many as the number of the slots17. A plurality of positioning slots18are formed on a top of the guide plate13for positioning the cassettes7. Also provided in the guide plate13below the positioning slots18is an air joint19for supplying air to the cassettes7individually.

FIG. 3shows an example of a cassette7. Right hand side in a Y direction of this figure faces the component mounting apparatus1. The cassette7mainly comprises a body45, a reel holder46, and a tape winder47. A reel8carrying a component supplying tape containing many components may be attached to the reel holder46. The component supplying tape is wound up on the reel8, and is driven by the tape winder47intermittingly. Components are picked up one after another by the component mounting apparatus1at a component pick up position75provided on the body45. Undercut fixing pins76are provided on a bottom of the body45of the cassette7. When the cassette7is attached to the component supply unit2, the fixing pins76are slid into one of the slots17formed on holder plate12. A locating pin77is provided on a right end surface of the body45in the Y direction of the figure. This locating pin77is to be located in the positioning slot18formed in the guide plate13for positioning cassette7relative to the component supply unit2. Also provided on the right end surface of the body45in the Y direction of the figure are a connector78and an air joint79. The connector78is to be connected to another connector provided on the component mounting apparatus for transmitting electric signals, which will be described later. The air joint79is to be connected to the air joint19provided in the guide plate13of the component supply unit2for supplying air for operating a shutter covering a component supplying tape located at the component pick up position75.

InFIG. 3, although the reel holder46is shown at a higher position of the cassette7than in the case of prior art, the reel holder46may be lowered in a Z direction of this figure as mentioned above, so that the reel8may be accommodated in the reel box9provided on the cart3of the present embodiment.

FIG. 4shows the component supply unit2structured as above, and the fixing device4for receiving the component supply unit2provided on a component mounting apparatus side. The fixing device4includes an end plate21, and a pair of arm plates22at both ends of the end plate21in an X direction of this figure. By this arrangement, blocking walls in three directions are formed by plates21and22. An air joint23is provided on the end plate21for supplying air to the component supply unit2. This air joint23is to be connected to another air joint provided to component supply unit2, which will be described below. Also provided on the end plate21are connectors33for transmitting and receiving electric signals. These connectors33are to be electrically connected to connectors78provided on the cassettes7(seeFIG. 3), respectively, when a corresponding cassette7is installed on the component supply unit2.

Both of the arm plates22are equipped with a guiding and positioning mechanism for positioning component supply unit2onto the component mounting apparatus1. Each arm plate22includes a horizontal guide surface24and a horizontal stopper26for guiding and positioning the component supply unit2in a Z direction (upper and lower direction) ofFIG. 4, a vertical stopper28and a positioning pin29for guiding and positioning component supply unit2in a Y direction (forward and backward direction) of this figure, and a vertical guide plate31and a guide roller32for guiding component supply unit2in the X direction (right and left direction) of the figure. The horizontal guide plate24and the positioning pin29position the component supply unit2onto a predetermined location of the fixing device4when it is installed. Other elements, i.e. horizontal stopper26, vertical stopper28, vertical guide plate31and the guide roller32serve to guide the component supply unit2when it is to be installed on or removed from the component mounting apparatus1. The positioning pin29according to the present embodiment serves to position the component supply unit2in the Y direction, as well as in the X direction. Four fixing holes27formed on both arm plates22may be used for permanently fixing the component supply unit2onto the fixing device4by screwing bolts through fixing holes37provided in the component supply unit2.

FIG. 5shows a bottom view of the component supply unit2for simultaneous changing. A stopper bolt16is provided on each of a pair of vertical surfaces14located at both ends of the base plate11in an X direction of this figure. This stopper bolt16serves as an element of guide mechanism for positioning the component supply unit2onto the fixing device4. A chained line A—A shows a blocking wall located at the component mounting apparatus1. A V-shaped slot35is formed in the vicinity of one end of the component supply unit2in an X direction, and a square shaped slot36is formed in the vicinity of another end thereof, respectively, both of which face the blocking wall. Both slots35and36engage with positioning pins29provided on the fixing device4, and position the component supply unit2in both X and Y directions. Four positioning holes38are used for positioning component supply unit2when the component supply unit2is mounted on the cart3. This will be described later. The air joint39of the component supply unit2is to be connected to the air joint23provided on the fixing device4when the component supply unit2is fixed to the component mounting apparatus1for supplying air to the component supply unit2. Introduced air is guided to the air joint19mentioned above (seeFIG. 2), and then supplied to each cassette7.

A pair of holding arms81shown by double-dashed lines inFIG. 5are elements of the cart3for holding the component supply unit2while it is mounted on the cart3. A guide slope82is provided at one end of each holding arm81. When the cart3is moved forward in the Y direction for installing the component supply unit2onto the component mounting apparatus1, the guide slopes82and the guide roller32mentioned above jointly work for regulating movement of the cart3in the X direction. Four fixing holes37may be used for permanently fixing the component supply unit2by screwing bolts as mentioned above. The component supply unit2may be fixed with bolts if changing component supply unit2at a setup time is not required, and only cassettes7are changed while the component supply unit2is being fixed to the component mounting apparatus1.

Now, structure of the cart3according to the present embodiment is described by referring to appended drawings.FIG. 6toFIG. 12show details of the cart3, whereinFIG. 6shows a side elevational view,FIG. 9shows a plan view, andFIG. 10shows a front elevational view. Referring toFIG. 6, the cart3mainly includes a base frame40, a pair of lifters50, a driver55, a holder80, and a pair of handles90. The component supply unit2holding a plurality of cassettes7may be mounted on the holder80. The base frame40comprises a trolley with four wheels including two caster wheels. A pedal42is provided on the base frame40for operating the lifters50.

Each lifter50mainly includes a supporting frame51(only one supporting frame51is seen inFIG. 6) firmly fixed to the base frame40, elevating rod53(same as above) movable vertically in both ways in a Z direction of this figure, and at least three guide rollers52for each elevating rod53to movably hold the rod53. The driver55, shown by broken lines, for driving the lifters50is located inside the base frame40. At least three guide rollers52are rotatably fixed to the supporting frame51and movably hold the elevating rod53from both sides in a Y direction ofFIG. 6. When the number of the guide rollers52is three, these guide rollers52should be allocated on both sides of the elevating rod53in a zigzag manner, or have a distance among each other in the Z direction so as to restrict movement of the elevating rod53in the Y direction. When the number of the guide rollers52is four, two rollers52, for example, may be allocated at an upper portion and the other two rollers52may be allocated at a lower portion of the rod53, while each set of two rollers52face each other in the Y direction of this figure.

InFIG. 6, the holder80is fixed to a pair of the elevating rods53of the lifters50. The holder80mainly includes a connecting bar89extending perpendicularly to this figure so as to connect a pair of the elevating rods53to each other, and a pair of the holding arms81(only one of them can be seen inFIG. 6) fixed to the connecting bar89and extending roughly horizontally in the Y direction of the figure. Two positioning pins83are attached to each of upper surfaces of both holding arms81. These positioning pins83fit into positioning holes38formed on a bottom of the base plate11of the component supply unit2for positioning the component supply unit2on the holding arms81. The cassettes7held by the component supply unit2may be either traditional type (i.e., a type having a reel8aat an upper position), or a modified type whose reel8may be accommodated in the reel box9provided on the cart3of the present embodiment. These reels8and8aare heavy, since a component supplying tape carrying many components are wound around the reel8or8a, as mentioned above. Accordingly, as clearly understood byFIG. 6, it is preferable to use cassette7whose reel8may be accommodated in the reel box9so as to lower a center of gravity of the component supply unit2, and to reduce an amount of extension of the reel8for easier handling of the cart3.

A pair of the handles90(only one of which can be seen inFIG. 6) is provided on the cart3for easier handling and lifting or lowering of the lifters50. Each handle90includes a hand frame91and a folding handle92at its one end. A grip93, attached to the hand frame91is used for pulling a release wire94to release hydraulic pressure of a hydraulic jack, and to lower the component supply unit2mounted on the cart3. The collecting box10, shown by a double-dashed line may be used for collecting used component supplying tapes.

FIG. 7is a side elevational view in an enlarged fragmentary cross section which shows relationships between the lifters50, fixed to the base frame40, and the driver55. The driver55mainly comprises a hydraulic jack56fixed to the base frame40, a jack side lever (first lever)57for changing an axial movement of the hydraulic jack56into a circular movement, a shaft58to hold the jack side lever57for rotation, a pair of rod side levers (second levers)60also held by the shaft58so as to transfer circular movement of the jack side lever57to a pair of elevating rods53for upward and downward movement. As shown in this figure, by making a lever length of the rod side levers60longer than a lever length of the jack side lever57, axial movement of the hydraulic jack56may be transferred to the elevating rods53in an expanded manner. Due to this expansion, a compact hydraulic jack with a short stroke may be employed, and hence, the hydraulic jack56may be accommodated inside the base frame40. Arm lengths of both levers57and60, though, may be arranged in any combination. An elevating pin61is fixed to each of the rod side levers60, with which a lower end of the elevating rod53makes contact.

FIG. 8shows the elevating rod53when it is lifted up by the elevating pins61due to extension of the hydraulic jack56and movement of other elements of the driver55. In prior art, since a lifter is operated directly by an output shaft of a hydraulic jack, a relatively large hydraulic jack is needed in order to obtain a necessary stroke. Moreover, since the lifter is located at a central portion of the cart3, the driver and the lifter occupy most of space in the central portion of the cart3(seeFIG. 18). As for the driver55of the cart according to the present embodiment, to the contrary, short stroke hydraulic jack56may be accommodated inside the base frame40, and movement of the hydraulic jack is transferred to a pair of the rod side levers60located at both side ends of the cart3via the shaft58. The rod side levers60lift up a pair of elevating rods53, respectively, which are also located at both side ends of the cart3. Due to this arrangement, a wide space with no obstacles may be obtained in a central portion of the cart3surrounded by the base frame40, a pair of the lifters50, and the holder80.

FIG. 9is a plan view of the cart3. The above-described arrangement may be seen more clearly in this drawing. Upper side of a Y direction of this figure faces the component mounting apparatus1. The hydraulic jack56is seen in a center of the figure, but is accommodated inside the base frame40and is operable in upward and downward directions perpendicular to the drawing. As mentioned above, the hydraulic jack of the prior art operates upward and downward at the central portion of the cart so as to directly move the component supply unit2. Most of the central portion of the cart, therefore, is used for the hydraulic jack as well as other driving elements. Consequently, utility space is hardly available in such an arrangement. According to the cart3of the present invention, to the contrary, axial movement of the hydraulic jack is converted into a circular movement of the jack side lever57. This circular movement is then transferred, via the shaft58, to the rod side levers60located at both side ends of an X direction of the figure in an expanded manner. Then, the elevating pins61fixed to the rod side levers60simultaneously lift up a pair of the elevating rods53. In other wards, by accommodating the hydraulic jack56in small size inside the base frame40, and by relocating elevating rods53for lifting the component supply unit2from the central portion to both side ends of the cart3, the cart3according to the present embodiment makes it possible to provide an area above the base frame40ofFIG. 9for a utility space. A pair of bearings59are provided for rotatably supporting the shaft58at both its ends.

Operation of the hydraulic jack56is now described by referring toFIG. 9. The hydraulic jack56has a lifting lever62for extending an operation shaft of the hydraulic jack56. One end of the lifting lever62is connected to a pedal42via a lifting wire63. Another end of the lifting lever62is connected to a return spring64which provides a return force to the lifting lever62.

As for retracting, or shortening the operation shaft of the hydraulic jack56, a release lever66is connected to the shaft68, which operates a hydraulic pressure release valve inside the hydraulic jack56. The release lever66is always pulled by a block spring67, so as to block movement of the release lever66and maintain hydraulic pressure of the hydraulic jack56. Further, one end of the release wire94, shown by double-dashed lines inFIG. 9, is connected to the release lever66. Another end of the release wire94is connected to the grip93attached to the hand frame91(seeFIG. 6) for releasing operation of hydraulic pressure of the hydraulic jack56by an operator. A control lever69is also provided for the hydraulic jack56at a hydraulic pressure releasing side. Depending on position of the control lever69, a hydraulic pressure releasing operation is prevented even when the operator grasps the grip93for releasing pressure. An absorbing spring70is provided as a part of the release wire94at the vicinity of its one end near the release lever66. This absorbing spring70absorbs a pulling force of a grip operation by elastic extension of its length. Detail of this mechanism will be explained later.

The control lever69is driven by a control shaft71which is also attached to the base frame40at an upper side of a Y direction inFIG. 9facing the component mounting apparatus1. When the cart3is moved close to the component mounting apparatus1at the upper side of the Y direction of this figure, an upper end of the control shaft71is pushed back by a control bracket72, shown by double-dashed lines, provided on the component mounting apparatus1. When the cart3is separated from the component mounting apparatus1, on the other hand, a control spring73pushes the control shaft71back to its original extended position. Also, the return spring74moves the control lever69back to its original position. These mechanisms will be explained in detail later.

FIG. 10shows a front elevational view of the cart3. Referring to this figure, a wide space in a central portion of the cart3surrounded by the base frame40, a pair of the lifters50located at both side ends of the base frame40in an X direction of the figure, and the holder80connecting both lifters50together may clearly be seen. A pair of the handles90is also fixed to both lifters50, respectively. The holder80mainly includes a connecting bar89connecting two of the elevating rods53together, and a pair of holding arms81fixed to the connecting bar89for mounting the component supply unit2. Double-dashed lines in the figure show the component supply unit2mounted on the holder80, reels8located at lower positions of the cassettes7, and a reel box9provided in the central space of the cart3for accommodating the reels8.

Now, operation of the cart3for mounting the component supply unit2structured as above is described by referring to appended drawings. Referring toFIG. 9, when an operator pushes the pedal42, the lifting lever62rotates via lifting wire63, and the hydraulic jack56extends. Since the lifting lever62may return to its original position by virtue of the return spring64, a plurality of pedal operations may be performed so as to extend the hydraulic jack56up to a desired length. This extension of the hydraulic jack56is transferred to the shaft58via the jack side lever57, and rotation of the shaft58is then transformed into vertical movement of a pair of the rod side levers60in an expanded manner. This vertical movement is then transferred to a pair of the elevating rods53located at both side ends of the X direction ofFIG. 9via elevating pins61attached to rod side levers60.

In the present embodiment, each of the elevating rods53is made of a deformed pipe whose cross section across its longitudinal axis is deformed into a flat circle. This elevating rod53having a flat circular cross section is movably supported by at least three guide rollers52, which are rotatably fixed to the supporting frame51.FIG. 11(A)shows detail of this structure. Each of the guide rollers52has a dent on its circumference as shown in its cross section inFIG. 11(A). The guide rollers52prevent the elevating rod53from moving in an X direction of this figure by engaging the dent with a protruding portion of the flat circular cross section of the elevating rod53. Further, since the guide rollers are arranged to hold the elevating rod53from both sides of the protruding portions of its flat circular cross section, the guide rollers52prevent the elevating rod53from moving in a Y direction as well. Since all these guide rollers52are rotatably fixed, they support the elevating rod53in such a manner that the elevating rod53may move up and down in a vertical direction, while its movements in X and Y directions are restricted.

The cross section of the elevating rod53is not limited to the flat circle as shown inFIG. 11(A), but it may be elliptical, or circular so long as the dent formed on the circumferences of the guide rollers52may engage with a surface of elevating rod53, and thereby prevent movement of the elevating rod53in the X direction. Alternatively, as shown inFIG. 11(B)the cross section of guide rollers52′ may have a protrusion on its circumference, and a channel may be formed on a surface of elevating rod53′ in an axial direction so that these protrusions of the guide rollers may engage with the channel of the elevating rod53′ for preventing movement of the elevating rod53′ in X and Y directions. In general, the cross sections of the elevating rod53,53′ and the guide rollers52,52′ may be formed in such a way that a first engagement portion is formed on the outer surface of the elevating rod and a second engagement portion is formed on the circumference of the guide roller, and the first and the second engagement portions may engage with each other so that the guide rollers restrict movement of the elevating rod in both X and Y directions, while the guide rollers permit vertical movement (movement in the Z direction) of the elevating rod.

Referring back toFIG. 9, by a series of operations starting from pushing the pedal42by the operator, the driver55lifts up both elevating rods53of the lifters50, the holder80fixed to the elevating rod53, and the component supply unit2. Since the base frame40of the cart3has wheels including caster wheels41, the operator can easily move the cart3back and forth for maneuvering it.

Next, an operation for lowering the lifter50, after being lifted up as mentioned above, is described. First, an operator grasps the grip93attached to the handle frame91(seeFIG. 6) for operating the release lever66of the hydraulic jack56shown inFIG. 9via the release wire94. By this operation, the shaft68, which is connected to the hydraulic pressure release valve, rotates, and hence hydraulic pressure is released which, in turn, retracts or shortens extended hydraulic jack56. Due to this retraction of the hydraulic jack56, the elevating pins61, holding the elevating rod53at an upper position, loose their supporting forces, and the holder80and component supply unit2mounted on the holder80are lowered by their own weight.

Now, movement of components related to the control lever69, which controls and restricts movement of the release lever66, is described by referring to the appended drawings. InFIG. 9, the control shaft71attached to the cart3moves the control lever69in three different stages when the control shaft71is being pushed by the bracket72provided on the component mounting apparatus1.FIG. 12(A)toFIG. 12(C)illustrate these three different stages. Each of these figures shows a position viewed from a front of the release lever66attached to the hydraulic jack56. The release lever66is fixed to the shaft68which operates the hydraulic pressure release valve inside the hydraulic jack56, and the release lever66may rotate both in clockwise and counterclockwise directions. The release lever66is normally pulled by the block spring67to prevent hydraulic pressure from releasing (clockwise direction in these figures). The block spring67is shown on the right hand side of the drawing. On an opposite side of the drawing, the release wire94, when pulled by the operator with a force overcoming a spring force of the block spring67, may move the release lever66in a direction for releasing hydraulic pressure (counterclockwise direction). Further, one end of the release lever66engages control lever69which may restrict movement of the release lever66depending on the stages.

FIG. 12(A)shows a stage where the cart3is completely separated from the component mounting apparatus1. In this stage, the control shaft71shown inFIG. 9is fully extended by virtue of the control spring73. In such a situation, the control lever69blocks movement of the release lever66of the hydraulic jack56so that the hydraulic pressure release valve is kept in a closed position. More precisely, first engaging portion69a, or one end of a slot formed in the control lever69, contacts with a portion of the release lever66for blocking counterclockwise rotation of the release lever66. Under such condition, even when the release wire94is pulled by the operator toward the left in this figure, the release lever66may not be moved because of the blocking mechanism mentioned above. An operator's pulling force of the release wire94is absorbed by extension of the absorbing spring70. This is a mechanism to avoid a risk of rapid descending of a lifted up component supply unit2by an operator's erroneous operation of releasing hydraulic pressure when the cart is separated from the component mounting apparatus1. The absorbing spring70prevents damage of related components in case the operator attempts to move the release lever66forcibly under such blocking condition.

FIG. 12(B)shows a stage where the cart3approaches the component mounting apparatus1, and the control shaft71comes into contact with the control bracket72(seeFIG. 9) provided on the component mounting apparatus1, and the control shaft71is pushed backward one step. With this contact of the control shaft71, the control lever69is moved one step toward the right in this figure. As a result of this movement, blocking of rotation of the release lever66by the first engaging portion69aof the control lever69is released, i.e., counterclockwise rotation of the release lever66becomes possible. In case the operator operates the grip93for pulling the release wire94toward the left in the figure, the release lever66rotates counterclockwise, and hydraulic pressure of the hydraulic jack56is released, thereby the elevating rods53are lowered. This movement permits the component supply unit2to be placed on the fixing device4of the component mounting apparatus1, which will be further described later. In case the operator does not grasp the grip93and the release wire94is not pulled, the release lever66is kept in the same position for maintaining hydraulic pressure by virtue of the block spring67.

FIG. 12(C)shows a stage where the cart3is completely pushed forward to the component mounting apparatus1. Under this condition, the control shaft71(seeFIG. 9) is fully pushed backward by the control bracket72provided on the component mounting apparatus1. By this movement of the control shaft71, the control lever69is moved further toward the right in this figure. By this movement, a second engaging portion69b, or another end of the slot formed in the control lever69, contacts a portion of the release lever66, thereby clockwise rotation of the release lever66is blocked. Further, the release lever66is forced to rotate counterclockwise, by overcoming a spring force of the block spring67, and the release lever66is locked at that position. Consequently, hydraulic pressure of the hydraulic jack56is released, and therefore, the elevating rods53of the lifters50are lowered and kept in a lowered position. Under this condition, even if the operator operates the pedal42for attempting to extend the hydraulic jack56erroneously, the elevating rods53will not be lifted up. This is a mechanism for avoiding a risk of damage against structural elements of the component mounting apparatus1, such as component sucking nozzles, when the component supply unit2is erroneously lifted up while it is being installed on the fixing device4of the component mounting apparatus1.

In the present embodiment, a distance between the component mounting apparatus1and the cart3is detected by using the control shaft71, which is a simple structure of a contact type sensor, for controlling the release lever66. Alternatively, the distance between the component mounting apparatus1and the cart3may be detected by using, for example, a perspective type sensor which detects distance by blocking infra-red radiation, or a response type sensor which radiates supersonic waves and detects reflected waves, and the like. The release lever66may also alternatively be controlled by using, for example, a solenoid which is operated based on signals transmitted from such sensors.

Next, operation of installing the component supply unit2, mounted on the cart3as mentioned above, onto the fixing device4of the component mounting apparatus1, and a guiding structure for positioning the component supply unit2are described by referring to the appended drawings. Referring toFIG. 4, the component supply unit2, mounted on the holder80of the cart3, is moved forward in the Y direction toward the fixing device4as shown by an arrow30. In the present specification, moving direction toward the component mounting apparatus1as shown by the arrow30is called “forward”. The component supply unit2is mounted on the holder80in such a way that the component supply unit2is placed on top of the holding arms81of the holder80, with four positioning pins83attached to the holding arms81fit into the positioning holes38formed on the component supply unit2(seeFIG. 5).

Under this condition, the elevating rods53are lifted up by operating the pedal42attached to the base frame40, and the component supply unit2is held at a predetermined level of height while it is moved toward the component mounting apparatus1together with the cart3. By this forward movement, the guide slopes82of the holding arms81shown on upper sides in the Y direction ofFIG. 5contact the guide rollers32provided on both arm plates22of the fixing device4shown inFIG. 4, respectively, and hence movement of the cart3in the X direction is restricted by the guide rollers32. Under such restriction, the cart3is further moved forward until the stopper bolts16attached to both vertical surfaces14of the base plate11of the component supply unit2come into contact with the vertical stoppers28provided on both arm plates22of the fixing device4, and hence further forward movement of the component supply unit2is once blocked.

FIGS. 13(A) to 13(F)show relationships between the stopper bolts16and various stoppers provided on the arm plate22of the fixing device4. First, as shown inFIG. 13(A), the stopper bolt16facing the arm plate22of the fixing device4is moved forward toward the fixing device4shown on the right side of a Y direction of this figure, and the stopper bolt16contacts the vertical stopper28inFIG. 13(B). At this position, aforementioned control shaft71is push backward one step (seeFIG. 12(B)). As a result, a locking condition for maintaining hydraulic pressure of the hydraulic jack56is eliminated, thereby the component supply unit2may be lowered.

By an operator's operation for lowering the component supply unit2, the stopper bolt16of the component supply unit2is lowered, and the bolt16fits into the slot20, located at the right hand side in the Y direction, of the horizontal stopper26provided on each of the arm plates22of the fixing device4. By this lowering operation of the component supply unit2, both side end portions of the base plate11at the bottom of the component supply unit2are placed on horizontal guide surfaces24provided on both arm plates22(seeFIG. 4). The component supply unit2is positioned in a predetermined horizontal direction at this stage.

When the component supply unit2is moved forward one step further (in the Y direction), the stopper bolt16, as shown inFIG. 13(D), moves forward in the Y direction of this figure inside the slot20located beneath the vertical stopper28. By this secondary movement of the component supply unit2, positioning pins29attached to the end plate21of the fixing device4fit into the V shaped slot35and the square shaped slot36, respectively (seeFIG. 5), and contact portions defining these slots.

At this moment, as can be seen inFIG. 5, movement of the component supply unit2in both the Y direction (forward or backward directions) and the X direction (right and left directions) ofFIG. 5are restricted by virtue of one of the positioning pins29and the V shaped slot35. At the same time, movement of the component supply unit2in the Y direction (forward or backward directions) is restricted by virtue of the other positioning pin29and the square shaped slot36. By employing such positioning mechanism, a high level of accuracy for positioning may be achieved compared to a prior art mechanism using one or two U shaped slot(s). After the component supply unit2is positioned, the clamp switch6(seeFIG. 1) is operated and the component supply unit2is clamped to the component mounting apparatus1, and a changing of a plurality of cassettes7, or component supply devices, may be completed at once.

FIGS. 14(A) and 14(B)show how the component supply unit2is clamped to the component mounting apparatus1.FIG. 14(A)shows that the component supply unit2passes over an air cylinder97attached to the fixing device4for clamping, and a clamp lever98connected to the air cylinder97. The component supply unit2moves forward to its predetermined fixing position. Then the clamp switch6of the component mounting apparatus1is operated and, as can be seen inFIG. 14(B), the air cylinder97extends to manipulate the clamp lever98so as to clamp the component supply unit2to the component mounting apparatus1for completing a clamping operation.

When the component supply unit2is firmly clamped, aforementioned control shaft71for controlling hydraulic pressure of the hydraulic jack is fully pushed backward. As a result of this movement of the shaft71, hydraulic pressure of the hydraulic jack56is maintained in a released position (seeFIG. 12(C)) for preventing the component supply unit2from being lifted. Lifting of the component supply unit2at this place may cause damage to structural elements of the component mounting apparatus1. Also, in this same clamped situation, the air joint23provided on the fixing device4is connected to the air joint39provided on the component supply unit2, and the connector33for transmitting electric signals is connected to the connecting point78provided on the end of the cassette7, thereby air supply and electric signal transmission are secured.

Next, an operation for separating the component supply unit2from the component mounting apparatus1is described. This operation is basically a reversed movement compared to an attaching operation. Namely, first, turn off the clamp switch6, and release the component supply unit2from the component mounting apparatus1. Then, as seen inFIG. 13(E), the component supply unit2is pull back so that the stopper bolt16of the component supply unit2contacts the horizontal stopper26attached to the fixing device4, and backward movement of the component supply2is once blocked. By this movement, the control shaft71extends by one step so as to release a locking position of hydraulic pressure release of the hydraulic jack56(see FIG.12(B)), and as a result, the hydraulic jack56enters an operable condition. The operator then operates the pedal42for lifting the component supply unit2sufficiently to make the stopper bolt16clear a level of the horizontal stopper26, as seen inFIG. 13(F). Then, by moving the cart3away from the component mounting apparatus1(toward the left in the Y direction), the component supply unit2returns to an original position as shown inFIG. 13(A), and a separating operation is completed.

As for positioning the component supply unit2onto the component mounting apparatus, the V shaped slot35and the square shaped slot36are formed on the component supply unit2, while the positioning pins29are provided on the component mounting apparatus1in the illustrated example. It should be understood that the present invention is not limited to this arrangement. For example, this relationship may be reversed, i.e. the positioning pins29may be provided on the component supply unit2, and the slots35and36may be formed in the component mounting apparatus. Alternatively, the V-shaped slot may be modified to be a square shaped slot35ahaving circular corners at an opening, as shown inFIG. 15(A), into which a V-shaped projection29aformed on fixing device4may fit. Another alternative is shown in FIG.15(B), in which a V-shaped projection35bis formed on the component supply unit2, which may be sandwiched by a pair of pins29bprovided on the fixing device4.

In these cases, aforementioned “V-shaped” does not necessarily mean that both sides of slanted walls forming the V character are straight and flat walls. These walls may be, for example, curved slanted walls so long as each wall preferably has a single point contact or a line contact with a side of the pins or projections. Also, the pin29is not necessarily to be a circular cylinder having a circular cross section, but rather it may be an elliptical cylinder, a spherical form, or any combination thereof, so long as preferably a single point contact or a line contact may be obtained with a side of the slots or openings.

A general relationship between component supply unit2and the fixing device4at contact points is described by referring toFIG. 15(C). When the component supply unit2having the V-shaped slot35is pushed against the component mounting apparatus1having the positioning pin29by a force z, for example, two contact points43and44are formed, each of which is either a single point contact or a line contact. These two contact points43and44favorably divide pushing force z into two component forces x and y pointing obliquely right and left in an X direction of this figure by having an angle between each other. In order to accurately position the component supply unit2, it is preferable that angles θ between a vector of the pushing force z and both vectors of the component force x and y are equal to or more than 45°. When the component supply unit2is pushed against the component mounting apparatus1, the component supply unit2is positioned not only in the Y direction by that pushing force, but also it is positioned in the X direction by these component forces x and y, extending both ways in the X direction. InFIG. 15(C), the vectors of pushing force z and both component forces x and y are shown as reaction forces in reverse direction for easier understanding. Alternatively, as shown inFIG. 15(D), either one of the component supply unit2or the fixing device4may have a projection29d, and the other one may have a V-shaped slot35dfor positioning the component supply unit2, thereby generating oblique component forces by virtue of plane-to-plane contact. Therefore, the phrase “two point contacts” used here includes this kind of plane-to-plane contact case.

The square shaped slot36(seeFIG. 5), or another contact point of the component supply unit2, may alternatively be formed as a flat surface without having the slot36for making contact with either the positioning pin29or a flat surface formed at the fixing device4. This other contact point of the component supply unit2may also be a circular projection or a circular dent for making contact with either the positioning pin29or a projection formed on the fixing device4. Since the V-shaped slot35positions the component supply unit2in both Y and X directions as describe above, the square shaped slot36side may be required to position the component supply unit2only in the Y direction. At a square shaped slot side, it is also desirable to make a single point contact or a line contact in order to accurately position the component supply unit2.

In the present embodiment, the component supply unit2is designed to be positioned in a horizontal direction by using base plate11located on its bottom. However, it is also possible to use an upper side of the component supply unit2as a base plate for positioning the component supply unit2. That is, for example, an upper surface of the base plate11may contact a horizontal guide plane provided on the fixing device4by pushing the component supply unit2from its bottom for positioning the component supply unit2in the horizontal direction. This case, however, needs some outside forces to push the component supply unit2upward against a base plane located above for a purpose of overcoming gravity.

Next, a second embodiment of the cart for changing a component supply unit according to the present invention is described. Cart3according to this present embodiment includes a buffer type fixing mechanism for securely positioning component supply unit2on holder80of the cart3so that the component supply unit2would not fall off the cart3while being mounted on the cart. This buffer type fixing mechanism also makes it possible to separate the cart3from the component supply unit2when it is installed on the component mounting apparatus1.

As mentioned before, the component supply unit2is equipped with a plurality of cassettes7, weighing 50 kg to 200 kg. Accordingly, if the component supply unit2falls off the cart3by accident, it may be dangerous and it may cost much by damaging precious components. As explained before by referring toFIG. 6, two types of cassettes7with different reel holding positions (which is either8or8a) may be used for the cart3according to the present invention. When the cassette7having the reel position8ais attached to the component supply unit2, a center of gravity of the component supply unit2is shifted toward the left in the Y direction of this figure. Therefore, if the component supply unit2is only placed on the cart without having any supports, more likely the component supply unit2falls off the cart3. If, for example, bolts are used to fix the component supply unit2onto the cart3for preventing the component supply unit2from falling, the cart3, which is fixed to the component supply unit2with the bolts, may hinder positioning of the component supply unit2when it is installed onto the component mounting apparatus1. The present embodiment provides a buffer type fixing mechanism for solving this problem.

FIG. 16shows, in enlarged scale, the buffer type fixing mechanism according to the present embodiment, which is arranged on holding arms81for supporting the component supply unit2on the holder80.FIG. 16shows a side elevational view of the holder80. Right hand side in a Y direction of this figure faces the component mounting apparatus1. Referring to the figure, the component supply unit2is mounted on the holding arms81of the cart3, and base plate11located on a bottom of the component supply unit2contacts upper surfaces of both of the holding arms81. In the illustrated embodiment, an internal thread is formed inside positioning holes38aof the base plate11. Shoulder bolts86are inserted into a large through hole84and a small through hole85formed on each of box-type holding arm81, and then the shoulder bolts86are screwed up into the positioning holes38a.

The large through hole84is designed to have sufficient space for screwing the shoulder bolt86after it is inserted into hole84. The small through hole85is designed to have a proper clearance between the hole85and a larger diameter of the shoulder bolt86for positioning the shoulder bolt86. A portion of the holding arm81surrounding the small through hole85provides a seat for a spring88. The spring88is compressed between a bolt head87of the shoulder bolt86and the seat around the small through hole85so as to render a spring force for pulling the shoulder bolt86downward in a Z direction ofFIG. 16. By this arrangement, the shoulder bolt86provides a pulling force for holding the component supply unit2in its position and preventing it from falling by pulling the base plate11toward the holding arm81.

InFIG. 16, one more positioning hole38located away from the component mounting apparatus1(left side in this figure) is designed only to hold positioning pin83. This positioning hole38, however, may also be arranged to have a similar buffer type mechanism with the shoulder bolt86and the spring88.

Operation of the buffer type mechanism described above is as follows. InFIG. 16, when a counterclockwise force is applied to the component supply unit2, the spring88withholds such applied force, if it is small, and prevents the component supply unit2from falling. When a relatively large force is applied to the component supply unit2, the spring88may absorb this applied force by its elasticity, and pull the component supply unit2back to its original position on the holding arm81. When even a larger force is applied to the component supply unit2, the spring88is compressed up to its minimum length, which means the spring88, the bolt head87of the shoulder bolt86and the holing arm81are integrated into a single rigid body to work together for holding the component supply unit2against this applied force.

When the component supply unit2held by such buffer type fixing mechanism is to be mounted on the component mounting apparatus1, the operator operates the grip93(seeFIG. 6) of the cart3for lowering both the holding arms81and the component supply unit2, after the cart3moves forward to a predetermined position. By this operation, the base plate11located on the bottom of the component supply unit2is placed on the horizontal guide plate24(seeFIG. 4) provided on the fixing device4of the component mounting apparatus1, and the component supply unit2is positioned in a horizontal direction. In this situation, if the cart does not have the buffer type fixing mechanism of the present embodiment, but rather the component supply unit2is firmly fixed to the holding arms81by bolts, horizontal positioning of the base plate11of the component supply unit2is hindered by the holding arms81. In case, for example, the cart3is inclined in a horizontal direction, and hence the holding arms81fixed to the cart3are also inclined, the base plate11would not fully contact the horizontal guide plate24. Accordingly, proper horizontal positioning of the component supply unit2on the component mounting apparatus1may not be achieved by such bolt type fixing mechanism.

According to the buffer type fixing mechanism of the present embodiment, on the other hand, after the base plate11of the component supply unit2is placed on the horizontal guide plate24, the holding arms81may be further lowered by compressing the spring88, and this allows the base plate11to be separated from the holding arms81. Accordingly, even in a case in which the cart is inclined, the holding arms81would not hinder the positioning of the component supply unit2, and therefore, the base plate11may be completely placed on the horizontal guide plate24. In other words, by providing the buffer type fixing mechanism of the present embodiment on the holding arms81, the cart3or the holing arms81would not hinder a positioning operation of the component supply unit2.

In the illustrated buffer type fixing mechanism, the shoulder bolts86are used for functioning as a positioning mechanism of the component supply unit2, as well as a holding mechanism to hold the component supply unit2on top of the holding arms81. Alternatively, at least two positioning pins83may be used to position the component supply unit2in its proper location, and separately some form of holding force may be used to place the component supply unit2firmly onto the holing arms81for achieving a similar buffer function. This holding force may be applied by an elastic material, such as a spring, to connect the component supply unit2and the cart3for pulling each other. The shoulder bolts86may alternatively be normal bolts as long as loosening between the bolts and the positioning holes38ais prevented.

Next, a third embodiment of the cart for changing a component supply unit of the present invention is described by referring to the appended drawings. Cart3according to this present embodiment is designed to be separated from the component mounting apparatus1, after component supply unit2is clamped to the component mounting apparatus1. If the cart3is separable, the cart3may be used for other purposes, such as installing another component supply unit2onto another fixing device4of the component mounting apparatus1.

Referring toFIG. 1, the cart3ais holding the component supply unit2a, which is already mounted on the component mounting apparatus1. This is because, as explained before, the collecting box10for collecting used component supplying tapes or their covering tapes, and the reel box9for accommodating the reel8of the cassettes7provided in the central area of the cart3may be fully utilized. Depending on a situation, however, it may be useful to make the cart3separable from the component mounting apparatus1by eliminating the collecting box10and the reel box9.

Toward this end, the cart3according to the present embodiment is designed to be separated from the component mounting apparatus1. In order to make the cart3separable, it is necessary to remove all elements which may interfere with the component supply unit2or other related elements remaining at a component mounting apparatus side when the cart3is separated from the component mounting apparatus1. These components that may interfere with others include the connecting bar89of the holder80which connects both of the elevating rods53as shown inFIG. 10, and a pair of the holding arms81fixed to the connecting bar89, in addition to the reel box and the collecting box.

The holding arms81may be fixed directly to the elevating rods53, thereby possible interference with other elements may be avoided. The connecting bar89may be eliminated so long as the holding arms81are fixed to other elements. The connecting bar89, however, also functions to strengthen the lifters50by connecting both of the elevating rods53together. Therefore, it may be required to add some alternative reinforcement to the lifters50if the connecting bar89is removed. Possible countermeasures for this, for example, are to strengthen a connecting portion between the supporting frame51and the base frame40, or to increase rigidity of the elevating rods53, both of which are relatively easy. All other mechanisms and structures may remain similar to those used for the cart3shown in the first embodiment. By making these measures for eliminating possible obstacles and applying necessary reinforcement, the cart3may be separated from the component mounting apparatus1after the component supply unit2is clamped to the component mounting apparatus1. Then, the cart3may be used for other purposes.

As explained above, according to the cart of the present invention for changing a component supply unit to be used for a component mounting apparatus, wide space in a central area of the cart may be obtained by accommodating a driver inside a base frame, and by locating a pair of elevating rods at both side ends of the cart. By providing a reel box for accommodating a reel portion of cassette7, and a collecting box for collecting used component supplying tapes and their cover tapes into such a box, total floor space for the component mounting apparatus may by smaller. Further, this advantage may be achieved by using an inexpensive mechanism such as linear moving bearings or rails on a lifter.

Furthermore, according to the present invention, falling of the component supply unit, or possible damage to the component mounting apparatus caused by erroneous lifting and lowering motions of the component supply unit, may be avoided by restricting a lowering motion of the component supply unit when it is separated from the component mounting apparatus, and by restricting lifting motions of the component supply unit when it is mounted on the component mounting apparatus, and hence, safety operations may be secured when the cart according to the present invention is used.

Further, by using a positioning mechanism of the component supply unit according to the present invention, repeated accurate positioning may be achieved by only pushing the component supply unit toward the component mounting apparatus in one direction.

Furthermore, by using a buffer type fixing mechanism for mounting the component supply unit onto the cart for changing a component supply unit, falling of the component supply unit may be avoided and positioning in a horizontal direction may not be hindered by the cart. By adding this function, it becomes possible to hold the component supply unit on the cart in a stable condition, without being influenced by variations of weight balance of the component supply unit due to the number of supplying devices attached to the component supply unit.

And, by making the cart for changing a component supply unit separable from the component supply unit and the component mounting apparatus, the cart may be used for any other purpose during a time that the component supply unit is attached to the component mounting apparatus.