Improvements in or relating to machine tools

Abstract: The present invention provides a transfer device for use in a machine tool of the type in which a workpiece item is moved in sequence between a plurality of operation stations, and in particular for transferring large blank materials through a multi-stage process by engaging and employing both a cross-bar-type (17) and a finger-type (22) transfer device. The cross-bar type transfer device includes a blank attachment member (18), adaptable to specific blank shapes, that enables transfer of large blank materials without sufficient rigidity for quicker or simpler transport methods. The finger-type transfer includes multiple fingers suitable for rapid transport of blank materials that, after initial processing, have sufficient rigidity for rapid transport.

Description: The invention relates to a transfer apparatus for use in a machine tool of the type in which a workpiece item is moved in sequence between a plurality of workpiece operation stations. In particular the invention relates to a transfer device equipped with feed bars having fingers for gripping an end part of a blank or workpiece item and to a transfer device equipped with cross bars having a blank or workpiece item attachment member. For conventional transfer devices, a typical method of transferring a workpiece or blank is to grasp an end part of the blank and transfer the blank by a feed-bar-type motion with a clamping motion. This method is conventionally implemented by a pair of feed bars arranged parallel to each other. The clamping motion operation is conducted at an approximate stroke rate of 45 strokes per minute. Workpiece items or blanks having a length dimension greater than say about 1300 mm, may have relatively low longitudinal stiffness properties along the length of the blank, and sagging is frequently encountered. As a result, the clamping operation, and subsequent transfer, is difficult to implement. With larger blank materials (for example, 2500 mm or greater), a cross-bar method for transfer is conventionally used. In the cross-bar method, a blank attachment member attaches to the upper surface of the blank material prior to transfer. The cross bar first attaches to the blank material and then transfers the blank material to the next processing stage. During processing, the cross-bars are held in a position that does not interfere with a die press or other operation. After the operation, the cross-bars return to the previous stage to transport the next workpiece item or blank. In the cross-bar method, the time duration for one cycle is large and the stroke rate per minute is low, typically around 10 per minute. As a result, the productivity rate of the machine tool is low. Furthermore, the cross-bar method requires a driving device to move the cross bars. As a result, a device employing the cross-bar method of transfer is large and complex, thereby increasing initial costs, maintenance costs, maintenance downtime, and replacement part costs. US-A-5,148,697 describes a press type machine comprising a plurality of working stations having upper and lower dies for pressing the workpiece. A transporting device is added to the press for sequentially transporting the workpieces towards an adjacent working station from a previous working station after pressing has occurred. The transporting device includes a pair of left and right guide bars disposed on opposite sides of the working stations in parallel to the transportation direction. A support rod is mounted on the lower surface of each of the guide bars and is driven in an upper and downward direction by a rack and pinion arrangement associated with each of the support rods. A feed plate is slidably mounted on the left-hand right guide bars over the entire length of the guide bars for sliding movement in the longitudinal direction of the guide bars. An actuating arrangement is provided for sliding the plates backwards and forwards in the longitudinal direction of the guide bars. The feed plates perform a cyclic motion by the upward and downward movement of the guide bars and the longitudinal movement of the feed plates. The left and right-hand side feed plates are interconnected by a plurality of cross bars transversely disposed there between. Each cross bar is provided with four suction cups for attracting and retaining an upper surface of the work piece being pressed and transported. There is a requirement to provide a transfer device that has a high rate of productivity. There is a further requirement to provide a transfer device that minimizes operational errors due to blank flexing. There is another requirement to provide a transfer device that is generally compact and jointly employs two types of transfer means. Briefly stated an aspect of the present invention relates to a transfer device for transferring large pliable blank materials through multi-stage processing by engaging both a cross-bar type and a finger-type transfer device along a process path. The cross-bar type transfer device includes a blank attachment member, adaptable to specific blank shapes, thus enabling transfer of large blank materials, which prior to processing, do not have sufficient rigidity for simpler transport methods. The finger-type transfer includes multiple fingers suitable for rapid transport of blank materials that, after initial processing, have sufficient rigidity for rapid transport. According to an aspect of the invention there is provided a transfer device which comprises: a pair of feed bars parallel to each other; said feed bars having an idle stage on an upstream side and at least a first and second stage on a downstream side; a first transfer means spanning said feed bars on said upstream side; said first transfer means including a pair of cross bars and a blank attachment member; said blank attachment member attachable to an external blank; characterised in that the said device further comprises a second transfer means provided along said feed bars on said downstream side; said second transfer means including at least a first pair of finger parts; said finger parts attachable to said external blank; and said first transfer means transferring said external blank from said idle stage to said first stage and said second transfer means transferring said external blank from said first stage to said second stage to transport said external blank to said downstream side whereby said external blank is rapidly transported. Preferably the transfer device comprises: at least a first guide affixed on an upper surface of each said cross bar along said downstream side. In preferred embodiments of the transfer device the said first transfer means comprises: at least a first pair of cross bars spanning said feed bars, said cross bars each having an opposite facing end affixed in said guide, said cross bars each having a second end slidably guided in said guide, a plate joined to said cross bars along a center portion of said cross bars, a blank attachment member provided on said plate, a pinion rotatably provided on said plate, a rack formed in a center portion of said feed bars, said pinion meshing with said rack, and said rack operable through an external driver whereby said plate is adjustable and operable away from said bolster according to said feed bars and said external driver whereby said external blank is progressively transported. The second transfer means comprises: at least a first pair of opposing finger members, said finger members extending toward each other between said feed bars, said finger members adjustable relative to said feed bars and said bolster to engage said external blank, said finger members operating according to said feed bars and engaging said external blank whereby said external blank is progressively transported. The transfer device preferably further comprises: a first conveyor on said upstream side opposite said cross bars, said first conveyor providing said external blank to said upstream side, a second conveyor on said down stream side opposite said feed bars, said second conveyor receiving said external blank from said downstream side, at least a first and second pair of guide parts along said feed bars, at least a first and second clamp lift unit below said feed bars, said first and second clamp lift unit lifting and guiding to said first and second guide parts, a slider provided along said downstream side of said feed bars, said slider guidably affixed to said downstream side of said feed bars, and said slider reciprocating with said feed bars whereby said external blank is provided to said downstream side and said second conveyor after processing. An embodiment of the present invention uses cross bars that have a blank attachment member and which are suitable for transferring large blank materials that, prior to processing, do not have sufficient rigidity. The present invention also jointly uses fingers that are suitable for rapid transport of blank materials that, after processing, are molded or pressed and have greater rigidity. Various embodiments of the invention will now be more particularly described, by way of example, with reference to the accompanying drawing, in which; Fig. 1 is a plan view of a transfer device. Referring now to Fig. 1, a press machine 28 is equipped with a bed, not shown, and employs a transfer device according to an embodiment of the present invention. A crown, also not shown, is supported on the bed by a plurality of vertical columns 1. Columns 1 are on each outside corner of press machine 28. A bolster 2, is fixed on top of the bed. It is to be understood, that while bolster 2 is fixed to the bed in this embodiment, the bolster 2 may be shiftably provided on the bed, depending upon specific customer requirements. A slide, not shown, moves vertically with respect to bolster 2, that is to say, in the direction perpendicular to the plane of the drawing of Figure 1. A plurality of lower and upper molds, not shown, are provided on the opposing surfaces of the bolster 2 and the slide. A plurality of movable feed bars 5, 6, and 7 are arranged in pairs, parallel to each other, along the top of the bolster 2. The feed bars 5, 6, and 7 transport the blank materials from die to die, as indicated by stage 24, 25, 26 and 27, during the operation of the machine 28. Feed bars 5, 6, and 7 are in three sections. A joint 12, allows separation of feed bars 5 from feed bars 6 for adjustment and maintenance. Similarly, a joint 13 allows separation of feed bars 6 from feed bars 7. As a result, when exchanging dies or performing other maintenance or machine setting operations the feed bars 6 and bolster 2 may be removed from the press machine 28. A slider 14 guides feed bars 5, 6, and 7 in a workpeice or blank transfer direction. Slider 14 is linked to one end of feed bars 7. A pair of upright pins 15 are provided on slider 14 extending away from a horizontal surface thereof. The upright pins 15 are inserted in holes, not shown, positioned on the end of feed bars 7 so that the slider 14 is connected to feed the bars 7. During operation, the slider 14 conducts a reciprocating advance-return motion of the feed bars 7, as shown in the direction left - to - right in the drawing. A servo motor 16, having a rack and pinion construction, not shown, serves as a driving means for the reciprocating advance-return motion of slider 14. Through the joints 12 and 13 and the pins 15, the feed bars 5, 6, and 7 also conduct an advance-return motion, in the direction left to right in the drawing, in conjunction with the advance-return motion of the slider 14. During reciprocation, pairs of U-shaped guides 8 and 9 guidably receive feed bars 6 and 7. The guides 8, 9 conduct a clamp-unclamp motion on feed bars 6 and 7. A pair of clamp-lift units 3 and 4 extend away from bolster 2 toward columns 1. Clamp-lift units 3 and 4 each have a ball-screw mechanism, not shown. The ball-screw mechanism serves as a driving means for a servo motor, not shown, on clamp lift units 3 and 4. The servo motor operates clamp-lift units 3 and 4 in the clamp-unclamp motion on feed bars 6 and 7. The guide parts 8 and 9 conduct a lifting and lowering motion of the feed bars by means of a rack and pinion mechanism which has, as a driving means, a separate servo motor positioned inside clamp lift units 3 and 4. In this way the clamp lift units 3 and 4 are capable of lifting and lowering the feed bars in the vertical direction perpendicular to the plane of the drawing. The guide parts 8 and 9, operated by the lift-clamp units 3 and 4, clamp and release the feed bars 6 and 7. In one embodiment, the clamp-unclamp operation alternates with the advance and return motion of the feed bars guided by the guide parts 8 and 9 In the above the discussion, feed bars 5, 6, and 7 may conduct two or three-dimensional motions, or both. However, feed bars 5, 6, and 7 may alternatively be constructed to conduct only a two-dimensional motion along a horizontal plane according to manufacturing or customer requirements. Where this alternative construction occurs, a cylinder in the form of a linear actuator (not shown) is provided on a blank attachment member 18, attached to a cross bar 17. The cylinder conducts the lifting and lowering motion of the blank attachment member 18. A conveyor belt 10 and a conveyor belt 11 are provided on opposite sides of the transfer device. It is to be understood that, conveyor belts 10, 11 may be formed as a single or multiple belt unit. The conveyor belt 10 conveys workpiece items or blank materials to an idle stage 23 at a constant rate. Idle stage 23 is positioned on an upstream side of the machine tool, to the left of the drawing in Fig. 1. The conveyor belt 11 transfers the product that has completed the final processing to a down-stream product receiver, not shown, but positioned to the right of the drawing. Feed bars 6 are equipped with cross bars 17 and multiple sets of fingers 22 for gripping an end-part of a blank material. In conjunction with either the above-described two or three dimensional movement, cross bars 17 and fingers 22, grip the blank end-part and transfer each blank to the next processing stage 23 - 27. A pair of guides 21 for installing cross bars 17 are fixed to feed bars 6 towards the upstream and thereof. Cross bars 17 each have two facing ends and two opposite ends. The facing ends of the pair of crossbars 17 are fixed to guides 21. The opposite ends of cross bars 17 are slidably guided in guides 21. A plate 20 is additionally provided on cross bars 17. A blank attachment member 18, such as a vacuum cup or magnet, is provided on plate 20. In the embodiment of Figure 1 four attachment members 18 are provided. Blank attachment member 18 engages a blank material for later processing or transfer. A pinion (not shown) is rotatably fixed on plate 20. A rack (not shown) is provided in the center part of cross bars 17. The rack meshes with the pinion on plate 20. As a result, a rack and pinion mechanism 19 is created by meshing engagement of the pinion and the rack. Blank attachment member 18 is maintained at a middle point between feed bars 6 by the rack and pinion mechanism provided between the cross bars and the plate 20. In this respect, it will be understood that movement of the feed bars with respect to one another during operation of the transfer devices will be accommodated by the rack and pinion mechanism to maintain the attachment members 20 centrally between the feed bars.. In sum, the above describes a first transfer device attached to feed bars 6. A second transfer device comprises at least a first pair of fingers 22 formed to grip the blank end-part, are attached to respective parallel feed bars 6. The fingers 22 operate in conjunction with the motion of feed bars 6. The fingers 22 operate to grip a workpiece item or blank material, and the guides 8 and 9 clamp the feed bars 6 and 7 prior to lifting by the clamp-lift units 3 and 4. The clamps are released when the feed bars have been lifted to a desired position so that the feedbars may be moved by the slider to an adjacent position where the workpiece item or blank material is lowered by the lift clamp units 3 and 4 and released by the fingers 22. In an alternative embodiment, the feedbars may be clamped throughout the advance and return motion. In such an embodiments the guides 8 and 9 and lift clamp units follow the advance and return motion of the feed bars. The fingers 22 transfer the blank material, brought to a first stage 24 by cross bars 17, to a second stage 25. Fingers 22 transfer the blank material to each subsequent downstream stage. It is to be understood, that while the present arrangement discloses stages 24 through 27, additional operational stages may be included or removed without changing the nature or scope of the invention. Each operational stage 24 through 27 is associated with a process number No. 1-4, as shown on Fig. 1. It is to be understood, that the process and stage order are positioned according to manufacturer or customer requirements. The first and second transfer devices allow the transfer and operation of press machine 28. The blank material, initially transferred to idle stage 23 by conveyor belt 10, is brought to the first stage 24 by the blank attachment member 18. The blank material is then molded by die process No. 1. In the present arrangement, it is to be understood, that the first stage 24 process is a process whereby the blank is stiffened by a bending or molding process to form a stiffened but unfinished item. Thus, after initial forming, the blank material is sufficiently stiff to be transferred by fingers 22. After initial formation, the blank 1 is then transferred from the first stage 24 to the second stage 25 by fingers 22. The fingers 22 operate by gripping the blank end-part. A product is molded in sequence at each of the stages downstream from the second stage 25. Conveyor belt 11 brings the final product to a product receiver, not shown. In the present embodiment, the cross bars 17 with blank attachment member 18 are used for carrying the blank material to the first stage 24 when sagging due to insufficient workpiece or blank stiffness is a processing concern. After the first stage 24, the blank material is molded and is sufficiently rigid to be transferred by fingers 22 to the later stage fingers 22. In other words, in one press machine, two types of transfer devices are used together in combination. As a result, a commercial advantage can be realized in terms of cost and higher productivity. Although only a single or few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiment(s) without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus although a nail and screw may not be structural equivalents in that a nail relies entirely on friction between a wooden part and a cylindrical surface whereas a screw's helical surface positively engages the wooden part, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope of the invention as defined in the appended claims.

Claims: A transfer device, comprises: a pair of feed bars(5, 6, 7)parallel to each other; said feed bars having an idle stage (23) on an upstream side and at least a first and second stage (24-27) on a downstream side; a first transfer means spanning said feed bars on said upstream side; said first transfer means including a pair of cross bars (17) and a blank attachment member (18); said blank attachment member attachable to an external blank; characterised in that the said device further comprises a second transfer means provided along said feed bars on said downstream side; said second transfer means including at least a first pair of finger parts (22); said finger parts attachable to said external blank; and said first transfer means transferring said external blank from said idle stage to said first stage and said second transfer means transferring said external blank from said first stage to said second stage to transport said external blank to said downstream side whereby said external blank is rapidly transported. A transfer device as claimed in Claim 1, further comprising: a bolster (2) extending below said feed bars; said feed bars operable away from and laterally along said bolster; said first transfer means and said second transfer means operating in sequence to transport said external blank from said upstream side along said feed bars to said downstream side whereby the speed of said transfer device is increased. A transfer device according to Claim 1 or Claim 2, further comprising: at least a first pair of guides (21); and each said guide on a first surface of each said cross bar. A transfer device according to Claim 3, wherein at least a first and second cross bar orthogonal on said feed bars; said cross bars having a first and a second end; said first ends proximate said second ends; said first ends adjustably fitted in said guides; said second end slidably guided in said guides; a plate (20) supported by and joined to said cross bars; a blank attachment member on said plate to attach an external blank; a pinion rotatably attached to said plate; a rack formed at a center section of said feed bars; said pinion meshing with said rack; said rack operable through an external driver; and said rack operating said plate and said blank attachment member to transport said blank toward said downstream side, whereby the speed of said transport device is increased. A transfer device according to Claim 2 or Claim 3 or Claim 4 when dependent directly or indirectly on Claim 2 wherein: said finger members (22) extending toward each other between said feed bars; said finger members adjustable relative to said feed bars and said bolster to engage said external blank; and said finger members operating according to said feed bars to engage said external blank and progressively transport said external blank toward said downstream side, whereby the speed of said transfer device is increased. A transfer device as claimed in any preceding claim further comprising: a first conveyor (10) between said feed bars on said upstream side; said first conveyor providing said external blank to said upstream side; a second conveyor (11) opposite said feed bars on said downstream side; said second conveyor receiving said external blank from said downstream side; at least a first and second pair of guide parts (8,9) along said feed bars; at least a first and second clamp lift unit (3, 4) below said feed bars; said first and second clamp lift unit lifting and guiding to said first and second guide parts; a slider (14) along said downstream side of said feed bars; said slider guidably fixed to said feed bars; and said slider reciprocating with said feed bars to provide external blank to said downstream side and said second conveyor whereby the speed of said transfer device is increased. A transfer device, according to Claim 1, further comprising: a rack formed in a center portion of said cross bars; at least a first guide (21) affixed on an upper surface of each said feed bar; a facing end and an opposite end on each said cross bar; said facing end of said cross bars affixed on said guides; said opposite end slidably guided in said guides; a plate (20) joined proximate said center portion of said cross bars; a pinion rotatively provided on said plate; and said pinion rotatively meshing with said rack member to provide adjustment to said plate and said cross bars whereby said external blank is rapidly transported. A transfer device as claimed in any preceding claim wherein each of said parallel head bars comprises a plurality of sections disposed in series and a plurality of joints connecting said sections, wherein said joints are detachable for separation of the feed bar sections. A transfer device as claimed in any preceding claim wherein said feed bars are disposed in a transfer direction of the device, and wherein the said cross bars span the said feed bars. A transfer device as clamed in Claim 1 or Claims 8 or 9 when dependent directly on Claim 1, wherein said feed bars comprise guide means disposed along said feed bars for slidingly guiding said cross bars. A transfer device as claimed in Claim 1 or any of Claims 8 to 10, wherein the said device further comprises: a plate disposed between said cross bars a rack disposed in a centre position between such cross bars; and a pinion rotatably integral to said plate and said rack meshes with said pinion forming a rack and pinion mechanism, wherein the said rack and pinion mechanism has a clamp position and an unclamp position and a movement of said cross bars causing said rack and pinion mechanism to switch between positions. A transfer device as clamed in any preceding claim, wherein said feed bars have a lift position and a down position for lifting and lowering said external blank. A transfer device as claimed in any preceding claim wherein said attachment member comprises a magnet. A transfer device as claimed in any one of Claims 1 to 12 wherein such attachment member comprises a vacuum cup.

Inventors: ARAI TOSHIHIKO, MAEDA NOBUYOSHI, ARAI, TOSHIHIKO, MAEDA, NOBUYOSHI
Applicants: AIDA ENG LTD, AIDA ENGINEERING CO., LTD.
Application year: 2001
Main classification: B21D43
IPC codes: B30B13, B21D43