Chip collecting apparatus for tip dresser

In a chip collecting apparatus for a tip dresser of the present invention, a chip pickup case mounted on a dresser main body is divided into an upper case and a lower case, and the lower end of an arm admission port formed in the upper case is opened downward. During teaching operation, the lower case is rotated to open the lower end of the upper case, through which the insertion of a first gun arm into a lower chamber can be visually checked, and thus an electrode tip provided at the end thereof and a dressing body for dressing the end of the electrode tip are guided such that the central axes thereof conform to each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a chip collecting apparatus for a tip dresser for collecting chips generated when dressing electrode tips.

2. Description of the Related Art

Conventionally, electrode tips used for spot welding or the like are worn out (or deformed) when welding work is repeated. When welding work is performed with a worn-out electrode tip, welding of desired quality cannot be obtained; accordingly, electrode tips are periodically dressed to maintain welding quality.

For example, Japanese Unexamined Patent Application Publication No. 6-122082 discloses a tip dresser for dressing electrode tips in which after the upper and lower surfaces of a dressing body have been tightly pressed by a pair of electrode tips provided at opposed ends of a welding gun, and the welding gun is swung around the central axis of each electrode tip for grinding, thereby dressing the electrode tips.

Recently, the recycle of chips is contemplated in view of cost reduction and environmental issues. Accordingly, a collection vessel is disposed under the dressing body to recycle the collected chips.

However, there is a problem in that the chips tend to be released by the relative swing or rotation of the dressing body and the electrode tips during grinding work, and all the chips cannot be collected into the collection vessel, resulting in a low collection rate.

Furthermore, when air is blown to the dressing body to prevent clogging of the dressing body, the chips are released by the blown air, so that the collection rate of the chips is further decreased.

Generally, copper is often used as an electrode tip for spot welding and the like. In order to maintain a proper welding quality, the frequency of grinding is increased to increase the amount of ground chips of the electrode tip, so that, in order to reduce material cost, it is necessary to increase the collection rate of the chips and effectively recycle them.

For this purpose, various techniques are proposed in which a chip collecting apparatus is mounted on the dresser main body having a dressing body for collecting chips generated during dressing the electrode tips.

For example, Japanese Examined Utility Model Publication No. 3-18067 discloses a technique of collecting chips generated during polishing or grinding electrode tips in such a way that a cover main body is mounted on a dresser main body, and an air inlet and an air outlet are formed between the upper and lower surfaces of the cover main body and the dresser main body. Compressed air after driving a dressing body held by a holder is guided through the air inlet to the holder, and then the compressed air is guided through the air outlet to a chip collection vessel connected to the end of the cover main body.

In general, the operation of moving the welding gun provided at the end of the welding robot toward the chip dresser is often memorized by teaching in advance.

However, when the cover main body for collecting the chips generated during dressing operation is mounted on the dresser main body, as in the above prior art, it becomes difficult to visually recognize the positional relationship between the electrode tips and the dressing body; therefore, it is necessary to temporarily remove the cover main body from the dresser main body and to perform teaching, posing a problem in increasing the number of processing steps required for teaching.

Furthermore, since the dresser main body is covered by the cover main body, the dressed state of the electrode tips cannot be checked from the exterior, causing inconvenience of being unable to check faulty dressing such as insufficient dressing and excessive dressing.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a chip collecting apparatus for a tip dresser capable of easily checking the positional relationship between electrode tips and a dressing body during teaching operation without detaching the whole device, significantly reducing processing steps required for teaching, and easily checking the presence or absence of faulty dressing during dressing operation from the exterior.

In the chip collecting apparatus for a tip dresser according to the present invention, including a tip dresser for dressing the electrode tips by pressing the electrode tips to a dressing body held by a dresser main body and relatively sliding the dressing body and the electrode tips, the dresser main body has a chip pickup case for covering the dressing body mounted thereon, the chip pickup case has an arm admission port allowing the insertion of gun arms having the electrode tips at the ends, the arm admission port has a shielding member allowing the insertion of the gun arms by elastic deformation, and the chip pickup case is divided in the vicinity of the arm admission port such that it can freely be opened and closed.

With such a configuration, the chip pickup case is divided in the vicinity of the arm admission port such that it can be opened and closed. Accordingly, during teaching operation, the divided portion of the chip pickup case is opened, so that the positional relationship between the electrode tips held at the ends of the gun arms and the dressing body can be recognized from the exterior.

The above and other objects, features and advantages of the invention will become more clearly understood from the following description referring to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1to4show a first embodiment of the present invention.

Reference numeral1denotes a welding gun1, such as a C-type welding gun, connected to a welding robot. The welding gun1has first and second gun arms2and3, to the ends of which electrode tips4and5are detachably attached to face each other. The electrode tips4and5are coaxially disposed and are relatively brought into close proximity to and apart from each other by advancing and retracting motions of at least one of the gun arms2and3.

Furthermore, a tip dresser11for dressing the ends of the electrode tips4and5is disposed at a position not to interfere with welding work in the range of operation of the welding robot.

A dresser main body11aextending laterally from the tip dresser11has a holder12at the end thereof for rotatably holding a dressing body13. The dressing body13is driven to rotate by a motor14hung from the dresser main body11a, and has concave cutters13aand13bon the lower and upper surfaces thereof, the cutters being capable of dressing the ends of the electrode tips4and5into a predetermined shape by polishing or grinding.

The dresser main body11ahas a chip pickup case15mounted at the end thereof. The chip pickup case15is formed by working a resin mold or a thin steel sheet, and is divided into an upper case16and a lower case17.

The top of the upper case16is slanting obliquely upward toward the rear. Also, an arm admission port16awith a predetermined width is opened from the front to the top of the upper case16, and the lower end of the arm admission port16apasses through the lower end of the upper case16. A hole16bpenetrating the end of the dresser main body11ais formed at the upper back of the upper case16.

A shielding member19is secured to the arm admission port16a. The shielding member19is composed of a pair of brush sections20and21arranged to face each other on the right and left sides of the arm admission port16a. The bases of brushes20aand21amade of nylon or the like and provided at the brush sections20and21, respectively, are fastened to the rim of the arm admission port16awith plates20band21b.

The ends of the brushes20aand21aare brought into contact with each other substantially at the center of the width of the arm admission port16a, so that the whole arm admission port16ais covered from the front to the top by the brushes20aand21a. Thus, the brushes20aand21aprevent chips generating while the electrode tips4and5are dressed from flying off to the exterior through the arm admission port16a.

Also, supporting plates22are disposed at the upper and lower four corners of the hole16bformed at the back of the upper case16. The front end of each supporting plate22is extended horizontally toward the arm admission port16a, the end of which is connected to the inner edge of the arm admission port16a, and contact portion with the hole16bis joined together.

When the end of the dresser main body11ais inserted into the hole16b, the upper and lower edges are positioned in a state in which they are supported by the supporting plates22. The upper case16is divided into an upper chamber16eand a lower chamber16fby the dresser main body11a, and the upper and lower surfaces of the dressing body13supported by the holder12provided at the end of the dresser main body11aare exposed to the upper chamber16eand the lower chamber16f.

The rear portions of the supporting plates22project outward from the hole16b. A pair of fixing blocks23is brought into contact with the projecting portions from above and down, and both ends of the fixing blocks23are fastened with bolts24, thereby fixing the dresser main body11a.

An air nozzle25is secured to the back of the upper chamber16eof the upper case16, and the end of the air nozzle25is oriented to the dressing body13exposed to the upper chamber16e. Chips adhered to the dressing body13is released by air blown out from the air nozzle25, thereby preventing clogging of the dressing body13.

As shown inFIGS. 2 and 3, the upper chamber16eand the lower chamber16fare communicated with each other through a void formed between the inner wall of the upper case16and a void formed in the holder12.

On the other hand, the upper end back of the lower case17is rotatably supported at the lower end back of the upper case16with a hinge26. The upper end outer periphery of the lower case17is formed along the lower end outer periphery of the upper case16. The lower case17freely opens and closes the upper case16around the hinge26, as shown inFIGS. 3 and 4. A bracket27projects from the back of the lower case17, and a slotted hole27aextending vertically is formed in the bracket27.

An end28bof a plunger28aof an air cylinder28, the rear end of which is secured to a column (not shown) or the like of the tip dresser11, is engaged with the slotted hole27a. The plunger28aof the air cylinder28is retracted and held ready in a state in which the front of the lower case17is opened, as shown in FIG.4. When the first gun arm2provided for the welding gun1is positioned in the lower chamber16f, the plunger28aprojects, and thus, the upper end of the lower case17is brought into contact with the lower end of the upper case16for closing, as shown in FIG.3.

The lower case17has a tapered chip guide surface17aconverging downward at the upper part thereof, under which a chip discharge port17bopened downward is formed. Furthermore, a chip collection vessel30is formed under the chip discharge port17b.

In this case, it is possible to use the lower part of a plastic bottle, the upper part of which is cut off under the neck, as a chip collection vessel30. In this case, the rim of the upper opening of the chip collection vessel30formed of a plastic bottle may be hung from the chip discharge port17bof the lower case17.

Next, the operation of this embodiment with such a configuration will be discussed. The lower case17provided for the chip pickup case15is held ready with the front part opened, as shown in FIG.4. When the welding robot is taught the operation of dressing, the pair of electrode tips4and5provided at the ends of the welding robot, which is set in a teaching mode, is guided to the dressing body13held by the holder12of the dresser main body11a, with the lower case17being in a standby state (in a state in FIG.4). At this time, since the lower end of the upper case16is opened, the electrode tip4mounted at the end of the first gun arm2can easily be guided into the lower chamber16fof the upper case16, and the central axis of the electrode tip4can be accurately conformed to the central axis of the cutter13aof the dressing body13while it is visually checked, high workability is provided.

Since the lower end of the arm admission port16acovered by the pair of opposite brushes20aand21ais also opened, the gun arm2can smoothly be guided into the lower chamber16f. At this time, when the chip collection vessel30is obstructive, it is moved out of the way in advance.

When the teaching during dressing operation has been completed in a predetermined way, the welding robot is moved, and the welding gun1is moved apart from the chip pickup case15and held ready in position.

Subsequently, dressing operation of the electrode tips4and5will be described. First, the pair of gun arms2and3provided for the welding gun1is moved toward the dresser main body11awith a predetermined space left therebetween, in accordance with preset teaching.

Both the gun arms2and3are brought in close vicinity of the front of the upper case16; the first gun arm2passes through the brushes20aand21ato advance into the lower chamber16fof the upper case16; and the second gun arm3is arranged at the upper part of the upper case16. At this time, since the lower end of the lower case17is opened, the first gun arm2can be advanced from the lower part of the arm admission port16ainto the lower chamber16fwithout interfering with the lower case17, as shown in FIG.4.

Then, the central axis of the electrode tip4mounted at the end of the first gun arm2is arranged onto the central axis of the dressing body13disposed on the holder12provided for the dresser main body11a. At this time, since the electrode tip4and the electrode tip5mounted at the end of the second gun arm3are arranged on the same axis, the electrode tip5is also arranged on the central axis of the dressing body13.

Furthermore, the gun arms2and3are moved to bring the electrode tips4and5relatively close to each other. Then, the first gun arm2rises toward the arm admission port16a, elastically deforms the brushes20aand21ablocking the arm admission port16aalong the outside shape of the first gun arm2, and brings the electrode tip4provided at the end thereof into contact with the cutter13aprovided at the lower surface of the dressing body13. At the same time, the electrode tip5provided at the end of the second gun arm3passes through the brushes20aand21afrom the above of the dresser main body11ato be positioned in the upper chamber16e.

At this time, the brushes20aand21adisposed at the front and top of the upper case16are elastically deformed along the outer peripheries of the gun arms2and3, and the peripheries of the gun arms2and3are closed.

On the other hand, when the first gun arm2is placed in position in the lower chamber16fof the upper case16, the plunger28aof the air cylinder28projects in synchronization therewith to rotate the lower case17clockwise, as shown inFIG. 4, and to bring the upper end of the lower case17into contact with the lower end of the upper case16, thereby integrating the lower chamber16ftherein with the chip guide surface17a.

When the electrode tips4and5are further brought close to each other, they are brought into contact with the cutters13aand13bprovided on the lower and upper surfaces of the dressing body13, respectively, and press the dressing body13therebetween. The dressing body13is driven to rotate by the motor14provided for the dresser main body11a, and air is blown out from the air nozzle25positioned in the upper chamber16etoward the dressing body13.

Chips adhered to the dressing body13is blown off by the air. The air blown to the dressing body13flows through a gap in the dressing body13and the void formed around the dresser main body11atoward the lower chamber16f, and is blown to the exterior through the brushes20aand21ablocking the front of the lower chamber16fand the chip discharge port17b.

On the other hand, the chips generated when the cutters13aand13bprovided for the dressing body13dress the electrode tips4and5by polishing or grinding are guided toward the lower chamber16fby air blow from the air nozzle25positioned in the upper chamber16e. At this time, the chips guided by air leaking out through the brushes20aand21acome into collision with the inner side of the brushes20aand21aand drop toward the bottom of the lower chamber16f.

The chips dropping toward the bottom of the lower chamber16fare guided toward the chip discharge port17balong the chip guide surface17a, and are collected into a chip collection vessel30disposed under the chip discharge port17b.

When dressing of the electrode tips4and5has been completed in a predetermined way, the plunger28aof the air cylinder28retracts in synchronization therewith, and the lower case17is thereby rotated around the hinge26, and is set in a standby state in which the front lower end of the upper case16is opened, as shown in FIG.4.

Next, the welding robot is operated to separate the first and second gun arms2and3from the dresser main body11aby a reverse operation to that when advancing them and to bring them into a standby state for the next spot welding.

When the chips collected into the chip collection vessel30reach a designated amount, or periodically, the chips collected in the chip collection vessel30are recycled.

According to this embodiment, as described above, since the chip pickup case15is divided into the upper case16and the lower case17, when teaching is performed to the welding robot, the electrode tip4provided at the end of the first gun arm2and the dressing body13can be positioned while the positional relationship therebetween is checked visually; therefore, high workability can be provided.

Since the lower case17maintains an opened state until the first gun arm2is located in position in the lower chamber16fof the upper case16, the first gun arm2can be advanced into the lower chamber16ffrom the lower part of the upper case16. As a result, there is no need to downwardly expand the arm admission port16aformed at the front of the upper case16in order to prevent the interference with the first gun arm2, allowing the entire length of the chip pickup case15to be significantly decreased in a state in which the lower case17is closed, so that downsizing can be achieved.

FIGS. 5to8show a second embodiment of the invention. A chip pickup case31according to this embodiment is divided into an upper case32and a lower case33having a bottom and acting as a chip collection vessel. The upper case32can be freely opened and closed left and right at the front side thereof. More specifically, the upper case32includes a back plate34, both-side plates35and36, and front flanges35aand36aformed by bending the front edges of the both-side plates35and36. The rear edges of the both-side plates35and36and both side edges of the back plate34are connected with each other with spring hinges37. The spring hinges37constantly apply a force to open the both-side plates35and36outward around it.

Also, the base ends of receiving plates38, which extend in opposite directions and the ends of which overlap vertically in a state in which the both-side plates35and36are closed (a state of FIG.7), are supported by the both-side plates35and36on the bottom side of the dresser main body11awith hinges39such that they can freely rotate vertically. One end of a stay40is rotatably supported at the lower surface of each receiving plate38, and the other end of the stay40is freely brought into and out of engagement with the hook41secured to the inside lower part of each of the side plates35and36.

In a state in which the both-side plates35and36are opened, as shown inFIG. 5, the ends of the receiving plates38extending from the inner surfaces of the both-side plates35and36intersect each other.

With such a configuration, when the operation at the time of dressing is taught to the welding robot, first, the ends of the stays40supporting the receiving plates38are disengaged from the hooks41secured to the both-side plates35and36. Then, as shown inFIG. 8, the receiving plates38are rotated downwards around the hinges39and stand still in substantially parallel to the inner surfaces of the both-side plates35and36.

Subsequently, the welding robot set in a teaching mode is operated, as is the first embodiment, to guide the gun arms2and3provided for the welding gun (C-type welding gun in the drawing)1toward the dressing body13held by the holder12of the dresser main body11afrom the front toward the upper case32.

At this time, since the both-side plates35and36of the upper case32are opened outwards by the urging force of the spring hinges37, the electrode tips4and5mounted at the ends of the gun arms2and3can be accurately guided to the dresser main body11afrom the front, and also, the central axes of the electrode tips4and5can be accurately conformed to the central axes of the cutters13aand13bprovided at both sides of the dressing body13while it is visually checked from the outside. Accordingly, high workability can be obtained while teaching is performed.

After the teaching operation has been completed in a predetermined way, the receiving plates38are raised, and an end of each stay40, the other end of which is supported on the bottom of the receiving plate38, is engaged with the hook41secured to the inner surface of each of the side plates35and36, and the receiving plates38are set in a standby state in which the ends thereof overlap, as shown in FIG.5.

Subsequently, a case of dressing the ends of the electrode tips4and5will be described. First, the pair of gun arms2and3provided for the C-type welding gun1is moved toward the dresser main body11ain accordance with preset teaching.

Next, the first gun arm2is advanced into the upper case32from the front of the upper case32. Then, the end of the first gun arm2or the electrode tip4provided at the end of the first gun arm2is brought into contact with the ends of the receiving plates38extending from the inner surfaces of the both-side plates35and36, as shown in FIG.6.

The ends of the receiving plates38intersect each other. When the first gun arm2is further advanced into the interior, the ends of the receiving plates38are pushed, and the both-side plates35and36connected to the receiving plates38are rotated in a direction to close each other around the spring hinges37against the urging force of the spring hinges37.

When the central axes of the electrode tips4and5are positioned on the central axis of the dressing body13disposed on the holder12provided for the dresser main body11a, the ends of the brushes20aand21a, which are secured to the front flanges35aand36abent from the both-side plates35and36forwardly, are brought into contact with each other to block the front and the top of the upper case32, and also to block the peripheries of the gun arms2and3by elastic deformation of the brushes20aand21a.

The positional relationship between the first gun arm2or the electrode tip4and the receiving plates38is controlled by adjusting the attachment positions of the receiving plates38or varying the widths of the receiving plates38.

After the dressing of the electrode tips4and5has been completed in a predetermined way, the welding robot is operated to separate the first and second gun arms2and3from the dresser main body11aby the reverse operation to that when the first and second gun arms are advanced, the pushing force of the first gun arm2or the electrode tip4to the receiving plates38is gradually released, and the both-side plates35and36are gradually opened in synchronization with the retracting motion of the first gun arm2by the urging force of the spring hinges37, thereby being returned to a standby state, shown in FIG.5.

According to this embodiment, as described above, the both-side plates35and36of the upper case32are supported on the back plate34with the spring hinges37, and they are opened at the front in a standby state. Accordingly, when teaching is performed to the welding robot, the central axes of the electrode tips4and5can be conformed to the central axes of the cutters13aand13bof the dressing body13while the positional relationship therebetween is checked visually; therefore, high workability can be provided. Furthermore, during dressing operation, since it can be visually checked immediately before the electrode tips4and5come close to the dressing body13, faulty dressing can be found relatively easily.

Also, since opening and closing operations of the both-side plates35and36are performed by the advancing and retracing motions of the welding gun1, which needs no power, the apparatus has a simple structure, and can be manufactured at low cost, and also it can easily be mounted on the dresser main body11a, so that high operability can be provided. Of course, it is also possible that the both-side plates35and36are positively opened and closed by combination with the air cylinder and a link.

FIG. 9shows a third embodiment of the invention.

A chip pickup case45according to this embodiment has a window45bopened in a side45athereof, through which the positional relationship between the dressing body13and the electrode tips4and5can be visually checked, the window45bbeing blocked by a transparent plate46made of acryl or the like.

An arm insertion port45copened in the front of the chip pickup case45is blocked by a pair of brushes47aand47bconstituting a shielding member47, and un upper-arm insertion port45dis formed in the top of the chip pickup case45whereas a chip guide surface45eis formed in a tapered shape at the bottom and a chip discharge port45fis opened at the end thereof.

According to this embodiment, since the positional relationship between the electrode tips4and5supported by the welding gun1and advancing into the chip pickup case45and the dressing body13can be visually recognized through the window45bfrom the exterior, not only the state in which teaching is performed but also the state in which dressing is performed can be recognized, so that faulty dressing such as insufficient dressing and excessive dressing can be prevented before they occur.

It is also possible that the window45bis formed at both sides or at the back of the case45. Also, it is possible that the window45bis covered with a lid capable of being freely opened and closed, in stead of the transparent plate46, and only when necessary, the lid is opened and the inside can be viewed therethrough.

The present invention is not limited to the above embodiments; for example, the brushes20aand21amay be rubber blades, and it is also possible to form the window shown in the third embodiment at the side or the back of the upper case16or32, shown in the first and second embodiments, respectively.

According to the present invention, as described above, the positional relationship between the electrode tips and the dressing body during teaching operation can easily be checked without detaching the whole device, thereby reducing the number of processing steps required for teaching.

Also, the presence or absence of faulty dressing during dressing operation can easily be checked from the exterior, thereby preventing faulty dressing.