JP2005238364A - Work holding chuck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance centering accuracy of a piston without depending on positioning accuracy of an automatic loader. <P>SOLUTION: A work locator 20 is arranged in a chuck body 2, and is provided with a centering part 22 capable of centering by fitting with a reference inner surface of a work W, and a guide part 23 having a diameter smaller than the centering part 22 and guiding the reference inner surface of the work W to the centering part 22. A temporary receiving member 25 vertically movably energized upward by a coil spring 26 and capable of holding the work W fitted to the work locator 20 in a temporary receiving position where the reference inner surface corresponds to the guide part 23, is arranged in a cutout part 24 arranged on the peripheral edge of the work locator 20. A clamp part 16 can fit the reference inner surface of the work W to the centering part 22 by downward pulling in the work W set in the temporary receiving position by the automatic loader. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a workpiece holding chuck used for clamping a cylindrical workpiece such as a piston in an internal combustion engine.

  As a chuck structure for holding a cylindrical workpiece such as a piston, first, in Patent Document 1, a reference plate (work locator) having a reference surface in a radial direction and a longitudinal (axis) direction is attached to the front end of the chuck body. The opening end of the workpiece (piston) is fitted into the reference surface, and a pair of fingers provided in the chuck body are opened and closed by advancing the draw bolt and sliding plate. A structure is disclosed in which a locking portion of a finger is engaged with an inner boss and is fastened to a reference plate.

  In Patent Document 2, an annular base (work locator) is attached to the front surface of a chuck body provided with a lever for gripping the outer diameter of the piston, and the open end of the unprocessed piston is defined by the loader as a base. A structure that fits into the outer periphery is described.

  Furthermore, in Patent Document 3, an annular base (work locator) is attached to the front surface of the chuck body, and the piston pin inserted into the piston is inserted into the piston by inserting the open end of the piston into the outer periphery of the base by a loader. A structure is described in which the piston is chucked by pulling it back in the axial direction by a finger that closes by retreating.

Japanese Utility Model Publication No. 52-160887 JP 2001-150209 A Japanese Patent Publication No.46-35832

  In Patent Documents 1 to 3, the piston is centered by fitting the reference inner surface of the opening end to a radial reference inner surface (centering portion) provided on the chuck side. In this case, the piston as a work is generally inserted up to the centering part by an autoloader for automation, but in such a configuration in which the piston is directly fitted into the centering part by the autoloader, The alignment accuracy depends on the positioning accuracy of the autoloader, and centering with higher accuracy than the positioning accuracy of the autoloader cannot be expected. When the fitting between the centering portion and the reference inner surface is made to have a higher accuracy than the positioning accuracy of the autoloader, the autoloader cannot be positioned with high accuracy, and both cannot be fitted.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a workpiece holding chuck capable of increasing piston centering accuracy without depending on positioning accuracy of an autoloader.

  In order to achieve the above object, the invention described in claim 1 is directed to a work locator having a centering portion which can be centered by being fitted to a reference inner surface of the work locator, and having a smaller diameter than the centering portion. The guide inner surface is provided with a guide portion for guiding the reference inner surface to the centering portion. On the chuck main body side, the reference inner surface can hold the workpiece at a temporary receiving position corresponding to the guide portion, and the workpiece from the temporary receiving position on the chuck main body side. The clamping means is configured to hold the workpiece at the provisional receiving position and pull it to the chuck body side, and perform an operation of fitting the reference inner surface of the workpiece to the centering portion. It is a feature.

According to the second aspect of the present invention, in addition to the object of the first aspect, the clamp means can be moved back and forth in the axial direction within the chuck body in order to provide a clamp means suitable for centering the work by the work locator. A pair of clamps that are provided on the slide body so as to be openable and closable in the radial direction of the work locator and that can be locked to the work piece in the temporary receiving position while being opened radially outward. It is set as the structure which comprises a part.
According to a third aspect of the present invention, in addition to the object of the first or second aspect, in order to allow the work fitted to the centering portion of the work locator to be unclamped without placing a load on the loader, The workpiece is moved away from the centering portion of the work locator by moving a predetermined stroke in the workpiece take-out direction.

According to the first aspect of the present invention, since the workpiece is centered by the centering portion of the work locator, the centering portion can be centered with high accuracy without depending on the positioning accuracy of the autoloader. .
According to the second aspect of the invention, in addition to the effect of the first aspect, it is possible to obtain a clamping means suitable for centering the work by the work locator.
According to the third aspect of the invention, in addition to the effect of the first or second aspect, at the time of unclamping, the workpiece is first forcibly removed from the centering portion by the stroke movement of the clamping means. Even if the reference inner surface and the reference inner surface fit with each other with high accuracy, the load can be reliably unclamped without placing a load on the loader.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing an example of a workpiece holding chuck according to the present invention, FIG. 2 is a sectional view taken along the line AA, FIG. 3 is a partially enlarged sectional view taken along the line BB, A chuck comprising a back plate 3 fixed to the upper end of the main shaft 30 with the axis line in the vertical direction, a cylindrical body 4 fixed on the back plate 3, and a front plate 5 fixed to the upper surface of the body 4. The main body 2 is provided with clamping means 6.
First, the clamp means 6 will be described. A pair of top jaws 7 are provided on the upper surface of the chuck body 2. The top jaws 7 and 7 are connected to master jaws 8 and 8 (described later), respectively, so that the top jaws 7 and 7 move together with the master jaws 8 and 8 in the radial direction of the chuck body 2.

Further, a cylindrical slide body 9 that moves up and down by a first cylinder (not shown) via a connecting sleeve 14 is provided in the body 4. An upper portion of the slide body 9 is formed in a narrow portion 9a, and guide grooves 9b of the master jaws 8 and 8 are provided in the narrow portion 9a in the radial direction of the slide body 9, and the master jaw is provided in the guide groove 9b. 8, 8 are guided to open and close in the radial direction.
On the other hand, a drive member 10 that moves up and down by a second cylinder (not shown) via a draw bar 15 is provided at the shaft center of the chuck body 2, and a pair of wedge members 11, 11 are connected to the drive member 10. In the upper part of the wedge member 11, wedge portions 12 are formed so as to be inclined away from the axis as going upward. The wedge portions 12 and 12 mesh with the wedge grooves 13 and 13 on the lower surface of the master jaws 8 and 8 formed at the same inclination angle as the wedge portion 12. Therefore, the master jaws 8 and 8 slide in the radial direction by the sliding contact between the wedge portion 12 and the wedge groove 13 accompanying the vertical movement of the wedge members 11 and 11.

  Clamp portions 16, 16 project upward from the end portions of the top jaws 7, 7 on the axial center side of the chuck body 2, penetrating through a center hole of the work locator 20 described later, and the work locator 20. Protrudes above. Each clamp portion 16 has a clamp piece 17 that is inclined so as to protrude outward as it goes downward on the outer surface, and a side shape including the clamp piece 17 is formed in a pin hole 41 of the workpiece W described later. It has a circular shape that can be freely inserted. 18 is a counter balance mechanism that is provided so as to abut on the radially outer surface of the top jaw 7 and has a weight 19 at the lower end, which counteracts the centrifugal force acting on the clamp portions 16 and 16 when the chuck body 2 rotates, The centrifugal force is prevented from acting on the workpiece via the clamp portion 16.

  As shown in FIG. 4, the workpiece W used here is a cylindrical piston whose upper end is closed, and an insertion groove 40 for a connecting rod is formed below and perpendicular to the insertion groove 40. A pin hole 41 for attaching a pin for connecting the connecting rod is formed. Reference numerals 42 and 42 denote a pair of side wall portions that are formed in a circular arc shape so as to close both ends of the insertion groove 40, and a reference inner surface 43 located concentrically on the lower portion of the inner peripheral surface of the side wall portions 42 and 42. 43, and relief surfaces 44, 44 having a diameter larger than that of the reference inner surfaces 43, 43 are formed below the reference inner surfaces 43, 43, respectively, and contact surfaces 45, 45 orthogonal to the reference inner surface 43 are provided above the reference inner surfaces 43, 43. Are formed respectively.

  On the other hand, in the chuck body 2, a ring-shaped work locator 20 is attached to the upper surface of the front plate 5 by an attachment portion 27 formed integrally with the work locator 20. As shown in FIGS. 3 and 6 and the like, the work locator 20 is provided with four stoppers 21, 21,.. In addition, an annular centering portion 22 that can be centered by fitting the side wall portions 42 and 42 at the reference inner surfaces 43 and 43 of the work W while being in contact with the stopper 21 on the outer peripheral surface, and the centering thereof. On the upper side of the portion 22, a guide portion 23 having a smaller diameter than the centering portion 22 is formed. The diameter of the guide portion 23 is about 0.1 mm smaller than the diameter size of the centering portion 22 (the diameter size of the circle of the reference inner surfaces 43 and 43 of the workpiece W).

In addition, a pair of semicircular cutout portions 24, 24 are provided point-symmetrically on the side surface of the work locator 20, and a small cylindrical temporary receiving member 25 is inserted into each cutout portion 24 and closed at the upper end. These are arranged so as to be movable in the vertical direction along the cutout portions 24, respectively. The temporary receiving member 25 is urged upward by an internal coil spring 26, and the hooking portion 25 a at the lower end of the temporary receiving member 25 comes into contact with the lower end step portion of the notch portion 24, thereby The protruding position is restricted. The protruding position where the hooking portion 25a contacts the lower end step portion of the notch 24 is a position for holding the workpiece W at a temporary receiving position P1, which will be described later, and the spring force of the coil spring 26 causes the workpiece W to move to the temporary receiving position P1. The strength is set such that the weight of the workpiece W is sufficiently loaded and the workpiece W can be held at the provisional receiving position P1 without being bent downward when placed on the provisional receiving member 25 at the corresponding protruding position by its own weight. A locking pin 28 is screwed onto the mounting portions 27, 27 toward the side surface of the temporary receiving member 25, and the locking pin 28 engages with a groove 29 formed on the side surface of the temporary receiving member 25 to temporarily The stopper of the receiving member 25 is intended.
When the work W is fitted to the work locator 20, as shown in FIG. 3, the temporary support member 25 is pushed downward against the bias of the coil spring 26 by the lower ends of the side wall portions 42, 42 of the work W. Thus, an upward biasing force is applied to the workpiece W at the position.

  In the workpiece holding chuck 1 configured as described above, when the workpiece W is clamped, first, the slide body 9 is positioned at the rising end, and the driving member 10 is moved upward in the axis. Then, the top jaws 7 and 7 are moved radially inward by the guides of the wedge portion 12 and the wedge groove 13, respectively, and the clamp portions 16 and 16 are brought closer to the axial center side of the chuck body 2 so that the workpiece W The set is allowed (FIG. 5). Here, after the workpiece W is supplied by the autoloader 31 so that the clamp portions 16 and 16 are inserted into the insertion groove 40 and face the pin hole 41, the side walls 42 and 42 are externally mounted on the work locator 20. Then, the work W is released. Then, the lower ends of the side wall portions 42, 42 of the workpiece W are placed on the temporary receiving members 25, 25. At this time, since the spring force of the coil spring 26 is set to be sufficiently large as described above, the workpiece W is received by the temporary receiving members 25 and 25 at the protruding position where the hooking portion 25a is in contact with the lower end of the notch portion 24. , Is held at the provisional receiving position P1 shown in FIG.

  At this provisional receiving position P1, the reference inner surfaces 43, 43 of the workpiece W are positioned outside the guide portion 23 of the work locator 20 having a slightly smaller diameter than that, the lower ends of the reference inner surfaces 43, 43, and the core of the work locator 20 The distance between the upper end of the protruding portion 22 is a distance Lt, and the distance between the contact surface 45 of the workpiece W and the upper surface of the stopper 21 is a distance Lo (Lo> Lt).

Next, when the drive member 10 is moved downward along the axis and the top jaws 7 and 7 are slid outward, the clamp portions 16 that slide outward simultaneously are fitted into the pin holes 41 of the workpiece W. In this fitted state, gaps L1 and L2 are set up and down between the clamp portion 16 and the pin hole 41 (Lo> L1).
Here, when the slide body 9 is moved below the drawing stroke (= L2 + Lo) axis, the lower end of each clamp piece 17 comes into contact with the lower end of the pin hole 41, and the workpiece W is drawn down the axis. By this operation, the reference inner surfaces 43, 43 of the workpiece W are fitted to the centering portion 22 of the workpiece locator 20, and the abutting surfaces 45, 45 of the workpiece W are abutted against the stopper 21 so that the workpiece W is clamped ( FIG. 7), processing becomes possible. In this clamped state, the amount of engagement of the reference inner surfaces 43, 43 with respect to the centering portion 22 is (Lo-Lt).

  When the machining of the workpiece W is completed, an unclamping operation is performed. First, the slide body 9 is moved upward in the axial direction by the same amount as the drawing stroke (= L2 + Lo). Then, from the state of FIG. 7, the upper end of each clamp part 16 contacts the upper end of the pin hole 41 to push up the work W, and the work W is lifted by (Lo-L1) as shown in FIG. Since the relationship between the gap L1 and the distance Lt in FIG. 6 is set such that Lt> L1, the workpiece W is lifted more than the amount of engagement (Lo-Lt) in the clamped state due to the rise of the clamp portion 16, The reference inner surfaces 43, 43 of the workpiece W are pulled out from the centering portion 22 (FIG. 8). Thereafter, the work W is pushed up via the temporary receiving member 25 by the urging force of the coil spring 26, and the work W returns to the temporary receiving position P1 in FIG. In this state, the autoloader 31 grasps the workpiece W, and finally moves the drive member 10 upward in the axial direction, thereby detaching each clamp portion 16 from the pin hole 41 radially inward. The workpiece W in the unclamped state is taken out by the autoloader 31.

  As described above, according to the workpiece holding chuck 1 of the above embodiment, the centering portion 22 that can be centered by fitting with the reference inner surface 43 of the workpiece W on the outer periphery of the work locator 20, and the centering portion 22. A guide portion 23 having a small diameter and guiding the reference inner surface 43 of the workpiece W to the centering portion 22 is provided, and the workpiece W can be held at the temporary receiving position P1 corresponding to the guide portion 23 on the chuck body 2 side. In addition, a provisional receiving member 25 that can allow the workpiece W to move from the provisional receiving position P1 to the chuck body 2 side is provided, and the clamping means 6 holds the workpiece W at the provisional receiving position P1 to hold the workpiece W at the chuck body 2. The workpiece W is centered by the centering portion 22 of the work locator 20 and the position of the autoloader 31 is determined by performing the operation of pulling in the side and fitting the reference inner surface 43 of the workpiece W to the centering portion 22. Decision Without depending on the accuracy, it is possible to centering with high accuracy by centering section 22.

The clamp means 6 is provided in the slide body 9 so as to pass through the work body locator 20 and the slide body 9 provided so as to be movable back and forth in the axial direction in the chuck body 2 and to be opened and closed in the radial direction of the work locator 20. The work locator 20 can be used to center the workpiece W by including a pair of clamp portions 16 and 16 that can be locked to the workpiece W at the provisional receiving position P1 while being opened radially outward. Suitable clamping means can be obtained.
The clamping means 6 is configured to move the workpiece W by a predetermined stroke in the direction of taking out the workpiece W to separate the workpiece W from the centering portion 22 of the work locator 20, so that the centering portion 22 and the reference inner surface 43 have high accuracy. Even if it fits, it can be reliably unclamped without imposing a burden on the autoloader 31.

In the above embodiment, the workpiece holding chuck set on the upward main shaft is disclosed, but the present invention can be applied to a horizontal or downward main shaft.
Further, the number and shape of the provisional receiving members are not limited to the above-mentioned form, but three or more pieces are evenly arranged in the circumferential direction of the work locator, or may be formed in an arc shape or a ring shape instead of a cylindrical shape. May be. Furthermore, it is not limited to the structure arranged on the periphery of the work locator, and can be provided so as to be able to appear and retract from the work locator as long as the workpiece can be temporarily received, or can be provided on the front plate away from the work locator. .

On the other hand, the guide portion and the centering portion provided on the work locator are not limited to those formed continuously on the peripheral surface of the work locator, but may be provided so as to be intermittent in the circumferential direction, or the guide portion may be tapered. It is possible to change the shape appropriately according to the shape of the inner peripheral surface of the workpiece, such as forming in a multistage diameter.
In addition, the clamping means is not limited to the structure by opening and closing the clamp part formed on the top jaw, but it can move a predetermined stroke in the axial direction by clamping the workpiece, such as those using fingers and wedge members introduced in the conventional technology If it is, it is not limited to the structure of the said form.

It is a top view of the workpiece holding chuck. It is the sectional view on the AA line of FIG. 1 in a clamped state. It is a partially expanded sectional view which follows the BB line of FIG. 1 in a clamped state. (A) is a bottom view of the workpiece, and (B) is a cross-sectional view taken along the line CC. It is explanatory drawing which shows operation | movement of the clamp part at the time of clamping. It is explanatory drawing (temporary receiving position) which shows clamp operation | movement, the left shows the positional relationship of a clamp part and a pin hole, and the right shows the operation | movement of the part in a circle | round | yen of FIG. It is explanatory drawing (clamp position) which shows clamp operation | movement, the left shows the positional relationship of a clamp part and a pin hole, and the right shows the operation | movement of the part in a circle | round | yen of FIG. It is explanatory drawing which shows an unclamp operation | movement, the left shows the positional relationship of a clamp part and a pin hole, and the right shows the operation | movement of the part in a circle | round | yen of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Work holding chuck, 2 ... Chuck body, 6 ... Clamp means, 7 ... Top jaw, 9 ... Slide body, 10 ... Drive member, 11 ... Wedge member, 16 ... Clamp part, 20 ... Work locator, 21 ... Stopper 22. Centering portion, 23 Guide portion, 25 Temporary receiving member, 30 Spindle, 31 Auto loader, W Work, 41 Pin hole, 42 Side wall portion, 43 Reference inner surface, 44 Relief surface, 45 ... Contact surface.

Claims (3)

A workpiece holding chuck provided with a ring-shaped workpiece locator that can be positioned by fitting a cylindrical workpiece into the chuck body, and a clamp means that can hold the workpiece positioned by the workpiece locator,
On the outer periphery of the work locator, there is a centering part that can be centered by fitting with the reference inner surface of the work, and a guide part that has a smaller diameter than the centering part and guides the reference inner surface of the work to the centering part. Provided on the main body side is a temporary receiving member whose reference inner surface can hold the workpiece at a temporary receiving position corresponding to the guide portion and which can allow the workpiece to move from the temporary receiving position to the chuck main body side. A workpiece holding chuck characterized in that the workpiece at the temporary receiving position is held and pulled toward the chuck body, and the reference inner surface of the workpiece is fitted into the centering portion.   Clamping means is provided in the chuck body so that it can move back and forth in the axial direction in the chuck body, and in the slide body that passes through the work locator and can be opened and closed in the radial direction of the work locator, and is opened radially outward The workpiece holding chuck according to claim 1, further comprising a pair of clamp portions that can be locked to the workpiece at the temporary receiving position. 3. The workpiece holding chuck according to claim 1 or 2, wherein the clamp means moves a predetermined stroke in the workpiece take-out direction to detach the workpiece from the centering portion of the workpiece locator.

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