Positioning device and work machine including the same

Abstract

To provide a positioning device capable of positioning a work-piece by a simple control.SOLUTION: A positioning device 10 positions a workpiece W onto a work position by causing a conveyance mechanism 20 which pushes up the workpiece W provided with a reference hole W5 on an upper surface up to the work position and a guide mechanism 30 which stands-by at the work position and guides the workpiece W to the work position to sandwich the workpiece W in the vertical direction. The conveyance mechanism 20 includes: a sliding table 24 on which the workpiece W is mountable and which is slidable integrally with workpiece W in the horizontal direction; and a push-up driving source 22 which elevates the sliding table 24. The guide mechanism 30 has a guide member 35 which stands by at the work position and can be abutted with an upper surface of the workpiece W. A guide projection 37 which is inserted to a reference hole W5 of the workpiece W and positions the workpiece W and a guide claw 36 which guides the workpiece W are provided on the lower surface of the guide member 35.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a positioning device for positioning a workpiece and a work machine equipped with this positioning device. [Background technology]

[0002] A screw tightening machine described in Patent Document 1 is known as an example of a conventional work machine that performs a predetermined task on a product with large dimensional errors, such as a cast product. This screw tightening machine includes a tool unit equipped with a screw tightening tool that rotates when driven by a rotary drive source, an articulated robot that moves the tool unit, a camera that captures images of the workpiece, and a control unit that calculates the coordinates of the work position from the camera's image capture. The control unit is configured to drive the articulated robot to transport the tool unit to the work position. The control unit of this work machine performs image analysis processing on the camera's image capture, calculates the relative position between the tool unit and the workpiece from the processing results, and controls the drive of the articulated robot to move the tool unit by the calculated relative position. In other words, when the work position and the tool unit are misaligned due to a positional error or dimensional error of the workpiece, conventional work machines move the tool unit in a direction that corrects the misalignment. This has the advantage of being able to automatically perform tasks such as screw tightening on workpieces with large dimensional errors, such as cast products. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-124765 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional work machines have a configuration in which the tool unit is moved to correct the positional deviation of the work position, which poses problems such as the need for expensive parts such as a camera that captures images of the work position and an articulated robot that moves the tool unit.In addition, there is also the problem that the control unit becomes complicated because it is necessary to perform image analysis processing of the captured images, calculate the relative position between the tool unit and the work position, and operate the articulated robot.

[0005] Therefore, an object of the present invention is to provide a positioning device that can correct the positional deviation between the work position and the tool unit with simple control, and a work machine that uses the positioning device. [Means for solving the problem]

[0006] The positioning device of the present invention was created in consideration of the above-mentioned problems, and comprises a conveying mechanism that pushes up a workpiece having a reference hole on its upper surface to a predetermined working position, and a guide mechanism that waits at the working position and guides the workpiece to the working position, and the conveying mechanism and guide mechanism position the workpiece at the working position by clamping the workpiece vertically.The conveying mechanism comprises a sliding table on which the workpiece can be placed and which can slide horizontally together with the workpiece, and a push-up drive source that raises the sliding table and the workpiece toward the working position, and the guide mechanism waits at the working position and has a guide member that can abut the upper surface of the workpiece, and the lower surface of the guide member is provided with a guide protrusion that is inserted into the reference hole in the workpiece to position the workpiece, and a guide claw that guides the workpiece so that the guide protrusion is inserted into the reference hole. In addition, it is preferable that the guide mechanism has a positioning drive source that moves the guide member back and forth between the working position and a standby position set above the working position, and that the positioning drive source is set to be stronger than the push-up drive source. Preferably, the guide mechanism includes a rotary drive source that rotates the guide member by a predetermined angle. Furthermore, it is preferable that the guide claws guide the workpiece so that the central axis of the workpiece is positioned on the rotation axis of the rotary drive source.

[0007] The positioning device of the present invention is characterized in that it comprises the positioning device and a tool unit that performs a predetermined operation on a workpiece fixed to the work position by the positioning device, and the tool unit performs the predetermined operation on a side surface of the workpiece. [Effects of the Invention]

[0008] According to the positioning device of the present invention, the workpiece is pushed up by the push-up drive source, so that the upper surface of the workpiece, which is set as the reference surface, can abut against the guide member, thereby positioning the workpiece in the vertical direction. Furthermore, when the workpiece is placed on a sliding table and the upper edge of the workpiece abuts against the guide claws, the workpiece can slide toward the working position, so the workpiece can also be positioned in the horizontal direction. These advantages provide the ability to position the workpiece at a predetermined working position without complex control. Furthermore, the guide member moves back and forth between the working position and the standby position above the working position, which has the advantage of making it easier to place the workpiece on the sliding table. Furthermore, since it has a rotary drive source, it has the advantage of being able to change the direction of the workpiece. Furthermore, since the guide claws position the center of the workpiece on the rotation axis, there is an advantage that there is no need to reposition the workpiece.

[0009] Furthermore, the working machine of the present invention has the advantage that it can be manufactured inexpensively because the workpiece is positioned at the working position by the positioning mechanism and no complicated positioning control is required. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic front view showing the structure of a screw removing device according to the present invention. [Figure 2] 2 is a schematic front view showing a state transitioning from the state in FIG. 1 to the next state. [Figure 3] 3 is a schematic front view showing a state transitioning from the state in FIG. 2 to the next state. [Figure 4] 4 is a schematic right side view showing the structure of the screw removing device according to the present invention in the state shown in FIG. 3. [Figure 5] 1 is an enlarged, partially cutaway front view of a main portion showing the structure of a screw removing device according to the present invention. [Figure 6] 6 is a cross-sectional view taken along line AA in FIG. 5, showing the structure of the screw removing device according to the present invention. [Figure 7] 6 is an enlarged plan view of a main part showing a state in which the fixed chuck is driven in the cross-sectional view taken along the line AA in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will now be described with reference to the drawings. Figures 1 and 4 show a screw removing device 10 as an example of a work machine that performs a predetermined operation on a workpiece W. This screw removing device 10 has a positioning device 11 that positions the workpiece W at a predetermined work position, a tool unit 40 that removes screws W4 from the workpiece W that has been positioned and fixed at the work position by this positioning device 11, and a control unit that controls the driving of these devices.

[0012] 1 and 4, the workpiece W has a hollow main body W1 formed by casting, a pair of cover members W2 and W3 fixed to the front and rear surfaces of the main body W1, respectively, and a number of screws W4 that fix the cover members W2 and W3 to the main body W1. The front and rear surfaces of the main body W1 are provided with a plurality of internal threads (not shown), and the screws W4 are threadedly engaged with these internal threads. These internal threads are formed based on the top surface of the main body W1 and a reference hole W5 formed on the top surface, and the internal threads formed on the front and rear surfaces are configured point-symmetrically with respect to a predetermined vertical axis (hereinafter referred to as the center axis of the workpiece) that is set based on the reference hole W5.

[0013] The positioning device 11 is composed of a transport mechanism 20 that transports the workpiece W to a predetermined working position, and a guide mechanism 30 that guides the workpiece W transported on this transport mechanism 20 to the predetermined working position. The transport mechanism 20 has a lower base 21 that is fixed at a predetermined height by a frame (not shown) or the like. An elevation drive source 22 (hereinafter referred to as a push-up drive source 22) that raises and lowers a drive unit in the vertical direction is fixed to this lower base 21, and an elevation platform 23 that rises and lowers in accordance with the drive of the push-up drive source 22 is fixed to the drive unit of this push-up drive source 22.

[0014] As shown in Fig. 5, the lifting platform 23 is provided with a loose-fitting hole 231 that penetrates in the vertical direction, and a sliding table 24 that extends horizontally is provided above the lifting platform 23. The sliding table 24 is provided with a rough guide shaft 241 that extends downward from the center of its underside and is loosely fitted into the loose-fitting hole 231 so as to be movable horizontally and vertically. The underside of the sliding table 24 is provided with a pair of holding protrusions 242, 242 at positions spaced a predetermined distance from the rough guide shaft 241 in the outer circumferential direction, and the holding protrusions 242, 242 are arranged point-symmetrically with respect to the rough guide shaft 241. The upper surface of the sliding table 24 is further provided with a plurality of fitting protrusions 243, 243 that extend upward, and a jig 25 that can hold the workpiece W is placed on it. This jig 25 is placed on the sliding table 24 and has a jig base 251 in which fitting holes 252, 252 that fit into the fitting protrusions 243, 243 are formed, and a lower jig 253 that abuts against the lower surface of the workpiece W and a pair of side jigs 254, 254 that abut against the side surfaces of the workpiece W are fixed to this jig base 251. Therefore, the workpiece W can move integrally with the sliding table 24.

[0015] The lower base 21 is provided with a pair of support arms 26 extending upward, each of which has free rollers 27 mounted on the outer periphery of the lifting platform 23. Each free roller 27 is composed of a cylindrical portion fixed to the support arm 26 and a steel ball 271 rotatably housed within the cylindrical portion, with its upper end projecting upward from the cylindrical portion. As shown in FIG. 5 , the free rollers 27 are positioned so that the upper end of the steel ball 271 is positioned above the lifting platform 23 when the push-up drive source 22 is in a lowered position. When the push-up drive source 22 is not in operation, the free rollers 27 support the sliding table 24 from below. When supported by the free rollers 27 in this manner, the sliding table 24 is slidable horizontally by the clearance between the rough guide shaft 241 and the loose-fitting hole 231 of the lifting platform 23. Furthermore, the support arm 26 is provided with a fixed chuck 28 that fits into the holding protrusions 242, 242 of the sliding table 24. The fixed chuck 28 is disposed on the outer periphery side of the holding protrusions 242, and a fixed claw 281 having a wedge-shaped fixed recess 282 at a location where it comes into contact with the holding protrusion 242 is attached to the drive section of the fixed chuck 28. As a result, when the fixed chuck 28 moves the fixed claw 281 toward the outer periphery as shown in Fig. 6, the sliding table 24 is free to slide horizontally, whereas when the fixed chuck 28 moves the fixed claw 281 toward the center as shown in Fig. 7, the fixed recess 282 of the fixed claw 281 fits into the holding protrusion 242 to fix the holding protrusion 242, thereby restricting movement of the sliding table 24.

[0016] The guide mechanism 30 has an upper base 31 fixed at a predetermined height by a frame (not shown) or the like, and a plurality of guide rods 311 pass through the upper base 31 so as to be able to move up and down in the vertical direction. A lifting plate 312 is fixed to the lower end of the guide rod 311, and this lifting plate 312 is guided by the guide rods 311 and is configured to be able to move up and down below the upper base 31. Also fixed to the upper base 31 is a lifting drive source 32 (hereinafter referred to as a positioning drive source 32) that drives a drive unit to move up and down in the vertical direction, and the lifting plate 312 is fixed to a drive unit of the positioning drive source 32. Also fixed below the lifting plate 312 is a rotation drive source 33 that rotates the drive unit in a direction parallel to the lifting plate 312, and a holding member 34 is fixed to the drive unit of the rotation drive source 33. A pair of locking claws 341, which are L-shaped when viewed from the front, are fixed to the underside of the holding member 34, and a guide member 35 is suspended from the locking claws 341. With this structure, when the positioning drive source 32 is driven, the guide member 35 can be raised and lowered between the standby position set above the working position and the working position.

[0017] The guide member 35 has a lower surface configured to be able to abut against the upper surface of the workpiece W, and is provided on the lower surface with a plurality of guide claws 36 that guide the workpiece W and a plurality of guide protrusions 37 that fit into the reference holes W5 of the workpiece W. The guide claws 36 have inclined surfaces that gradually slope downward in a direction away from the rotation axis of the rotation drive unit, and are positioned so that the inclined surfaces abut against the upper edge of the workpiece W. In this embodiment, two pairs of guide claws 36 are provided to sandwich the workpiece W from the front-to-back and left-to-right directions, and guide the workpiece W toward the center of the guide member 35. Meanwhile, the guide protrusions 37 are configured in approximately the same shape as the reference holes W5 of the workpiece W, and their tips are configured in a tapered shape. The guide protrusions 37 are configured shorter than the guide claws 36 so that the inclined surfaces of the guide claws 36 are inserted into the reference holes W5 after abutting against the workpiece W. When the guide protrusion 37 enters the reference hole W5, the workpiece W is positioned at a position where the central axis of the workpiece W overlaps with the central axis of the guide member 35 and the rotation axis of the rotary drive source 33 due to the tapered shape of the guide protrusion 37.

[0018] 2, the positioning drive source 32 is configured to lower the guide member 35 to a height where the lower end of the guide protrusion 37 enters the reference hole W5 of the workpiece W and where a slight gap is formed between the lower surface of the guide member 35 and the upper surface of the workpiece W. Furthermore, the positioning drive source 32 is set to have a force stronger than that of the push-up drive source 22 so that the guide member 35 does not succumb to the pressing force of the push-up drive source 22 and shift upward in position when the push-up drive source 22 is driven as shown in FIG.

[0019] The tool unit 40 is a so-called multi-axis tool unit as described in detail in Japanese Patent Application Laid-Open Nos. 2021-154452 and 2018-079554, both of which are incorporated herein by the present applicant. As shown in FIG. 4, the tool unit 40 includes a horizontal drive source 41 that reciprocates a drive unit in the forward and backward directions. A motor base 42 is fixed to the drive unit of the horizontal drive source 41, and multiple bit motors 43 are fixed to the rear surface of the motor base 42. The bit motors 43 are fixed so that their output shafts face forward. A tightening tool 45 is connected to the output shafts via two universal joints 44 that can transmit rotational drive force in an oblique direction. The tightening tool 45 is positioned on the axis of the screw W4 of the workpiece W when the workpiece W is in contact with the guide member 35. The tip of the tightening tool 45 is configured to be engageable with the screw W4 of the workpiece W. With this structure, when the horizontal drive source 41 is driven, the bit motor 43 and the tightening tool 45 fixed to the motor base 42 move simultaneously toward the screw W4, as shown by the two-dot chain line in Figure 4. Furthermore, because the output shaft of the bit motor 43 and the tightening tool 45 are connected via two universal joints 44, the bit motor 43 can transmit rotational drive force to the tightening tool 45 that is not positioned on the axis of the output shaft.

[0020] The control unit is connected to the positioning device 11 and the tool unit 40, and is configured to be able to control the driving of each unit.

[0021] Next, the operation of the screw removing device 10 configured as above will be described. First, the jig 25 holding the workpiece W is placed on the sliding table 24 by an operator or an external device. At this time, the fixed claws 281 of the fixed chuck 28 are brought into contact with the holding protrusions 242 as shown in Fig. 7, thereby restricting the sliding of the sliding table 24. This prevents the sliding table 24 from moving during the installation work, making it easy to install the jig 25 and the workpiece W.

[0022] After the jig 25 and workpiece W are placed on the sliding table 24, when a start signal is input, the control unit drives the positioning drive source 32 to lower the guide member 35 toward the workpiece W. At this time, when the guide claws 36 descend to the upper end of the workpiece W, the control unit drives the fixed chuck 28 to move the fixed claws 281 toward the outer periphery. This releases the restriction imposed by the fixed claws 281, allowing the sliding table 24 to move horizontally. As a result, the workpiece W is pressed against the inclined surfaces of the descending guide claws 36 and slides toward the center of the guide member 35. By being pressed by the guide claws 36 and urged toward the center of the guide member 35 in this manner, the guide protrusion 37 can be inserted into the reference hole W5 of the workpiece W. After the guide protrusion 37 is inserted into the reference hole W5, the workpiece W is further urged toward the center of the guide member 35 and positioned below the working position. Thereafter, the guide member 35 stops before its lower surface comes into contact with the upper surface of the workpiece W.

[0023] After stopping the guide member 35, the control unit drives the push-up drive source 22 to push up the lifting platform 23 and the sliding table 24 until the top surface of the workpiece W abuts against the guide member 35. At this time, because the push-up drive source 22 is configured to be weaker than the positioning drive source 32, the guide member 35 is not pushed up even when the top surface of the workpiece W abuts against the bottom surface of the guide member 35. As a result, the workpiece W is positioned at the working position where it abuts against the bottom surface of the guide member 35. In this way, the workpiece W is positioned based on the top surface that contacts the guide member 35 and the reference hole W5, so dimensional errors that occur on the bottom surface and side surfaces do not affect the position of the female screw.

[0024] Once the workpiece W is positioned at the work position as described above, the control unit drives the horizontal drive source 41 and bit motor 43 of the tool unit 40. As a result, the tightening tool 45 advances toward the screw W4 fixed to the main body W1 of the workpiece W while being rotationally driven. At this time, because the workpiece W is held between the lifting platform 23 and the guide member 35, it will not deviate from the work position even if the tightening tool 45 is pressed against it. Thereafter, when the screw W4 is released from the main body W1, the control unit stops the bit motor 43 and drives the horizontal drive source 41 again to move the tightening tool 45 backward.

[0025] After the tightening tool 45 is retracted as described above, the control unit drives the push-up drive source 22 to lower the sliding table 24 to the initial height at which it abuts against the free rollers 27. This allows the sliding table 24 to slide freely again. Thereafter, the rotation drive source 33 is driven to rotate the guide member 35 and the workpiece W fitted therein by 180 degrees. At this time, since the workpiece W is positioned so that its central axis overlaps the rotation axis of the rotation drive source 33, the 180-degree rotation causes the positions of the front screw W4 and the rear screw W4 to be swapped. After the workpiece W has rotated in this manner, the control unit drives the push-up drive source again to raise the workpiece W until it abuts against the guide member 35, thereby fixing the workpiece W in the working position again, and drives the tool unit 40 to remove the front screw W4 from the main body W1 in the same manner as when the rear screw W4 was removed.

[0026] As described above, the workpiece W is supported by the horizontally slidable sliding table 24. The guide claws 36 and the guide protrusions 37 guide the horizontally slidable workpiece W to a predetermined position. This structure allows the center of the workpiece W, even if its side surface cannot be used as a reference plane, to be positioned on the rotation axis of the rotary drive source 33. As a result, when the workpiece W is turned over, the front screw W4 is positioned on the axis of the fastening tool 45, allowing both the front and rear screws W4 to be removed from the main body W1 with a single tool unit 40. This offers advantages, such as a more compact and inexpensive manufacturing system compared to using multiple tool units 40. Furthermore, the structure in which the lifting drive source 22 lifts the workpiece W until it abuts against the guide member 35 allows the positioning of a workpiece W with an upward reference plane. This structure allows the workpiece W to be positioned at a predetermined height even when the bottom surface of the workpiece W cannot be used as a reference plane or when the reference plane must be directed upward due to equipment requirements. Furthermore, since positioning can be achieved only by linear driving of the positioning drive source 32, the push-up drive source 22, etc., there is an advantage that complicated control is not required and the device can be manufactured inexpensively.

[0027] The working machine according to the present invention is not limited to the above-described device, and various modifications are possible without departing from the spirit and scope of the invention. For example, the device is not limited to the screw removal device 10 that removes the screw W4 already fixed to the workpiece W as described above. It may also be a screw driver that fastens the screw W4 to the workpiece W or a drilling device that drills a hole at a predetermined position. An elastic member such as rubber may be fixed to the upper surface of the lifting platform 23 so that friction is generated between the lifting platform 23 and the sliding table 24 when the lifting platform 23 contacts the sliding table 24. The lower base 21 may be supported by a horizontally reciprocating transport device (not shown) and configured to be reciprocating between below the guide mechanism 30 and a predetermined placement position where the workpiece W is placed. By enabling reciprocating movement between the placement position and below the guide mechanism 30 using the transport device, there is an advantage in that a space is created above the sliding table 24 when the workpiece W and jig 25 are placed on or removed from the sliding table 24, making it easier to attach and detach them.

[0028] Furthermore, a steel plate or the like may be attached to the underside of the sliding table 24 at the contact points with the free rollers 27, preventing point loads from occurring on the sliding table 24, or allowing only the steel plate to be replaced in the unlikely event of deformation due to a point load. Furthermore, the tool unit 40 may be provided with a tool positioning means (not shown) that moves the tightening tool 45 in a direction perpendicular to the axial direction of the tightening tool 45, as in the screw tightening devices disclosed in Japanese Patent Application Laid-Open Nos. 2021-154452 and 2018-079554 by the present applicant. This allows for a simple movement of the tightening tool 45 to a position where it can engage with the screw W4, even when the screw W4 is positioned differently on the front and rear surfaces of the workpiece W, or when removing the screw W4 from a workpiece W (not shown) where the screw W4 is positioned differently from the workpiece W. [Explanation of symbols]

[0029] 10...Work equipment 11... Positioning device 20...Transport mechanism 22 ... Push-up drive source 24... Sliding table 25... Jig 30... Guide mechanism 32 ... Positioning drive source 35 ... Guide member 36 ... Guide claw 37 ... Guide protrusion 40...Tool unit W... Work

Claims

1. a conveying mechanism that pushes up a workpiece having a reference hole on its upper surface to a predetermined working position; a guide mechanism that waits at the work position and guides the work to the work position, In a positioning device in which the workpiece is positioned at the working position by the conveying mechanism and the guide mechanism sandwiching the workpiece in the vertical direction, The transport mechanism includes: a sliding table on which the workpiece can be placed and which can slide horizontally together with the workpiece; a push-up drive source that raises the sliding table and the workpiece toward a working position, the guide mechanism is on standby at the work position and has a guide member that can come into contact with the upper surface of the workpiece, A positioning device characterized in that the underside of the guide member is provided with a guide protrusion that is inserted into a reference hole in the workpiece to position the workpiece, and a guide claw that guides the workpiece so that the guide protrusion is inserted into the reference hole.

2. the guide mechanism has a positioning drive source that reciprocates the guide member between the working position and a standby position that is set above the working position, 2. The positioning device according to claim 1, wherein the positioning drive source is set to be stronger than the push-up drive source.

3. 2. The positioning device according to claim 1, wherein the guide mechanism includes a rotary drive source that rotates the guide member by a predetermined angle.

4. 4. The positioning device according to claim 3, wherein the guide claws guide the workpiece so that the central axis of the workpiece is positioned on the rotation axis of the rotary drive source.

5. a positioning device according to any one of claims 1 to 4; and a tool unit that performs a predetermined operation on a workpiece fixed to the operation position by the positioning device, The tool unit performs a predetermined operation on a side surface of the workpiece.

Images