JP4520534B2 - Electric hand - Google Patents

Description

  The present invention relates to an electric hand for gripping and positioning a workpiece or measuring length in automatic assembly, parts conveyance, inspection process, etc., and in particular, two pairs of hand members (finger, claw, chuck, etc.) The present invention relates to an electric hand of a type that grips a work in pairs.

  As this type of electric hand, there is one (work positioning apparatus) described in Japanese Patent Application Laid-Open No. 2004-106095. In this conventional one, four cam grooves having the same shape and the same length are formed in one cam plate at equal intervals with the same curve centering on the rotation center of the cam plate. The cam followers of four fingers arranged in a cross shape are slidably fitted in the grooves, respectively. By rotating one cam plate with a stepping motor, the four fingers are centered on the rotation center of the cam plate. By simultaneously sliding the same distance, the workpiece is gripped by four fingers and positioned (centered) on the rotation center of the cam plate.

However, this has the following problems.
(1) Although a circular or square workpiece can be positioned, it is difficult to position a workpiece having a long or short length such as a rectangle or an ellipse.
(2) Although a buffering mechanism using a spring is provided, only a rectangular workpiece having a small difference between the long and short lengths can be handled. In this case, correct positioning (centering) cannot be performed.
(3) Since it is the open loop control of the stepping motor, it is necessary to separately check the operation by a mechanism for that, and the centered work cannot be checked (measured).
(4) Since the precise thrust control of the finger cannot be performed, in the case of a fragile work or a work that is easily deformed, the finger contact is incomplete and positioning cannot be performed accurately.

JP 2004-106095 A

  A first object of the present invention is to provide an electric hand capable of accurately positioning (centering) a work having a long or short length such as a rectangle or an ellipse.

  A second object of the present invention is to provide an electric hand that can measure a workpiece and can accurately position a fragile workpiece or a workpiece that is easily deformed.

  To achieve the first object, according to the present invention, two pairs of hand members are opposed to each other, and cam followers of these hand members are slidable in cam grooves formed in a cam member rotated by a motor. In the electric hand in which the cam follower slides along the cam groove by the rotation of the cam member and the two pairs of hand members slide simultaneously at the same time, the cam member includes the first and second two cam members. The cam members are pivotally supported on the same axis, and a pair of the cam grooves are formed symmetrically in each of the first and second cam members, and the cam grooves of the first and second cam members The distances from the shaft center are different from each other, the diameters of the first and second cam members are different, and the cam groove of the large-diameter cam member is formed at a location beyond the outer peripheral edge of the small-diameter cam member. It is characterized by being .

  According to a second aspect of the present invention, in the above invention, the cam groove is formed so as to move away from the axis from one end to the other end along an Archimedean spiral centering on the axis of the cam member. It is what.

  According to a third aspect of the present invention, in the first aspect, the first and second cam members are separately rotated by respective motors.

  According to a fourth aspect of the invention, there is provided a housing for supporting the first and second cam members, wherein the housing includes an upper plate and a guide plate for supporting the two pairs of hand members, The upper plate is positioned at an upper end portion of the housing, the guide plate is installed on the upper plate, and a rail for slidably guiding the two pairs of hand members horizontally is provided on the guide plate. It is provided on the lower side.

  In order to achieve the second object, according to a fifth aspect of the present invention, in the above invention, the motor is a motor whose excitation current and generated torque are linear, and outputs an electric signal corresponding to the rotation amount. An encoder is attached.

According to the present invention, the moving distance between the first set of hand members slid by the rotation of the first cam member and the second set of hand members slid by the rotation of the second cam member is different. Therefore, a workpiece having a long or short length such as a rectangle or an ellipse can be accurately positioned (centered).
Further, since the first and second cam members are pivotally supported on the same axis, a compact design can be achieved.

  Further, the first and second cam members have different diameters, and the cam groove of the large-diameter cam member is formed at a location beyond the outer peripheral edge of the small-diameter cam member. The cam member can be easily processed as compared to the case where a cam groove that extends from the other cam member to the hand member side is formed in the cam member closer to the member.

  If the cam groove shape is formed along the Archimedes spiral as in the invention according to claim 2, the positional relationship between the rotation angle of the motor and the hand member becomes linear, and the thrust of the hand member generated by the rotation torque of the motor is the rotation angle. It is possible to obtain a constant thrust at any position without being changed by.

  When the first and second cam members are separately rotated by the respective motors as in the invention according to claim 3, the two pairs of hand members can be slid in synchronization by synchronizing the two motors. In addition, the operation and thrust of each pair of hand members can be controlled separately.

  When the rail for guiding the sliding of the two pairs of hand members is provided on the lower side of the guide plate as in the invention according to claim 4, dust generation from the sliding portion of the hand member can be prevented. There is also a dustproof effect on the sliding part.

  As in the invention according to claim 5, if a motor whose excitation current and generated torque are linear and provided with an encoder that outputs an electrical signal corresponding to the amount of rotation is used, In addition to being able to measure the length, even a fragile or easily deformable workpiece can be accurately positioned by precise thrust control of the hand member.

It is a top view of the electric hand used as a reference of the present invention. It is the XX sectional view taken on the line of FIG. It is the YY sectional view taken on the line of FIG. FIG. 3 is a sectional view taken along line ZZ in FIG. 2. It is a top view of the cam member in a reference example, (A) is a 1st cam member, (B) is a 2nd cam member, (C) shows the combined state of these cam members. It is a top view of the electric hand of Example 1 of the present invention. It is the XX sectional view taken on the line of FIG. It is the YY sectional view taken on the line of FIG. FIG. 8 is a sectional view taken along line ZZ in FIG. 7. FIG. 2 is a plan view of a cam member in Embodiment 1, where (A) shows a first cam member, (B) shows a second cam member, and (C) shows a combined state of these cam members. It is a top view of the electric hand of Example 2 of the present invention. It is the XX sectional view taken on the line of FIG. It is the YY sectional view taken on the line of FIG. It is the ZZ sectional view taken on the line of FIG. FIG. 6 is a plan view of a cam member in Embodiment 2, where (A) shows a first cam member, (B) shows a second cam member, and (C) shows a combined state of these cam members. It is a bottom view which shows the combined state of the guide plate and hand member in Example 2. It is the front view. It is the XX sectional view taken on the line of FIG. It is a right view. It is the YY sectional view taken on the line of FIG.

(Reference example)
First, the technique used as the reference of this invention is demonstrated with reference to FIGS.
1 to 5 show an electric hand which is a reference of the present invention. In this electric hand, the first and second motors 2 and 3 are placed side by side in the housing 1, and a cam mechanism 5 is formed in the housing 1 below the upper plate 4. A hand member guide mechanism 6 is configured outside the upper plate 4 outside.

  The two motors 2 and 3 are substantially the same, and the excitation current and the generated torque are linear. A rotary encoder 7 that outputs an electrical signal corresponding to the amount of rotation is attached.

  In the cam mechanism 5, a bearing plate 8 is fixedly installed in the housing 1, and a cam shaft 9 is rotatably supported by a bearing 10 in a bearing recess 8 a at the center. The first cam member 11A is fixed to the upper portion of the first cam shaft 9 so as to rotate integrally therewith. Further, the second cam member 12A is disposed below the first cam member 11A with the intermediate bearing 13 interposed between the cam shaft 9 and the first cam member 11A rotates integrally with the cam shaft 9. However, the second cam member 12A can rotate relative to the cam shaft 9 separately from the first cam member 11A.

  The first and second cam members 11A and 12A are shown in FIG. 5A with a plane of only the first cam member 11A, FIG. 5B with a plane of only the second cam member 12A, and FIG. These are discs of the same outer diameter, as shown in the superimposed plane. However, in the first cam member 11A, a pair of separated cam grooves 14 are formed along a point-symmetrical curve with the axis (rotation center) as the center, and the outer periphery of these cam grooves 14 is larger. In addition, a pair of separated escape grooves 15 are formed along a point-symmetrical arc line. On the other hand, the second cam member 12A is only formed with a pair of separated cam grooves 16 along a point-symmetric curve with its axis (rotation center) as the center.

  The mutual relationship between the first and second cam members 11A and 12A is as shown in FIG. 5C, that is, the pair of cam grooves 16 of the second cam member 12A are separated from the axial center. Is longer than the pair of cam grooves 14 of the first cam member 11A, and each of the first and second pair of cam grooves 14 and 16 has a curvature of the curve that is greater than that of the first. 2 is gentler, and the groove length is longer in the second than in the first. However, each of the first and second pairs of cam grooves 14 and 16 is away from the axis from one end to the other end along the Archimedes spiral centered on the axis (rotation center). It is formed as follows. The width of the escape groove 15 formed in the first cam member 11A is much larger than that of the cam grooves 14 and 16, and the length of the second cam member 12A from one end to the other end of the cam groove 16 in the length direction thereof. And the length and width of the cam member 12A included in both radial directions.

  In addition, teeth 11a and 12a such as gears are formed on the entire outer periphery of the first and second cam members 11A and 12A, and the teeth 11a of the first cam member 11A are formed by the first motor. The first drive gear 17 fixed to the second motor shaft and the teeth 12a of the second cam member 12A mesh with the second drive gear 18 fixed to the motor shaft of the second motor 3, respectively. . Accordingly, the first and second cam members 11A and 12A are rotated separately by the motors 2 and 3, respectively.

  On the other hand, the hand member guide mechanism 6 is configured such that four guide plates 19 are fixedly installed on the upper plate 4 of the housing 1 on the left and right and front and rear sides, so that a pair of left and right (first set) between the guide plates 19 A pair (second set) of guide grooves (rails) 20, 21, 22, 23 are formed in a cross shape as a whole. Then, two pairs of hand members 24, 25, 26, and 27, which are opposed to each other in a pair, are fitted into the pair of guide grooves 20, 21, 22, and 23 so as to be horizontally slidable. Has been. A ball slide structure is formed between each hand member and each guide groove.

  The first set of guide grooves 20 and 21 are longer than the second set of guide grooves 22 and 23, and accordingly, the first set of hand members 24 and 25 are longer than the second set of hand members 26 and 27. It has become.

  Each of the first set of hand members 24 and 25 has a pin-like cam follower 28 vertically planted, and each of the second set of hand members 26 and 27 has a pin longer than the first set of cam followers 28. Each cam follower 29 is vertically planted one by one. The lower ends of the cam followers 28 of the first set of hand members 24 and 25 are slidably fitted into the pair of cam grooves 14 of the first cam member 11A, respectively, and the second set of hand members 26 and 27 are inserted. The lower ends of the cam followers 29 are slidably fitted in the pair of cam grooves 16 of the second cam member 12A. A small bearing 30 is attached to the lower end of each cam follower 28/29.

Since the electric hand shown in this reference example has such a structure, its operation is as follows.
When the first and second motors 2 and 3 are driven in synchronization, the first and second cam members 11A and 12A rotate on the same axis at the same time, and the pair of cam grooves 14 of the first cam member 11A The cam followers 28 of the first set of hand members 24 and 25 slide along the pair of cam followers 29 of the second set of hand members 26 and 27 along the pair of cam grooves 16 of the second cam member 12A. To do.

  Since the first and second cam grooves 14 and 16 are in the size relationship as described above, the second set of hand members 26 and 27 is larger than the sliding distance of the first set of hand members 24 and 25. If the sliding distance becomes larger, for example, a rectangular work is placed so that the long side is between the first set of hand members 24 and 25 and the short side is between the second set of hand members 26 and 27, The rectangular workpiece can be accurately positioned (centered).

  In the sliding of these two sets of hand members 24, 25, 26, and 27, the cam grooves 14 and 16 are pivoted from one end to the other along the Archimedes spiral line centered on the axis (rotation center). Since the rotation angle of the motors 2 and 3 and the positional relationship between the hand members 24 and 25 and 26 and 27 are linear, the hand members 24 and 25 generated by the rotation torque of the motors 2 and 3 are formed. The thrusts 26 and 27 do not change depending on the rotation angle, and a constant thrust can be obtained at any position. The detailed reason is explained in Japanese Patent Laid-Open No. 2005-59118 invented by the present inventor and applied for a patent.

  The motors 2 and 3 are motors in which the excitation current and the generated torque are linear, and each is provided with a rotary encoder 7 that outputs an electrical signal corresponding to the amount of rotation. Therefore, the first set of hand members 24. 25 and the second set of hand members 26 and 27 can be controlled independently, and a rectangular workpiece can be measured in both the long and short directions, and a fragile workpiece or a deformable workpiece. However, it can be accurately positioned by precise thrust control of the hand members 24, 25, 26, 27.

Example 1
6 to 10 show an electric hand according to the present invention as a first embodiment. In this electric hand, the relationship between the first cam member 11B and the second cam member 12B is different from the reference example as follows.

  That is, as shown in FIGS. 10A, 10B, and 10C, the first cam member 11B and the second cam member 12B have different diameters, the former being small and the latter being large. Yes. And with respect to a pair of cam groove 14 of the 1st cam member 11B, a pair of cam groove 16 of the 2nd cam member 12B is formed in the place exceeding the outer periphery of the 1st cam member 11B of a small diameter, Even if the first cam member 11B does not have the clearance groove 15 as in the above-described reference example, the cam followers 28 of the first set of hand members 24 and 25 interfere with the cam followers 29 of the second set of hand members 26 and 27. It is supposed not to.

  In the first embodiment, the first cam member 11B and the second cam member 12B have such a relationship, and as shown in FIG. 7, the rotation of the first drive gear 17 causes the cam shaft 9 to rotate. Is transmitted to the first cam member 11B via the relay gear 17a fixed to the other, but the other configuration is the same as the above-described reference example, so the operation is also the same as the reference example.

(Example 2)
11 to 15 show an electric hand according to a second embodiment, which is a modification of the first embodiment. In this electric hand, in the hand member guide mechanism 6 for guiding the two sets of hand members 24, 25, 26, 27, the length of the hand members 24, 25, 26, 27 is set to the guide grooves 20, 21, 22, 23. The guide grooves 20 and 21 and 22 and 23 are covered with a guide plate 31 so that the guide grooves 20 and 21 and 22 and 23 are formed. That is, as shown in FIG. 16 to FIG. 20, the guide groove 20. 21 is formed on the upper plate 4 with the guide plate 31 having the lower surface formed with the guide grooves 20, 21, 22, 23 serving as rails facing downward. 21, 22 and 23 are also used as a top plate for covering from above.

  In this way, the sliding portions of the hand members 24, 25, 26, and 27 and the guide grooves 20, 21, 22, and 23 can be protected by the guide plate 31, so that the sliding portions are exposed to the outside. In addition to preventing dust, it also has an external dustproof effect. Further, since a part of the hand members 24, 25, 26, and 27 protrudes from the edge of the guide plate 31, the workpiece can be gripped and positioned (centered) on the guide plate 31.

  In addition, the arrangement relationship of the two sets of hand members 24, 25, 26, and 27 is opposite to that of the first embodiment. It is arranged in.

  DESCRIPTION OF SYMBOLS 1 ... Housing, 2 * 3 ... Motor, 4 ... Upper plate, 5 ... Cam mechanism, 6 ... Hand member guide mechanism, 7 ... Rotary encoder, 8 ... Bearing plate, 8a ... Bearing recessed part, 9 ... Cam shaft, 10 ... Bearing 11A, 11B: first cam member, 12A, 12B: second cam member, 11a, 12a ... teeth, 13 ... intermediate bearing, 14 ... cam groove, 15 ... relief groove, 16 ... cam groove, 17 ... first 1 drive gear, 17a ... relay gear, 18 ... second drive gear, 19 ... guide plate, 20, 21, 22, 23 ... guide groove, 24/25 ... first set of hand members, 26/27 ... first Two sets of hand members, 28 ... cam follower, 29 ... cam follower, 30 ... bearing, 31 ... guide plate.

Claims (5)

Two pairs of hand members are opposed to each other, and cam followers of these hand members are slidably fitted in cam grooves formed in a cam member rotated by a motor, and the cam follower cams by rotation of the cam member. In the electric hand in which two pairs of hand members slide linearly simultaneously by sliding along the groove, the first and second two cam members are pivotally supported on the same axis as the cam members. In each of the first and second cam members, the pair of cam grooves are formed in point symmetry, and the cam grooves of the first and second cam members are different from each other in distance from the axis. ,
An electric hand characterized in that the diameters of the first and second cam members are different, and a cam groove of a large-diameter cam member is formed at a location beyond the outer peripheral edge of the small-diameter cam member.   The said cam groove is formed so that it may distance from an axial center from one end to the other end along the spiral line of Archimedes centering on the axial center of the said cam member. Electric hand.   The electric hand according to claim 1 or 2, wherein the first and second cam members are separately rotated by respective motors. A housing for supporting the first and second cam members;
The housing includes an upper plate and a guide plate that support the two pairs of hand members,
The upper plate is positioned at an upper end of the housing;
The guide plate is installed on the upper plate,
The electric hand according to any one of claims 1 to 3, wherein a rail for slidably guiding the two pairs of hand members in a horizontal direction is provided below the guide plate.   5. The motor according to claim 1, wherein the motor is a motor whose excitation current and generated torque are linear, and an encoder that outputs an electrical signal corresponding to the rotation amount is attached. Electric hand.

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