JP2002219625A - Electric clamp device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric clamp device capable of buffering an impact generated when a clamp arm reaches the terminal position of the movement thereof. SOLUTION: This electric clamp device is provided with a rotary driving unit 14 for rotating with an electric signal, a gear mechanism 16 for transmitting the rotary driving force of the rotary driving unit 14, a ball screw mechanism 50 for converting the rotary movement transmitted by the gear mechanism 16 to the linear movement, a toggle link mechanism 26 for converting the linear movement transmitted by the ball screw mechanism 50 to the turning movement of the clamp arm, and an air cushion mechanism 18 for buffering an impact to be generated when the clamp arm 20 reaches the terminal position of the movement thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric clamping device capable of clamping a work positioned and conveyed on a carriage in an automatic assembly line or the like.

[0002]

2. Description of the Related Art Conventionally, for example, in an automatic assembly line of an automobile, a work such as an engine is transported to each station by a bogie, and various work steps or assembling steps are performed on the work at each station.

In each station, it is necessary to position a work at a predetermined position in order to fix the work to a jig. In recent years, a clamping device has been provided on a bogie itself.
A method is adopted in which a work is conveyed while being clamped on a trolley, and the trolley is positioned at each station.

In this method, a clamp arm for clamping a work is rotated at a substantially constant speed from a displacement initial position in an unclamped state to a displacement end position in a clamped state. It is structured to stop.

[0005]

In the above-described conventional clamping device, for example, a toggle lever tightening device 3 as shown in FIG. 4 is driven by a motor 1 as a driving source, and its driving force is reduced. The power is transmitted to the pinion 5 via the drive shaft 4. The driving force transmitted to the pinion 5 is transmitted to the gear 7 by the meshing of the pinion 5 and the gear 7, and the teeth 6 provided on the outer periphery of the spindle 2 mesh with the inner periphery of the gear 7. Then, the driving force is transmitted to the spindle 2. The driving force transmitted to the spindle 2 is configured to rotate the arm 8 via a link portion provided continuously above the spindle 2.

However, a large impact is generated at the initial displacement position and the final displacement position where the arm 8 for clamping the workpiece is rotated. Respectively, the smooth linear motion of the spindle 2 is hindered, and the durability of the members (spindle 2, gear 7, pinion 5) constituting the meshing portion is deteriorated. .

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-described problems. When the clamp arm rotates and reaches the displacement end position, the shock can be suppressed by the shock absorbing mechanism. It is an object to provide a simple electric clamp device.

[0008]

In order to achieve the above object, the present invention provides a clamp device for gripping a workpiece by a rotating clamp arm, comprising: a rotary drive source driven to rotate by an electric signal; A gear for transmitting the rotational driving force of the rotational drive source, a feed screw mechanism for converting the rotational motion transmitted by the gear mechanism into a linear motion, and a linear motion transmitted by the feed screw mechanism for rotating the clamp arm And a buffer mechanism for buffering an impact generated when the rotating clamp arm reaches the displacement end position.

In this case, the buffer mechanism is provided with a piston which is integrally displaced with a ball screw shaft provided in a feed screw mechanism, and a throttle valve which reduces the flow rate of a fluid which is pressed by the piston and discharged from the room to the outside. It is preferable to provide the following.

In addition, the throttle valve is provided with a first throttle valve which performs a throttle function of a fluid discharged to the outside when the clamp arm rotates to one side to reach a clamp state, and a clamp arm rotates to the other side. Then, when reaching the displacement end position in the unclamped state, it may be configured by the second throttle valve which performs the throttle function of the fluid discharged to the outside.

Further, it is preferable that the piston is formed to have a non-circular cross-section, and the cross-sectional shape of the inner peripheral surface of the cylindrical body on which the piston slides is formed corresponding to the cross-sectional shape of the piston.

In the present invention, the shock generated when the clamp arm reaches the displacement end position is suppressed by the buffer mechanism, so that the vibration due to the shock is preferably prevented from being transmitted to the gear mechanism and the like in the body. Is done.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electric clamp device according to the present invention will be described in detail below with reference to the accompanying drawings showing preferred embodiments.

FIG. 1 shows an electric clamping device 10 according to an embodiment of the present invention.

The electric clamp device 10 includes a body 12
And a rotation drive unit 14 disposed below the body 12
A gear mechanism 16 for transmitting the rotation driving force of the rotation drive unit 14, an air cushion mechanism (buffer mechanism) 18 provided below the ball screw shaft 22, and a substantially circular shape formed on the body 12. And a clamp arm 20 which is connected to a bearing 24 having a rectangular cross section which protrudes outside through a pair of openings (not shown).

The rotation drive section 14 is composed of, for example, an induction motor, a brushless motor, or the like, and is formed of a rotation drive source that is driven to rotate by inputting an electric signal.

As shown in FIG. 1, a rotational driving force transmitting portion 28 for transmitting the rotational driving force of the rotational driving portion 14 to a toggle link mechanism 26 is provided in the body 12,
The rotation driving force transmission unit 28 includes the gear mechanism 16 and a ball screw mechanism (feed screw mechanism) 50.

The gear mechanism 16 includes a first gear 32 coaxially connected to the drive shaft 30 of the rotary drive unit 14, and a second gear 38 meshing with a first gear 36 of the first gear 32. And a second gear 34 formed so as to be substantially parallel to the axis of the drive shaft 30. On the other hand, the ball screw mechanism 50 is connected to the second gear 3 via a plurality of connecting pins 40.
Ball screw nut 4 provided integrally with and rotatable
2 and a screw hole 44 through which the ball screw nut 42 passes
And a ball screw shaft 22 that is displaced in the axial direction by being screwed into the shaft. The second gear 34 and the ball screw nut 42 are rotatably supported by a first bearing member 46 and a second bearing member 48, respectively.

The second gear 34 and the ball screw nut 42
And are integrally connected via a plurality of connection pins 40,
The first and second bearing members 46 and 48 are provided so as to integrally rotate about the axis of the ball screw shaft 22 as a rotation center. Accordingly, the ball screw shaft 22 is rotated by the rotation of the second gear 34 and the ball screw nut 42.
Are provided so as to be able to move up and down freely.

The air cushion mechanism 18 includes an upper first block body 56 and a lower second block body 58.
A cylindrical body 60 integrally connected between the first block body 56 and the second block body 58;
And a piston 64 connected to the lower side of the cylinder and integrally displaced, and a piston 64 connected to the piston rod 62 and slidably displaced along the cylindrical body 60. A piston packing (not shown) is mounted on the outer peripheral surface of the piston 64 via an annular groove.

In this case, a chamber 66 closed by the first block body 56, the second block body 58, and the cylindrical body 60 is formed. As shown in FIG. The chamber is divided into a chamber 68 and a lower chamber 70. Further, as shown in FIG. 3, the piston 64 has a substantially hexagonal cross section in which the corners are chamfered in a curved shape, and the inner peripheral surface of the cylindrical body 60 has a cross section substantially corresponding to the shape of the piston 64. By forming it in a hexagonal shape, a rotation preventing function for the ball screw shaft 22 is performed.

In the present embodiment, the piston 6
4 is formed in a substantially hexagonal cross section, but is not limited to this, and may be any non-circular cross section capable of performing a rotation preventing function.

As shown in FIG. 2, the first block body 56 includes a ball screw shaft 22 and a piston rod 6.
A through-hole 72 for displacing the base member 2 in the vertical direction is formed, and a ring-shaped first cushion packing 74 is mounted on an inner peripheral surface of the through-hole 72 via an annular groove. By surrounding the outer peripheral surface of the piston rod 62 formed slightly larger than the diameter of the ball screw shaft 22 by the first cushion packing 74, a sealing function is exhibited, and the inside of the upper chamber 68 is kept airtight.

A first throttle valve 78 is screwed into a screw hole formed along the substantially horizontal direction of the first block body 56, and one end of the first throttle valve 78 is gradually contracted. A tapered portion 82 having a diameter is formed. The first throttle valve 78
The tapered portion 82 faces the small-diameter orifice 88 of the first passage 84 that communicates the upper chamber 68 with the outside, and increases the screwing amount of the first throttle valve 78 to reduce the amount of air flowing through the first passage 84. By suppressing the flow rate, the flow rate of air exhausted from the upper chamber 68 to the outside via the first passage 84 is regulated.

The lower second block body 58 is formed with a recess 90 facing the end of the piston rod 62, and the inner peripheral surface of the recess 90 has a ring-shaped second cushion packing through an annular groove. 76 is mounted. By surrounding the outer peripheral surface of the piston rod 62 with the second cushion packing 76, a sealing function is exhibited, and the inside of the lower chamber 70 is kept airtight.

A second throttle valve 80 is screwed into a screw hole formed along the substantially horizontal direction of the second block body 58, and one end of the second throttle valve 80 is gradually contracted. A tapered portion 82 having a diameter is formed. The second throttle valve 80
The tapered portion 82 faces the small-diameter orifice 88 of the second passage 86 for communicating the inside of the lower chamber 70 with the outside.
By suppressing the flow rate of the air flowing through the second passage 86 by increasing the screwing amount of the throttle valve 80, the air exhausted from the lower chamber 70 to the outside via the second passage 86 is reduced. The flow rate is regulated.

The first throttle valve 78 and the second throttle valve 80 are not limited to variable throttles, but may be fixed throttles.

A communication passage 92 communicating with the second passage 86 is formed in the recess 90, and when the piston rod 62 is sealed by the second cushion packing 76, the recess 9 is formed.
The air remaining on the lower side of 0 is exhausted to the outside through the communication passage 92.

The toggle link mechanism 26 is connected to the ball screw shaft 2 via a knuckle block 94 as shown in FIG.
2 is converted into a rotational motion of the clamp arm 20, and a link plate 96 connected to the upper side of the knuckle block 94 via the first pin member 98;
And a support lever 52 rotatably supported by a pair of substantially circular openings (not shown).

The link plate 96 is interposed between the knuckle block 94 and the support lever 52, and has a function of linking the knuckle block 94 and the support lever 52. That is, the link plate 96 is connected to the knuckle block 94 via a first pin member 98 which is axially mounted on one of the holes, and is supported via a second pin member 100 which is axially mounted on the other of the holes. It is connected to the lever 52.

The support lever 52 has a bearing portion 24 having a rectangular cross section exposed from the body 12 to the outside through an opening (not shown). A clamp arm 20 is detachably mounted on the bearing portion 24 to clamp a work (not shown). In this case, the support lever 52 is provided so as to rotate integrally with the clamp arm 20.

The linear motion of the ball screw shaft 22 is transmitted to a support lever 52 via a knuckle block 94 and a link plate 96, and the support lever 52 is provided with a bearing projecting from a set of openings formed in the body 12. Part 24
Is provided so as to be rotatable by a predetermined angle around the center of rotation.

The electric clamp device 10 according to the embodiment of the present invention is basically constructed as described above. Next, the operation and effect of the electric clamp device 10 will be described.

In the initial position, the power supply (not shown) is energized to rotate the rotation drive unit 14. Rotation drive unit 14
The first gear 32 meshing with the drive shaft 30 of the drive shaft 30
, And the second gear 34 rotates counterclockwise with respect to the first gear 32 by the second teeth 38 meshing with the first teeth 36 of the first gear 32. The ball screw nut 42 integrally connected to the second gear 34 via the plurality of connection pins 40 rotates, and the ball screw shaft 22 screwed to the ball screw nut 42 rises.

The linear motion of the ball screw shaft 22 is transmitted to the toggle link mechanism 26 via a knuckle block 94, and the rotary motion of the clamp arm 20 is caused by the rotation of the support lever 52 constituting the toggle link mechanism 26. Is converted to

That is, the linear motion of the ball screw shaft 22 causes the knuckle block 94 and the link plate 96 to move.
Is applied upwardly. The pressing force against the link plate 96 rotates the link plate 96 by a predetermined angle around the first pin member 98 and rotates the support lever 52 in the direction of arrow B under the linking action of the link plate 96.

Therefore, the bearing portion 24 of the support lever 52
When the clamp arm 20 rotates a predetermined angle in the direction of arrow B about the fulcrum,
Reaches the clamped state in which the workpiece is gripped.

Before the clamp arm 20 is rotated in the direction of arrow B to be in the clamp state, the ball screw shaft 2
The air in the upper chamber 68 is pressed by the piston 64 that rises integrally with the second passage 8, and the air passes through the first passage 8
The gas is exhausted to the outside through the line 4. At this time, the air flowing through the first passage 84 is reduced to a predetermined flow rate by the tapered portion 82 of the first throttle valve 78 facing the small diameter orifice 88 of the first passage 84, so that the piston 64 is gradually decelerated. While moving upward, the clamp arm 20
The shock generated when the actuator reaches the displacement end position is buffered.

Further, by adjusting the flow rate arbitrarily in the first throttle valve 78, it is possible to adjust the time and the speed until the clamp arm 20 reaches the displacement end position.

In the clamped state, the biasing state of the rotation drive unit 14 is maintained, so that the clamping force for gripping the workpiece by the clamp arm 20 is maintained substantially constant.

In order to release the clamped state to the unclamped state, the polarity of the current to the rotary drive unit 14 is reversed so that the first gear 32 rotates in the opposite direction to the above, and the ball screw When the shaft 22 moves down, the clamp arm 20 is displaced in a direction away from the work (direction of arrow A) and returns to the initial position (displacement end position).

Before the clamp arm 20 is rotated in the direction of arrow A to be in the unclamped state, the air in the lower chamber 70 is pressed by the piston 64 that descends integrally with the ball screw shaft 22. The air is discharged to the outside through the second passage 86. At this time, the second passage 8
The air flowing through the second passage 86 is throttled to a predetermined flow rate by the tapered portion 82 of the second throttle valve 80 facing the small-diameter orifice 88, whereby the piston 64 is displaced downward while gradually decelerating. Therefore, the shock generated when the clamp arm 20 reaches the initial position on the unclamping side is buffered.

Further, by adjusting the flow rate arbitrarily in the second throttle valve 80, it is possible to adjust the time and speed until the clamp arm 20 reaches the initial position.

Although the present embodiment has been described using the ball screw mechanism 50, the present invention is not limited to this. Of course, a feed screw mechanism (not shown) including a sliding screw may be used. It is.

As described above, when the clamp arm 20 rotates to reach one and the other displacement end positions, the impact is buffered by the air cushion mechanism 18, so that the ball screw nut 42 and the ball screw shaft 22 The transmission of the vibration caused by the impact is prevented at the meshing portion of the first gear 32 and the second gear 34 and the like. As a result,
The smooth linear motion of the ball screw shaft 22 is ensured, and the durability of the members forming the meshing portion can be improved.

[0046]

According to the present invention, the following effects can be obtained.

When the clamp arm rotates and reaches the displacement end position, the shock is suppressed by the shock absorbing mechanism. Therefore, the vibration caused by the shock is caused in the meshing portion of the feed screw mechanism, the meshing portion of the gear mechanism, and the like. Transmission is blocked. As a result, a smooth linear motion of the feed screw shaft can be ensured, and the durability of the member forming the meshing portion can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view along an axial direction of an electric clamp device according to an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of an air cushion mechanism provided in the electric clamp device shown in FIG.

FIG. 3 is a partial sectional plan view showing a shape of a piston.

FIG. 4 is a schematic configuration side view of a clamp device according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Electric clamp device 12 ... Body 14 ... Rotation drive part 16 ... Gear mechanism 18 ... Air cushion mechanism 20 ... Clamp arm 22 ... Ball screw shaft 26 ... Toggle link mechanism 28 ... Rotation drive force transmission part 30 ... Drive shaft 32 ... No. 1 gear 34 ... second gear 42 ... ball screw nut 52 ... support lever 60 ... cylindrical body 62 ... piston rod 64 ... piston 78 ... first throttle valve 80 ... second throttle valve 82 ... taper portion 84 ... first passage 86 ... Second passage 88 ... Orifice 94 ... Knuckle block 96 ... Link plate

Continuing from the front page (72) Inventor Hiroshi Yuba 4-2-2 Kinudai, Yawahara-mura, Tsukuba-gun, Ibaraki Prefecture F-term (reference) in SMC Corporation Tsukuba Technical Center GB33 GD14 HA13 HA32 3J069 AA50 EE10

Claims (4)

[Claims] 1. A clamp device for gripping a workpiece by a rotating clamp arm, a rotation drive source that is driven to rotate by an electric signal, a gear mechanism that transmits a rotation drive force of the rotation drive source, and the gear mechanism. A feed screw mechanism that converts the rotational motion transmitted by the feed screw mechanism into a linear motion; a toggle link mechanism that converts the linear motion transmitted by the feed screw mechanism into a rotation operation of a clamp arm; An electric clamp device, comprising: a buffer mechanism that buffers an impact generated when the terminal clamp reaches the end position. 2. The device according to claim 1, wherein the shock-absorbing mechanism is a piston that is displaced integrally with a feed screw shaft provided in the feed screw mechanism, and is pushed out by the piston to be discharged from the room to the outside. An electric clamp device, comprising: a throttle valve for restricting a flow rate of a fluid. 3. The throttle valve according to claim 2, wherein the throttle valve has a first throttle valve that performs a throttle function of a fluid discharged to the outside when the clamp arm rotates to one side and reaches a clamped state. A second throttle valve that performs a throttle function of a fluid that is discharged to the outside when the clamp arm rotates to the other side and reaches the displacement end position in the unclamped state. apparatus. 4. The device according to claim 2, wherein the piston has a non-circular cross-section, and a cross-sectional shape of an inner peripheral surface of the cylinder on which the piston slides and displaces corresponds to a cross-sectional shape of the piston. An electric clamp device characterized by being formed by: