JP4130331B2 - Electric clamp device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric clamp device that rotates a clamp lever with a driving force of a motor.
[0002]
[Prior art]
Conventionally, in this type of electric clamp device, a worm gear device is interposed between the motor and the clamp lever. The worm gear device includes a worm and a worm wheel that mesh with each other. The worm is connected to a drive shaft of a motor, and the worm wheel is rotated integrally with a clamp lever. When the motor rotates, the driving force is transmitted to the clamp lever via the worm gear device.
[0003]
[Problems to be solved by the invention]
However, in the conventional electric clamping device, when the workpiece is clamped, the rotation of the clamp lever suddenly stops, and at the same time, the rotation of the worm wheel also stops suddenly. At this time, the motor is stopped, but tends to continue rotating because it has inertial energy. Therefore, a large impact force is applied to the meshing portion between the worm wheel and the worm, and there is a possibility that these tooth tips will be excessively bitten or missing in the other tooth.
[0004]
The present invention has been made paying attention to such problems existing in the prior art. The purpose is to provide an electric clamping device that can prevent excessive biting and missing teeth at the meshing part of the worm wheel and worm by absorbing the impact force when the workpiece is clamped by the clamp lever. There is to do.
[0005]
[Means for Solving the Problems]
(Invention of claim 1 corresponding to the first to third embodiments)
In the first aspect of the present invention, a worm is connected to the drive shaft of the motor, a worm wheel meshed with the worm is provided with a clamp lever that rotates integrally with the worm wheel, and the driving force of the motor is supplied to the worm and worm wheel. In the electric clamp device that is transmitted to the clamp lever via the worm, the worm can slide along the axial direction of the drive shaft of the motor, and the worm and the worm wheel mesh when the clamp lever clamps the workpiece. The present invention is summarized in that a shock absorbing member that absorbs an impact force generated in the portion is provided , and a movable bearing that is slidable along the axial direction of the worm is provided between the worm and the shock absorbing member .
[0006]
With this configuration, when the motor is driven, the driving force is transmitted to the clamp lever via the worm and the worm wheel. The workpiece is clamped or unclamped by rotating the clamp lever. When the clamp lever clamps the workpiece, the impact force generated at the meshing part of the worm and worm wheel is absorbed by the compression coil spring, so each tooth tip is brought into contact with the other tooth at the meshing part of the worm and worm wheel. Excessive biting can be prevented and tooth loss can be prevented.
[0007]
(Invention of Claim 2 corresponding to Embodiments 1 to 3)
According to a second aspect of the present invention, in the electric clamp device according to the first aspect, the buffer member gives an elastic force in a direction in which the clamp lever clamps the workpiece.
[0008]
With this configuration, the elastic force of the compression coil spring always works in the direction of clamping the workpiece. For this reason, even if the power supply to the motor is interrupted during clamping, a clamping thrust is generated, so that the clamping force can be maintained.
[0009]
(Invention of claim 3 corresponding to embodiment 3)
According to a third aspect of the present invention, in the electric clamp device according to the first or second aspect, the buffer member is composed of a plurality of disc springs arranged in the axial direction of the worm. And
[0010]
With this configuration, the installation space for the buffer member can be reduced as compared with, for example, a case where a coil spring or the like is used for the buffer member. This makes it possible to reduce the size of the electric clamp device.
[0011]
(Invention of Claim 4 corresponding to Embodiments 2 and 3)
According to a fourth aspect of the present invention, in the electric clamp device according to any one of the first to third aspects, an Oldham coupling is provided between the drive shaft of the motor and the rotary shaft of the worm. It is a summary.
[0012]
With this configuration, when connecting the drive shaft of the motor and the rotary shaft of the worm via the key, it is necessary to cut the key groove for assembling the key, but if Oldham coupling is used, Such a cutting process becomes unnecessary. Therefore, the manufacturing cost can be reduced.
[0013]
(Invention of claim 5 corresponding to Embodiment 3)
According to a fifth aspect of the present invention, in the electric clamp device according to any one of the first to fourth aspects, a plurality of the worm wheels are provided so as to confront each other in the radial direction of the worm. The gist is that each clamp lever approaches or separates as it rotates.
[0014]
According to this configuration, when the worm rotates by driving the motor, the respective clamp levers rotate in directions toward or away from each other as the worm wheels rotate. In short, the workpiece is clamped by the clamp levers approaching each other, and the workpiece is unclamped by being separated.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
[0016]
As shown in FIGS. 1 (a), 1 (b), and 2, the electric clamp device 11 includes a cylindrical case 14 in which a worm 12 is accommodated, and both end openings are end caps 15, 16 respectively. It is blocked by. A compression coil spring 17 is provided on the inner end surface of the lower end cap 15, and a movable bearing 19 is supported on the upper end portion via a spring receiver 18. With such a configuration, the movable bearing 19 is movable along the axial direction of the worm 12 while bending the compression coil spring 17.
[0017]
A fixed bearing 20 is provided in the upper end opening of the case 14 at a predetermined distance from the movable bearing 19. The lower end portion of the worm 12 is inserted into the movable bearing 19 located on the lower side of the case 14, and the upper end portion of the worm 12 is inserted into the fixed bearing 20 located on the upper side, so that the worm 12 can rotate. It has become. In addition, since the worm 12 is supported on the movable bearing 19, the worm 12 can move in the vertical direction together with the movable bearing 19.
[0018]
As shown in FIGS. 1A, 1B, and 3, a motor 25 that is rotatable in forward and reverse directions is fixed to the outer end surface of the lower end cap 15, and its drive shaft 25a is connected to the lower end cap 15. It is inserted into the case 14 through a through hole 15a formed in the central portion of the. The tip of the drive shaft 25a of the motor 25 is slidably inserted into an insertion hole 12b formed in the lower end of the rotating shaft 12a of the worm 12. The drive shaft 25a of the motor 25 and the rotary shaft 12a of the worm 12 are respectively formed with key grooves 27a and 27b extending in the axial direction thereof, and the motor is connected via the key 26 provided in the key grooves 27a and 27b. Twenty-five rotational forces are transmitted to the worm 12.
[0019]
The key 26 is press-fitted and fixed in one of the key grooves 27a and 27b, and is slidably engaged in the other. Thus, the worm 12 can slide along the axis of the drive shaft 25 a of the motor 25 while being guided by the key 26. Incidentally, in this embodiment, the key 26 is press-fitted and fixed in a key groove 27a formed in the drive shaft 25a.
[0020]
As shown in FIGS. 1A, 1B, and 2, a housing 29 is attached to a side portion of the case 14, and a worm wheel 30 engaged with the worm 12 is accommodated therein. The worm wheel 30 is rotatable by inserting a rotating shaft 30 a through a bearing 31 provided in the housing 29. Both end portions of the rotating shaft 30 a of the worm wheel 30 protrude from the housing 29, and a clamp lever 32 is connected to the protruding portion via a key 33.
[0021]
Then, as the worm wheel 30 rotates with the rotation of the worm 12, the clamp lever 32 moves between the unclamping position P1 shown in FIG. 1 (a) and the clamping position P2 shown in FIG. 1 (b). It is designed to rotate. When the clamp lever 32 is located at the unclamping position P1, a workpiece (not shown) is released from the clamp, and when it is located at the clamping position P2, the workpiece is clamped.
[0022]
Now, in the electric clamp device 11 configured as described above, when the motor 25 rotates in a predetermined direction with the clamp lever 32 disposed at the unclamp position P1, the clamp lever 32 is moved to the clamp position P2. Rotate towards. When the clamp lever 32 reaches the clamp position P <b> 2, energization to the motor 25 is cut off, and a workpiece (not shown) is clamped by the clamp lever 32.
[0023]
When the workpiece is clamped, the worm wheel 30 is also suddenly stopped as the clamp lever 32 is suddenly stopped at the clamp position P2. As a result, the power supply to the motor 25 is cut off.
[0024]
Even when the energization of the motor 25 is interrupted, the motor 25 has inertial energy, so that the worm 12 acts in the same direction as the clamping direction. However, since the rotation of the worm wheel 30 is restricted in the clamped state, the worm 12 starts to slide so as to approach the motor 25. The compression coil spring 17 is compressed against the elastic force by the slide of the worm 12, that is, linear motion, and the inertia energy of the motor 25 is absorbed. Furthermore, since the elastic force of the compressed compression coil spring 17 acts in the direction of increasing the clamping force of the clamp lever 32, the clamping thrust can always be applied even when the motor 25 is de-energized.
[0025]
Therefore, according to the present embodiment, the following effects can be obtained.
(1) When the clamp lever 32 clamps the workpiece, the impact force generated at the meshing portion between the worm 12 and the worm wheel 30 can be absorbed by the compression coil spring 17. Therefore, it is possible to prevent each tooth tip from excessively biting into the other tooth base at the meshing portion between the worm 12 and the worm wheel 30. Therefore, when unclamping, the worm 12 and the worm wheel 30 can be smoothly rotated in a direction opposite to the direction when clamping, and a smooth unclamping operation can be obtained.
[0026]
(2) When the clamp lever 32 clamps the workpiece, the impact force generated at the meshing portion between the worm 12 and the worm wheel 30 can be absorbed, so that missing teeth can be prevented.
[0027]
(3) The elastic force of the compression coil spring 17 that absorbs the impact force generated at the meshing portion between the worm 12 and the worm wheel 30 always works in the direction in which the clamp lever 32 clamps the workpiece. Therefore, even when energization to the motor 25 is interrupted during clamping, the clamping thrust can be generated by the elastic force of the compression coil spring 17, and the clamping force can be maintained.
[0028]
(Second Embodiment)
The second embodiment will be described focusing on the differences from the previous embodiment. In addition, about the same structure as the said 1st Embodiment, the description is abbreviate | omitted and the same code | symbol is attached | subjected.
[0029]
As shown in FIGS. 4 and 5, an Oldham coupling 40 is interposed between the rotating shaft 12 a of the worm 12 and the driving shaft 25 a of the motor 25. The Oldham coupling 40 includes a drive coupling member 41 connected to the drive shaft 25 a of the motor 25 by a screw 43 and a driven coupling member 42 formed integrally with the rotary shaft 12 a of the worm 12. The coupling members 41 and 42 are engaged with each other in a concavo-convex relationship. With such Oldham coupling 40, the rotational force of the motor 25 is transmitted to the worm 12, and the worm 12 is allowed to be displaced in the axial direction of the drive shaft 25a of the motor 25.
[0030]
Therefore, also in the second embodiment, substantially the same effect as that of the first embodiment described above can be exhibited. In particular, in the second embodiment, the Oldham coupling 40 is used instead of the key 26 described in the above embodiment. Therefore, it is not necessary to cut the key grooves 27a and 27b for engaging the key 26 as compared with the case where the motor 25 and the worm 12 are driven and connected by the key 26. Thus, it is not necessary to perform highly accurate processing, and the manufacturing cost of the electric clamp device 11 can be reduced by using the versatile and relatively inexpensive Oldham coupling 40.
[0031]
(Third embodiment)
The third embodiment will be described focusing on the differences from the previous embodiment.
As shown in FIGS. 6 and 7, the worm 12 is meshed with two worm wheels 30 arranged to face each other in the radial direction. When the motor 25 rotates in a specific direction, the clamp levers 32 provided on the worm wheels 30 rotate in directions approaching each other, and a workpiece (not shown) is clamped by both the clamp levers 32. When the motor 25 rotates in a direction opposite to the clamping direction, the clamp levers 32 rotate in directions away from each other, and the workpiece is unclamped. 7 shows a state where the clamp levers 32 are spaced apart from each other, that is, an unclamped state.
[0032]
In this embodiment, a fixed bearing 20 is provided on the lower side of the worm 12 and a movable bearing 19 is provided on the upper side. Further, the compression coil spring 17 shown in the above embodiment is omitted, and a disc spring 50 is provided in contact with the movable bearing 19 instead. When both the clamp levers 32 clamp the workpiece, the impact force generated at the meshing portion between the worm 12 and the worm wheel 30 can be absorbed by the disc spring 50, and the same effect as in the above embodiment can be achieved. Moreover, since the disc spring 50 is smaller than the compression coil spring 17, the length of the electric clamp device 11 in the vertical direction can be made compact.
[0033]
(Another embodiment)
The embodiment of the present invention may be modified as follows.
In the electric clamp device 11 shown in the first and second embodiments, the disc spring 50 shown in the third embodiment may be used in place of the compression coil spring 17.
[0034]
In the third embodiment, two worm wheels 30 that can rotate integrally with the clamp lever 32 are engaged with one worm 12, but three or more worm wheels 30 may be engaged with the worm 12.
[0035]
Next, in addition to the technical idea described in the claims, the technical idea grasped by the above-described embodiment will be described below.
(1) A worm coupled to a drive shaft of a motor is engaged with a plurality of worm wheels arranged so as to face each other in the radial direction, and a clamp lever is integrally provided on the rotation shaft of each worm wheel. An electric clamping device that transmits driving force to a clamp lever via a worm and a worm wheel.
[0036]
【The invention's effect】
According to the present invention, when the workpiece is clamped by the clamp lever, the impact force is absorbed, thereby preventing excessive engagement and missing teeth at the meshing portion between the worm wheel and the worm. can do.
[Brief description of the drawings]
FIG. 1 is an electric clamp device according to a first embodiment, wherein (a) shows an unclamped state and (b) is a front sectional view showing a clamped state.
FIG. 2 is a cross-sectional plan view of the electric clamp device according to the first embodiment.
FIG. 3 is a cross-sectional view showing a connecting portion between a drive shaft of a motor and a rotary shaft of a worm in the first embodiment.
FIG. 4 is a front sectional view of an electric clamp device according to a second embodiment.
FIG. 5 is a plan sectional view of an Oldham coupling in a second embodiment.
FIG. 6 is a front sectional view of an electric clamp device according to a third embodiment.
FIG. 7 is a cross-sectional plan view of an electric clamp device according to a third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Electric clamp apparatus, 12 ... Worm, 25 ... Motor, 25a ... Drive shaft, 30 ... Worm wheel, 32 ... Clamp lever, 17 ... Compression coil spring (buffer member), 40 ... Oldham coupling, 50 ... Disc spring (buffer) Element).

Claims (5)

A worm is connected to the drive shaft of the motor, a worm wheel meshed with the worm is provided with a clamp lever that rotates integrally with the worm wheel, and the driving force of the motor is transmitted to the clamp lever via the worm and the worm wheel. In the electric clamping device as described above,
A worm is slidable along the axial direction of the drive shaft of the motor, and a shock absorbing member that absorbs an impact force generated at a meshing portion between the worm and the worm wheel when the clamp lever clamps a workpiece is provided ,
An electric clamp device comprising a movable bearing that is slidable along the axial direction of the worm between the worm and the buffer member . The electric clamp device according to claim 1, wherein the buffer member applies an elastic force in a direction in which the clamp lever clamps the workpiece. 3. The electric clamp device according to claim 1, wherein the buffer member includes a plurality of disc springs arranged in the axial direction of the worm. 4. The electric clamp device according to claim 1, wherein an Oldham coupling is provided between the drive shaft of the motor and the rotary shaft of the worm. The worm wheel is provided in a plurality so as to face each other in the radial direction of the worm, and each clamp lever approaches or separates as each worm wheel rotates. The electric clamp device according to item.

Images