JPH0511364Y2 - - Google Patents

Description

[Detailed Description of the Invention] In the present invention, a piston and a piston rod are supported on a cylinder body so as to be slidably movable along the axial direction of the cylinder body by controlling the supply and discharge of pressure fluid, and the piston and the piston rod are A sliding/rotational motion conversion mechanism using a ball screw that converts the sliding motion of the piston rod into rotational motion is provided, and a brake capable of applying a braking force to an output shaft portion connected to the helical shaft of the motion conversion mechanism, as well as the aforementioned helical shaft. The present invention relates to a fluid pressure cylinder equipped with a rotation amount detector capable of detecting the amount of rotation of the cylinder.

The fluid pressure cylinder configured as described above moves the piston and the piston rod in sliding motion by supplying pressure fluid, and adjusts the position of a movable part such as a work table or a machining tool attached to the tip of the piston rod within a one-dimensional plane. When changing the position, the sliding motion is converted into rotational motion via a motion conversion mechanism using a ball screw, and the slight sliding position is detected as a greatly amplified amount of rotation, and the detected rotation is When the amount reaches a set value, by stopping the supply of pressure fluid and activating the brake at the same time, the position of the movable part within a one-dimensional plane can be controlled with extremely high precision. have.

However, since such a fluid pressure cylinder incorporates the above-mentioned motion conversion mechanism, one end of the helical shaft constituting the motion conversion mechanism is connected to the shaft center hole of the piston rod through a guide member or the like. A structure in which the guide member, etc. is supported so as to be able to rotate freely so as to be in sliding contact with the inner circumferential surface, and the guide member etc. is strongly slid against the inner circumferential surface of the shaft core hole of the piston rod in order to prevent wobbling from occurring in the rotation of the screw shaft. Because of this, unnecessary rotational force is more likely to act on the piston and piston rod during sliding movement than in a case where such a ball screw type motion conversion mechanism is not incorporated. The piston rod unexpectedly rotates around its axis due to such rotational force, and as a result, the posture of the movable part, especially in the two-dimensional plane, collapses, making it difficult to control the position of the one-dimensional inner surface with high precision. There is a possibility that the effect will be halved.

Therefore, in order to truly improve the various machining precisions involved in controlling the position and posture of moving parts, it is essential to prevent the piston and piston rod from rotating. ] or [] were adopted.

[] As shown in FIG. 3, the outer circumferential surface of the piston rod 3 and the inner circumferential surface of the sliding guide portion 1H of the cylinder body 1 relative to the piston rod 3 are formed into irregularly shaped surfaces such as squares.

[] As shown in FIG. 4, a bracket 51 that slidably supports a guide shaft 50 parallel to the piston rod 3 is fixed to the cylinder body 1, and the piston rod 3, the guide shaft 50, etc. are connected to each other. A member 52 for integral connection is provided.

In the case of the former [], not only does the machining of the sliding guide portion 1H of the piston rod 3 and the cylinder body 1 require a high degree of skill and a great deal of effort, but it is also necessary to ensure the seal between the piston rod 3 and the cylinder body 1. In addition, in the case of the latter [], there is a disadvantage that the entire cylinder becomes large because a component for preventing rotation is located protruding from the outer periphery of the cylinder body 1. There is.

The present invention was developed in view of the above circumstances, and it is possible to control the position of the piston and piston rod within a two-dimensional plane with extremely high precision, while at the same time making the entire cylinder as small as possible and easy to process. It is an object of the present invention to provide a fluid pressure cylinder that can ensure the desired rotation prevention and achieve a remarkable improvement in processing accuracy while being inexpensive.

In the fluid pressure cylinder according to the present invention, which has been made to achieve the above object, a piston and a perfectly circular piston rod are slidable along the axial direction of the cylinder body by controlling the supply and discharge of pressure fluid. A spiral shaft is movably supported and rotatably installed between the shaft core hole of the piston rod and the head cover, and a large number of balls rolling in the spiral groove of this spiral shaft can be circulated. A sliding/rotational motion conversion mechanism using a ball screw is provided which converts the sliding motion of the piston and the piston rod into an amplified rotational motion by a nut body that is held and fixedly connected to the piston, and the screw in the motion conversion mechanism The output shaft of the shaft is provided with a rotation amount detector capable of detecting the amount of rotation of this screw shaft, and when the amount of rotation detected by this rotation amount detector matches a set value, pressure fluid is supplied to the cylinder body. and a brake for applying a braking force to the screw shaft, the axial center of the piston rod being aligned with the axial center of the inner circumferential surface of the cylinder body and the outer circumferential surface of the piston. The piston rod is eccentric to the piston rod so as to prevent the piston rod from rotating.

[Function] While forming the inner circumferential surface of the cylinder body and the outer circumferential surfaces of the piston rod into perfect circular shapes that are most easily machined, by making the axis of the cylinder body and the axis of the piston rod eccentric. During the sliding movement of the piston and piston rod, even if the rotational force of the helical shaft converted by the sliding movement acts on the piston rod, the rotational force is transferred between the inner circumferential surface of the cylinder body and the outer circumferential surface of the piston. The piston and the piston rod are prevented from rotating in a predetermined manner by the contact force of the piston and the piston rod, and the piston and the piston rod are prevented from rotating in a one-dimensional plane (sliding direction).
The position control of the tip of the piston rod can be extremely precisely controlled by highly accurate position control and posture control in a two-dimensional plane using a rotation stopper.

[Effect] As described above, according to the present invention, the position control of the piston and piston rod within a one-dimensional plane is extremely possible due to the presence of the motion conversion mechanism using the ball screw, the rotation amount detector, and the brake. This can be done with high precision and prevents unnecessary rotation during sliding movement of the piston and piston rod.
In other words, by reliably preventing rotation, the position and posture control of the movable part attached to the tip of the piston rod can be performed reliably and accurately, and various machining precisions associated with these controls can be significantly improved. . Moreover, the structure for preventing rotation does not require any special processing technology, which not only facilitates processing and ensures a reliable seal, but also allows the piston rod to be aligned with the axis of the inner peripheral surface of the cylinder body. Since the cylinder is simply made eccentric with respect to the cylinder, the entire cylinder, which has the above-mentioned high precision performance, can be made as small as possible without any protruding parts on the outside.

As shown in FIGS. 1 and 2, the cylinder body 1 consists of a cylinder tube 1C having connection ports 1A and 1B for supplying and discharging pressure fluid, a head cover 1D, a rod cover 1E, and the like. 2 is a piston, 3 is a piston rod, 4 is a pin for fixing the screwed piston 2 and piston rod 3, 5 is a piston packing, and 6 is a piston gasket.

By supplying and discharging pressure fluid to both cylinder chambers 1F and 1G in the cylinder body 1 defined by the piston 2, the piston 2 and the piston rod 3 are connected to the cylinder tube 1C.
It is constructed so that it can be slid integrally in the axial direction.

The inner circumferential surface of the cylinder tube 1C, the outer circumferential surface of the piston 2, and the outer circumferential surface of the piston rod 3 are each formed in a perfect circular shape when viewed in the axial direction, and the axial center a of the piston rod 3 is aligned with the inner circumferential surface of the cylinder tube 1C. It is displaced in a direction perpendicular to the axis b of the circumferential surface and the outer circumferential surface of the piston 2.

By displacing the axes a and b in this manner, relative rotation between the cylinder body 1, the piston 2, and the piston rod 3 can be prevented.

Further, the cylinder body 1 includes a sliding rotation conversion mechanism 7 using a ball screw that converts the sliding motion of the piston 2 and the piston rod 3 into rotational motion, and a braking force is applied to the screw shaft 8 of this mechanism 7. A possible electromagnetic brake 9 and a pulse encoder (an example of a rotation amount detector) 10 for detecting the amount of rotation of the screw shaft 8 are provided.

To configure the sliding rotation conversion mechanism 7, the screw shaft 8 consisting of a screw shaft portion 8a and an output shaft portion 8b is inserted between the head cover 1D of the cylinder body 1 and the shaft center hole 3a of the piston rod 3. bearing 1
1, 11 and an annular guide member 12 so that the piston 2 can only rotate freely, and a nut body 13 that is screwed onto the screw shaft 8 is fixedly connected to the rear end of the piston 2.

The nut body 13 holds a large number of balls 14 that roll in the spiral groove of the screw shaft 8. This group of balls 14 circulates within the nut body 13.

Then, by controlling the supply and discharge of pressure fluid to both cylinder chambers 1F and 1G in the cylinder body 1,
When the piston 2 and the nut body 13 are moved together, the screw shaft 8 is rotated accordingly, and the pulse encoder 10 captures the amount of rotation. piston 2
There is a one-to-one correspondence relationship between the amount of displacement and the amount of rotation detected, including the direction. The amount of displacement is then greatly amplified and becomes the amount of rotation.

The output signal of the pulse encoder 10 is counted by the control, and when it matches a set value, the control signal of the controller closes the electromagnetic valve in the pressure fluid circuit. At the same time, the electromagnetic brake 9 is activated.

It is preferable to use a microcomputer or the like as the controller to which the pulse encoder 10 is connected.

Note that as the pressure fluid, any of hydraulic pressure, water pressure, pneumatic pressure, etc. may be used.

Next, another embodiment will be described. Illustrations omitted [] As the brake 9, other than an electromagnetic brake,
Hydraulic brakes, hand brakes, drum brakes, or anything else is fine.

[] The rotation amount detector 10 may be anything other than a pulse encoder. It may also be one that takes a mechanical output form.

[] The controller which inputs the rotation amount detector 10 may control anything.

[] The rotation amount detector 10, the brake 9, and the sliding rotation conversion mechanism 7 may be omitted.

[Brief explanation of the drawing]

1 and 2 show an embodiment of a fluid pressure cylinder according to the present invention, with FIG. 1 being a longitudinal sectional side view and FIG. 2 being a sectional view taken along the line -- in FIG. FIGS. 3 and 4 are perspective views of essential parts of a conventional fluid pressure cylinder, respectively. 1... Cylinder body, 2... Piston, 3...
Piston rod, 7...Sliding rotation conversion mechanism, 10
...Rotation amount detector.

Claims (1)

[Scope of utility model registration request] A piston 2 and a perfectly circular piston rod 3 are supported on the cylinder body 1 so as to be able to slide freely along the axial direction of the cylinder body 1 by controlling the supply and discharge of pressure fluid. A helical shaft 8 is installed between the hole 3a and the head cover 1D so as to be rotatable only, and a large number of balls 14 rolling in the spiral groove of the helical shaft 8 are held in a circulatory manner and are fixedly connected to the piston 2. A sliding rotational motion conversion mechanism 7 using a ball screw is provided which converts the sliding motion of the piston 2 and the piston rod 3 into an amplified rotational motion by means of a nut body 13. A rotation amount detector 10 capable of detecting the rotation amount of the screw shaft 8 is provided on the output shaft portion 8b of the screw shaft 8, and when the rotation amount detected by the rotation amount detector 10 matches a set value, the cylinder body 1 and a brake 9 for applying a braking force to the screw shaft 8, the axis a of the piston rod 3 is aligned with the inner circumference of the cylinder body 1. A fluid pressure cylinder characterized in that the piston rod 3 is prevented from rotating by being eccentric with respect to the axis b of the surface and the outer peripheral surface of the piston 2.