JPS58180806A - Linear driving device - Google Patents

Abstract

PURPOSE:To miniaturize an apparatus, by a method wherein an insertion hole is bored on a piston body, a female screw is provided in the insertion hole and a threaded rod to be screwed in the female screw, whose one end is connected with a motor, is inserted in the above insertion hole. CONSTITUTION:An insertion hole 5 is bored on a piston body 3 and a female screw 8 is provided in the insertion hole 5. On the one hand, a threaded rod 7 formed a male screw 22 is inserted inside the insertion hole 5 for making screw fit in the female screw 8, and a motor 9 is connected with one end of the threaded rod 7 for making the threaded rod 7 into a rotatable state. With this, as the titled device is made into constitution combining a hydraulic cylinder and a screw type linear driving device compactly with each other, strong linear driving force by means of hydraulic pressure and accurate positioning by means of screwing motion can be made and the whole of an apparatus can be miniaturized as well.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in linear drive devices used in, for example, NC machine tools and NC robots.

Conventionally, in machine tools and the like, objects are often moved linearly in vertical or horizontal directions, and in this case, +, 1 is often used as a dynamic or double-acting type fluid pressure cylinder.

This type of hydraulic cylinder can only provide a relatively large driving force and has poor positioning capabilities. In particular, when stopping at a so-called mid-stroke position other than the stroke end, an error of several millimeters occurs each time the movement occurs, making it difficult to accurately stop at a predetermined position.

However, this fluid pressure cylinder has the disadvantage that it cannot be reliably held at a predetermined stop position because fluid leakage occurs to some extent.

In order to solve this problem, a screw type linear drive device is known which combines a screw mechanism and a motor.

Since this device uses a screw mechanism, positioning from the same direction of rotation is extremely accurate, although there is some discrepancy.

However, this device had a drawback in that it could not produce the same driving force as a hydraulic cylinder unless the horsepower of the motor was considerably increased. For this reason, it is larger than a fluid pressure cylinder (compared to a hydraulic cylinder) and cannot be used in cases where installation space is limited.

The present invention was devised in view of the above-mentioned problems and to solve them.The purpose of the present invention is to obtain a large linear driving force, to perform accurate positioning, and to be able to achieve relatively high linear driving force. An object of the present invention is to provide a linear drive device that can be constructed in a small size.

The linear drive device of the present invention includes a cylindrical cylinder body, a slidable piston body fitted inside the cylinder body, a cylinder chamber formed in the cylinder body, and a cylinder chamber bored in the piston body. an insertion hole, a through hole drilled in the rear wall of the cylinder body, a screw rod rotatably inserted into the insertion hole and the through hole, and a screw rod provided in the piston body and screwed into the screw rod. The cylinder body is characterized by a female screw, and a motor attached to the rear wall of the cylinder body and connected to its rotating shaft or screw rod.

In other words, it is a compact and skillful combination of a fluid pressure cylinder and a screw type linear drive device, and it exhibits the large linear driving force of a fluid pressure cylinder and the accurate positioning function of a screw type linear drive device. However, the entire structure can be made relatively compact.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of embodiments of the present invention will be explained below based on the drawings showing embodiments of the present invention.

The drawing is a longitudinal sectional view showing the structure of a linear drive device according to the present invention.

A linear drive device 1 according to the present invention includes a cylinder body 2, a piston body 3, a cylinder chamber 4, an insertion hole 5, a through hole 6, and a threaded rod 7.
, a female screw 8, and a motor 9.

The cylinder body 2, the piston body 3, and the cylinder chamber 4 constitute a so-called fluid pressure cylinder, and the insertion hole 5 and the through hole 6
, a screw rod 7, a female screw 8, and a motor 91 constitute a screw type linear drive device.

The cylinder body 2 has a cylindrical shape, and in this example is composed of a cylinder tube 10 serving as a peripheral wall, a rod cover 11 serving as a front wall, and a cylinder cover 12 serving as a rear wall.

Female threads are provided on the front and rear inner surfaces of the cylinder tube 10, and male threads are provided on the rear outer surface of the rod cover 11 and the front outer surface of the cylinder cover 12, respectively, and by screwing these together, the rod Cover 11 is cylinder tube 1
A cylinder cup <-12 is attached to the front side of the cylinder tube IO, and a cylinder cup <-12 is attached to the rear side of the cylinder tube IO.

OIJ songs 3 and 13 for sealing are interposed at the connecting portions of each member.

The rod cover 11 includes a rod through hole 14 bored in the center and a port 15 that reaches the cylinder chamber 4 (piston rod chamber) on the front side.

The Norinda cover 12 includes a port 16 that reaches the rear cylinder chamber 4 (tail chamber).

The piston body 3 is connected to the cylinder tube 10 of the cylinder body 2.
It consists of a piston 17 that is slidably fitted inside the rod cover 11, and a piston rod 18 that is slidably fitted into the rod through hole 14 of the rod cover 11 and is connected to the piston 17.

QIJ songs 9 for sealing are provided between the piston 17 and the cylinder tube 10 of the cylinder body 2, and between the piston rod 18 and the rod cover 11 of the cylinder body 2, respectively.
...or there is an intervention.

/The cylinder chamber 4 is formed inside the cylinder body 2, and in this example, there is a piston rod chamber 20 on the front side and a tail base 21 on the rear side depending on the piston 17 of the piston body 3.

The insertion hole 5 is bored in the piston body 3 and is formed inside the piston rod 18 from the rear surface of the piston 17. The rear side of the insertion hole 5 is formed into a large diameter female screw hole.

(1) The through hole 6 is bored in the rear wall of the cylinder body 2, that is, in the center of the cylinder cover 12. The front and back of the through hole 6 are large diameter bearing housing cavities.

The threaded rod 7 is provided with a male thread 22 approximately in the front half thereof, and then has a flange portion, a non-threaded portion, and a male threaded portion formed respectively, and a connecting hole for connection is bored from the rear end.

When the male screw 22 is loosely fitted into the insertion hole 5,
The threadless portion is fitted into the through hole 6. The threadless portion is supported by the bearings 23 and 24 fitted in the bearing housing cavity, and the threaded rod 7 becomes rotatable relative to the cylinder body 2.

The front bearing 23 is an angular bearing and is located between the flange of the screw rod 7 and the cylinder head <-12, while the rear bearing 24 is a thrust bearing and is located between the flange of the screw rod 7 and the male thread of the screw rod 7. screwed into the set screw 2
It exists between the cylinder cover 12 and the locking nut 26 fixed at 5.

Note that there is a space between the threadless part of the threaded rod 7 and the cylinder cover 12.
An O-ring 27 for sealing is provided.

The female screw 8 matches the male screw 22 of the screw rod 7 and is provided on the piston body 3.

In this example, instead of being directly formed on the piston body 3, it is provided at the center of a separate screw piece 28.

The screw piece 28 is screwed into the female screw hole of the insertion hole 5 and fixed to the piston body 3 by a lock nut 29 which is also screwed into the female screw hole. The screw piece 28 and the lock nut 29 are prevented from loosening by a set screw 30, and a small exhaust pressure hole 31 is bored in the screw piece 28.

The motor 9 may be a servo motor or a pulse motor, most preferably a pulse motor, and is equipped with a rotating shaft 32. The main body of the motor 2) has bolts 3 attached to the rear wall of the cylinder body 2, that is, the rear of the cylinder cover 12.
On the other hand, the rotating shaft 32 is inserted into a connecting hole provided at the rear of the screw rod 7 and connected by +)-his 34.

In the figure, 35 is a bracket of the fixed body, 36 is a mounting hole drilled in the bracket, 37 is a mounting screw screwed into the rod cover 11 of the cylinder body 2, and 38 is a mounting nut screwed into the mounting screw r. , 39 is the piston rod 1 of the piston body 3
8 is a screw hole for mounting the movable body screwed at the tip, 40 is an insertion hole for a set screw drilled in the cylinder cover 12 of the cylinder body 2, and 41 is a boron implanted in the rod cover 12 of the cylinder body 2. The rod, 42, is a boronized through-hole drilled in the piston 17 of the piston body 3 and into which the boronized rod is fitted, and 43 is an O-ring interposed between the boride rod and the piston 17, respectively.

The borided rod 41, borated through hole 42.0 ring 43 are
+1J If the rotation is stopped against a moving object or a fixed object, it can be omitted.

11, 45 is piping, 46 is a control valve, 47 is a pump, 4
Reference numeral 8 indicates a tank, and the control valve 46 and motor 9 are electrically connected to the control device 5o through wiring 49, respectively.

In the linear drive device 1 according to the present invention, the supply and discharge of the pressure fluid, the direction of the screw, the rotation direction of the motor, etc. are set so that the forward and backward movement by the pressure fluid corresponds to the forward and backward movement by the screw mechanism. has been done.

In this example, when the motor 9 rotates forward, the screw rod 7 and the female screw 8
As the piston body 3 moves forward, the pressure fluid from the pump 47 reaches the tail chamber 21. Conversely, when the motor 9 reverses, the screw rod 7 and the female screw 8 cause the piston body 3 to move backward. It is set so that the pressure fluid from the pump 47 reaches the piston rond chamber 2o.

Next, the operation in such a configuration will be explained.

゛The forward movement signal is sent from the control device 50 to the motor 9 and the control valve 4.
6, the motor 9 rotates normally and the control valve 46 is switched to the right position.

When the control valve 46 is in the right position, the pressure fluid from the pump 47 reaches the tail chamber 21 via the control valve 46 → piping 45 → port 16. Therefore, the piston body 3 is pressurized in the forward direction by the pressure fluid.

Under such a pressurized state, if the screw rod 7 does not rotate, the piston body 3 will not move forward.

However, since the motor 9 rotates in the normal direction, the screw rod 7 also rotates in the same direction, and the piston body 3 moves forward due to the male screw 22 of the screw rod 7 and the female screw 8 on the piston body side.

At this time, the fluid in the piston Rondo chamber 20 flows from port I5→
The water is returned to the tank 48 via the piping 44 and the control valve 46.

A stop signal is sent from the control device 50 to the motor 9 and the control valve 46.
, the motor 9 is stopped and the control valve 46 is placed in the neutral position shown in the figure.

Therefore, the piston body 3 is reliably held at its stop position by the screw rod 7 and the female screw 8.

Next, when a reverse signal is issued from the control device 50, the motor 9 rotates in the reverse direction and the control valve 46 moves to the left position.

When the control valve 46 is in the left-hand position, the pressure fluid from the pump 47 reaches the piston rond chamber 20 via the piping 44 and the port 15, and pressurizes the piston body 3 toward the backward movement side.

Under this pressurized state, the motor 9 rotates in reverse, so the piston body 3 moves backward due to the screw rod 7 and female screw 8.

In this case, the fluid in the tail chamber 21 is returned to the tank 48 via the port 16 → the piping 45 → the control valve 46.

When moving forward and backward, the pressure on the piston body 3 caused by the pressurized fluid and the screw movement of the threaded rod 7 and female screw 8 caused by the rotation of the motor 9 may not necessarily synchronize reliably. 3 can move forward or backward well.

Also, depending on the signal from the control device 50, fast feed or slow feed can be performed when moving forward or backward.

Even if there is a slight leakage of the pressurized fluid during movement or stoppage, the screw rod 7 and female screw 8 mechanically operate or stop the feed or stop, making it extremely reliable.

In this embodiment, a so-called double-acting fluid pressure cylinder is illustrated, which is equipped with two cylinder chambers 4, a piston rod chamber 20 and a tail chamber 21, and supplies pressurized fluid to these chambers. It may also be a single-acting fluid pressure cylinder that supplies pressure fluid to only one of the cylinder chambers.

Of course, a structure like a ram cylinder may also be used.

As described above, according to the present invention, the following excellent effects can be achieved.

(1) Since it has a structure that combines a fluid pressure cylinder and a screw type linear drive device, it can exhibit a powerful linear drive force due to fluid pressure and an accurate positioning function due to screw movement.

As a result, fast feed, slow feed, and stopping can be performed well, and NC
It can be easily applied to machine tools, NC robots, etc.

(2) The load on the piston body is borne by the pressure fluid, and the motor only performs the positioning function, so the motor can be small and the cost is low.

(3) Since the screw mechanism is incorporated inside the fluid pressure cylinder and the motor is attached to the rear of the fluid pressure cylinder, the combination is cleverly and compactly made, so that the overall size can be reduced.

Therefore, it can be easily installed in places where space is limited.

[Brief explanation of drawings]

The drawing is a longitudinal sectional view showing the structure of a linear drive device according to the present invention. 1... Linear drive device 2... Cylinder body 3... Piston body 4... Cylinder chamber 5... Insertion hole 6...・Threaded hole 7...Threaded rod 8...Female screw 9...Motor

Claims (1)

[Claims] A cylindrical cylinder body, a slidable piston body fitted inside the cylinder body, a cylinder chamber formed in the cylinder body, an insertion hole bored in the piston body, and a piston body fitted inside the cylinder body and capable of sliding. a through hole drilled in the rear wall, a screw rod rotatably inserted into the insertion hole and the through hole, a female screw provided on the piston body and screwed into the screw rod, and the norinda body. A linear drive device characterized by comprising a motor attached to the rear wall of the machine and connected to its rotating shaft or screw rod.