JPH0478356A - Friction drive feeding device - Google Patents

Abstract

PURPOSE:To maintain stable and smooth feeding for a long period of time without generating the abnormal abrasion and rattling of balls by providing a fluid pressure medium accommodating chamber in the state of surrounding the inner peripheral wall of a sleeve, and also a pressure regulating means for regulating the pressure of an accommodated fluid pressure medium. CONSTITUTION:A sleeve 1 is provided with a fluid pressure medium accommodating chamber 4 formed concentrically with the inner peripheral wall of the sleeve 1 in such a way as to surround this inner peripheral wall, and a fluid pressure medium 5 is filled therein. This fluid pressure medium accommodating chamber 4 is formed as close as possible to the inner peripheral surface of the sleeve 1 in such a way that the inner peripheral wall thereof is expanded slightly in the direction of a center axis by the pressure at the time of increasing the pressure of the fluid pressure medium 5 so as to press balls 3 to the peripheral surface of a rotary shaft 2 with the specified pressure. The fluid pressure medium 5 is filled into the fluid pressure medium accommodating chamber 4 from its opening part 4a. A screw plug 6 is screwed into the opening part 4a of the fluid pressure medium accommodating chamber 4. The pressure of the fluid pressure medium 5 is heightened by this screw-in, and the pressure of the filled pressure medium 5 can be regulated by regulating the screw-in quantity of the screw plug 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for precisely linearly feeding a table or head of a mechanical device.

[Conventional technology]

It is made by inserting a round bar-shaped rotating saw soft into a cylindrical sleeve.
By holding the rotating shaft with a large number of friction balls or rollers arranged along a spiral retainer formed on the inner peripheral surface of the sleeve, relative rotational motion between the sleeve and the rotating shaft is converted into linear motion. Such friction-driven feed devices are known.

In such a friction-driven feeding device, the linear movement force between the sleeve and the rotary shaft is achieved by the frictional rotation of the holes or rollers interposed between them. Dimensional accuracy between rotating shafts must be set strictly.

For this reason, conventionally, as shown in FIG. 6, the sleeve side is divided into two blocks IA and 1B, and both blocks are tightened with port screws IC.

Thereby, the frictional force of the ball 3 interposed between the rotary shaft 2 and the round rod-shaped rotating shaft 2 can be adjusted by adjusting the amount of tightening of the screw 1c.

However, the ball 3' that has fit into the gap 10 at the joint between the blocks IA and IB has the disadvantage that it is rubbed against the edges of the blocks IA and IB, causing abnormal wear. If it falls into the gap ID, the contact condition with the rotating shaft deteriorates, causing wobbling in this area and causing a problem in that the feeding accuracy decreases.

[Problem to be solved by the invention]

The present invention has been made to solve the above problems, and its purpose is to provide a friction drive that can maintain stable and smooth feeding over a long period of time without causing abnormal wear or rattling of the balls. Our goal is to provide a feeding device.

[Means to solve the problem]

The above object is to provide a fluid pressure medium storage chamber surrounding the inner circumferential wall of the sleeve, without dividing the sleeve as in the past, and to provide means for adjusting the pressure of the fluid pressure medium accommodated in this chamber. can be achieved.

Alternatively, the fluid pressure medium storage chamber may be connected to the rotating shaft 71.
Furthermore, a fluid pressure medium storage chamber may be provided both around the inner circumferential wall of the sleeve and inside the rotating shaft.

As the pressure regulating means, it is recommended to use a screw plug provided in an opening communicating from the fluid pressure medium storage chamber to the outside.

[For production]

As described above, in the present invention, the pressure of the fluid pressure medium injected into the fluid pressure medium storage chamber provided around the inner circumferential wall of the sleeve or inside the rotating shaft is adjusted using the pressure adjustment means. Appropriate and uniform tightening can apply pressure to the balls or rollers interposed between the rotating shaft and the rotating shaft. It is possible to provide extremely smooth feeding without causing excessive wear or rattling.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a sectional view along the axial direction showing one embodiment of the friction drive feeding device according to the present invention, FIG. 2 is a partially enlarged view thereof, and FIG. 3 is an exploded sectional view showing another embodiment. 4 and 5 are cross-sectional views showing still another embodiment, FIG. 6 is an explanatory view of a conventional device, and FIG. 7 is an experimental graph showing the effects of the friction drive feeding device according to the present invention.

First, the embodiment shown in FIG. 1 will be explained.

In Figure 1, ■ is a sleeve with a cylindrical inner circumferential surface.
A spiral retainer Ia that guides a large number of balls or rollers 3 is formed on the inner peripheral surface. As shown in Fig. 2, the cross-sectional shape of the retainer 1a has a shape of a 7-shaped groove into which the balls fit, and the balls are supported at two points by the slopes of this groove and roll. . The round rod rotating shaft 2 is inserted into the sleeve l, and the sleeve l
It is held by a large number of holes 3, 3 arranged in parallel within a spiral retainer on the inner circumferential surface of the holder.

In the embodiment shown in FIG. 1, a fluid pressure medium storage chamber 4 is formed concentrically with the inner peripheral wall of the sleeve 1 so as to surround the inner peripheral wall of the sleeve 1, and a fluid pressure medium 5 is filled inside the sleeve 1. ing. This fluid pressure medium storage chamber 4 is formed as close to the inner circumferential surface of the sleeve as possible, so that when the pressure of the fluid pressure medium is increased, the inner circumferential wall bulges slightly in the direction of the central axis due to the pressure, and the ball 3.3 It is configured to press against the outer peripheral surface of the rotating shaft 2 with a predetermined pressure. The fluid pressure medium 5 is injected into the fluid pressure medium storage chamber 4 through the opening 4a.

The fluid pressure medium 5 includes paraffin, liquid paraffin, high viscosity oil, resins in the pond, water, other liquids,
Alternatively, fluid powder, a mixture of liquid and powder, and others may be used.

A screw plug 6 is inserted into the opening 4a of the fluid pressure medium storage chamber 4, and by screwing it in, the pressure of the fluid pressure medium 5 is increased, so by adjusting the screwing amount of the screw plug 6. The pressure of the injection pressure medium 5 can be adjusted.

Of course, any pressure adjustment means other than the screw plug may be used, for example, the pressure may be adjusted using a pressure pump through a check valve.

As described above, by adjusting the pressure of the fluid pressure medium 5 injected into the fluid pressure medium storage chamber 4 using the screw plug 6,
Figure 7 groove of retainer 1a of sleeve 1 and rotating shaft 2
The pressing force of the ball 3°3 against the outer circumferential surface of the sleeve l can be finely adjusted, and when the shaft 2 is rotated in the appropriate press-contact state, the ball 3 rotates due to friction, and this rotating ball 3 presses against the inner circumferential surface of the sleeve l. spiral retainer 1a
The rotation of the shaft 2 is converted into a linear motion of the sleeve l by pressing the groove surface of the sleeve l. By operating the screw plug 6 and appropriately adjusting the pressure contact force of the ball, the sleeve! And rotating shaft 21! *It is possible to perform transmission without slipping, and this allows stable and highly precise feed to be provided.

The function of converting the rotational motion of the rotating shaft 2 into the linear motion of the sleeve 1 is almost the same as the relationship between a male screw and a female screw, in which the rotation of the rotating shaft is frictionally transmitted to the balls, and the balls arranged in a spiral form The sleeve l moves linearly, and even if the rotational speed and direction of the rotating shirt are constant, the moving speed of the unit can be changed in various ways by changing the helical pitch at which the balls are arranged.

The ball has a structure in which it makes a helical motion at 340° and returns to its original position at 20°, and the distance between the inner circumferential surface of the sleeve l and the outer circumferential surface of the rotating shaft 2 can be adjusted by changing the screw position of the screw plug 6. It can be changed within a range of about 10 μm, and by this adjustment, the friction between the shaft and the ball can be made good, and rotational/linear motion can be converted by friction without slipping.

FIG. 3 is an exploded sectional view showing another embodiment, in which a sleeve 12 is accommodated and fixed inside a cylindrical housing 7, and a rotating shaft 14 is inserted through the inside of the sleeve 12.

Four portions 7a are formed on the inner wall surface of the housing 7, this recess is sealed with an elastic membrane 8 made of rubber or the like, a fluid pressure medium 9 is injected into the recess through an opening 7b, and the recess is sealed with a screw plug 10. 11 is a flange attached to Haunonga.

The sleeve 12 is a cylindrical body whose outer diameter is equal to the inner diameter of the housing 7, and a spiral retainer 12a with a predetermined pitch is formed on the inner peripheral surface of the sleeve 12, similar to that shown in FIG. Balls 13.13 are arranged. A rotary shaft 14 in the shape of a round bar is inserted into and held inside the ball 13 of the sleeve 12.

Therefore, when the screw plug lO attached to the housing 7 is screwed in to increase the pressure of the fluid pressure medium 9, the sleeve 12 is compressed from its entire outer periphery via the elastic membrane 8, and is pressed against the ball 13 or the rotating shaft 14. Therefore, the screw plug l
By adjusting O, the pressing force of the ball can be appropriately adjusted, and the rotational movement of the rotary shaft 14 is transmitted to the sleeve 12 via the ball 13 without slipping, and the sleeve 12 and the housing 7 fixed integrally therewith are Adjust so that it is converted into linear motion.

In the embodiment shown in FIG. 4, a plurality of rollers 16 are held at both ends of the inner peripheral surface of the sleeve 15, and the rollers 16 are arranged along a spiral with a predetermined pitch. The round bar-shaped rotating shaft 21 is inserted. sleeve 1
5 is provided with a fluid pressure medium storage chamber 17 so as to surround its inner circumferential surface, and a fluid pressure medium 18 is injected into the chamber through an opening 19 to fill the chamber.

The pressure of the fluid pressure medium 18 is controlled by the screw plug 2 provided in the opening 19.
By adjusting the pressure, the roller 16 relative to the rotating shaft 21 can be adjusted.
The pressure contact force can be adjusted.

When the rotary shaft 21 is rotated, the plurality of rollers 16 in pressure contact therewith are frictionally rotated without slipping, and the sleeve 15 is moved linearly along the rotary shaft 21.

If the pitch of the helical retainer on the inner circumferential surface of the sleeve 15 that guides the roller 16 is configured to be variable, it is possible to change and control the moving speed and amount of movement by converting rotational to linear motion.

FIG. 5 shows a fluid pressure medium storage chamber 2 in a rotating shaft 22.
In this embodiment, a fluid pressure medium 23 is injected and filled into the fluid pressure medium 2a, and the pressure thereof is adjusted by a screw plug 24. Of course, this rotary shaft 22 is used by being inserted into a sleeve similar to those in the previous embodiments, and the rotational motion of the rotary shaft 22 is transmitted to the sleeve via balls or rollers, and the linear motion of the sleeve is transmitted to the sleeve. It is something that is converted.

When the screw plug 24 provided at one end of the rotating shaft 22 is screwed in, the fluid pressure medium 23 is pressurized to expand the rotating shaft 22 and increase its outer diameter, thereby increasing the pressing force of the ball or roller in contact with it. By adjusting this, the rotational motion of the rotary shaft 22 can be stably converted into linear motion of the sleeve.

The adjustment range of the outer diameter of the rotating shaft 22 is, for example, an outer diameter of 8 m.
When tested in a shaft of m, the fluid pressure medium 16
When not pressurized at all, its outer diameter is 8 mm - 0,013
When the fluid pressure medium 16 was pressurized to 15 kgf/d, the outer diameter could be expanded to 8 mm + 0.016 mm.

As described above, according to the present invention, the contact pressure between the shaft and the ball or roller can be finely adjusted by adjusting the pressure of the pressure medium injected into the fluid pressure medium storage chamber, so accurate rotational/linear motion can be achieved. This makes it possible to perform conversion and provide stable linear feed.

FIG. 7 shows the results of an experiment on the relationship between load kgf and rotational speed RPM using a rotating shaft with an outer diameter of 12 mm. Rotational speed 5000PPM is linear speed 3゜button/
min, 2500RPM sets the pitch to be 1.8n+/min, and the conventional one uses a sleeve size of about -16μm with respect to the shaft, and the one of the present invention uses a sleeve size of about -16μm in the fluid pressure medium storage chamber of the sleeve. Adjust the pressure medium to adjust the sleeve size to approximately -20.8 mm relative to the shaft.
The one adjusted to μm was used. According to the experimental results, the conventional type stopped feeding at a load of approximately 23 kgf, but the type of the present invention was able to perform linear feed up to a load of 60 kgf.

In this way, in the present invention, slippage is eliminated by finely adjusting the contact pressure between the sleeve, the rotating shaft, and the hole without dividing the sleeve.
It is understood that the conversion rate of rotation/linear motion due to contact friction is high, and accurate feed control is possible up to high loads, that is, control of feed speed and position can be performed with extremely high precision.

〔Effect of the invention〕

As described above, in the friction drive feeding device according to the present invention, the sleeve is integrally formed without being divided as in the conventional case, and the fluid pressure medium storage chamber is formed in the sleeve or the rotating shaft, and the pressure medium is contained in the sleeve or the rotary shaft. The pressure adjustment means is provided so that the contact pressure of the ball or roller bearing interposed between the sleeve and the shaft can be finely adjusted. Sliding, shifting, and loss between the soyaft and ball are eliminated, rotational/linear motion conversion is accurate, extremely stable linear feed is possible, and feed speed and position can be controlled extremely precisely. This also prevents abnormal wear of the ball and improves durability.

In addition, the friction drive feeding device according to the present invention does not require a screw for the rotating shaft and uses a brane shaft, so the structure is simple and manufacturing costs can be reduced.
The pitch can be changed and the moving stroke can be extremely long, making it extremely useful as a linear reciprocating device. Therefore, electrical discharge machining, wire electrical discharge machining, electrolytic machining,
It can be used as a feeding device for X- and Y-axis table feeding, Z-axis, C@electrode feeding, and U- and V-axis head feeding for electrical discharge coating machining, electrical discharge stud machining, etc., or can also be used for small hole drilling processing using measuring instruments, lasers, etc. It is extremely effective as a feeding device for parts that do not require high pressure or high load such as processing. Furthermore, since the friction drive feed device according to the present invention has good energy efficiency and little loss, it can be used in place of conventional feed screws in parts that do not require high loads.

[Brief explanation of drawings]

FIG. 1 is a sectional view along the axial direction showing one embodiment of the friction drive feeding device according to the present invention, FIG. 2 is a partially enlarged view thereof, and FIG. 3 is an exploded sectional view showing another embodiment. 4 and 5 are cross-sectional views showing still another embodiment, FIG. 6 is an explanatory view of a conventional device, and FIG. 7 is an experimental graph showing the effects of the friction drive feeding device according to the present invention. 1-・・・-・・-・・・−・−−−−−・−Sleeve 1a ・・・・・−−−1−・・−・・・・・1
) Chee t2・・−・−・・・−・・−・−・−−−−−
・・・−・Rotating shaft 3−・・・・・・・−・−・・
・・−・−・・・Hall 4・・・・・・・・・・
・・−・−−−−−・・・−・−・Fluid pressure medium storage chamber 4a−・−・・・−・−・−・・
−・・−・Opening 5 ・・−・−・−・−・・・・・・・
・−・−・・・−Fluid pressure medium 6−・・−・−・−
・・・−・・・・・・・・・・−・−・Screw plug 7・・−
···········································································································································································································−.
・・−・−・・Recessed portion 8 ・−・−・・−・・・・
−・−・・・・・−・Elastic membrane 9・−・・・・・・・・・・−・
・・・・・・・・−・・・・・・−Fluid pressure medium IO・
・・・・・・－・・−・−・−・・・・−・・
- Threaded plug flange sleeve retainer ball rotating soyaft sleeve loaf fluid pressure medium storage chamber fluid pressure medium/opening --- screw plug --- --- --- −−−・−・Rotating shaft・−・・・・・・・One rotation shaft・・・・・・−
・・・・・・・・・・・・・・・－Fluid pressure medium storage chamber・
・−・・・・・・・・−−−−−−−・・Fluid pressure medium ・−−−−・−・−・・−・−・・・・・・・・・・・・
Screw plug 1------・・- 2・・a 5-m---・・−・− 6−−−−−・−−−・−・7−−−−−・20・・2a 23 − ・・ 24・−・ Patent Applicant Agent of INR Research Institute Co., Ltd. (7524) Mogami Shota Section Figure 6 Figure 4〇m-÷kgf

Claims (1)

[Claims] 1) A round rod-shaped rotating shaft (2) is inserted into a cylindrical sleeve (1) having a spiral retainer (1a) on the inner circumferential surface,
In a friction drive feeding device that converts relative rotational motion between the sleeve and the rotary shaft into linear motion by holding the rotary shaft with a large number of friction balls or rollers (3) arranged along the retainer (1a). A fluid pressure medium storage chamber (4) is provided so as to surround the inner circumferential wall of the sleeve (1), and a pressure adjustment means (6) for the fluid pressure medium (5) accommodated therein is provided. Friction driven feed device as described above. 2) A friction drive feed device according to claim 1, wherein the fluid pressure medium receiving chamber (4) is formed in the sleeve itself. 3) A friction drive feeding device according to claim 1, wherein the fluid pressure medium storage chamber (7a) is provided in a housing (7) that accommodates the sleeve. 4) The friction drive feeding device according to claim 1, wherein the pressure adjusting means for the fluid pressure medium is a screw plug (6) provided in an opening (4a) communicating from the fluid pressure medium storage chamber to the outside. 5) The friction drive feeding device according to claim 1, wherein resin such as paraffin, liquid paraffin, and high viscosity oil is used as the fluid pressure medium. 6) A round bar-shaped rotating shaft is inserted into a cylindrical sleeve with a spiral retainer provided on the inner circumferential surface, and the rotating shaft is held by a large number of friction balls or rollers arranged along the retainer. In a friction drive feeding device that converts relative rotational motion between rotating shafts into linear motion, a fluid pressure medium storage chamber (15a) is provided inside the rotation shaft (15), and a fluid pressure medium ( 16) The above-mentioned friction drive feeding device is characterized in that it is provided with pressure regulating means (17). 7) The friction drive feeding device according to claim 6, wherein the pressure adjusting means for the fluid pressure medium is a screw plug (17) provided at an opening communicating from the fluid pressure medium storage chamber (15a) to the outside. 8) The friction drive feeding device according to claim 6, wherein resin such as paraffin, liquid paraffin, and high viscosity oil is used as the fluid pressure medium. 9) A round rod-shaped rotating shaft is inserted into a cylindrical sleeve with a spiral retainer on the inner circumferential surface, and the rotating shaft is held by a large number of friction balls or rollers arranged along the retainer. In a friction drive feeding device that converts relative rotational motion between rotating shafts into linear motion, a fluid pressure medium storage chamber is provided so as to surround the inner peripheral wall of the sleeve, and a fluid pressure medium storage chamber is also provided inside the rotation shaft. The above-mentioned friction drive feeding device is characterized in that it is provided with: and means for adjusting the pressure of the fluid pressure medium in each of the storage chambers.