JP2001205538A - Mounting structure of mover to feed drive system of machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a feed mechanism of a machine tool when, typically, a workpiece and a tool collide with each other. SOLUTION: A pair of abutting surfaces 1a and 6b; 1a and 8b is formed in the linkage process between a mover 1 and a nut 5 as a movable member constituting a feed drive system, and the static frictional force that develops between the pair of surfaces restrains the mover 1 and the nut 5 relatively in the feed direction of the mover 1. During a normal machine tool operation, the static frictional force developing between the pair of surfaces transmits driving force from the nut 5 to the mover 1, and on application of an impulse to the mover 1, the pair of surfaces is slid relatively in the feed direction of the mover 1 to exhaust the striking energy. The contact surface pressure of the surfaces 1a and 6b; 1a and 8b is regulated with a wedge 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for attaching a moving body to a feed drive system in a machine tool.

[0002]

2. Description of the Related Art In a machine tool, a workpiece may collide with a tool or a spindle due to a defect in a control program or a malfunction of a control device. When such an event occurs, in the worst case, there is a risk that the machine tool, for example, its feed drive system may be damaged.

[0003] As a protection system for preventing breakage of a machine tool in the event of a collision as described above, an increase in the drive current of a servomotor constituting a feed drive system at the time of a collision is detected to detect the energization of the servomotor. Or to stop
It is known to detect a decrease in the gap of the hydrostatic bearing at the time of a collision and stop the energization of the servomotor.

[0004]

However, in the above-mentioned conventional method, control delay cannot be completely eliminated. Therefore, if a collision occurs while moving the tool at high speed, the damage is completely eliminated. There is a problem that can not be prevented.

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and has a structure of a machine tool capable of effectively protecting the machine against collision, specifically, a structure for attaching a moving body to a feed drive system. It is intended to provide.

[0006]

In order to achieve the above object, the present invention relates to a structure for attaching a movable body to a feed drive system of a machine tool, wherein a movable member constituting the feed drive system is connected to the movable body. In the process, a pair of surfaces that come into contact with each other is provided, and the movable body and the movable member are relatively restrained with respect to a feed direction of the movable body by a static friction force acting between the pair of surfaces, so that a normal operation of the machine tool is performed. Sometimes, the driving force is transmitted from the movable member to the moving body by the static friction force acting between the pair of surfaces, and when an impact is applied to the moving body, the pair of surfaces are moved in the feeding direction. The structure is such that the energy of the impact is consumed by sliding relatively to.

In this case, it is preferable that a wedge is provided between the movable member and the movable body, and the wedge adjusts the force of pressing the pair of surfaces to adjust the static friction force. It is.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a moving body. The moving body 1 may be, for example, a member that holds a main shaft, or a feed drive system that feeds another moving body different from the illustrated moving body 1 in the vertical direction in FIG. 1 or the vertical direction in FIG. It may be a base.

As shown in FIG. 1, the moving body 1 is guided by a guide member (not shown) provided on the base 2 and can move only in the left-right direction in FIG. Here, the base 2 may be an immovable member or another moving body different from the moving body 1 that is fed by another feed driving system in a direction perpendicular to the plane of FIG. Is also good.

The base 2 supports the servomotor 3 by a support 2a. A screw shaft 4 is attached to the servomotor 3. A nut 5 that forms a ball screw mechanism together with the screw shaft 4 is screwed to the screw shaft 4 via a ball (not shown). The above-described servo motor 3, screw shaft 4 and nut 5 constitute a feed drive system.

A nut 5 which is a movable member of the feed drive system is fitted into a ring-shaped fitting 6, and the nut 5 and the fitting 6 are firmly connected to each other by bolts 7 so as not to be relatively movable.

The fitting 6 has a movable body 1 on one side of its peripheral surface.
It has an inclined surface 6a inclined along the feeding direction. A wedge 8 having an inclined surface 8 a complementary to the inclined surface 6 a is attached to the fitting 6 via a bolt 9.

The combined body composed of the fitting 6 and the wedge 8 is fitted into the moving body 1. That is, the inclined surface 6 of the fitting 6
a outside surface 6b (the surface seen upward in FIG. 1) and wedge 8
Is in contact with the inner side surface 1a of the moving body 1 with a predetermined contact surface pressure.

Accordingly, the inner surface 1a of the moving body 1 and the fitting 6
Outer surface 6b other than the inclined surface 6a and the outer surface 8b of the wedge 8
The moving body 1 and the nut 5
Are relatively restricted with respect to the feed direction of the moving body 1.

Further, stoppers 10 and 11 for preventing the moving body 1 from being excessively displaced with respect to the fitting 6 and the wedge 8 are attached to the moving body 1 so as to face one end surfaces of the fitting 6 and the wedge 8. I have. Further, a stopper (stopper surface) 1b for preventing the fitting element 6 and the wedge 8 from being excessively displaced with respect to the moving body 1 is formed inside the moving body 1 so as to face the other end surface of the fitting element 6 and the wedge 8. ing. Clearances are provided between one end surfaces of the fitting 6 and the wedge 8 and the stoppers 10 and 11, and between the other end surfaces of the fitting 6 and the wedge 8 and the stopper surface 1b.

The moving body 1 includes a nut 5 and a fitting 6.
And limit switches 12 and 13 for detecting the displacement of the moving body 1 with respect to the wedge 8.

Next, the operation will be described.

At the time of the initial adjustment of the machine tool, first,
The bolt 9 is appropriately adjusted so that the moving member 1
By adjusting the relative position (in the feed direction), the contact surface pressure between the outer surface 6b of the fitting 6 and the inner surface 1a of the moving body 1 and the outer surface 8b of the wedge 8 and the inner surface 1a of the moving body 1 are adjusted. Adjust the contact pressure. The smaller the gap 20 between the fitting 6 and the wedge 8 by tightening the bolt 9, the higher the contact surface pressure becomes. Between the outer surface 8b of the wedge 8 and the moving body 1
The maximum static friction force acting between the inner surface 1a and the inner surface 1a increases. Since the relative positional relationship between the fitting 6 and the wedge 8 changes with the adjustment of the bolt 9, the hole 8c of the wedge 8 into which the bolt 9 is inserted is set to be a long hole.

When the feed drive system is operated in this state, during normal operation, the driving force of the nut 5 is increased by the fitting 6 and the wedge 8.
The moving body 1 is moved by exactly the same amount that the nut 5 has moved.

On the other hand, when an excessive impact load is applied to the moving body 1 due to a member such as a tool or a spindle attached to the moving body 1 colliding with the work, the fitting 6
Slip occurs between the outer surface 6b of the moving body 1 and the inner surface 1a of the moving body 1 and between the outer surface 8b of the wedge 8 and the inner surface 1a of the moving body 1. Due to the occurrence of the slip, the energy received by the moving body 1 due to the collision is between the outer surface 6b of the fitting 6 and the inner surface 1a of the moving body 1 and between the outer surface 8b of the wedge 8 and the moving body 1. Is consumed as heat energy between the inner surface 1a and the inner surface 1a. For this reason, it is possible to prevent an excessive load from being applied to the ball screw mechanism of the feed drive system.

When the slip occurs, the limit switch 12 or 13 is operated, and a control device (not shown) stops the servomotor 3 based on a signal from the limit switch 12 or 13.

According to this embodiment, unlike the case where the electric control device is used, the problem of control delay does not occur in principle, so that even when the moving body 1 receives an impact load, the feed drive mechanism can be completely completed. Can be protected.

Although the embodiment shown in FIG. 1 shows an example in which the wedge 8 is attached to the fitting 6, the wedge 8 is attached to the moving body 1 via a bolt 14 as shown in FIG. Is also good. In this case, the relative position between the wedge 8 and the fitting 6 can be adjusted by adjusting the amount of tightening of the bolt 14, whereby the outer surface 6b of the fitting 6 and the inner surface 1a of the moving body 1 can be adjusted. And the contact surface pressure between the outer surface 8b of the wedge 8 and the inner surface 1a of the moving body 1 can be adjusted. In the case of the embodiment shown in FIG. 2, by adjusting the position of the wedge 8 and then removing the bolt 14,
It is possible to cope with a case where a rightward impact is applied to the moving body 1 and a case where a leftward impact is applied to the moving body 1 in the figure.

Further, in the embodiment shown in FIG. 1, the static friction force is adjusted by the wedge 8, but a spring capable of adjusting the set load is interposed in the process of coupling the nut 5 and the moving body 1. Alternatively, the static friction force may be adjusted.

[0026]

As described above, according to the present invention,
When an excessive load such as a collision is applied, breakage of the machine tool can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a mounting structure according to the present invention, and is a sectional view of a main part of a feed drive system and a moving body of a machine tool.

FIG. 2 is a view showing another embodiment of the mounting structure according to the present invention, and is a cross-sectional view of a main part of a feed drive system and a moving body of a machine tool.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Moving body 1a, 6b A pair of surfaces which contact each other 1a, 8b A pair of surfaces which contact each other 5 Nut (movable member which comprises a feed drive system) 8 Wedge

Claims (2)

[Claims] 1. A mounting structure for a moving body with respect to a feed drive system of a machine tool, wherein a pair of surfaces which come into contact with each other in a process of coupling a movable member constituting the feed drive system and the movable body are provided. The movable body and the movable member are relatively restrained with respect to a feed direction of the movable body by a static friction force acting between the movable body and the movable member during a normal operation of the machine tool by the static friction force acting between the pair of surfaces. The driving force is transmitted from the member to the moving body, and when an impact is applied to the moving body, the energy of the shock is consumed by relatively sliding the pair of surfaces in the feed direction. A mounting structure characterized in that: 2. A wedge is provided between the movable member and the moving body, and the static friction force is adjusted by adjusting a force of pressing the pair of surfaces by the wedge. The mounting structure according to claim 1.