JPH04294970A - Vibration absorption device for cam work machine - Google Patents

Abstract

PURPOSE:To improve a work accuracy and also to improve a work efficiency by offsetting the vibration that the rocking motion in X axial direction of the carriage synchronous with the spindle rotation of a cam work machine gives to a machine by a balance weight. CONSTITUTION:A balance weight 16 is provided movably in an X axial direction on a grindwheel post 9 and vibration is offset with the balance weight being rocked in the opposite direction by setting to the rocking motion of the grinding wheel post.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for absorbing vibrations caused by swinging of a grindstone head or a tool rest of a cam processing machine such as a cam grinder or a cam lathe.

0002

2. Description of the Related Art Conventionally, for example, an NC cam grinder, as shown in FIG.
The X-axis servo motor 104 is rotated synchronously with the spindle drive shaft (hereinafter referred to as C-axis) servo motor 103, and the workpiece is rotated by spindle rotation. The cam was created by swinging the grindstone back and forth in accordance with the change in the radius from the center of rotation of the W.

0003

[Problems to be Solved by the Invention] The method described in the conventional technique for performing generating processing by swinging the grindstone back and forth in accordance with the rotation of the spindle has the problem that as the rotation speed of the spindle increases, the number of swings of the grindstone increases. The problem is that this kinetic energy vibrates the entire machine and adversely affects machining accuracy. The present invention was made in view of the above-mentioned problems of the conventional technology, and its purpose is to offset the kinetic energy caused by the rocking of the grindstone head to prevent machine vibration;
The present invention aims to provide a vibration absorbing device that can improve processing accuracy.

In order to achieve the above object, the vibration absorbing device for a cam processing machine according to the present invention provides a cam processing machine that performs cam generation processing by swinging a movable table having a tool in the X-axis direction in synchronization with the rotation of the main shaft. In the grinding machine, a balance weight is provided on the movable table so as to be movable in the X-axis direction, and means is provided for swinging the balance weight in the opposite direction in synchronization with the rocking of the movable table. This cancels out the vibrations caused by

[0005]

[Operation] From the input cam shape data, calculate the X-axis position data of the moving table with respect to the spindle rotation angle, taking into account the grindstone diameter, etc., and at the same time calculate the weights of the moving table and balance weight, which have been input in advance, and the moving table. The swing distance in the X-axis direction (
The swinging distance of the balance weight is determined from the cam lift amount), and the balance weight is swung in the opposite direction in synchronization with the moving table to cancel out the vibration caused by the swinging of the moving table.

[0006]

[Embodiment] An embodiment will be explained with reference to FIGS. 1 and 2. In an NC cam grinding machine, a table 2 is movably placed on a sliding surface in the Z-axis direction cut on the front side of a bed 1 installed on the floor, and a grindstone head 3 and a tailstock are mounted on the table 2. Each of the stands 4 is fixedly mounted so that its mounting position can be moved. A main spindle 5 is rotatably supported on the headstock 3, and the main spindle 5 is rotated by a C-axis servo motor 6 fixed to the grindstone head, and a chuck 7 is fitted at the tip.

A guide stand 8 having an X-axis guide on its upper surface is fixed to the rear of the bed 1, and a grindstone 9 is placed on the X-axis guide so as to be movable and positionable. It is moved and positioned by an X-axis servo motor 11 fixed to 1 via a ball screw 12. A whetstone shaft 13 is rotatably supported on the whetstone head 9, and a whetstone 14 is removably fitted to the left end of the whetstone shaft.

A guide 15 in the X-axis direction is attached to the top surface of the grindstone head 9, and a balance weight 1 is mounted on this guide 15.
6 is movably mounted, and the balance weight 16 is fixed to the guide table 15 along an axis parallel to the X axis (hereinafter referred to as the U axis).
It is moved and positioned by a servo motor 17 via a ball screw 18.

The block diagram part in FIG. 1 is a servo system for controlling the rotation of each servo motor 6, 11, and 17 to create a cam surface.
is the part that stores the NC program input from a tape reader or keyboard, and the X/C axis control circuit 22
is a part that calculates the position data of the X-axis relative to the rotation angle of the C-axis based on the shape data of the cam, taking into account the diameter of the grinding wheel, etc., and outputs a control signal to the X-axis drive unit 23 and the C-axis drive unit 24. The X-axis drive unit 23 is a part that supplies power to the X-axis servo motor 11, and the C-axis drive unit 24 is a part that supplies power to the C-axis servo motor 6. The above is the same as the conventional NC servo system for cam generation. be.

[0010] Grinding wheel head/balance weight weight storage section 25
is the input total weight of the grindstone head 9 and the balance weight 1
The balance weight swing distance calculation unit is a part that calculates the swing distance of the balance weight 16 from the weight of the grindstone head, its swing distance, and the weight of the balance weight. The U-axis control circuit 27 is a part that outputs a control signal to move the balance weight 16 in the opposite direction of the grindstone head by a swing distance calculated in synchronization with the X-axis data from the X/C-axis control circuit 22, and the U-axis Drive unit 2
8 is a part that supplies electric power to the U-axis servo motor 17.

Next, a method of calculating the motion conditions of the balance weight 16 with respect to the grindstone head 9 for vibration absorption will be explained. For example, when the grindstone head 9 swings by a distance a (lift amount of the workpiece W) to generate the cam surface of the workpiece W, the grindstone head 9 swings at a sin(2πf)t. Take it. However, f is the frequency. The force F of the headstock 9 that causes the entire machine to vibrate can be expressed as F=Mh·ah. However, Mh is the weight of the whetstone head, and ah is the acceleration of the whetstone head. Therefore F=Mh
・(2πf)2 ・a・sin(2πf)t.

Next, the balance weight 16 is adjusted to the frequency f(H
z) in the opposite direction by a distance b, the force F' that causes the whole machine to vibrate can be expressed as F'=Mw·aw. However, Mw is the weight of the balance weight, aw is the acceleration of the balance weight, therefore, F'=Mw・(2πf)2
・b・sin(2πf)t. However, b is the swing distance of the balance weight. The difference Fδ in the force that vibrates the machine without the balance weight 16 and with the balance weight is Fδ=F−F′=Mh・a−Mw・b,
If Mh・a=Mw・b…■ is satisfied, vibration is 100%
It can be absorbed.

To explain with a more specific example, if we apply the above equation (2) assuming that the grindstone head is 350 kg, the balance weight is 10 kg, and the lift amount of the workpiece is 2 mm, then
350 x 2 = 10 x 70, balance weight 16
70 mm in the opposite direction to the grindstone head 9. The balance weight swing distance calculation unit 26 uses the above formula■
This is the part that calculates the swinging distance b of the balance weight.

Next, the operation of this embodiment will be explained. When the cam shape data of the workpiece W is input from the NC program storage unit 21 to the X/C-axis control circuit 22, the position data of the X-axis relative to the rotation angle of the C-axis is determined, and the control signals for the C-axis and the X-axis are obtained. is output, and at the same time the NC program storage section 21
The lift amount of the cam (the X-axis swing distance of the grinding wheel head 9) is output to the balance weight swing distance calculating section 26, where the balance is calculated based on the respective weights input from the grinding wheel head/balance weight weight storage section. The swing distance of the weight 16 is determined.

[0015] Then, the determined swing distance is determined by the U-axis control circuit 27.
is output to the U-axis control circuit 27 based on the synchronization command.
/ Outputs a control command to move the balance weight 16 in the opposite direction with respect to the grindstone head 9 in synchronization with the control command of the C-axis control circuit 22.

Power is supplied from the X-axis drive unit 23 according to the control output of the X/C-axis control circuit 22, and the
The axis servo motor 11 is driven, and in synchronization with this, power is supplied from the C-axis drive unit 24 to drive the C-axis servo motor, and the grinding wheel head is rotated in accordance with the change in the radius dimension from the rotation center of the workpiece W cam surface. 9 is moved in the X-axis direction, and the cam surface is created. Then, in accordance with the X-axis movement of the grindstone head 9, power is supplied from the U-axis drive unit 28 according to a control command from the U-axis control circuit 27, and the U-axis servo motor 17 is driven, and the balance weight 16 is moved in the opposite direction. This cancels out the kinetic energy caused by the rocking of the grindstone head 9.

Note that when the main shaft rotation speed is high, the movement speed of the balance weight 16 becomes faster, and the U-axis servo motor 17
If the tracking ability of It is also possible to prevent a decrease in efficiency.

[0018]

[Effects of the Invention] Since the present invention is constructed as described above, it achieves the following effects. During cam generation processing, a balance weight that oscillates synchronously in the opposite direction is installed on the movable table, which oscillates in synchronization with the spindle rotation, to cancel out the vibrations caused by the oscillation of the movable table, thereby improving machining accuracy. improves. Furthermore, since less vibration occurs, it is possible to speed up the rotation of the main shaft, improving machining efficiency.

[Brief explanation of drawings]

FIG. 1 is a top view of a cam grinder having a vibration absorbing device according to the present embodiment and a circuit diagram of an NC servo system.

FIG. 2 is a partial side view of a cam grinder having the vibration absorbing device of this embodiment.

FIG. 3 is a top view of a conventional cam grinder and a circuit diagram of an NC servo system.

[Explanation of symbols]

5 Main shaft 9 Whetstone stand 16 Balance weight 17 U-axis servo motor

Claims (1)

[Claims] Claim 1: In a cam processing machine that generates a cam surface by swinging a movable table having a tool in the X-axis direction in synchronization with the rotation of the main shaft, a balance weight is placed on the movable table in the X-axis direction.
The balance weight is provided so as to be movable in the axial direction, and includes means for swinging the balance weight in the opposite direction in synchronization with the swinging of the movable table, thereby canceling out vibrations caused by the swinging of the grindstone head. Vibration absorption device for cam processing machines.