JP2868136B2 - Vibration absorber of cam processing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, for example, as shown in FIG. 3, an NC cam grinder uses a workpiece W based on cam shape data stored in an NC program storage unit 101 in consideration of a grinding wheel diameter and the like.
Position data in the X-axis direction of the grindstone head 102 with respect to the rotation angle of the (spindle) is obtained, and the X-axis servomotor 104 is synchronously rotated with respect to the spindle drive shaft (hereinafter referred to as the C-axis) servomotor 103 to perform machining by the spindle rotation Generating a cam is performed by swinging the grindstone head back and forth in accordance with a change in the radius dimension from the rotation center of the object W.

[0003]

The method of generating a workpiece by swinging the grinding wheel head back and forth in accordance with the rotation of the spindle described in the prior art is based on increasing the number of rotations of the grinding wheel head when the rotation speed of the spindle is increased. There is a problem that the kinetic energy causes the whole machine to vibrate and adversely affects the machining accuracy. The present invention has been made in view of such problems of the related art, and aims at canceling the kinetic energy due to the swing of the grinding wheel head to prevent machine vibration,
An object of the present invention is to provide a vibration absorbing device capable of improving processing accuracy.

[0004]

In order to achieve the above object, a vibration absorbing device for a cam processing machine according to the present invention is characterized in that a movable table having a tool is swung in an X-axis direction perpendicular to the main shaft in synchronization with main shaft rotation. In the NC cam processing machine which performs the cam surface creation processing , the balance weight is further increased by X on the moving table.
The weight and cam of the moving table are provided so as to be controllable in the axial direction.
Vibration is absorbed from the lift amount of the
Calculate the swing distance of the balance weight required to adjust
Means, wherein the calculated value is synchronized with the swing of the moving table.
A means is provided for swinging the balance weight in the opposite direction by the swing distance, thereby canceling the generation of vibration due to the swing of the moving table.

[0005]

According to the present invention, the X-axis position data of the movable base with respect to the spindle rotation angle is obtained from the input cam shape data in consideration of the grinding wheel diameter and the like. The swing distance of the balance weight is determined from the swing distance in the X-axis direction (the lift amount of the cam), and the balance weight is swung in the opposite direction in synchronization with the moving base to cancel the vibration caused by the swing of the moving base. Let it.

[0006]

An embodiment will be described with reference to FIGS. In the NC cam grinder, a table 2 is movably mounted on a sliding surface in the Z-axis direction cut on the front side of a bed 1 set on the floor, and a grindstone head 3 and a tailstock are placed on the table 2. The bases 4 are fixedly mounted so that the mounting positions can be moved.
The headstock 3 is rotatably supported on the headstock 3, and is rotated by a C-axis servomotor 6 fixed to the grindstone head, and a chuck 7 is fitted to the tip.

A guide table 8 having a guide in the X-axis direction is fixed on the upper surface behind the bed 1, and a grindstone table 9 is mounted on the X-axis guide so as to be movable and positionable. 1 is moved and positioned via a ball screw 12 by an X-axis servo motor 11 fixed to 1. A grindstone shaft 13 is rotatably supported by the grindstone stand 9, and a grindstone 14 is detachably fitted to the left end of the grindstone shaft.

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

The block diagram of FIG. 1 is a servo system for controlling the rotation of each of the servomotors 6, 11 and 17 to create a cam surface.
Position of the X-axis with respect to the rotation angle of the C axis portion, X / C-axis control circuit 22 in consideration of the grinding wheel diameter, etc. than the shape data of the cam to be remembers the NC program input from the tape reader or a keyboard, etc. This is a part for obtaining data and outputting a control signal to the X-axis drive unit 23 and the C-axis drive unit 24. The X-axis drive unit 23 supplies power to the X-axis servomotor 11, and the C-axis drive unit 24 supplies power to the C-axis servomotor 6. The above is the same as the conventional NC servo system for creating a cam. is there.

[0010] Wheel head and balance weight weight storage unit 25
Is the total weight of the wheelhead 9 and the balance weight 1
The balance weight swing distance calculator 26 stores the weight of the balance weight 6, and calculates the swing distance of the balance weight 16 from the weight of the grindstone head and the swing distance and the weight of the balance weight. The U-axis control circuit 27 outputs a control signal for moving the balance weight 16 in the opposite direction of the grinding wheel head by the swing distance calculated in synchronization with the X-axis data from the X / C-axis control circuit 22; The drive unit 28 is a part that supplies power to the U-axis servo motor 17.

Next, a method of calculating the motion condition of the balance weight 16 with respect to the grindstone table 9 for absorbing vibration will be described. When the wheel head 9 swings by a distance a (the lift amount of the cam workpiece W) to generate the cam surface of the workpiece W, the wheel head 9 moves the workpiece swinging at a · sin (2πf) t. Take an example. Where f is the frequency. The force F for vibrating the entire headstock 9 machine can be expressed by F = Mh · ah. Where M
h is the weight of the grinding wheel head, and ah is the acceleration of the grinding wheel head. Therefore F =
Mh · (2πf) ² · a · sin (2πf) t

Next, the balance weight 16 is set to a frequency f (H
By moving in the opposite direction by the distance b in z), the force F ′ for oscillating the entire machine can be expressed by F ′ = Mw · aw. Where Mw is the weight of the balance weight, aw is the acceleration of the balance weight, and therefore F ′ = Mw · (2πf) ²
・ B · sin (2πf) t Where b is the swing distance of the balance weight. The difference Fδ between the force for oscillating the machine when there is no balance weight 16 and when the balance weight is provided is Fδ = F−F ′ = Mha · Mw · b, and satisfies Mha · M = Mw · b. If the vibration is 10
Can absorb 0%.

More specifically, for example, when the grinding wheel head is 350 kg, the balance weight is 10 kg, and the lift amount of the workpiece is 2 mm, the above equation is applied.
350 × 2 = 10 × 70, balance weight 16
May be synchronously moved in the opposite direction with respect to the 70 mm grinding wheel head 9. The balance weight swing distance calculation unit 26 is a part that calculates the balance weight swing distance b by the above equation.

Next, the operation of this embodiment will be described.
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, X-axis position data with respect to the rotation angle of the C-axis is obtained, and the C-axis and X-axis control signals are obtained. Is output, and at the same time, the NC program storage unit 21
The amount of cam lift (the X-axis swing distance of the wheel head 9) is output to the balance weight swing distance calculator 26, where the balance is calculated by the respective weights input from the wheel head / balance weight weight storage unit. The swing distance of the weight 16 is obtained.

The obtained swing distance is determined by the U-axis control circuit 27.
At the U-axis control circuit 27 based on the synchronization command.
A control command for moving the balance weight 16 in the opposite direction with respect to the grinding wheel head 9 is output in synchronization with the control command of the / C axis control circuit 22.

The power is supplied from the X-axis drive unit 23 by the control output of the X / C-axis control circuit 22,
The axis servomotor 11 is driven, and power is supplied from the C-axis drive unit 24 in synchronization with the axis servomotor 11 so that the C-axis servomotor is driven. 9 moves in the X-axis direction, and the cam surface is created. Then, power is supplied from the U-axis drive unit 28 in accordance with the control command of the U-axis control circuit 27 in accordance with the X-axis movement of the grinding wheel head 9, the U-axis servo motor 17 is driven, and the balance weight 16 is moved in the opposite direction. The kinetic energy due to the swing of the wheel head 9 is offset.

If the rotation speed of the main shaft is large, the moving speed of the balance weight 16 increases, and the U-axis servo motor 17
Is exceeded, the spindle speed is reduced, or the reduction rate is input to the balance weight oscillating distance calculation unit 26 to reduce the oscillating distance within a range that does not hinder practical use. It is also possible to prevent a decrease in efficiency.

[0018]

Since the present invention is configured as described above, the following effects can be obtained. A balance weight that oscillates synchronously in the opposite direction is provided on the movable table that oscillates in synchronization with the spindle rotation during cam generation processing, so that vibrations caused by the oscillating movement of the movable table are canceled out, so machining accuracy is improved. improves. Further, since the generation of vibration is reduced, the rotation of the spindle can be accelerated, and the machining efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a top view of a cam grinder having a vibration absorbing device of 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 the present 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 Spindle 9 Wheel head 16 Balance weight 17 U-axis servo motor

Claims (1)

(57) [Claims] 1. A in synchronism with the spindle rotation to oscillate the moving base to the main shaft and perpendicular X-axis direction having a tool NC cam processing machine to perform generating process of the cam surface, the balun <br on said moving platform /> further provided X-axis direction moving controllable Suueito, the
The weight of the moving platform, the lift amount of the cam, and the van rasway
Balance weight necessary to absorb vibration from the weight of the
Means for calculating the swing distance of the balance weight, and the balance weight is calculated by the calculated swing distance in synchronization with the swing of the moving table.
It is provided with means for swinging the site in the opposite direction, the vibration absorbing device of a cam machine, characterized in that to cancel the occurrence of vibration due to the swing of the movable carriage.