JPH0746401Y2 - Tailstock force control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a tailstock pressure control device for a machine tool.

<Prior Art> When grinding a shaft-shaped workpiece, for example, a cam shaft, a work is supported by a spindle center and a tailstock center, and a drive fitting provided on the spindle side is engaged with a key groove of the work, The rotation of the spindle is transmitted to the work, and the grinding of the cam part is performed with a grindstone.
When engaging the keyway of the work with the drive fitting, the brake device arranged between the spindle center and the tailstock center stops the rotation of the work, and the drive fitting is placed in the keyway at one location of the work. The drive shaft is engaged by rotating the main shaft at a low speed until it is engaged.

<Problems to be solved by the invention> Recent camshafts tend to have smaller journal diameters,
In addition, the tailstock has a strong pressing force to withstand the resistance during grinding.

Therefore, the braking force of the braking device that abuts on a journal with a small diameter is small, and the pressing force of the tailstock is strong. The work may not stop when it rotates at a low speed, and it may rotate with the face plate, and the drive fitting may not be engaged with the keyway forever.

<Means for Solving the Problems> The present invention has been made in order to solve the above-mentioned conventional problems, and is characterized by a main shaft, a main shaft center mounted on the main shaft, and the main shaft. A tailstock provided with a drive fitting which is provided on the top and which engages and disengages with a keyway of the work, and a tailstock center advancing / retreating cylinder for advancing / retreating a tailstock center facing the main spindle center, and the main spindle and tailstock. And a brake device that is arranged between the base and a spindle center, a tailstock center, and abuts against the supported work to brake the rotation of the work,
A fluid pressure switching valve for controlling the supply and discharge of forward and backward pressure fluid to and from the tailstock center advancing / retreating cylinder, and for advancing the tailstock center advancing / retreating cylinder when the drive fitting is engaged with the key groove. And a control means for reducing the pressure of the fluid pressure passage.

<Operation> With the above configuration, the work is held by both the center of the spindle and the tailstock, the work is braked by the brake device, and then the control means is operated to reduce the forward pushing force of the tailstock center advance / retreat cylinder. , The driving metal fitting is engaged with the key groove of the work, and then the control means is operated to increase the pressing force of the tailstock to perform grinding.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a spindle, 2 is a face plate fixedly mounted on the spindle 1, 3 is a spindle center mounted on the spindle 1, and 4 is a chuck device attached to the plate surface of the face plate 2. In this chuck device 4, a drive fitting 5 that engages and disengages with a key groove 8 provided in a work W supported by the spindle center 3 is pivotally supported by a pivot pin 6, and a spring 7 constantly engages the key groove 8. It has a structure in which it is urged to rotate in the direction.

Reference numeral 9 denotes a tailstock facing the spindle 1. As shown in FIG. 3, a tailstock center 10 is mounted on a ram 9a which is moved forward and backward by a tailstock center advancing / retreating cylinder 21. A work W is held between the center 10 and the spindle center 3.

11 is sandwiched between the spindle center 3 and the tailstock center 10,
In addition, it is a grindstone for grinding the rotating work W by the drive fitting 5.

Reference numeral 12 denotes a brake device which is arranged between the main shaft 1 and the tailstock 9. As shown in FIG. 2, this brake device 12 has
A bracket 14 fixed on the table 13 is provided with a steady rest 15 for contacting the outer diameter of the work W from two directions, and an arm 16 is pivotally supported so that the work W is attached to one end of the arm 16. The brake shoe 18 is in contact with the outer diameter of the brake arm 18, and the other end of the arm 16 is connected to a brake operating cylinder 19 by a rod 20.

FIG. 3 shows a pressure control device for the tailstock. P is a high pressure line for supplying pressure oil to the tailstock center advancing / retreating cylinder 21, and R is a low pressure line for discharging the pressure oil from the tailstock center advancing / retreating cylinder 21 to the tank. Reference numeral 22 denotes the high-pressure line P and the low-pressure line R, and the tailstock center advance / retreat cylinder 2
1, which is a pressure oil switching valve installed in the connection lines 27a and 27b to the front and rear chambers, and the ram 9a is moved forward or backward by switching the pressure oil switching valve 22.

24 is a pressure relief circuit. In this pressure relief circuit 24, a fixed throttle 23 is arranged in a connection line 27b connected to the rear chamber of the tailstock center advancing / retreating cylinder 21, and the connection from the fixed throttle 23 to the tailstock center advancing / retreating cylinder 21 side. Between the line 27b and the low pressure line R, there is provided a decompression switching valve 25 and a check valve 26 provided on the low pressure line R side and having a weak valve opening pressure so that the upstream side has a determined low pressure.

Since the present invention has the structure as described above, one end of the work W is attached to the spindle center 3 and the pressure oil switching valve 22 is switched to supply high pressure oil to the rear chamber of the tailstock center advancing / retreating cylinder 21. Then, the ram 9a is moved forward, the tailstock center 10 is attached to the other end of the work W, and the work W is held between the centers 3 and 10. Then, the brake device 12 is operated to restrain the rotation of the work W held between the centers 3 and 10, and the depressurization switching valve 25 of the depressurization circuit 24 is switched to the depressurization side.

As a result, the high pressure oil on the upstream side of the fixed throttle 23 of the connection line 27b connected to the rear chamber of the tailstock center advancing / retracting cylinder 21 is transferred to the rear chamber of the tailstock center advancing / retracting cylinder 21. A cylinder for advancing and retreating the tailstock center 10 is released to the low pressure line R so that a weak exhaust pressure determined by the opening pressure of the check valve 26 is applied as a pressing force for supporting the work W.
The pressure oil supplied to the rear chamber of 21 is depressurized.

Therefore, when the pressurizing force of the tailstock center 10 is weakened and the main shaft 1 is rotated at a low speed to engage the drive fitting 5 with the key groove 8 of the work W, the work W being braked by the brake device 21.
Is not rotated by the face plate 2, the chuck device 4 and the work W are reliably rotated relative to each other, and the drive fitting 5 is engaged with the key groove 8.

After the drive fitting 5 is engaged with the key groove 8, the pressure reducing switching valve
25 is closed, the pressure oil supplied to the rear chamber of the tailstock center advancing / retreating cylinder 21 is set to a high pressure, the pressure force of the tailstock center 10 is returned to the original state, and then the grinding cycle is started.

<Effects of the Invention> As described above, the present invention provides the fluid pressure switching valve for controlling the supply and discharge of the forward and backward pressure fluid to the tailstock center advancing / retreating cylinder, and the above when the drive fitting is engaged with the key groove. Since the structure is provided with a control means for lowering the forward fluid pressure passage of the tailstock center advancing / retreating cylinder, the work is clamped between the spindle and the tailstock center, and the spindle is rotated at a low speed so that the drive metal fittings are mounted. When engaging with the keyway of the work, the control means can reduce the pressurization force of the tailstock center, which eliminates the conventional rotation of the work with the face plate due to the strong pressurization. Even if there is a tendency for the braking force of the brake device to decrease due to the reduction of the outer diameter, the rotation of the work piece due to the brake device is improved, and the drive fitting is securely placed in the key groove. To engage Have a real benefit of being able to

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional side view of an essential part showing an example of a machine tool to which the present invention is applied, FIG. 2 is a side view of a brake device, and FIG. 3 is a circuit diagram of the present invention. . 1 ... spindle, 3 ... spindle center, 4 ... chuck device,
5 ... Drive fittings, 8 ... Keyway, 9 ... Tailstock, 9a ...
Ram, 10 ... tailstock center, 12 ... brake device, 21 ...
… Tailstock center forward / backward cylinder, 22 …… Fluid pressure switching valve,
23 ... Fixed throttle, 24 ... Pressure relief circuit, 25 ... Pressure reducing switching valve, 26 ... Check valve, 27a, 27b ... Connection line.

Claims (1)

[Scope of utility model registration request] 1. A spindle, a spindle center mounted on the spindle, a drive fitting provided on the spindle for engaging and disengaging with a key groove of a work, and a tailstock center opposed to the spindle center. A tailstock having a tailstock center advancing / retreating cylinder, and a brake device arranged between the spindle and the tailstock for braking the rotation of a work supported by the spindle center and the tailstock center. , A fluid pressure switching valve for controlling supply and discharge of forward and backward pressure fluid to and from the tailstock center advancing / retreating cylinder, and advancement of the tailstock center advancing / retreating cylinder when the drive fitting is engaged with the key groove. A tailstock pressurizing force control device comprising: a control means for reducing the pressure of the fluid pressure passage for the tailstock.