DE1248431B - Device for adjusting the clamping force of a chuck operated by pressure medium - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

B 23 b

German KL: 49 a -27/04

Number: 1248431

File number: P 302061 b / 49 a

Filing date: September 20, 1962

Opened on: August 24, 1967

The invention relates to a device for adjusting the clamping force of a pressure medium actuated Chuck with a double-acting clamping cylinder, the clamping side of which with a high pressure for roughing and then a low pressure for finishing is, the release side is put under pressure during the transition from high to low pressure will.

The pressure on the release side of the clamping cylinder is necessary because of the elasticity of the clamped Workpiece, especially in the case of a chuck with a self-locking gear, is not sufficient for the to bring about the necessary resetting of the clamping jaws. In a known device of the above Design, the pressure on the release side is generated by a spring acting against the tensioning piston. This design has the disadvantage that the return path of the clamping jaws is not accurate enough can be limited because the tensioning piston in particular because of the diameter of each clamped workpiece dependent bias of the return spring after each switch from high to the low hydraulic pressure remains in a slightly different position, so that the different Workpieces are clamped differently when finishing and consequently after Machining and unclamping can still be out of round.

To avoid this disadvantage, it is already

beat the transition from strong to 2

to bring about the weaker restraint.

that when roughing on the clamping side includes two by an inflow line and an Abdes double acting piston applied high flow conduction interconnected solenoid pressure temporarily on the release side of the piston 35 valves, one of which selectively affect the inflow lets and connects the clamping side with an initially line with a high pressure source and the drain pressureless auxiliary cylinder. This is intended to connect the pipeline with a relief pipeline (Fig. 1) be enough that the tensioning piston is just like that or the inflow line with a low pressure source moves far that the clamping force on the joins and blocks the drain line and of weaker value necessary for finishing decreases. 40 which the other optionally the clamping side of the clamping according to the invention is the specified disadvantage for cylinders with an inflow line and the release side odei a device of the type mentioned on the clamping cylinder with a relief line another way, namely eliminated that the clamping side over a throttle point with a Entbeim Transition from the high to the low voltage load line connects. According to a further education nod the release side of the clamping cylinder by means of a 45 manure of this embodiment has the drain line Valve via pressure medium lines with a source between the solenoid valves a branch for the pressure medium under low pressure supply, which is fed into the can be connected and the clamping side of the clamping cylinder leads relief line. The throttle point can, however if this connection exists during a one-off also through controlled leaks of a rotatable adjustable be formed for a limited time via a throttle point with 50 plates, which connects the second can be connected to a relief line. Solenoid valve with the clamping cylinder

A preferred embodiment of the invention provides.

709 638/294

Device for adjusting the clamping force of a chuck actuated by pressure medium

Applicant:

La Precision Industrielle S. A., Rueil Malmaison, Seine-et-Oise (France)

Representative:

Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Puls and Dr. E. Frhr. v. Pechmann, patent attorneys, Munich 9, Schweigerstr. 2

Named as inventor:

Jean Marie Garnet,

Bougival, Seine-et-Oise (France)

Claimed priority:

France of September 26, 1961 (874213)

3 4

To the handling of the invention in front of a block 24 formed in which a needle valve direction To facilitate, it is finally expedient, body 25 is screwed, the conical end Provide three electrical control buttons, of which 25 a (the one, as shown, with spiral grooves one can be provided as a tension button when actuated, the second elec- tric) a narrow drainage passage in solenoid valve makes voltage-free, the second as 5 the base channel 24 a of the body 24 spared. if Release button when the same valve is pressed under the pressure medium compressed air, the control device voltage can sets and the third as a shift key in processing can also be designed differently, z. B. as a filter actuation the first solenoid valve continuously cushion.

energized and the second valve via the lines 13 and 14 open into the opening

a timing relay a current pulse of limited io gen D and E of the solenoid valve EF ₂ . In order to

Duration supplies. are the two valves on the one hand through which the open-

The drawing shows an exemplary embodiment of the line 26 connecting the openings F and G (the object of which is shown schematically. Branch 26 a leads to the opening of the control device R It shows), on the other hand through which the opening H of the

1 shows a circuit diagram of a solenoid valve EV ₁ according to the invention with the central inlet device in the valve position during the opening K of the solenoid valve EV ₂ connecting-roughing, the line 27 connected. The opening L of EF ₂

F i g. 1 a, which is introduced into the chuck for roughing, via the line 28 to the storage container 19.

clamped workpiece with exaggerated The two valves have a similar design.

Deformation, ao leads. They both include a slide with three

Fig. 2 to 4 different successive constrictions (29 or 30), which by means of a spring

Valve positions when switching the chuck (31 or 32) is biased upwards and through

before finishing, actuated with the help of the winding (35 or 36)

F i g. 3a the workpiece after switching, electromagnetic plunger (33 or 34) after

Fig. 4a the workpiece after finishing, »5 can be driven down.

Fig. 5 shows the valve position for unclamping the As in a slide valve that is on the

Workpiece. three entry openings on one side and

In Fig. 1 the rotating part of a work side is two outlet openings and a slide

machine tool by a chuck 1 with clamping ber with three constrictions, is known,

cylinder 2 and its pulley 3 indicated, 30 is the middle inlet opening alternately with

these three organs firmly connected to each other while connected to the two outlet openings

and with two roller bearings 4 in one body 5 which are not connected to the central inlet opening

are stored, the one with the rotating, cylindrical dene outlet opening each with the closest

Part that it includes, the manifold of the tensioned, outer inlet opening in connection

Cylinder forms. 35 occurs.

The attached to the piston 6 of the clamping cylinder Fig. 1 shows the entire device in the

Piston rod 7 has an annular groove 7 a, in which the rough machining of workpiece 10.

Radially inwardly pointing ends of angle- Both valves are switched off. That under high

lever 8 to engage. The pressure pointing in the axial direction, coming from the memory 18

End of each bell crank takes one of the tensioning 40 fluid enters through opening A of the elec-

bake 9, between which the workpiece 10 is held solenoid valve EV ₁ and out at the opening H ,

is, in the radial direction with. The cylinder chambers 11 at K in the solenoid valve EV ₂ to go through

and 12 on both sides of the piston 6 will exit again via line and opening D and the chamber

gen 13 or 14 optionally a pressure medium, z. B. Oil, U to reach pie chamber 12 empties by

fed. The lines 13, 14 open in between 45 the fluid through E into the electromagnet

the fixed and the rotating part of the valve EV ₂ enters and exits through the opening L and

divided circumferential grooves 15 and 16, which get into the storage container 19,

Via radial bores with the cylinder chambers 11, in this way the piston acts on the

12 related. Rod 7 exerted a pulling force to the left, and

The lines 13 and 14 are alternately with 50 the jaws 9 clamp the workpiece 10 strongly in the help of the solenoid valves EV ₁ and EV ₂ pressure- radial direction inwards,
medium supplied. In the case of three jaws (FIG. 1 a), the opening A part of the solenoid valve EV ₁ opening into the middle is deformed into a triangle. In this deformed line 17 this is a part under high pressure, the tool can, however, drill holes like standing liquid (double arrow) from a 55 10 a, which, as long as the part is clamped, is completely pressurized by a pump P ₁ are cylindrical, but this is no longer supplied to memory 18, the pump P ₁ from applying as soon as the part is no longer clamped.
Reservoir 19 sucks. The opening B of this elec- The following figures show the valve positions tromagnetventils EV ₁ is via the line 20 a for the processing stages, through which finally coming from the accumulator 21, under black-deformed workpieces can be obtained,
chem pressurized liquid (simple arrow) As shown in Fig. 2 can be seen, is routed after the coarse. A pump P ₂ feeds the accumulator 21. Processing the solenoid valve EV ₁ switched on

The opening C of the solenoid valve EV ₁ is tet. The line 27 is then through the opening H.

in connection with the return channel 23, which is also the one entering through the opening B and out of the

if the draining pressure medium comes from the rule 65 accumulator 21, under weak

device R takes up. In the expression shown, fluid is supplied. on

management example, that of a hydraulic device, the pressure in the chamber 11 is produced in this way.

this control device is canceled by. As a result of elastic deformations and

Claims (5)

the jamming of the chuck, this does not affect the workpiece 10 as a relaxation. As in Fig. 3, the solenoid valve EV2 is then turned on for a very short time, while the solenoid valve JSF1 also remains on. The line 27 continues to supply fluid under low pressure to the opening K of the solenoid valve EF2. By switching on the solenoid valve JSF2, however, the connection between the opening Ä and the opening £ is established, so that the pressure now comes into effect in the chamber 12, while the chamber 11 due to the connection established between the opening D and the opening G does so tends to deflate. However, since the solenoid valve EF1 remains switched on, the evacuation path established in this valve between the openings / 7 and C is blocked, so that evacuation can only take place via the line 26 a through the control device R. The emptying process can be slowed down by the regulating action so that it is avoided that the chuck jaws release the workpiece 10. In practice, three control parameters are available, namely: the value of the weak pressure of the accumulator 21, the on-time of the solenoid valve EV2 and the regulation of the outflow from the control device R. Thanks to the momentary pressure reversal (Fig. 3a), the outer circumference increases 10 b of the workpiece 10 by releasing the jaws its circular shape again, while the originally circular bore 10 a now appears deformed. After the short on-time of the valve has expired, the valve is switched off. The resulting state according to FIG. 4 is the same as that shown in FIG. that is, a weak clamping pressure is in effect in chamber 11 while chamber 12 is emptying. The jamming and deformation of the jaws, the lever 8 and the rod 7, due to which the deformation of the workpiece 10 stopped, have disappeared. During the subsequent fine machining (FIG. 4a), as shown at 10c, a circular hole is made again on the workpiece 10, while the jaw pressure is not sufficient to deform this workpiece. After the completion of the processing (Fig. 5), the solenoid valve EV2 is turned on, while the solenoid valve EV1 is turned off and returns to its original position. The high-pressure medium coming from the accumulator 18 through the opening A exits at H of the solenoid valve EV1 and, since it re-enters at K, is passed via the opening E and the line 14 to the chamber 12. The workpiece is thus released from the chuck, since the chamber 11 is emptied due to the direct connection between F and C for the line 26, which receives the pressure medium from the chamber 11 via D and G. A certain duty cycle of the solenoid valve JSF2, which ensures the instantaneous pressure reversal in the chuck, can be obtained by means of a correspondingly delayed relay which can be excited by means of pulses. In automatic machines, this impulse can come from an end position contact. In manually operated machines such as lathes, the combination of energizing the solenoid valves to obtain the desired switching sequences can be achieved without difficulty by means of three push buttons, one of which switches off the current in the solenoid valve EV2 in order to effect the tensioning, the second the The current is switched on in order to bring about the relaxation, and the third button operated during the rough and fine machining ensures the constant excitation of the solenoid valve EV1 and supplies a momentary excitation pulse to the solenoid valve EV2. Patent claims: 1. Device for adjusting the clamping force of a chuck which can be actuated by pressure medium and has a double-acting clamping cylinder, the clamping side of which can be successively acted upon with a high pressure for roughing and then with a low pressure for finishing, the release side under pressure during the transition from high to low pressure is set, characterized in that during the transition from high to low clamping pressure the release side (12) of the clamping cylinder (2) by means of a valve (EV ₂ ) via pressure medium lines (13,14,17, 20, 26, 27) with a source (21) can be connected for the pressure medium under low pressure and the clamping side (11) of the clamping cylinder can be connected to a relief line (23) via a throttle point (R) if this connection exists for an adjustable limited time. 2. Device according to claim 1, characterized by two solenoid valves (EV ₁ , EV ₂ ) connected to one another by an inflow line (27) and an outflow line (26), one of which (EV ₁ ) optionally the inflow line with a high pressure source (18) and the drain line connects to a relief line or connects the inflow line to a low pressure source (21) and blocks the outflow line and of which the other (EV ₂ ) optionally the clamping side (11) of the clamping cylinder (2) with an inflow line and the release side (12) of the clamping cylinder with a relief line (28) or the clamping side via a throttle point (R) with a relief line. 3. Apparatus according to claim 2, characterized in that the drain line (26) between the two solenoid valves ( EV ₁ , EV ₂ ) has a branch (26a) which leads via a controllable throttle valve (R) into the relief line (23). 4. Apparatus according to claim 2, characterized in that the throttle point is formed by controlled leaks of a rotatable distributor (5, 15 and 16) which connects the second electromagnetic _{valve (£ F 2} ) to the clamping cylinder (2). 5. Device according to one of claims 1 to 4, characterized by three electrical control buttons, one of which as a tension button when actuated the second solenoid valve (EV ₉ ) de-energizes, of which the second as a release button when actuated the same valve below