DE937862C - Control device for the hydraulic drive for reciprocating parts of machine tools - Google Patents

Description

Control device for the hydraulic drive for reciprocating Parts of machine tools The invention relates to a control device for a hydraulic drive with two or more liquid pumps of the same or different types Performance for floating parts, e.g. B. Carriages for machine tools.

There is a hydraulic drive for machine tools known at the same as that of the hydraulic fluid through two pumps driven by a power source Delivery rate is generated, with a pressure relief valve connected to each delivery line and behind the one pressure relief valve. Switch tap to establish the connection is provided with the other delivery line. Through a control housing Switch the pumps in such a way that either both pumps work together and only simple ones Generate pressure or, if the second pump is short-circuited, only one pump, but with double pressure is effective.

It has also been suggested for a hydraulic drive for reciprocating parts of machine tools two or three each one constant Provide pumps conveying the amount of liquid, the one always being the same A pump that promotes the senses and is equipped with a reversing valve in a closed power system switched, st, in which the second pump delivers. The third pump, however, is only intended to achieve an accelerated return.

The first-mentioned drive has the disadvantage that only two speed levels can be set, taking that of the low speed appropriate Setting is characterized in that one of the two pumps is interposed a pressure relief valve is short-circuited. The overpressure valve has. here a pronounced throttling effect, resulting in a considerable loss of power, the compensated for by a correspondingly large and expensive drive motor for the pumps must become.

The second known drive, with each of the three a constant amount of liquid conveying pumps does not allow any change in the feed rate at all, because two of the three pumps always act against each other to stabilize the feed must, while the third pump alone to achieve an accelerated return is provided.

Despite the considerable technical effort, it is with the known Drives not possible to have a larger number of feed speeds in simple Way to produce such as this when processing different materials with different Tools to utilize the respective permissible feed rates are desirable is.

With the invention, the disadvantages mentioned can be avoided, and it can be a drive with lossless regulation without throttling with a combination can be built up of non-adjustable and therefore simple pumps, with simple Way several speed levels can be achieved. This is done according to the invention with a control for the hydraulic drive of reciprocating parts, in particular machine tool parts, using several on the Machine part to be driven switchable pumps, achieved in that the pressure side each pump on the one hand via a check valve to a common to the hydraulic Motor leading pressure line, on the other hand to an electromagnetically to, actuating, overflow valve connected to the storage tank on the suction side is connected, each solenoid via a contact one by hand or by the moving machine part towards the end of its back and forth movement controlled switch and a contact associated with the reciprocating movement Selector switch is to be energized, through the setting of which the circuits for actuation any overflow valve can be prepared .. 'Also the supply and discharge of the pressure medium to the corresponding direction of movement of the drive In a further development of the invention, supply and discharge lines can be carried out electromagnetically Valves to be operated are made via special switching contacts the switch mentioned.

It is particularly advantageous if, when using three pumps, their. Funding services in the ratio i :: 2: q. stand. Then settle for this small one Set the number of pumps to seven evenly increasing speed levels, as will be shown later. In the drawing is an embodiment for a hydraulic drive according to the invention shown schematically. With i "and e are two fixed cylinders, in each of which one with a piston rod 2Q or 2, connected piston is arranged to be movable back and forth. The two piston rods 2a and 2 ,. are connected to the machine part 3 to be moved, for example the piston rod 2a for the feed movement, the piston rod 2 ,. for the return movement intended. is.

The hydraulic system has in the illustrated embodiment three liquid pumps q., 5 and 6, for example as gear pumps, rotary piston machines Od. The like. Can be formed, the pressure fluid through a common suction pipe 7 suck in from a storage container 8. The pressure side of every liquid pump is via a spring-loaded check valve9. a common pressure line is connected.

Each liquid pump q., 5, 6 is one with the pressure side of the pump connected electrical overflow valve 1i, 12, 13 assigned. The overflow valves are to a common return line 1q opening into the liquid container 8. connected. The return line 1q. itself is via a spring-loaded check valve 15 connected to the pressure line zo. 'The pressure line io is one end to one Mounting body 16, and the other end to a mounting body 16 connected. Each of these two mounting bodies includes a solenoid 17 or 17 actuatable Valve 18, or 18 ", a check valve iga or i9, and a valve 2o" or 2o ,. a. The cylinder i "is the cylinder via a pipe 2i with the mounting body r6" i, connected via a pipe 22 to the assembly body 16a. A return pipe 23 b.zw. 24 leads back from the assembly body 16 or 16 ″ to the liquid container B.

The switching means are two electrical selector switches 25a and 25, and one to close the various circuits serving Sehalter 26 with four Switching contacts: ktzn or contacts 27, 28, 29, 30 provided. The switch 26 is for three positions O (stop), R (return) and A (feed) built and can be either by hand or by means of not shown, arranged on the movable machine part Operate the stops.

Before the mouth of the return pipe 23 or 2q. there is a storage flap 3 i or 32, which are connected to contacts located in the area of the switch contact 27 of the switch 26. The contacts 28, 29, 3o are connected to the solenoids of the overflow valves ii, i2 :, 1 3 . The selector switch 25 is via a line 35 to the solenoid i7, and via a line 36 to the flap 32 and to the contacts 28; 29, 3o connected. The selector switch: 25 "is connected via a line 37 to the SolenGid 17a and via a line 38 to the Stauklapp0 3 i and to the contacts 28, 29, 3o-. The electrical part of the device is connected to a power source via the both lines 33 and 34.

The mode of operation of the device described is as follows: For the purpose of moving the machine part 3 in the sense of the VOT thrust movement, the switch 26 is turned to position A and the liquid pumps 4, 5, 6 are put into operation. The following circuits are closed: line 33, solenoid 17a, line 38, closed baffle flap 3 i, line 39, switch contact 27, line 34. The solenoid 17a lifts the valve i8 "into the position in which the cylinder 1r over the is tubes 22 and 24 connected to the reservoir 8 and io completed in the mounting body 16, the end of the pressure line located. at the same time, the non-drawn, is connected in parallel to the solenoid 17d relay coil of the selector switch 25 turned on, a switch with three parallel to the Line 37 is actuated and the line 37 connects to the three contacts 28, 29, 30. This has the consequence that the three solenoids of the overflow valves 11, 12, 13 connected in parallel and connected to the line 33 via the line 4o via the Line 37, the line 38, the damper 31, the line 39, the switching contact 27 connected to the line 34 and the outputs of the overflow valves are completed in the direction of the return line 14 by lifting the valve body from the open positions shown in the drawing.

The three pumps 4, 5, 6 that are switched on convey the pressure fluid that is sucked in via the check valves 9 to the pressure line 1o and, from this via the check valve igr of the, mounting body 16 "and the line 21 after the cylinder i ', so that the movable machine part 3 by the piston 2 "in the sense of the advance to the right is moved. At the same time causes the piston rod 2, shifted; with the latter connected piston expelling the pressurized fluid from the cylinder ir, via the line 22 and the line 24 released by the valve 18a after the reservoir 8 flows back.

At the end of the feed movement, the switch 26 is out of position A folded into position R. The solenoid 17, and the relay coil connected in parallel of the selector switch 25 "are de-energized, so that the valve 18" in its previous, the Pipe 24 shut-off position falls back and the overflow valves 11, 12, 13 their outputs release in the direction of the return line 14. The conveyed by the pumps 4, 5, 6 Hydraulic fluid therefore no longer reaches the pressure line io, but flows back into the reservoir B through the return line 14 without pressure.

The switch 26 pivoted to position R causes the closure of the circuit via the Solen.oid 17 "and the relay coil connected in parallel of the selector switch 25r so that the valve 18 is raised and the cylinder 1a is over the lines.2i and 23 are connected to the reservoir 8, while the solenoids the overflow valves i i, 12, 13 are switched on and the pumps 4, 5, 6 die Hydraulic fluid via the pressure line io, the pressure relief valve iga and the pipe 22 after the cylinder i, promote to the machine part 3 in its starting position move back to the left. In the circuit of the solenoid 17, and the one connected in parallel Relay coil of selector switch 25r is closed storage flap32. The promotion of pressure fluid to the cylinder 1r has the backflow of the pressure fluid located in the cylinder 1a in the reservoir 8 result.

The flap 31 holds the. Circuit closed via solenoid 17d, as long as the switch is in position A. But she will interrupt this circuit, as soon as pressure fluid flows out of the pipe 23. The flap 32 is in the circuit this solernoides, 17 "which they when hydraulic fluid escapes from the pipe 24 interrupts. The two stowage flaps thus act as safety devices and prevent the opposite movement of the machine part 3, as long as the latter is still in a Direction is moved. Because one caused by one or the other baffle flap Power interruption also the solenoids dter overflow valves i i, 12, 13 de-energized will fall. the valve bodies of the latter return to the open positions, and the pumps convey the pressure fluid that has been sucked in without pressure via the pipe 14 after the reservoir 8 back.

After switching the switch 26 from one to the other end position the machine part 3 is still in motion, so that, depending on the direction of movement, hydraulic fluid is still flowing out of one or the other cylinder. These Hydraulic fluid causes the backshield valve 2o "to open or gor for the purpose the possibility of passage into the tube 24 or 23. The resulting in the cylinder Pressure is used to brake the moving machine part. This pressure lets through Change of the spring tension of the pressure relief valve 2oä or gor on good and yet Adjust bumpless braking.

In the exemplary embodiment described, the three pumps 4, 5, 6 work in parallel on both the cylinder 1a and the cylinder ir, so that the speed of the moved machine part is the same in advance and in return. But it can be done for the. Advance and return achieve different speeds, such that, for example, the return speed is greater than the foreshoe speed and a maximum is reached by switching on the three existing pumps. The reduced feed rate, however, can be brought about by only one or two pumps delivering pressure fluid to the pressure line 1o, while the pumps not intended for delivering pressure fluid; can run without pressure in that the pumped hydraulic fluid is transferred into the return line 14. This can be achieved in the described circuit arrangement in a simple manner that all three existing overflow valves 11, 12, 13 are operated for the return through the selector switch 25r to block their outputs in the direction of the Rückleiturig 14, while for the feed through the Selector switch 25 ″, for example, only switches on the solenoid ii, which interrupts the lines in the selector switch 25a leading from the salenoids 12 and 13 via the switching elements 29 and 30 , so that only the pump q: delivers pressure fluid to the pressure line io, while the pumps 5 and 6 operate without pressure after the return line 14. The necessary circuit changes can be made conveniently on the selector switches to achieve the desired speeds for the advance and return without having to make changes to the other parts of the device.

Pumps of the same or unequal, constant or adjustable delivery rates can be used. If, for example, three pumps 4, 5, 6 are used with delivery rates in a ratio of 1: 2: 4, then the following seven speed levels can be achieved according to the delivery rates: Pump delivery rate .4 i 5 2 4 + 5 3 6 4 4 + 6 5 5 + 6 6 4 + 5 + 6 7 The number of speed levels that can be achieved can be increased as required by the number of pumps used and adapted to the prevailing conditions. The number of overflow valves to be used and the number of switching contacts on switch 26 and on the counting switches must be selected to be the same as the number of pumps to be arranged in order to be able to utilize all possible combinations. If such a device is to be provided for planing machines, for example, a number of different speed levels is available for the advance of the machine table, depending on the number of pumps used, and there is the possibility of switching the appropriate pumps in parallel to generate the advance as closely as possible to get the optimal cutting speed of the tool used. As a rule, as high a speed as possible is required for the return, which is above the feed speed and which is achieved by a different combination of the two to be switched in parallel. Pumping can be achieved. By means of the device described, the feed rate can be adjusted while maintaining the maximum. Regulate the return speed and unchanged delivery rates of the individual pumps. Other possible applications for the device are: Spindle drilling machines with hydraulically moving tables, grinding and milling machines with automatic, hydraulic table mechanisms, lathes with hydraulically actuated, large slides or such mi@tvolillhydrauli.schem longitudinal and transverse feeds, hydraulic presses, etc.

As a power source for the electrical control equipment for remote operation of the valves is one with a low level, excluding any risk of contact Voltage chosen.

Claims (3)

PATENT CLAIMS: i. Control for the hydraulic drive of reciprocating parts, in particular. of machine tool parts, using several. Pumps that can be switched to the machine part to be driven, characterized in that the pressure side of each pump (4, 5, 6) on the one hand via a check valve (9) to a common pressure line (io) leading to the hydraulic motor (ia, 2a, Ir, 2r), on the other hand, it is connected to an electromagnetically actuated overflow valve (11, 12, 13) connected to the storage container (8) on the suction side, each solenoid coil via a contact (28, 29; 30) one by hand or by the moving machine part in each case towards the end of its reciprocating movement controlled switch (26) and a contact of a selector switch (25a, 25r) assigned to the reciprocating movement is to be excited, through the setting of which the circuits for actuating any predetermined overflow valve (11, 12, 13) vo @prepared. 2. Control according to claim i with a device for alternating distribution. of the pressure medium to the consumer point assigned to the respective direction of movement (1a, 2 "or 1, 2r) and to divert the pressure medium displaced by the consumer (motor) to the Storage container, characterized in that the devices for distributing the Pressure medium consist of electromagnetically operated valves (iga, 18r), the switching contacts arranged on the switch (26) when the direction of movement is changed (27) _ be controlled. 3. Control according to claim i or 2 with several pumps, characterized by the use of three pumps (4, 5, 6), their delivery rates are in a ratio of 1: 2: 4. Referred publications: German patents No. 591 811, 6oi 552, 653 104, 657 392, 704 656.