JPH0224617B2 - - Google Patents

Description

[Detailed description of the invention] Screw presses installed as die forging machines for structural reasons often exceed 40 MN (meganewtons) because the impact force is limited by the friction wheel transmission (friction screw press). And, as a general rule, if an impact force of 80 MN or more is required, the screw press is equipped with a gear transmission. For this purpose, the flywheel is provided with an external toothing, into which a gear rim formed by the external toothing engages a motor-driven pinion. An electric or hydraulic motor is used to drive the pinion.

The drive type with an electric motor has the advantage that the energy supply is simpler, but high peak currents occur. This is because the necessary energy to be supplied to the flywheel must be obtained within a short stroke time during which the flywheel is accelerated to a predetermined rotational speed.

Therefore, special wiring is required to limit the peak current, which increases the construction cost and increases the cycle time. Since in each working interval the electric motor is accelerated twice from standstill to the required speed and then braked, a corresponding loss of current heat cannot be avoided, and moreover the ineffectiveness consumed by the motor The disadvantage is that it generates electricity. The desired torque requires a correspondingly large and heavy motor, and this heavy motor has an unfavorable torque-to-moment of inertia relationship, leading to the following structural disadvantages: That is, by mounting the screw with its flywheel and gear rim axially and immovably on the upper side of the press stand and by engaging the screw nut in the carriage of the press, the screw is subjected to undesirable pressure and torsional stresses. This is a factor that creates a structural defect that leads to

Hydraulic motors, especially axial piston motors, have smaller construction dimensions and significantly lower power weight than electric motors, so they are arranged individually or in pairs in the diameter range on either side of the drive pinion. It has the following structural advantages: That is, a screw with a flywheel and gear rim is fitted into a nut inserted in the upper side of the press stand, so that only torsional stress is applied at the top of the nut, and only pressure at the bottom of the nut. Added. To supply the hydraulic motor, an oil station is required, consisting of an electric motor, an oil pump, a high-pressure storage and control device, as well as a filtration device, an oil cooling device, etc. This oil station is located adjacent to the press on the factory floor, basement or bench and is connected to a hydraulic motor via a flexible high pressure conduit that compensates for the movement of the press. The construction costs for this are quite high, especially considering also the requirements for operational safety.

The invention relates to a screw press of the type described above, which is equipped with a gear transmission driven by a hydraulic motor. That is, a screw press comprising a flywheel coupled to rotate together with the screw via a sliding clutch, and a screw moving axially in a nut inserted into a cross beam at the top of the press stand, the flywheel An external tooth row is formed over a width corresponding to the sum of the maximum press stroke and the drive pinion width, and a plurality of pinions are provided that engage with the gear rim made of this external tooth row. , the plurality of pinions are driven by one or each pair of hydraulic axial piston motors, the axial piston motors with geared rims surrounding the upper crossbar of the press stand. Relates to forms that are located on a platform. The object of the invention is to reduce the construction cost of a screw press of the type described above and to increase its operational reliability. The present invention achieves this object by providing one pinion for each pinion on the platform.
An adjustable and reversible pump, which is driven by an electric motor, is each associated with one or each pair of axial piston motors.

The advantage of the screw press according to the invention is that it has a high electric drive efficiency. This is because the extensive load offset that can occur with hydraulic tanks in conventional drive types with a central oil supply is eliminated. In addition, there are also disadvantages caused by electricity in purely electric drives (in particular high peak loads, wiring to limit this high peak load, reactive power of the motor) and screw bearings caused by electric drives. In order to avoid structural shortcomings in the hydraulic drive and to ensure operational reliability in the hydraulic drive, other hydraulic structural parts (one oil motor or a pair of oil motors each assigned to one pinion) can be avoided. The disadvantages of having a separate oil pump and control medium) are largely avoided by eliminating the high-pressure oil line, in particular the part that compensates for the movements of the press. Overall, the advantages of the inventive solution are significant over prior art solutions.

It is also possible to configure the platform surrounding the upper crossbeam of the press stand at the same time as a storage container for oil and a cooling container. In order to increase the reliability of operation, a further embodiment of the invention provides a press stand in which the platform has a container, a cooler, a filter for the oil and a control element arranged in the oil circuit. It is configured as an oil sump surrounding the upper crossbar of the oil tank and as a leakage chamber for the total oil volume in the oil circuit.

According to a further embodiment of the invention, each axial piston motor or each pair of axial piston motors is assigned to one pinion,
and a controllable and reversible pump in the conveying direction, each driven by an electric motor, are arranged in a closed circuit, which supply pressure and a plurality of stepped pressures (of which A compact design and increased reliability of operation result if one stage of the pump is closed off for the control medium (which can be controlled as brake pressure) and is connected to the filling pump.

Next, the configuration of the present invention will be specifically explained with reference to the embodiments shown in the drawings.

The screw press stand 1 consists of a lower horizontal beam 2, an upper horizontal beam 3, and a support 4 that form a press stand.
and a preloaded tensile rod 5 which connects the transverse beams 2, 3 and the column 4 by means of a tensioning head 6. A vertically movable carriage 7 in the upper half of the forging die (not shown) is guided by the support 4, and the lower half of this carriage 7 is attached to the table surface 8 of the lower cross beam 2. Fixed. The carriage 7 is moved by a screw 9. The screw 9 is fitted into a nut 10 inserted into the crossbar 3 at the top of the stand 1. The nut 10 is supported axially on the one hand via a collar surface in a correspondingly stepped hole in the crossbar 3 and on the other hand by a ring 11 fixed to the crossbar 3. ing. Furthermore, a rotation holding member (not shown) for the nut 10 is provided within the cross beam 3. screw 9
The lower end head 12 is rotatably but axially immovably connected to the carriage 7 by a double-acting axial bearing 13. A clutch disc 16 is fixed to the pin 14 of the screw shaft 15, and this clutch disc 16 is connected to the flywheel 1.
Frictionally connected to 7. For this purpose, the clutch disc 16 is clamped between the boss 18 of the flywheel 17 and the pressure ring 19 by means of a clamping pin 20. The torque transmitted by the frictional connection is adjusted by adjusting the preload of the spring packet 21 on the clamping pin 20. flywheel 1
The gear rim 22 of No. 7 is provided with an external tooth row over its entire width, and the pinion 2 engages with this external tooth row.
3, the gear rim 22 is driven. In the illustrated embodiment, a plurality of pinions 23, for example six pinions 23, are provided on the outer periphery of the gear rim 22 (see FIG. 3). The pinion 23 is a bearing pedestal 24
It is bearing inside. This bearing pedestal 24 is supported by a platform 25 surrounding the upper crossbar 3 of the stand 1. Each pinion 23 is driven by an axial piston motor 26o placed above the pinion 23 and an axial piston motor 26u placed below the pinion 23. The width of the gear rim 22 is selected such that during the entire stroke of the screw 9 carried out by this gear 22, the pinion 23 always fully engages the external toothing of the gear rim 22. The axial piston motors 26o, 26u respectively assigned to the pinion 23 are supplied with oil by a respective oil pump 27 driven by a respective electric motor 28. In this case, the bearing pedestal 24 of each pinion 23 is connected to the axial piston motors 26o and 26u assigned to the pinion 23 and the oil pump 27.
and an electric motor 28. The oil supply pressure and supply amount of each oil pump 27 can be adjusted, and the oil supply direction can also be reversed.
Each oil pump 27 is connected via two parallel conduits 29 to a control block 30 with control medium. The control block 30 itself is connected via two parallel conduits 31 to the associated upper and lower axial piston motors 26, respectively. The container or containers for storing, cooling and filtering the oil are indicated at 32. This container 32 supplies oil to fill the circuit and receives oil flowing from the circuit. An oil container 32 can be assigned to each circuit or a common oil container 32 can be assigned to the circuits of the screw press halves or to the entire circuit. The platform 25 is configured as a sump 33 having an inner side wall 33i, an outer side wall 32a and a bottom 33b. In this case, the oil sump 33 is designed with sufficient dimensions to supply the full hydraulic pressure and to receive the entire amount of oil present in the oil circuit.

The details of the drive device will be explained below based on the schematic hydraulic circuit diagram shown in FIG. a flywheel 1 with a screw 9 and a gear rim 22 connected to the screw 9;
7 is driven via a number of pinions 23, six in the embodiment of FIGS. 1-3. Only one of these six pinions 23 is shown in FIG. Each pinion 23 is driven by a pair of axial piston motors, or by one axial piston motor 26 as shown in FIG. Oil is supplied to the axial piston motor 26 by an oil pump 27, and this oil pump 27 is connected to the electric motor 2.
8. By reversing the conveyance direction of pump 27, the rotation direction of axial piston motor 26 is also reversed. The axial piston motor 26 serves in one direction of rotation as a working stroke for a downward movement of the screw 9, and in the other rotational direction as a return stroke for an upward movement of the screw 9 and back to its starting position. The electric motor 28 is operated at an approximately constant efficiency during the acceleration phase for the downward and upward movements of the screw 9 and at a constant rotational speed which maintains a high electrical efficiency of the electric motor 28. This constant motor efficiency is converted and fully used by the oil pump 27, which acts as a torque converter. For this purpose, the oil pump 27
is a pressure gauge 35 and a control device 36 related to the pressure.
and an adjustment device 37 which is operated via. The adjusting device 37 serves to pivot the piston axis towards the drive axis in the preferred axial piston pump used in this embodiment. This swiveling range is limited to a swiveling angle for the working stroke and return stroke of the screw 9, each depending on the desired screw rotation speed. This turning angle defines the conveyance amount of the oil pump 27 at a constant rotation speed of the electric motor 28. Adjustment device 37
A piston-cylinder device is used as a pump, the load of which is applied to the pressure reservoir 4 via a control device 36 of a pump 39 driven by an electric motor 38.
This is done in contact with 0.

During the working stroke of the screw 9, that is, the carriage 7
During its downward movement, the flywheel 17 is accelerated by the drive until a predetermined rotational speed is achieved, ie until the energy required for the forging operation is stored. The conveyance amount of the pump 27, which corresponds to this rotational speed, is kept constant, and thus the rotational speed of the flywheel 17 is also kept constant. Just before the upper forging die half, which is fixed to the carriage 7, strikes the forged product present in the lower forging die half, the magnetically controlled four-stroke valve 41 is moved from its non-working position (see FIG. 4) to the left. By being displaced, the conduit 31 leading to the axial piston motor 26 is closed for a short time. In the non-working position of the four-stroke valve 41, the conduit 42a connecting this four-stroke valve 41 to the pressure limiting valve 42 is suddenly severed, so that within this conduit 42a the pressure limiting valve 42 is completely activated and the relief valve 42b is closed. A pressure (maximum operating pressure) is formed which is controlled by 4
When the control piston is shifted to the left in the stroke valve 41, the pressure in the conduit 42a disappears, so that a short circuit is formed in the conduit 31 against the slight spring force of a closing spring (not shown) in the pressure limiting valve 42. . During this time, the conveying direction of the pump 27 is reversed. As soon as the press stroke ends, the four-stroke valve 41 returns to its non-working position, so that the screw 9 is driven in the opposite direction and accelerated to a predetermined rotational speed. Immediately before the end of the upward movement of the screw 9, the rotational speed of the pump 27, and thus of the flywheel 17 and the screw 9, decreases to zero during the remaining stroke of the screw 9. By decreasing the rotational speed, the control piston in the four-stroke valve 41 is moved from its non-working position to the right and the conduit 42a is connected to the second pressure limiting valve 43. The pressure adjustable by this second pressure limiting valve 43 limits, via the pressure limiting valve 42, the pressure occurring in the conduit 31 to the pressure required for braking the flywheel 17.

Pressure limiting valves 42, 43 and 4-stroke valve 4 during reverse rotation
A small amount of oil leaked out by the pump 45 is pumped by a motor 44.
is fed back into the closed circuit by pump 2
7, a pressure-controlled three-stroke valve 46, centered by a spring, is provided, which is regulated by a pressure-limiting valve 47. This three-stroke valve 46 is connected in such a way that the respective low-pressure side of the closed circuit is connected to a pressure limiting valve 47 . In this case, the supply pressure is maintained by pump 45. In order to keep the oil clean and cooled, it flows out of the circuit and into a container 3.
The oil collected in part 32b of 2, pre-cleaned by settling and directed to part 32c of container 32 is pumped by a pump 49 driven by an electric motor 48 to a filter 50 and a cooler. 5
1 and stored in a portion 32a of the container 32.

According to the illustrated embodiment, an axial piston motor 26 (constant motor) and an axial piston pump 27 (regulating pump), ie, an axial piston machine, are provided. This is because this axial piston machine is the most suitable. However, the invention is not limited only to this axial piston machine; suitable oil pumps and oil motors according to other construction principles can also be used. Instead of the preferably closed circuit according to the exemplary embodiment shown, the oil motor and the oil pump can also be operated in an open circuit.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of a screw press according to an embodiment of the present invention, FIG. 2 is a side view, FIG. 3 is a plan view, and FIG. 4 is a schematic hydraulic pressure of the screw press according to FIG. 1. It is a circuit diagram. 1... Stand, 2, 3... Horizontal beam, 4... Support, 5... Tensile rod, 6... Tightening head, 7...
...carriage, 8...table surface, 9...screw,
10... Nut, 11... Ring, 12... Head, 13... Axial bearing, 14... Pin, 1
5...screw shaft, 16...clutch disc, 1
7... Flywheel, 18... Boss, 19... Pressure ring, 20... Tightening pin, 21... Spring packet, 22... Gear rim, 23... Pinion, 24
... Bearing pedestal, 25 ... Platform, 2
6, 26o, 26u...Axial piston motor, 27...Oil pump, 28...Electric motor, 29...Conduit, 30...Control block, 31
... Conduit, 32 ... Container, 33 ... Oil sump, 32
a, 32b, 32c... portion, 32a... side wall,
33b...bottom, 33i...side wall, 35...pressure gauge, 36...control device, 37...adjustment device, 38
...Electric motor, 39...Pump, 40...Pressure reservoir, 41...4-stroke valve, 42...Pressure limiting valve,
42a... conduit, 42b... relief valve, 43...
Pressure limiting valve, 44...motor, 45...pump,
46...3-stroke valve, 47...pressure limiting valve, 48...
...Electric motor, 49...Pump, 50...Filter, 51...Cooling section.

Claims (1)

[Scope of Claims] 1. A flywheel 17 coupled to rotate with the screw 9 via a sliding clutch, and a nut 1 inserted into the upper horizontal beams 2 and 3 of the press stand 1.
A screw press comprising a screw 9 that moves axially within 0, wherein the flywheel 17 is provided with an external tooth row over a width corresponding to the maximum press stroke plus the width of the drive pinion. A plurality of pinions 23 are provided which engage with the gear rim 22 consisting of this external tooth row, and each of the plurality of pinions 23 is connected to one or each pair of hydraulic axial piston motors 26, 26O, 26U. Axial piston motors 26, 26O, 26 equipped with the gear rim 22 are adapted to be driven by
In the version in which U is arranged on a platform 25 surrounding the upper transverse beams 2, 3 of the press stand 1, one axial piston motor 26 is provided for each pinion 23 on the platform 25. or a pair of axial piston motors 26O, 26U, each with an adjustable and reversible pump 27 driven by an electric motor 28;
A screw press characterized by having correspondingly arranged parts. 2. the platform 25 has a container 32, a cooler 51, a filter 50 for the oil and a control element 30 arranged in the oil circuit;
2. Screw press according to claim 1, which is configured as an oil sump 33 surrounding the upper crossbar 3 of the press stand 1 and as a leakage chamber for the total oil quantity in the oil circuit. 3. An axial piston motor 26 or a pair of axial piston motors 26O, 26U assigned to each pinion 23 and an adjustable pump 27 with reversible conveying direction act as control elements for the supply pressure and the plurality of pressure stages. and is arranged in a closed circuit connected to a filling pump 45, one of the plurality of pressure stages being controllable as a brake pressure. The screw press described in item 2.