Press with an eccentric crank drive of the unit of the upper plunger and a method of its operation

FIELD: machining by pressure.

SUBSTANCE: the invention is dealt with the field of machining by pressure and may be used in presses for pressing powder-shaped masses, in particular, the metal powder-shaped masses. The press contains at least one connecting rod, a crankshaft and a connected with it and capable to rotate gear with an eccentric crankshaft drive for driving the unit of the upper plunger. The gear is set in rotation at least by one engine using at least one worm gearing. The press is equipped with electronic control, which is supplied with a function of a reversing mode of operation of the crankshaft. At the press operation a run of the unit of the upper plunger is reversed shortly before reaching of the upper and-or the lower dead point of the eccentric crankshaft drive. The second alternative of operation of the press offers to regulate a run of the unit of the upper plunger so, that the lower dead point of the eccentric crankshaft drive is passing a short way. In result the invention ensures an increase of accuracy of produced pressed items and an over-all performance, and also an increase of the performance index of efficiency of the press operation and expansion of its operational capabilities.

EFFECT: the invention ensures increased accuracy of produced pressed items, over-all performance, increased performance index of the press operation efficiency and expansion of its operational capabilities.

15 cl, 2 dwg

 

The invention relates to a press for compacting powdered mass, in particular a metal powder, using having at least one connecting rod, and a crankshaft eccentric crank drive for actuating block of the upper punch, according to the restrictive part of paragraph 1 of the claims, as well as to method of operation of the press.

In compaction of metal powders and metal powders for many years using a mechanical powder presses for the manufacture of pressed from a powder parts. These mechanical presses, performed usually in the form of eccentric presses or crank-knee presses, high operating speed when the sinusoidal trajectory of the punch with highly progressive nature of changes in tonnage during the working cycle. For the manufacture of particularly complex molded parts are used preferably powder presses, forging dies which are driven by hydraulic cylinder-piston systems. Using the appropriate electronic control can be optimally manage the individual forging stamps on efforts and progress pressing, so there extrusion products, which, despite its complex shape differ maximally pic is annoy density inside the volume of the shaped body. However, compared to mechanical presses hydraulic presses usually have lower operating speeds and significantly higher energy consumption.

Accepted as the prototype of the Federal Republic of Germany patent DE 4114880 A1 is known a press for compacting powdered mass, which is made in the form of a mechanical eccentric press with a drive motor for moving the upper punch press. The crankshaft eccentric drive for the upper punch is connected with the possibility of joint rotation with the toothed wheel, which is driven by a worm gear, which in turn is driven by a motor. The direction of rotation of the motor and the crankshaft does not change during operation. To move the matrix is provided by a hydraulic cylinder-and-piston system. The feature of this known press is that it has a code switch, which determines the operating position of the upper punch and emits a corresponding signal to the electronic control system of this press. In addition, a frequency Converter, which affects the motor and receives from the electronic control system regulating signals, so that the drive movement is controlled. Upper plug is installed in the cylinder pressure measurement with prob is the possibility of moving in the direction of pressing, this hydraulic movement of the upper punch is controlled by the electronic control system of the press. Due to this combination, mechanically driven eccentric press with additional hydraulic actuators dies of the press is achieved that even the most complex in the form of pressed powder parts can be produced in large quantities, and ensures the consistency of the size and density of the pressed parts.

The task of the invention consists in the creation of such a press, whereby it becomes possible to combine known for mechanical presses and seals pressproof preferred sinusoidal trajectory and the progressive nature of the change forces with relatively simple technical implementation hydraulic actuator advantage of the relatively high flexibility of the press and approaching the ideal course of pressing at high reproducibility of the speed and position of the dies for pressing. Energy consumption this pressure must be small relative to the created actuation forces. Settings press should be regulated in a simple way to optimize travel and energy consumption. In addition, there should be created the way to work this press.

This task is solved by using a press with those specified in paragraph 1 of the claims traits. In the dependent claims indicate the preferred versions of this press. The method of operation of the press according to the invention is distinguished by the features of independent points 14, 15 of the claims.

The press, according to the invention, has to drive his block upper punch eccentric crank drive, which contains at least one connecting rod (usually they are located in pairs), which at its one end is connected to the block of the upper punch, and at its other end is eccentric to the crankshaft. The connection to the crankshaft is carried out, for example, with the help of the eccentric disk. With the crankshaft is connected with the possibility of rotation of the toothed wheel. This toothed wheel is mounted with the possibility of bringing in rotation at least one, preferably two worm gears, which are expediently located diametrically opposite relative to the crankshaft and driven by the engine, preferably each individual engine. Processes move the press is managed by an electronic control device. Essential feature of the invention consists in the fact that the electronic control is aimed at ensuring the reverse operation of the crankshaft. When the crankshaft is preferably rotated in the angular range m is it than 180° . In accordance with the reverse rotation of the toothed wheel unit upper punch due to the force transmission rod moves up and down, i.e. between the position of the pressing and the position of the filling/removal. Thus, unlike conventional mechanical presses with eccentric crank drive the crankshaft in the press, according to this invention, does not full speed.

Because of the particularly high density of torque relative to the structural volume and relatively low centrifugal moment GD2hydraulic motors, which ensure highly dynamic drive, their use is preferred to drive the motors. Due to the location of the two worm gears with the corresponding individual motor at a relatively low structural volume at the expense of the power transmission worm gear to create twice as much torque on the crankshaft without increasing the load of the teeth of gear wheels, respectively, of the worm gear.

Particularly useful to perform control so as to be able preferable to include two hydraulic motor press regarding their inclusion in the hydraulic circuit means for selecting in parallel or in series. If parallel enabling is when two hydraulic motors each motor is half the size of the stream, while the sequential inclusion through each engine passes the full amount of the flow. This means when the same hydraulic unit a, respectively, twice the operating speed. It has special advantages, in particular when pressing small parts with small structural height.

In addition, it is preferable if the press has a matrix that is installed with the possibility of a managed movement by a hydraulic cylinder, as is in principle known for hydraulic presses. In addition, the press may contain driven hydraulically adapter stamp. In this case, it is expedient to provide a Central electric motor, which actuates a hydraulic pump unit of the upper punch and the other hydraulic pump to the hydraulic cylinder of the matrix and/or driven hydraulically adapter stamp.

To determine the current location of the block of the upper punch is advisable to use an electronic measuring system for indirect or preferably direct measurements. For example, there may be provided an electronic measuring system path to determine the current position of the top of the press slide, which is the block the top of the punch, or there may be provided an electronic angle sensor for determining the current angular position of the crankshaft.

A special advantage of the press according to this invention, the moving parts of the stamp which is managed by an electronic control device is preferably controlled by simple means relative to the volume flow and pressure flow of hydraulic means you can have a direct impact on the work of the eccentric crank drive. Thus, you can very easily and accurately hydraulically affect both the speed and torque of the eccentric crank drive. In addition to this advantage is that due to the eccentric crank drive is significant transmission of the generated pressure force. The necessary pressing force of course most in the area of the bottom dead point of the block of the upper punch. However, in this position, press the gear ratio between the driving force and the pressing force is maximum. This leads to the conclusion that it is necessary to press drive capacity, you can choose a much smaller compared with the hydraulic pressure is made with the same maximum pressing force. Due to this also greatly humanised the total energy consumption during the pressing cycle.

The press, according to the invention, provides a cycle time that is less than the cycle time of working purely mechanically with a conventional drive motor of the press with an eccentric crank drive. This is possible when the control pressure is adjusted so that the turn ends clearly before reaching the top dead center of the eccentric crank drive and then reversed. In a conventional mechanical press must always be the full path.

The cycle time of a conventional mechanical press is largely determined by the necessary operations for removal of the molded parts. This includes, in particular, the need to maintain a clamping force during the liberation of the matrix, which is created by using a located in the upper punch hydraulic cylinder-and-piston system. In continuous operation, this cylinder-piston system during the reverse movement of the block upper punch should do the pull-out movement to save the clamping force and after release of the matrix quickly return to its original position. This requires either the availability of especially productive (expensive) hydraulics or approval of base speed (rotational speed) of the press with the time required to move a cylinder-piston system. In the press, according to the image is the shadow, can significantly reduce the speed of the block of the upper punch in the area of the bottom dead point, or even to temporarily hold it at zero until it is extracted molded part. Due to this, you can have a very small hydraulic costs of the movement of the cylinders to maintain the clamping force. After removing from the mold block upper punch with maximum speed to return to its original position.

Also preferred mode of operation of the press according to the invention, is provided when the progress in the area of the bottom dead point of the block of the upper punch is adjusted so that the bottom dead point thatthey pass to pressing slightly. Thus, the press works in a range of angle of rotation of the crank, which slightly exceeds 180° (absolute angle). After reaching the end point when the reverse mode press the program must pass the dead point at 180°. This means that a maximum simply by double pressing with a maximum pressing force at the lowest point in each cycle. This is of particular advantage for certain molded parts.

Below is a detailed description of the exemplary embodiment of the invention with reference to the drawings, which depict:

figure 1 - sectional view of the press according to the invention, and

figure 2 - course changes characteristic pair of the press EAN depending on the angle of rotation of the crank.

Figure 1 shows schematically a section of the press, according to the invention, and shows only the drive unit 2 of the upper punch (i.e. the top of the press slide, which supports the block upper plug). This block 2 upper punch, which, depending on the form of manufactured molded parts can hold one or more of the upper punches, is mounted for sliding in the frame 1 of the press. Molded part is created in an enclosed between the matrix 9 and, for example, still resting on frame 1 of the press unit 8 of the lower punch forming a hollow space, which includes one or more of the upper punches. It is advisable provided by a mechanical adjusting device 10, which is installed with the original and final position of unit 2 of the upper punch. Through the connecting rod 3 block 2 upper punch is driven through the installed in the frame 1 of the press with the possibility of rotation of the crankshaft 4. During the rotation of the crankshaft 4 is provided for unit 2 of the upper punch approximately sinusoidal character of change of speed. Made in the form of a worm wheel gear 5 is connected with the possibility of joint rotation with the crankshaft 4. A connecting rod connected to the crankshaft 4 through the eccentric disk, which can be executed as a single unit with a gear wheel is 5. The left and right of the gear 5 has two diametrically opposite relative to the Central axis of the crankshaft of the two worm worm gears 6.1, 6.2. Both of the worm are driven by respective hydraulic motor 7.1, 7.2. The crankshaft 4 is (not illustrated) of the electronic angle sensor, which can indirectly determine the actual position of the unit 2 of the upper punch. To move the block 2 upper punch provided by a hydraulic pressure system, which is also not shown and which provides other hydraulically driven parts of a pressing stamp (for example, matrices, block bottom plug or adapter stamp). All moving parts of the press are controlled not depicted in figure 1 electronic control device, which controls the valves and pumps of the hydraulic system on the basis of measuring values of the angle sensor or the system used direct measurements.

While figure 1 provides the location of the eccentric crank drive in the lower part of the base 1 of the press, in the practical implementation of the press, according to the invention, the preferred may be the location of the eccentric crank drive over unit 2 of the upper punch, i.e. in the upper part of the pre is CA. This does not affect the principle of operation of the press.

The principle of operation of the press, according to the invention is as follows.

Both of the worm worm gears 6.1 and 6.2 through hydraulic motors 7.1, 7.2 are impacted supplied hydraulic pumps hydraulic means are in accordance with the gear ratio of the worm gear 6.1, 6.2 torque on the toothed wheel 5 and the corresponding rotary movement of the crankshaft 4. Electronic control is made so that when switching the direction of rotation of the hydraulic motors 7.1, 7.2 is provided by reversing the rotary movement of the crankshaft in the angle range, for example, 120. With appropriate choice of the number of rotations of the hydraulic motors 7.1, 7.2 crank actuator reaches the zone of the lower dead point. The control pressure can be adjusted so that, if necessary, the final position of the pressing is achieved on the other side of the bottom dead point of the connecting rod 3. In this case the absolute dead center position of the press is traversed once in the operating cycle and then again at the beginning of "idle", which is provided by double pressing. By reducing the rotation of the crankshaft to the range, obviously the smaller 180°, eliminates the need to complete, consuming a relatively long time, depression and/or peaks of the sine curve motion. Thus you can easily save about 30-50% of the cycle time. This possibility exists only when the reversing operation, according to this invention, but not for the press with the usual eccentric drive, which regularly performs full speed. If necessary, due to changes in the volume flow of the hydraulic means, due to the high gear ratio torque worm gears 6.1, 6.2 and crank action of the connecting rod 3 to create a high pressing force at a relatively low speed unit 2 of the upper punch, which has a positive effect on the compaction of the powder. The movement block 2 upper punch for opening the mold and to release the molded body is achieved by switching the direction of rotation of the hydraulic motors 7.1, 7.2. Hydraulic motors 7.1, 7.2, you can choose to include in parallel or in series in the hydraulic circuit means with the respective valve circuits. The first is recommended, particularly for the working stroke (seals), and the last - especially at idle (removing molded parts). When remaining constant stream of supply of hydraulic pump, this means that idle runs with half the effort, but with double speed than the actual working cycle. Thus, in the press, according to the invention, combined preferably slow labour movement with a large pressing force and a quick return movement with less effort. Thus, the drive power of the press can be used substantially evenly throughout the cycle pressing than in conventional hydraulic presses. Naturally, you can optionally do not change during the entire pressing cycle parallel or series connection, the latter is especially recommended for achieving high performance in the manufacture of molded parts with a relatively small height, for which sufficient small tonnage. In principle, the press, according to the invention, can operate as a conventional mechanical press in continuous mode, i.e. without reversing drive motor. This still provides the advantage of easy reconciliation operating speed. For the press it is expedient to provide electronic control, which provides motion control with freely programmable adjustable angles and speeds.

Figure 1 in the upper right part shows the sinusoidal course of the moving block 2 upper punch depending on time. In the selected example, the rotation of the crankshaft 180°and unit 2 of the upper punch moves from the upper m is rtoi point FROM the bottom dead center UT. The time necessary for this is designated as tv. Because subsequent movement from the bottom dead center UT to the top dead point FROM is not in hydraulically parallel and sequential inclusion of hydraulic motors 7.1, 7.2, although there is a rotation of the crankshaft 4 by the same amount, however the required time on the basis of the constancy of the flow supply of the hydraulic pump becomes smaller and is only tr. Therefore, the second part respectively compressed in the direction of the time axis. In phantom lines, as well as +/- on the chart indicated that the final position of the upper punch in the zone of the dead points can be changed in positive or negative directions. The part of the working cycle, in which the compaction of the powder in the mold is indicated by the position of A.

Figure 2 to illustrate the character of change of some characteristics of the press according to the invention, depending on the angle α rotation of the crank Cam crank drive. This shows only part of the range of the angle and rotation of the crank from 130 to 180° (bottom dead point). The example refers to the press, in which the range of the angle of rotation of the crank from 130 to 180° corresponds to the path of movement of the block upper punch at about 0 mm Thus, the curve s motion paths in figure 2 indicates the distance of the block of the upper punch from the bottom dead point. This path of movement corresponds approximately to the actual process of pressing in the press, i.e. the phase of compaction of the powder.

Indicated by the position of the curve F shows the nature of changes in the actual tonnage for a representative molded body, which is the maximum height that can handle the press. With increasing compaction of the powder, which is the force F pressing strongly increases from about angle α rotation of the crank, equal to 140°, to the value of 2340 kN at the bottom dead point.

Corresponding to each pressing force torque Mdon the crankshaft is at the specified proportions of the size press at an angle of rotation of the crank 140° value 7125 Nm. Then torque increases sharply and reaches at an angle of approximately 160° its maximum with the value 45500 Nm. The pressing force at the point of maximum torque is 1225 kN. After reaching the maximum torque with increasing angle α rotation of the crank is greatly reduced and is at the bottom dead point zero, while the pressing force reaches its maximum value. Torque on the crankshaft is directly proportional to crutes the th moment of the hydraulic motors and thereby the hydraulic pressure. From the graph that the average pressing force is applied the maximum torque, and for a further increase in tonnage is not necessary not only to increase torque, but that torque even drops to zero at the bottom dead point. The nature of the change effort is usually typical for powder presses with eccentric crank drive. The area under the torque curve Mdis the work spent on the compaction molded body.

In the example of execution shown in figure 2 the ratio of the tangential force on the toothed wheel 5 when the maximum torque (45500 Nm) is only 364 kN, while really acting on extruded product of the force F pressing is 1225 kN. This means that in this place the working stroke under specified conditions of press and subject to compaction of the powder is transferred efforts on actual tonnage (1225 kN) at a ratio of 1:3,37 and with respect to the final tonnage (2340 kN) in the ratio 1:to 6.43. Figure 2 shows the maximum possible transmission V efforts also depending on the angle α rotation of the crank. In particular, in the area of the latter angular degrees before reaching the bottom dead point has been particularly progressive increase is the transfer V efforts. When the angle α rotation of the crank 165° the value of V is 1:3, 175° - already 1:10 and reaches at 177,5° a value of about 1:20. Such relationships can actually use and implement in the manufacture of molded parts with very little by way of pressing. In this case, to achieve specified in the previous example, the maximum tonnage 2340 kN required tangential force on the toothed crank wheel drive only about 116 kN. This is approximately 1/3 of the required tangential force 364 kN for molded bodies of the previous example with the greater height of the molded body. In line with this for the manufacture of respectively lower molded parts need only be reduced to 1/3 the capacity of the drive. Between these extreme values of the ratio of transmission tonnage from about 1:6 to about 1:20 lies normal operating range of the powder press. Compared to the press, according to the invention, conventional hydraulic press with direct piston drive even with a reasonable load control and speed would be at least three times more power consumption.

The flexibility of the press, according to the invention, it should be specified that by changing the amount of supply of the hydraulic pump can be right near St is only to modify the core speed press, as well as speed within individual segments of the cycle. While management costs is minimal. For the account of the respective switch hydraulic valve can optionally be entered in the pressing cycle time stops or decrease in idle time moves.

Particularly preferable to use proposed in the invention, the drive unit of the upper punch of the powder presses, other planes of movement (the matrix, the adapter stamp) also are driven hydraulically and which are for General hydraulics main drive motor. This is especially useful because the need for power block of the upper punch and die, as a rule, does not occur simultaneously, but one after another, and that a large flight feathers are the Central moments of the actuator to relieve peak load block upper punch in the range of the angle of rotation of the crank 160° and later in the lower dead point (the angle of rotation of the crank 180°) for the separation of the matrix. The press, according to the invention has a sinusoidal speed variation of the displacement and effort and provides more precision manufactured of pressed bodies, has a higher efficiency, is very flexible in terms of the parts being manufactured, significantly increases productivity and makes the considerable progress in manufacturing technology.

The list of items

1 a Bed of the press

2 Block upper punch

3 Rod

4 Crankshaft

5 Gear

6.1, 6.2 Worm gear

7.1, 7.2 Engine

8 the Lower punch

9 Matrix

10 regulation

1. A press for compacting powdered mass, in particular, metal powder, with the eccentric crank drive for the drive unit (2) upper plug containing at least one connecting rod (3)and crankshaft (4) and United him with the possibility of rotation of the toothed wheel (5)and gear (5) is installed with the actuator through at least one worm gear (6.1, 6.2) from at least one engine (7.1, 7.2), and with electronic control, wherein the electronic control performed with the possibility of a reverse mode of operation of the crankshaft (4).

2. The press according to claim 1, characterized in that the electronic control is made so that during the working and idling the crankshaft (4) is rotated in an angular range less than 180°.

3. The press according to claim 1 or 2, characterized in that there are two worm gear (6.1, 6.2).

4. The press according to claim 3, characterized in that the worm gear (6.1, 6.2) are installed with the possibility of the actuator from the corresponding individual motor (7.1, 7.2).

5. The press according to any one of claims 1 to 4, characterized in that h is on at least one engine (7.1, 7.2) is designed as a hydraulic motor.

6. Press on any of PP 5, characterized in that the worm gear (6.1, 6.2) are diametrically opposed relative to the axis of rotation of the toothed wheel (5).

7. The press according to any one of claims 1 to 6, characterized in that the electronic control is made so that the bottom dead center of the eccentric crank drive for reaching the end position of the pressing in the end of the stroke moves to a small value.

8. Press on any of pp.5-7, characterized in that the electronic control is made so that provided a choice of parallel and series connection of the hydraulic motors (7.1, 7.2) relative to the supply of the hydraulic medium.

9. The press according to any one of claims 1 to 8, characterized in that it contains a matrix (12)mounted for movement by a hydraulic cylinder.

10. The press according to any one of claims 1 to 9, characterized in that it contains a hydraulically driven adapter stamp.

11. The press according to claim 9 or 10, characterized in that a Central motor for the shared drive hydraulic pumps for supplying pressure to the hydraulic motors (7.1, 7.2) for the drive unit (2) of the upper punch, and also for the hydraulic cylinder of the matrix (8) and/or hydraulically Privodino the effect adapter stamp.

12. The press according to any one of claims 1 to 11, characterized in that provided for the electronic measurement system is the way to determine the actual position of the block (2) of the upper punch.

13. The press according to any one of claims 1 to 11, characterized in that provided electronic angle sensor for determining the actual position of the crankshaft (4).

14. The method of operation of a press for compacting powdered mass, in particular, the metal powder according to claims 1 to 13, characterized in that the stroke unit (2) of the upper punch reversiruyut shortly before reaching the top and/or bottom dead point eccentric crank drive.

15. The method of operation of a press for compacting powdered mass, in particular, the metal powder according to claims 1 to 13, characterized in that the stroke unit (2) of the upper punch is adjusted so that the lower dead point of the eccentric crank drive moves to a small value.



 

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