JPH04289000A - Device for controlling energetic and dynamic characteristic of driving device in forming machine - Google Patents

Abstract

PURPOSE: To remarkably decrease an action of body force of an upper die holder by highly implementing processes of braking and accelerating an operation protective device of a press acting on a body force relating on one hand to starting and braking processes and on the other hand to a crank angle, above all in a link press which executes sheet metal forming and solid forming. CONSTITUTION: An action to balance a mass of an upper die holder 8 and an upper die 28 is suspended in an upper angular range of a crank, and an upper pressure medium chamber 31 is able, on one hand, to supply compressed air at least through one press safety valve 20, a shut off mechanism 18 and a pressure adjusting device 19 and, on the other hand, to discharge pressure through the press safety valve 20 and a silencer 30, a piston rod 27 has a stopper 29 at an end projecting out of a balance cylinder 23, and this stopper 29 cooperates with a stopper 25 fixed to the upper holder 8 through an impact damper 26.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to the energy characteristics of drives in forming machines, in particular in link presses for sheet metal forming and solid forming, which act on the one hand on starting and braking processes and on the other hand on object forces related to the crank angle. The present invention relates to a device for controlling dynamic characteristics.

0002

BACKGROUND OF THE INVENTION The starting and braking processes of intermittent molding machines are carried out preferentially by friction clutches and brakes which can be engaged asynchronously. In that case, during adjustment processes in clutches and brakes, irreversible energy losses disadvantageously occur on their friction surfaces due to heat generation as a physical effect due to inelastic torsional impacts, which are caused by continuous wear processes. . The limited heat load capacity of the friction material on the one hand and the increased service life when the continuous stroke and number of switchings are greatly increased on the other hand require considerable material and production costs, especially for the manufacturer.

[0003] In order to reduce the thermal load on the clutches and brakes and to reduce wear, a non-controlled actuating cylinder is arranged in the machine body, the piston rod of which is eccentric to the crankshaft, which delivers an accelerating torque at top dead center. DD
- Proposed in WP Patent No. 100063. This external torque at top dead center acts against the brake holding torque, so that the ram is accelerated unexpectedly in the event of a brake failure. Furthermore, energy remains in the brakes and clutches in the form of residual heat, depending on the overrun angle from the extended position of the working cylinder.

[0004] The larger the overrun angle, the more
Energy recovery rate becomes smaller. Additionally, additional material and manufacturing costs are required to implement this approach. In the above-mentioned publication, it is proposed to employ a hydraulic servo device consisting of a displacement unit acting as a pump and a motor, a controllable position switching valve and a hydraulic accumulator. The maximum power demand for large acceleration or braking movements on the one hand and short acceleration and braking times and variable time on the other hand is important when selecting equipment (displacement units, valves and hydraulic accumulators) in large structures and piping systems. Requires large inner diameter. This approach also requires considerable material and manufacturing costs in production, and additional costs for molds and care at the user's expense. Further, the servo device is violently vibrated due to the impact of the hydraulic accumulator being turned on by the position switching valve, producing a large amount of noise.

[0005] In another known scheme in SU-EB Patent No. 643683, a spring is employed in the planetary gear which is arranged between the clutch shaft and the secondary transmission and is connected to the friction block support of the brake. It is proposed that. This approach also cannot be realized without significant outlay, especially for additional planetary gearing. Furthermore, in this case, driving protection measures have to be taken because of the bias torque acting against the brake during standstill. Energy recovery is also not sufficient. Additionally, shock loads during the starting process create dynamic torques and vibrations, which result in high noise and wear.

In the case of forming machines and in particular lever or link presses, the number of free strokes can only be increased to a limited extent. This is because the dynamic forces and torques in the drive system produce severe shock and return movements of various magnitudes, which act destructively and result in noisy operation and loud noise. The main reason for this is the balanced upper die holder, whose mass effect becomes more noticeable as the number of strokes increases due to the movement of the link mechanism, especially in the upper angular range of the crank.

In DD-WP patent No. 147927, a throttle is inserted between the balance cylinder and the pressure medium accumulator to partially reduce the pressure under the balance piston during the upward stroke of the ram, This is known to reduce dynamic loads. However, this effect is limited because the minimum cross-sectional area of the aperture cannot be made smaller. Furthermore, a large amount of heat is generated in the diaphragm due to unused energy.

[0008] In DD-WP Patent No. 256288, an additional hydraulic device is proposed which compensates for hydraulic body forces by generating a variable counteracting torque at rotation angles where the play may change suddenly. ing. In order to implement this device, additional hydraulic equipment with a large internal diameter and construction as well as a long holding time of the valve are required due to the extremely high torque change rate. Moreover, during the compensation process irreversible energy losses occur which are further increased by no-load losses.

[0009]

SUMMARY OF THE INVENTION The object of the invention is to provide a driving protection device which, on the one hand, realizes braking and acceleration processes to a high degree and, on the other hand, significantly reduces the effect of body forces on the upper die holder. It is in.

0010

According to the invention, this object is achieved by the measures according to claim 1.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments shown in the drawings.

The drive, whose energy and dynamic properties are controlled, consists of a flywheel 1, a clutch 2 and a brake 4 with an actuating element 5.

The parts of the secondary transmission to be accelerated and braked are designated as rotating mass 3. The eccentric shaft or crankshaft 6 is connected in a known manner via a connecting rod 7 to an upper mold holder 8 and to an upper mold 28 arranged thereon. Balancing cylinders 23 are arranged on both sides of the upper mold holder 8, which are additionally connected to the press frame. The piston rod 27 of the piston 22 is provided with a stopper 29 and an impact damper 26 at its end projecting from the balance cylinder 23. This stopper 29 cooperates with a stopper 25 fixed to the upper mold holder 8.

Upper pressure medium chamber 3 of balance cylinder 23
1 is connected to a press safety valve 20 via piping. One port of which is connected to a silencer 30 and the other port of a shut-off mechanism 18, which is preferably configured as a check valve.
and is connected to the pressure medium source 11 via a pressure regulator 19 . This pressure medium source 11 likewise has a pressure regulator 21
and is connected to the lower pressure medium chamber of the balance cylinder 23 via a pressure medium accumulator 24 . Furthermore, the pressure medium source 11 is connected via a pressure regulator 12 and a pressure medium accumulator 13 to the actuating element 5 of the brake 4 via a press safety valve 16 on the one hand, and to the pressure regulator 14 and the pressure medium accumulator 15 and the position on the other hand. It is connected to the actuating element of the clutch 2 via a switching valve 10 and a press safety valve 9. A position switching valve 17 for position monitoring and a silencer are connected to the port of the press safety valve 16. A line additionally extends from the second port of the position control valve 10 and extends in parallel to the pressure regulator 14 and the pressure medium accumulator 15 .

When the press safety valve 16 is switched on, the actuating element 5 of the brake is supplied with compressed air and the clutch 2 is placed in the closed position in a known manner without overlap by the press safety valve 9 and the pressure medium accumulator 15. A significantly reduced acceleration torque acts on clutch 2 by means of pressure regulator 14 . This acceleration torque is, for example, at most twice as large as the friction torque acting on the secondary transmission under load.

[0016] This small acceleration torque starts the starting process. Depending on the obtained crank angle, the lowering of the upper die holder 8 and the upper die 28 from the area of the top dead center causes a rotational mass of the eccentric shaft or crankshaft 6 and the secondary transmission via the connecting rod 7 to be lowered. 3 is supported in the acceleration process. The piston 22 and piston rod 27 are connected to the pressure regulator 19,
21 and the press safety valve 20, when synchronizing with the clutch 2, the stopper 25 on the upper mold holder 8 is moved so as to reach the impact damper 26 of the stopper 29. By turning on the position switching valve 10, torque necessary for performing the molding process is generated in the clutch 2.

When the forces are balanced during the upward movement of the upper mold holder 8, the piston 22 with the piston rod 27
will stop automatically. After a time delay, the clutch 2 is disconnected from the secondary transmission by shutting off the press safety valve 9, and the rotating mass 3 of the secondary transmission is stopped at top dead center by the braking action of the upper die holder 8 and the upper die 28. At this top dead center, the brake 4 acts as a holding brake by blocking the press safety valve 16.

The press safety valve 20, which is designed as a position control valve, is shut off when the top dead center range is not reached or exceeded, or when an emergency stop signal is introduced.

[0019]

According to the present invention, the energy characteristics and dynamic characteristics of the drive device can be improved with an inexpensive and noiseless device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a device based on the present invention.

[Explanation of symbols]

8 Upper mold holder 19 Pressure regulator 20 Press safety valve 23 Balance cylinder 25 Stopper 26 Impact damper 27 Piston rod 28 Upper mold 29 Stopper 30 Silencer

Claims (7)

[Claims] 1. A device for controlling the energy characteristics and dynamic characteristics of a drive device in a molding machine during acceleration and braking, the drive device consisting of a flywheel, a clutch, a brake, and a secondary transmission device, The motion is transmitted to the holder by an eccentric shaft or a crankshaft via a connecting rod or a link mechanism, and in order to balance the mass of the upper mold holder and the upper mold, a plurality of piston cylinder units supplied with compressed air are arranged on the upper mold. In a device for controlling the energy and dynamic characteristics of a drive in a molding machine, which is arranged on both sides of the mold holder and is additionally connected to the press frame, the upper mold holder (8) and the upper mold (
28) is discontinued in the upper angular range of the crank, and the upper pressure medium chamber (31) of the balance cylinder (23) on the one hand has at least one press safety valve (20), the shut-off mechanism (18) and the pressure Compressed air can be supplied via the regulator (19) and pressure released via its press safety valve (20) and muffler (30) on the one hand, and the piston rod (27) is connected to the balance cylinder (2).
3) has a stopper (29) at the end protruding from the upper mold holder (8), and this stopper (29) works together with a stopper (25) fixed to the upper die holder (8) via an impact damper (26). A device for controlling the energy characteristics and dynamic characteristics of a drive device in a molding machine, characterized by: 2. Device according to claim 1, characterized in that a programmable pressure regulator is used as the pressure regulator (19). 3. Device according to claim 1, characterized in that both stops (25, 29) are of adjustable and programmable design. 4. Device according to claim 1, characterized in that both stops (25, 29) are shock- and return-proof. 5. Device according to claim 1, characterized in that a check valve is preferably used as the shut-off mechanism (18). 6. In order to bring the clutch shaft to a high rated speed during the acceleration process and to minimize residual wear in the clutch, the clutch (2) is operated for a period of time before the start of the braking process of the secondary transmission. 2. Device according to claim 1, characterized in that it is switched off only after the stop (29) has stopped. [Claim 7] The stopping point of the piston rod (27) can be adjusted according to mold characteristics, taking into account friction, stroke number, upper mold mass, ram movement variability, and reduction in rotational speed conditioned by operation. 2. The device according to claim 1, characterized in that: