JPH01130824A - Double acting press elastically deforming sheet - Google Patents

Abstract

PURPOSE: To precisely adjust a necessary force holding sheet metal by directly controlling, in servo-hydraulic way, operation chamber pressure with which force in a piston/cylinder unit is decided. CONSTITUTION: Corresponding to piston/cylinder units 11, 11', 11", 11"' and each of force transmitters 15, 15', 15",15"' belonging to them, measuring taps of the force transmitters are connected to the input terminals of controllers 19, 19', 19", 19"' of them. Proportional valves 20, 20', 20", 20"' can be electrically predictively controlled through electro-hydraulic pilot valves with the controllers. The electro-hydraulic pilot valve is opened large or small according to the size of a control signal, and the proportional valve 20 is opened large or small according to this electro-hydraulic increase. With the proportional valves 20, 20', 20", 20"', hydraulic oil is pressed from a pressure source to pressure chambers 14, 14', 14", 14"' which decide force, or is exhausted to an oil reservoir, or the pressure chambers can be held in closed condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The invention relates to a sheet holding ram guided in a press stand and driven reciprocatingly by a symmetrically arranged connecting rod to support a sheet retainer of one of the tools. , the force flux between the plastic deformation ram, which is provided within the sheet holding ram and reciprocates relative to it and which is separately driven reciprocally and supports the plastic deformation punch of the same tool, and the respective connecting rod and the sheet retainer. one piston/cylinder unit in each case, the pressure chambers of the piston/cylinder unit determining the transmittable force being subjected to an individually controllable hydraulic pressure for each piston/cylinder. This invention relates to a double-acting press that plastically deforms a thin plate.

[Prior Art] Such double-acting presses are used in industrial manufacturing processes, and are also used by the applicant.

The joints between the lamina holding rams and the plastic deformation rams and the respective connecting rods are constructed in such a way that they can be adjusted in height relative to the corresponding rams and are therefore movably guided relative to the rams. . Furthermore, at least in the case of the sheet-holding ram, a hydraulically actuated piston/cylinder unit is connected to the force bundle between the connecting rod bearing and the ram. The pressure chamber of this piston/cylinder unit, which determines the force, is set at a presettable constant pressure.

In fact, a relatively low controllable air pressure can be achieved by a stage piston acting as a pressure transducer with a very large area ratio between the small and large piston surfaces.
A correspondingly proportionally changed hydraulic pressure is converted. It is therefore possible to directly control the force-determining pressure chambers of the piston/cylinder unit by pneumatic pressure. Hydraulic pressure is used only passively as a pressure transmission medium. The pressure is regulated to a low pressure level by air pressure. The purpose of the intermediate short-stroke piston/cylinder unit is to limit the transmittable force to a predeterminable value. If the pre-adjusted pressure or force value is exceeded,
The stage piston is now displaced to the low pressure side, which causes the machine to stop.

As is well known, various thin plate parts are manufactured by temporary replacement using a press having the configuration described in the five general concepts. When changing the press equipment from the original thin plate press part to another workpiece material, it is necessary not only to replace the press tool but also to replace the press adjustment data with a new tool or a new workpiece material. Replacing the press manufacturing data takes significantly more time and costs than the original replacement of the tool. A large number of trial presses must be made before the press can press new workpiece material for an extended period of time with high quality and uniform accuracy. Even if all adjustment data for a given workpiece or tool are accurately and meticulously determined from previous production steps and thus adjusted for the new production run, time-consuming and expensive testing is required. It is not possible to avoid the mechanical pressing process. Furthermore, various factors that are not yet fully understood and are outside of our scope may be influential.

[Problem to be Solved by the Invention] The object of the invention is to provide a method according to the generic concept in such a way that, after changing to another sheet metal or a corresponding tool, it is possible to adjust accurately, quickly and reproducibly to changed production conditions. The purpose is to configure a press based on the configuration of

In particular, such a replacement should be possible even with significantly fewer test press strokes than before.

[Means for Solving the Problem] According to the invention, this object is achieved by the configuration described in the characterizing part of claim 1. The direct servo-hydraulic control of the force-determining working chamber pressure in the piston/cylinder unit connected midway between the respective laminar retainer connecting rods ensures high reproducibility and no hysteresis and inertia phenomena. The required holding force for each thin plate can be precisely adjusted without any problems.

The servo-hydraulic sheet holding force control is precise, reproducible and inertia-free, allowing the target value to be adjusted to the stroke or crank angle according to a preset program, even during the press cycle. You can change it accordingly. The sheet retention force can be selectively increased or decreased during the pressing process with precisely reproducible accuracy. This depends on the particular material to be pressed, and tests may need to be carried out in special cases.

Further advantageous embodiments of the invention can be learned from the dependent claims.

[Examples] Next, the present invention will be explained with reference to various embodiments shown in the figures.

The double-acting press shown schematically in longitudinal section in FIG. 1 comprises a press stand 2 and a press table 10,
A lower tool 9 for the sheet metal 1 to be pressed is fixed on this press table 10. Inside press stand 2,
A sheet holding ram 4, which can be driven back and forth by symmetrically arranged connecting rods 6 and 6°, is guided vertically. An original plastic deformation ram 3 is provided inside the thin plate holding ram 4,
This is guided in a reciprocating manner relative to the laminate holding ram 4 and is likewise symmetrically arranged by several connecting rods 5.
It can be separated and reciprocated by. Thin plate holding ram 4
The thin plate retainer 7 of the upper tool is fixed to the plastic deformation ram 3.
A plastic deformation bunch 8 of the upper tool is fixed to. When the upper tool is lowered, first the sheet holder is placed with a constant force on the plate which is not yet pressed and lies above the lower tool 9. Only when the edge of the plate is clamped with a constant force, the plastic deformation bunch 8 comes into contact with the laminate 1 and slides the edge of the laminate from the edge fixing element by a certain dimension into the die mold to remove the laminate l. Press. In this case, the magnitude of the force of the laminar cage is of particular importance.

The force of the laminar holder must be optimized for each material to be processed and maintained as precisely as possible at the found value during the entire press cycle. The invention is particularly based on this aspect, as will be explained in more detail below.

If the sheet holding ram 4 and the compositional deformation ram 3 pass through the lower dead center position, this dead center position must correspond to the overall height of the lower tool 9 and the upper tool 7.8. Since this total height may differ, the thin plate holding ram 4 and the composition deforming ram 3
The height of each is adjusted. In the oral embodiment, this is simplified in the form of a connecting rod bearing cylinder 12 which supports a connecting rod bearing and in which each ram is mounted vertically displaceably. In general, this connecting rod bearing cylinder is not supported and guided in a ram (but in a press-resistant vertical guide in the form of a crosshead. In each case, an adjusting spindle 13 is located inside the connecting rod bearing cylinder 12. is provided, which is engaged with a nut screw provided at the lower end of the connecting rod bearing cylinder.The adjusting spindle itself is
can be rotated by means of a worm wheel 28 which surrounds it so that it does not rotate, thus changing the height of the ram relative to the connecting rod bearing. The worm wheel 28 itself can be turned within a certain range by means of a worm (not shown) and a corresponding electric drive.

At the lower end of the adjusting spindle 13 there is provided the above-mentioned piston/cylinder unit 11, which forms a pressure chamber 14 with suitable hydraulic connections between the corresponding piston and the cylinder surrounding it. . Depending on the spatial extension of the lamella retainer 7 and the lamella retainer ram 4, a total of four connecting rods (only two connecting rods 6.6' are shown in the figure) and the Different surrounding parts 17.17
', 17'', 171 are provided with four connecting rod bearings of the laminar retaining ram 4. The other piston/cylinder units 11.11', 11'', 11'' are therefore
They are provided around each of them. It is extremely meaningful to partially adjust the thin plate holding force to a small extent without fixing the thin plate to be pressed constant around the entire circumference. This depends individually on the respective workpiece material and the tools installed therein. Also, they need to be tested individually. However, once this has been determined, the corresponding production parameters can be quickly adjusted again with exact reproducibility for subsequent batches produced according to the invention.

Respective slat retaining portions 17, 17', 17" and 1
In order to precisely adjust the holding force of the lamella to 7"° without hysteresis and inertia, in the embodiments shown in FIGS. 1 to 5 and 7, the respective holding part 17. 17', 17'' and 17°'' are provided with at least one force transducer 15.15', 15'' and 15''' which is separately integrated into the lamella holder. It consists of an elongation measurement band 36 glued to the surface of the wall of the thin plate retainer 7, which applies the holding force to the thin plate.As shown in FIGS. 5 and 7,
The integrated stretch measuring band 36 can be constructed by four stretch resistors, in which case the individual stretch resistors are combined into a Wheatstone bridge. However, in this case it should be noted that the individual bridge arms of the Wheatstone bridge are either parallel to the direction of force application 37 or at right angles. In the embodiment shown in FIGS. 4 and 5, forest-shaped recesses 34 are provided on opposite sides of the support wall 35, on the smooth bottom of which elongation measuring strips 36 are attached. This recess 34, on the one hand, allows a highly sensitive elongation measurement zone to be placed on the wall 35.
It is offset from the outer surface of the housing and recessed for protection. On the other hand, the recesses ensure that the wall 35 is weak in its load capacity precisely in places with a low notch effect, so that the remaining disc-shaped central web acts as a kind of compression spring. None, the thin plate is deformed to a certain limit depending on the holding force.It shows a slight notch effect.
Measures to weaken 5 are shown in Figure 6. In this case, two horizontally aligned holes 32 are provided, which
A biconcave narrow portion 33 is sandwiched between them, which is perpendicular to the direction of force application 37 .

This narrow part 33 similarly plays the role of a kind of compression spring, which can be loaded with a thin plate holding force, and the amount of deformation can be measured using an elongation measuring band provided at the narrowest part of this narrow part. 36 can be determined as the load amount. It is conceivable to fit another force transmitter in the form of hole 32 into a single hole by means of a pressure spring. However, on the other hand, a weakened point consisting of the entire wall section 35 and provided with a stretch measuring zone has the advantage that there are no joints in the force flux that would cause hysteresis phenomena in the force measurement.

A force transmitter constructed entirely of the wall operates completely without hysteresis, which is important for this application. Next, the servo-hydraulic thin plate holding force control device will be explained with reference to the hydraulic circuit diagram shown in FIG. At the top of this figure are the different pressure chambers 14, 14', 14'' and 14° provided at different parts of the circumference of the laminar cage.
” four piston/cylinder units with 11,
ll', 11'' and 11''' are shown. Also shown are the aforementioned four different force transmitters 15, 15', 15" and 15°", which are powered by one integrated accumulator 38 and connected in parallel with each other to this accumulator. ing. Measuring taps for the stretch resistance of the force transmitters, each forming a Wheatstone bridge, are tapped out separately for each force transmitter. Each regulator 19.19', 19'', 19'''
Each piston/cylinder unit 11.11'
, 11", 11'" and the respective force transmitters 15.15', 15", 15'" belonging thereto, and the force at the input terminals of these regulators 19.19', 19", 19°". The transmitter measurement tap is connected. For each of the four above-mentioned regulators 19 there is a setpoint value regulator 18, 18', 1
g', 18°", whose output terminals are likewise connected to the regulator input terminals. The force transmitter and the setpoint value regulator both emit similar and comparable electrical signals. Regulation. The device 19 compares the target signal with the actual signal, and according to the difference between the two, sends out a corresponding signal to its output terminal, and this signal performs an adjustment operation to adjust the detected target value/
Actual value deviations are removed again. For this purpose, a proportional valve 20.20' for each of the four control sections
, 20'', 20''' are provided. The proportional valve can initially be electrically predictively controlled by a regulator via an electrohydraulic pilot valve. The electrohydraulic pilot valve is supplied with hydraulic pressure from a control oil pump 21 that draws in from a separate control oil sump 24 . Considering the high sensitivity of the electrohydraulic pilot valve, this circulation circuit is kept particularly clean, as indicated by the filter 23. Depending on the magnitude of the control signal, the electrohydraulic pilot valve is opened more or less (opened), and depending on this electrohydraulic increase, the proportional valve 20 is opened more or less. proportional valve 20.20', 20''. , 20°", the pressure chambers 14.14', 14" in which the hydraulic fluid determines the force from the pressure source
, 14° or drained into a sump, or the pressure chamber can be kept closed. The pressure source consists of an accumulator 25 and a hydraulic oil pump 22 which keeps the corresponding accumulator under pressure at all times. All four pressure chambers 14.14'', 14'', 14° are therefore kept in such a way that the sheet holding forces obtained in the force transmitters 15.15', 15'', 15°'' are kept at a predetermined target value. °° pressure can be controlled. If the holding force of the thin plate decreases regionally below a predetermined target value, the proportional valve activates the pressure source 22/2.
5, and the pressure in the corresponding pressure chamber 14 increases. If, on the contrary, the plate holding force rises regionally above the predetermined setpoint value due to a fault, the proportional valve opens in the direction of the operating oil sump and thus determines the force in the pressure chamber 14.
The internal pressure decreases. If a predetermined plate holding force is achieved in such a control action, the proportional valve associated therewith returns to the central closed position shown, in which case the pressure in the pressure chamber 14, which determines the force, is maintained. This operation occurs very quickly because the amounts of control and hydraulic fluid transferred are relatively small. The control sequence is very short and is activated with sufficient hysteresis phenomena, so that the control action is also reproducibly precise.
7.17', 17'', 17°'' against overload, the respective servo hydraulic control circuits are connected to overpressure valves 26
．． Equipped with 26′, 26″, 26°″. Operating line and associated pressure chamber 14. , 14', 14'', 14
If the pressure rises above a presettable maximum value in °, the hydraulic fluid is discharged at the overpressure valve 26. By discharging the operating oil held at high pressure, an emergency cutoff switch 27 common to all four overpressure valves is activated, thereby stopping the press operation.

The embodiment of the hydraulic circuit shown in FIG. 8 is such that instead of the force transmitters combined in the lamella holder, each individual pressure transmitter 16, 16', 16', 16'''' transmits the force. It differs from the circuit shown in FIG. 7 in that each pressure chamber 14.14", 14", 14°" is provided with a regulator 19.19' which converts it into an electrical signal and to which this electrical signal belongs;
, 19'', and 19°0 input terminals.

In other respects, the operation of the hydraulic circuit shown in FIG. 8 is similar to the operation of the circuit shown in FIG. The difference is that the force is not regulated directly (the pressure in the pressure chambers 14.14', 14', 14°, which determines the force, is regulated to a presettable target value). .

Another difference in FIG. 8 is that the target value may change depending on the crank angle. An angle transmitter 3 is mounted on the crankshaft 29 of the press, which is schematically shown.
0 is coupled, and this angle transmitter 30 is connected to the crankshaft 29
It sends out an electrical signal corresponding to the instantaneous position of the axis. These electrical signals are sent to four different functional transmitters 31.31'
, 31'', 31''. This functional transmitter is
Depending on the crank angle, different function values can be delivered, which function values determine the associated setpoint value adjuster 18.1.
8', 18', 18°''.The fast response of the control section allows relatively rapid adjustment of setpoint values that change during the stroke.For example, Lamina holding area 17.17', 17''
, 17°", the sheet holding force can be raised or lowered stepwise within the press cycle as required. The individual function transmitters 31.31', 31", 31'" are After being optimized for a given workpiece material, it can be taken out and replaced with another function transmitter optimized for other workpiece materials. This exchange of function transmitters
This can be done by switching in a control center in which global function transmitters optimized for the various processing materials are installed in groups and kept in standby.

[Brief Description of the Drawings] Fig. 1 is a sectional view showing one embodiment of the present invention, and Fig. 2 is a sectional view showing an embodiment of the present invention.
The piston/cylinder unit (
A sectional view partially showing details of the frame (■ part) in Figure 1.
The figure is a sectional view taken along the line III-In in Fig. 1, Fig. 4 is a partial sectional view showing the configuration of a force transmitter constituting the device shown in Fig. 1, and Fig. 5 is a sectional view of the device shown in Fig. 4. 6 is a partial sectional view showing the configuration of a force transmitter in another embodiment of the invention; FIG. 7 is a hydraulic circuit diagram of the device shown in FIG. 1 with a force transmitter; FIG. 8 is a hydraulic circuit diagram of the device according to the invention with a pressure transmitter. 6.6′, 6″, 6°”... Connecting rod, 7...
Thin plate retainer, 11.11', 11'', 11'''...
Piston/cylinder unit 14.14', 14'',
14°"... Pressure chamber 15.15', 15", 15'
"... force transmitter, 16.16', 16", 16°"
... Pressure transmitter, 17.17', 17", 17°"
...Thin plate retainer peripheral portion 18.18', 18'', 1
8゛...Target value transmitter, 19.19', 19'', 1
9°"... Adjuster, 20.20', 20゛, 20°
”... Proportional valve, 22, 25... Pressure source, 32
... Hole, 33 ... Narrow part, 34 ...
・ Recessed portion, 35... Support wall portion, 36...
・Elongation measurement. Application agent

Claims (1)

[Claims] 1) A thin plate holding ram that is guided in the press stand and driven back and forth by a symmetrically provided connecting rod to support the thin plate retainer of one of the tools; plastic deformation rams which are reciprocating relative to each other and are separately driven back and forth and support plastic deformation punches of the same tool, and one piston in each case provided in a force flux between the respective connecting rod and the laminar retainer; a cylinder unit, in which the pressure chambers of the piston/cylinder unit determining the transmissible force are capable of applying individually controllable hydraulic pressure to each piston/cylinder;
In a double-acting press that plastically deforms a thin plate, a pressure transmitter (16, 16', 16'' , 16'') or one connecting rod (6, 6', 6'', 6''')
) of the thin plate cage (7) belonging to the respective areas (17,
17', 17'', 17'''), a force transmitter that constantly detects the component of the lamella holding force distributed in this area (17, 17', 17'', 17''') of the lamella retainer (7). (15, 1
5', 15'', 15''') are provided, these pressure transmitters and force transmitters each generate an electrical signal corresponding to a pressure value or a force value, and a respective pressure transmitter (16,
16', 16'', 16''') or force transmitter (15, 15
', 15'', 15''') are provided with setpoint value transmitters (18, 18', 18'', 18''') which emit signals of the same type; Adjusters (19, 19', 19'', 19
″′) corresponds to each pressure transmitter (16, 16′, 16″)
, 16'') or force transmitter (15, 15', 15'', 1
These regulators are installed in the proportional valve (20
, 20', 20'', 20''') and pressure sources (22, 2
5), the piston/cylinder unit (11, 1
1′, 11″, 11″′) is increased, decreased or kept constant depending on the setpoint/actual value deviation so as to immediately return to the setpoint value. Double acting press. 2) Each regulator (19, 19', 19'', 19''
2. Press according to claim 1, characterized in that the target value of ') can be varied as a function of stroke or crank angle, each in a repeating pattern during each press cycle. 3) Force transmitters (15, 15', 15'', 15''')
characterized in that it is constructed in the form of an elongation measuring strip (36) provided on the support wall (35) of the laminar retainer (7),
The press according to claim 1 or 2. 4) Press according to claim 3, characterized in that, instead of the elongation measuring strip (36), the supporting capacity of the wall (35) is weakened in places precisely when the notch effect is low. 5) A pair of horizontally aligned holes (32) are provided in the wall (35), these holes sandwiching between themselves a vertically standing biconcave narrowing (33). 5. Press according to claim 4, characterized in that the section is provided with one or several elongation measuring bands (36). 6) At least one side of the wall (35) has a potted groove (34).
5. Press according to claim 4, characterized in that the smooth bottom of the press is provided with one or several elongation measuring bands (36).