DE1234487B - Control of open-die forging presses - Google Patents

Description

Control of open-die forging presses To automate the forging process There are numerous control devices in bar forging and finish forging have been developed, which are partly of a purely mechanical nature, partly of a purely hydraulic nature are; other devices are of the electro-hydraulic type with low or non-contact Distance measuring options according to the analog or digital measuring method. This, automatic Control devices partially offer the possibility of preselecting the reversal at certain points on the saddle path. The change of direction can lead to a transition. effect hydraulic low pressure medium to high pressure medium or in the automatic Reversal to retraction after reaching a preselected pressing path, d. H. one a certain depth of penetration into the workpiece. Also is the automatic termination the retraction of the upper forge saddle at a preselected distance above that Forging and subsequent advancement towards the workpiece known. These control devices usually also have display devices that are mechanically, with or without translation, or electrically by means of remote transmission, scales or illuminated number displays on the control panel the controlled saddle paths and thus the achieved thicknesses of the pieces indicate.

There are also known controls that allow the speed of the entire saddle path by comparing electrical quantities via controlled throttle valves, to be adjusted to a preselected value within certain limits.

However, this has not yet been the case with hydraulic open-die forging presses provided with automatic control and recognized as advantageous, is the application according to the invention of the known, according to optimal deformation speeds controlled mode of operation, namely riding with the help of a setpoint specification of the walking beam movement and only during the conversion taking place actual value acquisition, as well as actual and target value display and differential control of the control.

So that the device for measuring and displaying the actual working speed not due to the high idle stroke speeds of the forge saddle due to too high Display area is affected in their display accuracy, is their measurement and Display function regarding the actual speed depending on the beginning of the Working stroke or from placing the upper forging saddle on the workpiece automatically can be switched on and / or automatically at the start of the upward gear according to the invention can be switched off. The means of measuring, displaying and regulating the actual speed according to predetermined target speeds are known per se. Both analog as well as digital measuring methods.

A hydraulic open die forging press with valve or slide control to carry out the operation according to the invention is, for. B. with one with the Moving bar coupled digital actual value transmitter, an adjustable digital setpoint transmitter and an actual and target value comparison device for detecting and displaying the Overflow and a correction device for the switching points of the control provided and characterized in that an additional device known per se with a display device for determining the actual speed with the walking beam is connected and a setpoint speed specification device with differential value detection _to control one in the operating fluid supply line upstream of the valve or slide block provided throttle valve is arranged.

On the basis of the respective actual speed read from the display device and the comparison with the target speed, the helmsman can determine the actual speed of the forge saddle then accelerate positively or negatively as desired and so on the most favorable penetration speed in each case for metallurgical and other reasons achieve.

If it turns out to be useful, the penetration speed in different To make heights of the workpiece different in size, in order to use the cheapest in every height To work penetration speed, the additional device according to the invention designed so that they the target speed during one of several strokes existing workflow, for example after each stroke of the Press or passage of the forging through the press, according to a specified setpoint program changes. In the case of pressing strokes with a large penetration depth, the specified setpoint program (if necessary) different for different lifting sections prescribe optimal forging saddle speeds.

Depending on the material composition of the forging, there is an upper one and a lower temperature limit for the possibility of hot deformation. The effort therefore, the forming work required per workpiece is as quickly as possible perform. The invention enables the deformation speed to be optimized be realized, which varies depending on the material, piece size, etc. between, for example 320 mm / sec. and 20 mm / sec. These values are known per se.

In other words: According to the invention, the blacksmith has the option of to specify the optimal deformation speeds as target speeds in each case and to register and display the actual speeds, thereby enabling the Has the option of changing the latter during the forging process and the specified Adjust target speed. He also has the option of staying the same Forging program, with constant starting temperatures and constant Material qualities of the workpieces to be machined one after the other, the deformation speeds during the course of each forging process by hand or automatically according to a predetermined one Change program to meet the technological demands of the deformation process adapt at optimal speeds. The optimal one for processing a piece Penetration speed of the forge saddle is generally either for one entire deformation process or piece by piece for the individual sections of the penetration? path calculated or empirically determined and given to the open-die forging press, so that you get the optimal penetration speed for the later workpieces of the same type either continuously or, in the case of large penetration depths, even for each individual section of the deformation path.

For the forming of metals on extrusion presses, speed, Measuring, display and control devices known that cover the entire Preßstempelweg des record only from a single press ram stroke existing work process. she serve to maintain a known deformation-favorable speed to force the ram.

With these devices, the speed is over the entire ram path measured and not just over a part as in forging. In addition, the deformation paths and times are many times greater than the extremely short distances and times of the open-die forging process.

In the open die forging process, the technological process continues also from a great many successive work and idle strokes together.

In an open die forging process, the constantly decreasing Material temperature and material cross-sections the optimal forming speed and so that the pressing speed in each case different for the individual work strokes great. The actual speeds should therefore be changed until the entire Forming work on the forging is finished.

The technological process in open die forging is therefore fundamental different from the technological process of extrusion, although it is in both Cases is a hot forming process. This also follows from the following Considerations that in particular- should show how the blacksmith to the optimal Target speeds reached.

The build-up speed of the total pressing force of a hydraulic Open die forging press depends on the size of the inflow cross-section for the Pressure medium in the feed line to the press cylinder.

The total resistance to deformation of a forging is dependent a) on the specific deformation resistance, which occurs with increasing deformation speed and falling forging temperature increases, b) from that due to upsetting or expansion increasing forging surface.

In open die forging under hydraulic presses, it therefore arises a deformation rate during the penetration of the forging saddle into the Workpiece that results from the balance that developed between the Adjusts the total deformation resistance and the build-up speed of the total pressing force.

At a very high rate of deformation, the blacksmith can no longer on the conveyor belt of the material between the disintegrating areas of scale recognize whether the deformation stroke and degree of deformation resulting at this speed causes the surfaces or edges to burst.

He must therefore reduce the build-up speed of the total pressing force by throttling reduce the inflow cross-section for the pressure medium by hand until it an assessment of the effect on the flow diagram of the forged metal is possible. He can therefore do not work with optimal speed of deformation. The entire forging process is thereby unnecessarily elongated, eliminating the various well-known economic Disadvantages arise.

If the blacksmith receives an exact and within the meaning of the invention also readable display device in the forming time, which takes only a fraction of a second for the respective actual speed of the forming process, then it can be empirically quickly approach the optimal actual speed values and thus the optimal Target speed values for the deformation of similar forgings in principle determine.

This becomes a forging process for large numbers of forged pieces programmable with optimal forming speed. For not yet empirically determined Forging processes on individual pieces can have corresponding target speed values are set up and also complied with with the help of such a display device will.

With the aid of the measuring and display device proposed according to the invention can set deformation speeds in every forging shop for its production program which are then worked out by the respective work preparation department for similar Workpieces are used to rationalize the forging processes.

Based on the drawings, for example, one for executing the Invention suitable control device described.

With 1 in FIG. 1 designates columns of a forging press, on which a traveling beam 2 is slidably arranged. An upper saddle 3 is attached to the crossbar 2 and faces a lower saddle 5 connected to base plates 4. Retraction cylinders 6, the pressure pistons 7 of which are connected to the crossbar 2, are arranged to the side of the lower saddle 5. A cylinder spar 8, which carries a press cylinder 9, is attached above the moving spar 2. A pressure piston 10 guided in the press cylinder 9 is fastened to the traveling beam 2. To limit the stroke 1 stroke limiting sleeves 12 are provided on the columns. A toothed rack 14 is attached to the Laufhohn 2 via a cross member 13 and moves a scoring 115 and thus a pulse generator 17, preferably a Hall generator, via a shaft 16. The pulse generator 17 is connected to a pulse evaluation circuit 19 via a line 18. A line 20 leads via a manually operable pulse generator 23 (preselection) and a line 24 to a difference counter 25 which actuates the fields 26a of a train number display device 26. The pulse generator 23 is connected to a rotary switch 27 on the one hand and to a blocking circuit 22 via a supply line 28 on the other hand. The blocking circuit 22 has a connection 21 to the pulse evaluator 19 and a connection 30 to the difference counter 31, which has a zero key 32, which resets the counter to zero if desired. Counting devices 33 and 34 actuated by the difference counter 31 give the switching commands for the valves 46, 47, 48, which are arranged in the pipes 38, 39, 40 and connected to the valve control 37 via lines 43, 44, 45, via a line 36 to a valve control 37. The valve control 37 can be switched over or switched off via a limit switch 49 and a selector switch 50 for stretch forging or finish forging. The difference counter 31 is assigned an overflow counter 53 which actuates a field 26 b of the train number indicator 26 via a line 54.

The stroke measuring device described is to be set so that the upper edge of the lower saddle 5 forms the zero point for the measurement. But since the undersaddle can have different heights depending on the size of the lower saddle 5, the zero point the stroke measuring device can be corrected. This is well known.

If you measure z. B. when placing the handlebar 2 on the stroke limiting bushes 12 between the lower edge of the upper saddle 3 and the upper edge of the lower saddle 5 still has a distance of 283 mm, the measuring device must be set to the value 283 when 1 mm equals one pulse.

For example, if the forging dimension is 1283 mm, the Pivot button 27 another 1000 pulses from the pulse generator 23 to the difference counter 25 and 31 so that the train number display 26 in the fields 26a the number 1283 displays. After the upper switching point on the counter 33 and on the counter 34 the switching point from filling water to press water is specified, the lower Switching point by means of the pressing device in the stretch forging operating mode or Finish forging controlled by the difference counter 31. The selector switch 50 enables the switchover to one of the two operating modes.

As a result of the inertia forces, the switching time of the solenoid valves, the different The temperature of the forging over its length and the bearing surface oscillates Crossbar 2 differently far beyond the lower switchover point. This so-called overshoot is indicated to the helmsman when the lower switching point is reached a counter 53 is turned on, which receives the positive pulses from the differential counter 31 receives her and this after the end of the press stroke on the field 26b of the train number display 26 makes visible. This amount does not exceed 9 mm, so that a field 26a for the display is sufficient. For example, if 5 is displayed on field 26a, then it is white the helmsman that the crossbar swings 2 5 mm far beyond the lower switching point. In order to compensate for the overshoot, a series of pulses is generated with the swivel button 27 generated by five pulses in the pulse generator 23. The impulses have a negative Sign and reduce the forging dimension by 5 mm (= 5 pulses), so that the new Forging dimension is 1278 mm.

With this process, a so-called packet shift is carried out been, d. i.e. the upper switchover point, the switchover point »filling water / press water« and the lower switching point have been shifted by 5 mm at the same time. As a result the blocking of the pulses via the line 28 from the pulse generator 23 to the difference counter 31 by the blocking circuit 22, while by the pulse generator 17, a Hall generator, If pulses reach the difference counter 31, the packet shift takes place in stages and steady while pressing. Will overshoot again with the next stroke measured, the correction is made in the same way.

This part of the control device described so far is the state of the Technology, but not pre-published in the special design.

The device described below, which is used to measure the respective speed of the upper saddle 3 during the forging stroke, shows a line 55 which gives commands from the counters 33 and 34 to a locking switch 56 which, at the beginning of the pressing stroke, receives the pulses from a transmitter 59 (on Cylinder scorn 8), for example a Hall generator with a high number of pulses per second, forwards to an amplifier 61. The number of pulses corresponds to the number of revolutions of the pinion 58 when the rack 57 moves, which is moved together with the rack 14. The transmitter 59 generates a pulsating voltage 60, which is amplified in an amplifier 61 to form a pulsating voltage 62 and is converted into square-wave pulses 64 in a pulse shaper, a so-called Schmitt trigger 63. The square-wave pulses are fed to a counter 68 via a gate circuit 65 (gate). The pulses counted in a time unit, for example one second, in the counter 68 are fed to a memory 72 after the time unit has elapsed and, amplified via an amplifier 73, are given to a luminous digital display 74, where the number of pulses appears as a numerical value and a measure of the speed of the Upper saddle 3 is during the unit of time of the measurement. After pulses have been entered into the counter 68 for the duration of a unit of time, the gate circuit 65 receives a pulse from a reducer 76, namely from the reducer stage with a frequency of 1 Hz, which opens the gate circuit 65 and thus the accumulation of further pulses from Pulse shaper 63 (Schmitt trigger) to counter 68 (for 10-4 seconds) is interrupted. The frequency divider 76 consists of a number of stages f-213 Hz to f = 1 Hz (frequency), which work according to the circuit of a bistable multivibrator (flip-flop circuit) and the frequency obtained from a crystal oscillator 77 to half the reduce the previous stage. In the exemplary embodiment, the quartz oscillator 77 has a frequency of 8.192 kHz, which it feeds to the first reduction stage f = 21s of the reduction 76 and which is reduced in the frequency reduction 76 to a frequency of 1 Hz. Simultaneously with the pulse from the reduction stage with the frequency of 1 Hz to the gate circuit 65, the memory 72 receives a pulse which deletes the previous number from the memory 72.

The memory 72 receives a further pulse at a very short interval from the scaling stage, which involves entering the number from the counter 68 into memory 72 causes, d. H. the filling of the memory initiates.

Immediately afterwards, a further pulse causes the number in the counter 68 cleared so that it is available for counting a further pulse train. In turn the gate circuit 65 receives a pulse from the reduction stage 76 Another pulse that establishes the connection between the Schmitt trigger 63 and the counter 68 closes so that the generated pulses can again accumulate in the counter 68. After the square-wave pulses 64 in the again for the duration of a unit of time Counter 68 is counted up by a pulse from scaler 76, as before described, the gate circuit 65 opened. The same work cycle is then repeated. The numbers from the previous numerical value which have meanwhile reached the memory 72 are amplified by an amplifier 73 and in the luminous numeric display 74 as Numerical value shown. This allows you to read directly which upper saddle speeds can be measured during the unit of time passed through.

This structure is also state of the art, but not previously published.

Normally the control of the displayed pressing speed done by hand. However, the displayed speed value can also be compared can be used with a setpoint for automatic speed control, wherein the control value is formed in the up and down counting counter 78 and the Throttle valve 79, which before the press control 37 in the press water supply line 80 is installed, is fed.

Should the deformation speed measurement and display not follow the digital, but the analog measuring method, then, as shown in FIG. 2 shows the transmitter 59, for example, a correspondingly designed potentiometer be. This potentiometer voltage is only given to the difference meter 81, when the locking switch 56 by the switching commands coming via the line 55 has cleared the way for measurement. The values of the difference meter 81 are with the display device 82, for example a Braunsehen tube, made visible. But you can also at the same time by preselecting the differential voltage accordingly be used via the amplifier 83 and the throttle valve 79 in the press water supply line 80 to regulate the speed of the press stroke.

From the circuit diagram according to FIG. 1 and 2 result that switching commands of automatic forging press controls at the start of the press stroke and at the end of the press stroke to be tapped to the helmsman with the help of a display device to give the press the possibility of either the course of the deformation speed to be observed during the press stroke alone or an average value of this speed display that will enable him to determine if he is through the throttle valve the optimal deformation speed specified for him in the press water supply line has set. It is thereby possible for him to manually for the next press stroke Correct the deformation speed so that it corresponds to the optimum value. If the effort is to be made, this correction is independent of attention of the press control man, then the circuit diagram shows that there are ways there, the correction of the deformation speed can also be carried out automatically. The indicated ways to do this are of course only exemplary.

Claims (5)

Claims: 1. Application of the known for optimal deformation speeds controlled mode of operation on open-die forging presses, equipped with a setpoint specification the movement of the spar and only the actual value acquisition during the forming process, Actual and setpoint display and differential control of the control. 2. Hydraulic open die forging press with a valve or slide control to carry out the operating mode according to Claim 1 with a digital actual value transmitter coupled to the moving bar, a adjustable, digital setpoint generator and an actual and setpoint comparison device for detecting and displaying the overflow and a correction device for the Switching points of the control, characterized in that one known per se Additional device (57, 58, 59, 61, 63, 65, 68, 72, 73, 76) with a display device (74) is connected to the moving beam (2) for determining the actual speed and a target speed setting device with difference value detector (78) for Control of one in the operating medium supply line (80) upstream of the valve or slide block (37) provided throttle valve (79) is arranged. 3. Control device after Claim 2, characterized in that the additional device is the target speed during a work sequence consisting of several strokes, for example after every stroke of the press or passage of the forging through the press, accordingly a given program changes. 4. Control device according to claim 3, characterized characterized in that the specified setpoint program for pressing strokes with a large penetration depth different for different stroke sections optimal forging saddle speeds prescribes. Publications considered: German Patent No. 653 967; British Patent No. 857,485; Journal "Konstruktions", issue 4, 1961, Pp. 130 to 134; Journal "AEG-Mitteilungen", issues 1 and 2, 1961, pp. 18 to 21, 34 to 38 and 45 to 48; Zeitschrift "Maschinenbautechnik", issue 5, 1959, p. 237 bis 240; Journal "Werkstatt und Betrieb", issue 6, 1958, pp. 337 to 341; magazine "Steel and Iron", April 5, 1956, pp. 393 to 397.