DE2830165A1 - Drop hammer controlled by computer programme - has row of proximity switches to vary height of hammer lift - Google Patents

Abstract

A drop-hammer (1) for forging a workpiece (9) is raised by a belt (3) which passes around a pulley (4) and is driven by a second pulley (5). This second pulley (5) is pressed against the first pulley (4) by a hydraulic cylinder (7) which is actuated by a control valve (10) and a pedal (6). In existing drop hammers the height to which the hammer is raised is controlled by a single proximity switch (8a). The appts. uses a number of such switches (8a) placed one above another and connected to a computer so that the height of hammer lift can be controlled by a preset programme.

Description

Microprocessor control for belt drop hammers.

The present invention relates to an electronic belt drop hammer control , which are used to control the forging processes for workpieces of various shapes and material properties and also allows forging to be carried out fully automatically and with great accuracy.

The current state of the art can be explained in such a way that the belt drop hammers of the old and new generation without exception hydraulically or hydropneumatically operated and controlled and thus, due to the dependency on the skill of the operator, none allow optimal performance in terms of the quality of the parts and the size of the committee The operator has to concentrate fully on the forging process in order to achieve the holding the glowing forging correctly in the die and on the other hand the drop hammer to be steered in such a way that the necessary height of fall is reached with each stroke These two things can only be achieved with the utmost concentration, he gets tired Operator very quickly, the quality of the workpiece suffers and the risk of accidents increases very sharply.

The present invention is represented by Figure 1 so that a an elevator belt (3) hanging hammer (l) when releasing a fall brake (8) with his own weight hits a corresponding die (2) in which a high-temperature, Glowing steel piece (9) forged and molded according to the incorporated die shape After this process has been completed the hammer (l) is thereby pulled up again to a certain height of fall by pressing the foot control device (6) a pressure valve (7) is actuated, which attaches the pressure roller (5) to the elevator belt (3) presses and thus the latter is taken along by the lifting disc (4) until the desired new height of fall has been reached O This process is repeated with every blow of the hammer (l) O A forge run, for example, can consist of a series of several blows, but only after the last stroke of a series does the fall brake (8) come into effect again, which keeps the hammer (l) in the rest position until you step on the foot control device (6) a new stroke series for a new workpiece (9) begins.

As mentioned at the beginning, it is very difficult and requires one long training period to operate the sling hammer in such a way that as few rejects as possible and the risk of accidents for the operator is kept as low as possible A high level of concentration when operating the drop hammer is therefore necessary, as the blacksmith at the same time must bring the workpiece into the die, the foot control device has to operate, very sensitively, and at the same time while flipping of the workpiece into the next die shape must observe whether the drop hammer (l) is in the required stroke height (starting position) has been reached Said operation of the operator's foot control device during the entire working time can almost only stand on the left foot. The whole thing leads to the fact that many Rest breaks must be taken and that the training of other operators takes a lot of time.

In order to eliminate all of these technical and human inadequacies, it has the inventor set himself the task of a microprocessor control device develop that allows the forging process to be carried out with a single movement of the foot initiate, the stroke cycle with several strokes automatically perform and ultimately monitor and correct whether the correct pitches An additional procedure prevents the formation of pronounced Loops on impact with the hammer O the latter are particularly harmful because when pulling up the hammer again, vas with very great force and very high speed happens, first there is no load and then in a fraction of a second the full one The load of the hammer strains the belt, which after a while causes the elevator belt to tear leads and makes a repair necessary, for better understanding of the drawing according to Figure 1 tz the following designations are listed: 1 = hammer (bear) 2 = Die (consisting of upper and lower part) 3 = elevator belt 4 = lifting disc 5 = pressure roller 6 = foot control device (electro-pneumatic) 7 = pressure valve with piston 8 = fall brake 8a = emergency stop safety switch 9 = workpiece lo = hydraulic control unit 11 = Inductive proximity switch (Figure 2) 12 = switching power supply 13 = microprocessor with program and arithmetic memory 14 = output amplifier or switching stages for actuators Structure description: According to Figure 1, all hydraulic-pneumatic control units are so on the belt hammer arranged that the functional sequence during forging is carried out exclusively by the operator is controlled via the foot control device (6). If he steps slowly on the latter, so first releases the fall brake (8), the hammer (1) falls down onto the die (2), whereby shortly before the glowing workpiece (9) was passed underneath using pliers Stepping on the foot pedal of the foot control device (6) opens the pressure valve (7) and so that the pressure roller (5) is pressed onto the strap (3) and thus also onto the Lifting disc (4), which pulls the belt up together with the hammer, for another The operator has to push the pedal back briefly, which has the consequence that the pressure valve (7) opens, the pressure roller (5) goes back, the elevator belt (3) becomes free and the hammer falls back onto the die (2). This is repeated until the last stroke of a cycle has been carried out, i.e. the workpiece is completely forged is and the operator the foot pedal of the foot control device (6) completely in the starting position Then the fall brake (8) closes again and then A new forging process can be added in the vicinity of the drop brake (8) a circuit breaker (8a), which prevents the hammer from exceeding its allowable Maximum stroke height and would destroy the drop hammer.

Another difficulty can arise when the operator is brief takes too much time before the hammer hits the die when giving the Command to pull the hammer up again strap a more or less large loop, if the strap is now pulled up quickly is done, this is initially done without a load, since the loop is pulled away first.

But then suddenly the full weight of the hammer, about 1200 kg, hangs on the Lifting and thereby the belt ar: hammer can tear off.

FIG. 2 explains the basic structure using a block diagram the microprocessor control with the approximation chantern (sensors) Sl bj s S7 (11), the Switching power supply (12), the complete process control (13) with Proararnnsneicher, Rechennsrerk and arithmetic memories, output stages and finally the output amplifiers and switching stages for the actuator control (14). The foot control device is equipped with a changeover contact provided, with the help of which the drop hammer is controlled via the microprocessor control will.

The hydraulically working Aagregat (lo) brings about the cooperation between hydropneumatic and electronic operation, but it should be noted that each control device is fully functional in itself.

The inventor has worked on the design of the processor control set the task of addressing the serious disadvantages of hydropneumatic control, such as already described, to bypass and for the operator a simple and easy to use To give process control that is also able to work more precisely, less to tire and produce less waste.

The sensors (11) each deliver one when the hammer drives past Voltage pulse that is used in the processor part for measurement and control purposes In order to be able to control different impact heights with as few sensors as possible, In the exemplary embodiment, a certain spacing was established between the individual Sensors selected, which is described in Fig. 3 0 The following functions now, regardless of the hydropneumatics, which only work manually, with the help of the Carry out microprocessor control and the corresponding entered program: l) Start of the drop hammer. The hammer is programmed for the first time on the desired and programmed It does not matter whether the hammer is in rest position beforehand or in any intermediate position.

2) Drop the hammer and again after hitting the die Pull up to the next height of fall, creating what is known as the loop formation of the elevator belt prevented and when pulling up the next height of fall with as much as possible great accuracy can be achieved.

To l): After switching on the power supply, the electronic is located Control in its basic state and awaits the actuation of the foot switch (6) If the latter is now pressed, the electronics cause the hammer to be raised If the hammer now reaches a height of 10 cm above the die, the buoyancy (pulling up due to its high kinetic energy, sets the hammer continues its way up, then slows its movement, finally reaches the turning point and then falls back down.

The formula is now derived from the times calculated by passing over the sensors and the times calculated with them (Figure 5) gained the lift time necessary to bring the hammer to the level of the lowest sensor.

where t is the pick-up time to the lowest sensor, tó the time from lowest sensor up to the reversal point.

0 From the time tx, the buoyancy time to the following sensors is calculated according to the formula Here, h is the height to the lowest sensor, 0 h is the height to the corresponding other sensors, n tx is the buoyancy time to reach a height of 10 cm.

Explanation in Figure 5.

The values for the buoyancy times determined when pulling up are theoretically and only approximately agree with reality, since the The grip of the pull-on strap (friction) changes continuously and cannot be rolled A correction program has now been developed which combines the target height with the actual height compares and corrects the lift time accordingly, so that the target heights after achieved with a few test strokes and kept constant throughout the entire operation The latter was technically implemented as follows: The program provides determines how high the hammer has come. Is the deviation from the target height just like that large that the next lower or next higher sensor in relation to the target height is not exceeded or fallen short of by the hammer, then the fine control is set The time difference between the target time and the actual time is determined here and corrected the lift time of the respective stroke so that the height of fall of the relevant impact reached in the next program cycle with a large approximation - If the hammer falls below the next lower sensor in relation to the nominal height or the next higher is exceeded, the coarse control starts.

This means that a fixed value is added or subtracted to the buoyancy time so that the hammer reaches its target height with a large approximation in the next program cycle.

(Figure 6) Determine when to pull up of the hammer after the fall: the hammer should then be pulled up when its kinetic Energy has been fully released to deform the workpiece (forging) pulled up too early, then the hammer can no longer deliver its full energy but pulled up too late, the impact of the hammer creates a loop in the elevator belt as described earlier, this problem was solved as follows: As already explained at the beginning, there are sensors along the fall path of the hammer, their Distances are determined according to Fig. 3 The lowest sensor is used for starting and to catch the hammer if, for whatever reason, it is not the lowest Measuring sensors reached (help with low heights below 30 cm) The Voryang is playing now so that the next two sensors are always below the height of fall can be used as measuring sensors. A mathematical method was found which allows fall times regardless of different gravitational acceleration to calculate.

The formula for calculating the fall time according to the selected distance ratio of the sensors is as follows: tl is the time from the beginning of the fall until the hammer leaves the upper measuring sensor.

t2 is the time from the beginning of the fall to leaving the lower one Measuring sensor through the hammer.

t3 is the time at which the hammer hits the die.

In theory, this would also be the time to pull up the hammer. (Figure 4) Since every machine within its command transmission and command execution is subject to so-called dead times, this must also be done here must be taken into account.

The latter can be regarded as constant after a one-off determination. Thus, the valid formula for determining the point in time for the command is "pull the hammer up" Where K represents the constant determined. (For dead time) The microprocessor used would have been too slow to solve the given task. Therefore, a special calculation method was developed. The program for this provides a complete intermediate result every 300 microseconds when the hammer falls so that the calculation result is already available after passing the lower measuring sensor. A time delay caused by the microprocessor cannot take effect.

Programmatic solution for calculating the pull-up time for the hammer according to the formula If the computing time is eliminated: Without taking the dead time into account, the formula for the fall time would be In order to avoid the cumbersome calculation of the square root, the whole equation is put into the square, so it reads 2 2, 3 4 t2 - 3 tl From the beginning of the fall until the next sensor is exited, a new value 2 3 is displayed every 300 microseconds tl calculatedOA time unit always corresponds to 300 micro-seconds. From this point in time until the next sensor is left, a new value 4 t2² - 3 t1² is calculated every 300 micro-seconds.

Sensor has passed, so is after 300 microseconds at the latest the exact value of the time (squared) before the hammer hit the die At the beginning of the fall, the number is simultaneously every 300 Nicro seconds of the time units summed up ursd squared.

(t3) After passing the 20 sensor, only the value t32 is counted on and compare when it coincides with the already calculated value 4 t2 - 3 tl At the time of the match, the hammer has actually reached the die.

Now the dead time has to be taken into account, which became 2 .2 like this achieves that the time counter t3 is preloaded by the dead time 2 2 2 t3 = 4 t2 - 3 tl reached earlier by the dead time and the hammer is activated after Immediately pulling up on the die. (Figure 4) The solution described the sling hammer control problem of the present invention can be added are controlled by additional controlling or monitoring functions, such as those in the Sub-claims are cited.

Claims (1)

P A T E N T A N S P R Ü C H E: 1. Microprocessor control for Ri emenfal hammers or beating hammers in general, the principle of which is that Forged workpieces due to the impact of a freely falling hammer be deformed, compressed or embossed, characterized in that optical or inductive or capacitive proximity switches (sensors) along the Fallg des Hammers are arranged so that the upper or lower edge of the hammer each have one Switching process triggers that the sensors are in a distance ratio of 3: 4 (Fig 3) are mounted on a common rail, which can be moved relative to the die is that the microprocessor computer with the help of the respectively passed sensors according to the formula of free fall, the respective fall time of the hammer is calculated that this calculated fall time is used by the program for a functional circuit is going to pull the hammer up again sooner or later that by a special The computer program the same beats in a cycle of several Strikes individually and repeatedly controlled and corrected, (compliance with a specific impact height) that the control electronics are designed so that the number of the beats within a cycle, the beat heights of the individual beats, the Pause times between the individual strokes and ultimately the dead time of the controlled system is adjustable and preselectable, that setting the minimum and maximum pitches are monitored by computer and under-c the exceedance shut down the device that continuously monitors in a certain time interval whether the foot switch is still operated or not, (safety circuit) that to prevent the computer from looping after determining the respective Fall time accordingly ahead of time before the hammer hits the die command for pulling up again, 2) microprocessor control for belt drop hammers according to claim l, characterized in that a locking circuit ensures that the The hammer immediately stops in its respective position when the foot is removed from the foot control device (foot pedal) is taken. 3) microprocessor control for belt hammers according to claim 1 and 2, characterized in that each program error or each operating voltage drop or failure immediately shuts down the control device. 4) microprocessor control for belt hammers according to claim 1 to 3, characterized in that the hydraulic unit belonging to the electronic control unit is also monitored by means of a pressure sensor. 5) microprocessor control for belt hammers according to claim 1 to 4, characterized in that, for example, in bar forging, the last blow of a cycle is executed as a cutting stroke, so the computer does the necessary Must also set and guarantee the stroke height. 6) Nikropro ze 5 sors control for R 1. emenfal liner according to claim 1 to 5, characterized in that the computer has separate counters with Display for statistical evaluations the number of impact cycles and the number] of the interrupted cycles (rejects) are added up and displayed. 7) microprocessor control for belt hammers according to claim 1 to 6, characterized in that by using smaller sensors, the closer Clearances enable the accuracy of the measured value acquisition to be increased and so that the striking heights can be adhered to even more precisely. 8) microprocessor control for belt hammers according to claim 1 to 7, characterized in that with optical scanning of the hammer any one Point on the hammer can be scanned.