JPS583773B2 - Forging machine mold position control device - Google Patents

Description

[Detailed Description of the Invention] A forging machine is the first processing machine of equipment for manufacturing round bars, square bars, stepped shafts, discs, rings, sleeves, etc., and is a first processing machine that hot-processes billets or blooms. It is machined and manufactured into a product.

The present invention relates to a mold position control device that improves the accuracy of finished dimensions of this forging machine.

Conventional forging machines use a hydraulic press to control the position of the mold, and almost all of the finished dimensions are controlled based on on/off control.

For this reason, unless the deformation load for each forging stroke is constant, good precision cannot be obtained and the product yield is poor, and if the number of strokes per minute is increased, the impact force increases and the life of the mold is shortened.

There is also a method of detecting the positional deviation of the cylinder that drives the mold and correcting the deviation of the cylinder so as to maintain the normal position of the cylinder. This cannot be corrected, causing the mold to shift as shown by the broken line in Figure 1A, and furthermore, if the deformation load of the workpiece changes during deformation, residual deviation remains at the point where it is pushed out. there were.

The present invention rectifies these deficiencies.

Embodiments of the present invention will be described below based on the drawings.

An example of a forging machine to be controlled by the control device according to the present invention has the following configuration.

A swinging link 4 is pivotally connected to a piston rod 3 of a cylinder 2 disposed on a base 1, and one end of the swinging link 4 is pivotally connected to a slider 7 that is slidable in the direction of expansion and contraction of the cylinder 2. A mold 5 is provided in part, and the other end of the swing link 4 and a crankshaft 9 to which a driven gear 8 is fixed are connected by a link 10.

The driven gear 8 meshes with a drive gear 11, and the drive gear 11 is connected to the flywheel 6 and to an electric motor 12 via a belt or the like.

The fixed end of the slider 7 opposite to the mold is connected to a pull-back cylinder 13 disposed on the base 1, and a mold position detection scale 14 is attached to the fixed end of the mold.
is engaged with a pulse transmitter 21 for detecting the position of the mold.

The cylinder 2, the pull-back cylinder 13, and the accumulator 17 communicate with a pressure oil pump 18.
A switching valve 15 is connected between the cylinder 8 and the cylinder 2 from the cylinder 2 side.
A relief valve 19 is attached to the pressure oil pump 18 provided with the servo valve 16.

In the forging machine configured as described above, the drive gear 11 and the driven gear 8 are rotated by driving the electric motor 12 and rotating the flywheel 6, and the oscillating gear connected to the crankshaft 9 of the driven gear 8 by the link 10 rotates. The movable link 4 swings around the pivot point with the piston rod 3 and moves the slider 7, thereby causing the mold 5 to crank.

Also, the pressure oil pump 18 is driven to accumulate the pressure oil set in the relief valve 19 in the accumulator 17.

The pressure oil accumulated in the accumulator 17 is sent to the cylinder 2 through the servo valve 16, and the position control of the mold 5 is performed by moving the swing center of the swing link 4.The pressure oil is also sent to the pull-back cylinder 13, and is sent to the cylinder 2 to control the position of the mold 5. Perform the pullback operation in step 5.

In the position control using the servo valve 16 described above, when a load occurs, pressure oil is sent from the accumulator 17 to the cylinder 2 in order to correct the deflection of the pace 1, but when the push-off point is passed and the return stroke begins. The load rapidly becomes 0 kg, and the mold position is overshot by the amount of oil fed under pressure, so the servo valve 16 is operated to discharge the oil in the cylinder 2 to the tank (0 kg/cm2).

Therefore, when the push-off point is passed, the switching valve 15 is operated to fill the cylinder 2 with oil, and when a load is generated, the switching valve 15 is operated again to perform position control using the servo valve 16.

By operating the switching valve 15 in this manner, the amount of oil used is reduced.

Next, a die position control device for a forging machine will be described.The following explanation relates to the left side die position control, but the same applies to the right side.

In Figure 2, 21. 22 is a pulse transmitter, force is a hydraulic pressure detector, which becomes a load detector by multiplying the cylinder area, 24 is a mold placement indicator, 25 is a mold push-off position indicator,
26 is a crank angle indicator, 27 is a finishing dimension setting device, 2
8 is a push-cut angle setter, 29 is a gate, 30 is a function generator, 31 is a comparator, 32, 33, 34, 35, 36, 3
7, 38, 39 are arithmetic units, 40, 41 are amplifiers, 42 are D/A converters, 43 are amplifiers, 44, 45, 46, 47
, 48 is an arithmetic unit, 50 is a gate, 51 is a Halt element,
52 is a switching valve driven amplifier, 53 is a pressure crank angle setter, 54 is a comparator, 55 is a hold element, and 56 is a comparator.

The position of the die 5 of the forging machine is determined by the crank angle, that is, the position of the crankshaft 9 of the driven gear 8. If R is a constant determined by the eccentricity of the crankshaft 9 and the link mechanism, then the crank angle θ and the stroke of the die 5 are determined by the crank angle θ and the stroke of the die 5. The relationship with S is S=Rsinθ, and if all the movement amounts of the mold are (+), then S=R(1
+sin θ) (S=0 to 2R) (1).

In addition, due to the crushing load of a forging machine, the base 1, swing link 4, etc. are deflected, and the working fluid in the cylinder 2 is compressed, causing the die 5 to draw a trajectory that deviates from the trajectory when there is no load. The machine only needs to control the position at the push-off point with high precision.

In general, the load generated by the workpiece changes until near the push-off point, and the trajectory of the mold 5 described above will deviate quickly if the load is rapidly generated.

In order to correct the displacement of the mold 5 due to the load that occurs during processing, the servo valve 16 detects the load and responds to changes in the load.
The position of the mold 5 is controlled by driving the cylinder 2 through the cylinder 2.

The hydraulic pressure detector 23 detects the load generated during forging via the working fluid of the cylinder 2 (the load may also be detected using a strain in a link mechanism, etc. or a load cell), and the detected load is detected. Differentiate it with a liquid calculator 33 and convert it into a signal to determine the load change,
The amplification device 40 amplifies the oil to a level corresponding to the flow rate of oil to the cylinder 2, and inputs it to the calculator 38.

Further, the movement of the mold 5 is detected by the pulse transmitter 21, and the mold position indicator 24 counts the pulses from the pulse transmitter 21 to detect the position of the mold and input it to the calculator 32.

Further, pulses from a crank angle detection pulse transmitter 22 attached to the crankshaft 9 are counted by a crank angle indicator 26 to detect a crank angle θ, which is input to a function generator 30.

The function generator 30 converts the stroke amount of the mold 5 from the above equation (1) and inputs it to the calculator 46.

Further, the finishing dimension set by the finishing dimension setting device 27 is input to the computing unit 46, and a signal corresponding to the trajectory in which the mold is to be moved is inputted to the computing unit 32 via the computing unit 45, together with the signal from the function generator 30. ．． The calculator 32 calculates the difference between the input signal of the mold position indicator 24 and the signal input from the calculator 45, that is, the positional deviation (positional deviation) of the mold 5 from the trajectory in which the mold 5 should move. calculate.

The D/A converter 42 converts the calculation result into an analog signal, amplifies it with the amplifier 41, and inputs it to the arithmetic unit 38.

The arithmetic unit 38 receives the signal from the amplifier 40 and the amplifier 41.
The flow rate command signal to the cylinder 2 is outputted by combining the signal with the signal of .

In the present invention, the output of the arithmetic unit 38 is processed by a circuit to be described later, but it may also be connected to the servo valve drive amplifier 43 since quite good results can be obtained by directly commanding the opening of the servo valve 16. .

The opening degree of the servo valve 16 and the flow rate are in a proportional relationship, but the flow rate is proportional to the square root of the difference, so when the differential pressure decreases, the flow rate decreases, and equivalently, the loop gain decreases.

Therefore, the calculator 38 has a limiter characteristic.
4.35 is connected, when the output of the operator 38 is positive, the operator outputs the same signal as the operator 38, and when the output of the operator 38 is negative, the operator outputs the same signal as the operator 38. 35 outputs, and when either one of the arithmetic units 34 and 35 outputs, the output of the other is set to O.

The signals from the calculators 34, 35 and 37, 36 are input to the calculators 38, 39, respectively.

The calculator 36 outputs the square root of the differential pressure between the pressure PA corresponding to the accumulator pressure set in the relief valve 19 and the pressure obtained by the hydraulic pressure detector 23, obtained by the calculator 47. 37 is tank pressure (0 kg/crn2
) and the pressure obtained by the hydraulic pressure detector 23.

The calculator 38 divides the output of the calculator 34 by the output of the calculator 36 and outputs an opening signal to open the servo valve 16 in the pressurizing direction, and the calculator 39 divides the output of the calculator 35 by the output of the calculator 31. An opening signal for opening the servo valve 16 in the direction of pressure reduction is output.

The computing unit 48 combines the signals from the computing units 38 and 39 and outputs an opening command signal for the servo valve 16.

That is, the circuit from the arithmetic unit 32 to the arithmetic unit 48 is connected to the cylinder 2.
This converts the flow rate command signal to an opening command signal for the servo valve 16.

The servo valve drive amplifier 43 amplifies the signal from the computing unit 48 to a level sufficient to drive the servo valve 16, thereby operating the servo valve 16.

The above-mentioned control device drives the cylinder 2 via the servo valve 16 to repeatedly control the position of the mold 5 for each stroke. In other words, if the feed rate of the forged object is constant, the load generated for each stroke will be almost constant, and the position control will also repeat an almost constant pattern.

Therefore, in such a case, position control is performed using the following control circuit.

The comparator 31 compares the push-off angle setting signal set by the push-off angle setting device 28 with the signal from the crank angle indicator 26, and when they match, an instantaneous pulse is generated and the push-off point is pushed off via the gate 29. The position indicator 25 is held.

The difference between this held push-off position signal and the signal from the finishing dimension setter 27 becomes a finishing dimension error, but since the difference is the same value for every stroke, this difference is calculated by the calculator 44 and sent from the finishing dimension setting device 27 to the calculator. When the setting value passed through step 46 is added to and corrected by the calculator 45, the positional deviation at the push-off point is almost eliminated, and highly accurate mold position control can be achieved.

Next, the aforementioned switching valve 150 control section will be described (first
(see figure).

A forging pass start signal B from an operation switch (not shown) is input to the hold element 51 through the gate 50, the hold element 51 is held, and its output is amplified by the switching valve drive amplifier 52, and the output is used to switch. Valve 15 is operated to connect servo valve 16 and cylinder 2.

The position control of the mold 5 by the servo valve 16 is performed until the mold 5 reaches the push-off point of the initial stroke.

The comparator 31 detects the bold element 5 at the point where the angle detected by the pulse transmitter 22 and the crank angle indicator 26 matches the angle set by the push-cut angle setting device 28.
1 is reversed, the polarity of the switching valve drive amplifier 52 is switched, and the switching valve 15 is operated to seal the oil in the cylinder 2 and disconnect the servo valve 16.

From the next stroke, the crank angle at the push-off point is determined based on the push amount of the forged object, and the pressure crank angle setting device 5
3, input this setting signal and crack angle indicator 2.
6 is compared by a comparator 54, and the signal from the comparator 54 is inputted to a hold element 51 through a gate 50, which holds the element 51 and also controls the switching valve 15 by a switching valve drive amplifier 52. The servo valve 16 and the cylinder 2 are communicated with each other until the hold element 51 is reversed at the push-off point to control the mold position.

Also, the pressure at the push-off point is memorized by the hold element 55, and from the next stroke, this value is compared with the value detected by the hydraulic pressure detector 23 by the comparator 56, and if the memorized value is exceeded, the pressure crank is turned off. Even before the angle set by the angle setting device 53 is reached, the output signal from the comparator 56 is passed through the gate 50 to hold the hold element 51, and the servo valve 16 and the cylinder 2 are connected to perform position control.

As described above, according to the present invention, the mold of the forging machine moves in a sinusoidal manner with less impact (i
(iii) Servo valve Since the operation is performed not only by position deviation but also by adding an amount proportional to the change in applied load, good position control is possible. By performing the correction and further disconnecting the servo valve with a switching valve at the push-off point of the first stroke, the amount of oil in and out for each stroke can be reduced to just one stroke, which saves energy. It can exhibit excellent effects.

[Brief explanation of the drawing]

FIGS. 1A, 1B, 2C are diagrams showing the relationship between the deviation of the mold position due to the bending of the frame and the operating position of the switching valve, and FIG. 2 is an explanatory diagram of the control device according to the present invention. 14 is a mold position detection scale, 15 is a switching valve, 16 is a servo valve, 21.22 is a pulse transmitter, 23 is a hydraulic pressure detector, 24 is a mold position indicator, 25 is a mold push-off indicator,
26 is a crank angle indicator, 27 is a finishing dimension setting device, 4
2 is a converter A, 43 is a servo valve driven amplifier, 51.5
5 is a hold element, 52 is a switching valve driven amplifier, 53 is a pressurizing crank angle setter, and 54 and 56 are comparators.

Claims (1)

[Claims] 1. A horizontally opposed structure having mechanisms on the left and right sides of which the center of swing of the swing link is pivotally connected to the rod of the hydraulic cylinder, and the mold connected to the swing link is driven in a sinusoidal manner by a crank mechanism. In the die forging machine, a position detector for the die is provided near the die mounting part, a crank hemp detector is provided in the crank mechanism, and a load detector for detecting the pressing load of the die is provided, Calculates the positional deviation of the mold by comparing the signals from the position detector and crank angle detector with the setting signal from the mold position setting device, and also calculates the positional deviation due to deflection based on the signal from the load detector. Position deviation correction circuit Compares the signal from the crank angle detector with the setting signal from the push-off angle setter to determine the position deviation of the mold at the push-off point and inputs it to the position deviation correction circuit, as well as the push-off angle setting device. A circuit for holding a mold position detection signal up to a point, and a crank angle detector and a pressure angle setting device for detecting a pressurization operation start point of the mold. a circuit configured to generate a push-off completion signal based on a signal from the device and issue a switching valve drive signal based on both signals; and a servo valve that operates the cylinder based on a correction signal from the position deviation correction circuit. A mold position control device for a forging machine, comprising a switching valve that disconnects communication between the cylinder and the servo valve based on the drive signal.