JPH0349837Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a speed monitor for a press machine that detects fluctuations in the angular velocity of the press machine due to causes such as wear or slippage of the clutch brake of the press machine, sudden overload, or sudden fluctuations in power supply voltage. .

[Conventional technology]

When the number of consecutive strokes is specified, the press device repeats the same operation for each stroke unless there is a particular problem, and if the press speed differs for each stroke, there is always a reason for this. Examples of causes of this include wear and slippage of the clutch brake, load fluctuations due to uneven materials or mold breakage, or sudden fluctuations in power supply voltage.
If this condition is left unattended, it will cause a loss of synchronization with related devices and, in the worst case, damage to the device, so it is desirable to deal with it promptly. In order to deal with these speed fluctuations, the most commonly used method is to install a speed meter in the press equipment and have a supervisor visually observe the speed to detect speed abnormalities.

[Problem that the invention attempts to solve]

By the way, press equipment does not rotate at a constant speed over the entire crank angle, but repeatedly loses and recovers kinetic energy in each press cycle, and as this kinetic energy increases and decreases, the The angular velocity also varies. Therefore, the speedometer needle does not stop at a fixed point, but swings left and right depending on the crank angle even during normal operation, making it difficult to detect speed abnormalities. Furthermore, this method of detecting speed abnormalities using a speedometer assumes that a guard is always present, and is completely ineffective if there is no resident guard.

[Means to solve the problem]

The present invention was developed in view of the current situation, and provides a speed monitor for a press machine that can immediately detect any fluctuation in the angular velocity of the press machine for any reason and take corrective action. The purpose is to provide the following: In summary, the speed monitor of the press device of the present invention includes a speed detection means for detecting the angular velocity of the crankshaft, a sampling circuit for sampling the angular velocity detected by the speed detection means for each crank angle, and a crank angle. Storage means for storing the angular velocities sampled at each crank angle for one press stroke or more; and: an average value for calculating the average value of the angular velocities for one press stroke or more for each crank angle stored in the storage means. Calculating means: a setting device in which permissible error data for angular velocity is set; and: an average value of angular velocities for one press stroke or more for each crank angle calculated by the average value calculating means and set in the setting device. The upper limit of the allowable error for each crank angle is calculated based on the allowable error data, and an error signal is generated when the angular velocity sampled for each crank angle exceeds the upper limit of the allowable error for each crank angle. Generated upper limit comparison unit: The average value of the angular velocity for one press stroke or more for each crank angle calculated by the average value calculating means and the allowable error data set in the setting device for each crank angle. a lower limit comparison unit that calculates a lower limit value of the allowable error for each crank angle and generates an error signal when the angular velocity sampled for each crank angle exceeds the lower limit value of the allowable error for each crank angle; A speed abnormality is detected when the angular velocity in the press stroke is significantly different from the angular velocity at the same crank angle in the previous press stroke.

[Effect]

That is, according to the speed monitor of the press device of the present invention, the angular velocity of the crankshaft is detected for each crank angle, and each speed for each crank angle is stored in the memory for at least one press stroke. Compare the velocity with the angular velocity at the same crank angle of the previous press cycle.
It is designed to detect the presence or absence of speed abnormalities.

【Example】

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. Reference numeral 1 denotes an encoder installed on the crankshaft of a press machine. Pulse a is generated at , and pulse b is generated at, for example, top dead center every time the crankshaft makes one stroke. Next, 2 is a ring counter type counter that makes one cycle every 360 counts, and the counter 2 is incremented by the pulse a generated by the encoder 1.
Therefore, the output c of the counter 2 indicates the crank angle. Further, 3 is a differentiating circuit that differentiates the output c of the counter 2 with respect to time, and since the output c of the counter 2 indicates the crank angle, the output d of the differentiating circuit 3 indicates the angular velocity. Next, 4 is a sampling circuit, to which the output d of the differentiating circuit 3 is given as data to be extracted, and the pulse a generated by the encoder 1 is given as a sampling clock. The output d of the differentiating circuit 3 indicates the angular velocity, and since the pulse a is generated every time the crank angle advances by 1 degree, the sampling circuit 4 samples the angular velocity for each crank angle. The output e of the sampling circuit 4 is output from the memory 5.
It is also added to the upper limit comparison section 6 and the lower limit comparison section 7. In this embodiment, in order to average out variations during the creation of the reference data, the average value of the angular velocities in the previous four strokes, for example, is stored in the memory 5 as the reference angular velocity. Therefore, the memory 5 is divided into four areas M1 to M4, and each area M1 to M4 has at least 360 addresses. In the figure, 8 is a counter for specifying any of the areas M1 to M4 of the memory 5, and the counter 8 is 4.
It is constituted by a ring counter that makes one cycle by counting, and is incremented by the pulse b generated by the encoder 1 every press stroke. Then, the output f of the counter 8 is used as an address for selecting any one of the areas M1 to M4 of the memory 5. Also, each area M1 to M4 specified in this way
The address of each address within is specified by the output c of the counter 2. Next, 9 is an average value calculation circuit that calculates the average value of each speed for each crank angle, and the average angle g calculated by the average value calculation circuit 9 is given to the upper limit comparison section 6 and the lower limit comparison section 7. The upper limit comparison section 6 and the lower limit comparison section 7 are given a permissible error rate h from a setting device 10 constituted by a digital switch, etc., and the upper limit comparison section 6 and the lower limit comparison section 7 are each given the following (Equation-1). and (Equation-2) are performed, and when the inequality is established, an error signal i and an error signal j are output. e>g×(1+h) (Formula-1) e<g×(1+h) (Formula-2) Then, the error signal i and error signal j are given to the output relay 12 via the OR gate 11. Incidentally, the output relay 12 is used, for example, to cut off the power supply or to cut off the electromagnetic valve of the clutch brake. Next, the operation of this embodiment will be explained with reference to the above matters and the time chart shown in FIG. First, the encoder 1 generates a pulse a every time the crank angle advances by 1 degree, and also generates a pulse b at the top dead center every press stroke. The counter 2 is incremented by a pulse a generated every time the crank angle advances by one degree, and the differentiating circuit 3 differentiates the output of the counter 2 indicating this crank angle with respect to time. Therefore, the output d of the differentiating circuit 3 indicates the angular velocity at that crank angle, and the sampling circuit 4 samples the output d of the differentiating circuit 3 using the pulse a as the sampling clock, so the output e of the sampling circuit 4 indicates the angular velocity at each crank angle. This shows the angular velocity at each point. The output e of this sampling circuit 4 is given to an upper limit comparison section 6 and a lower limit comparison section 7, and is compared with the upper and lower limit values of the allowable error for the average value of angular velocity at the same crank angle stored in the memory 5. Ru. By the way, the memory 5 is divided into areas M1 to M4, and for example, the output of the counter 8 is [0.0]
When , the area M1 of the memory 5 is selected, when the value is [0.1], the area M2 is selected, when the value is [1.0], the area M3 is selected, and when the value is [1.1], the area M4 is selected. Then, the counter 8 is incremented for each press stroke and goes around once every 4 counts. Therefore, if the current count value of the counter 8 is [0.0], the angular velocity for each crank angle one stroke before is shown in the area M4. However, the area M3 stores the angular velocity for each crank angle two strokes ago, the area M2 stores the angular velocity for each crank angle three strokes ago, and the area M1 stores the angular velocity for each crank angle four strokes ago. ing. When data is read out, data regarding the same crank angle in all areas M1 to M4 of the memory 5 is read out and provided to the average value calculation circuit 9. More specifically, if the count value of the counter 2 is N (N is 0 to 359), the sampling circuit 4
gives the angular velocity when the crank angle is N degrees in the current press stroke to the upper limit comparators 6 and 7, and also gives the angular velocity when the crank angle one stroke before is N degrees from address N in area M4 of the memory 5. is read out, and from address N in area M3 of memory 5, the angular velocity when the crank angle two strokes ago is N degrees is read out, and from address N in area M2 of memory 5, the crank angle three strokes ago is read out. The angular velocity when the crank angle is N degrees is read out, and the angular velocity when the crank angle four strokes ago is N degrees is read out from address N in the area M1 of the memory 5, and each is given to the average value calculation circuit 9. The average value calculation circuit 9 calculates the average value of the angular velocity for four strokes when the crank angle is N degrees, and provides it to the upper limit comparison section 6 and the lower limit comparison section 7. The upper limit comparator 6 compares the output e of the sampling circuit 4, the output g of the average value calculation circuit 9, and the setter 10.
Perform the calculation of (Equation-1) using the output h as a variable,
If the angular velocity when the crank angle in the current press stroke is N degrees exceeds the upper limit of the tolerance based on the average value of the angular velocity when the crank angle is N degrees in the previous four strokes, an error signal i is generated. . Similarly, the lower limit comparison section 7 outputs the output e of the sampling circuit 4 and the output g of the average value calculation circuit 9.
and the output h of the setting device 10 are used as variables to calculate (Equation-2), and the angular velocity when the crank angle in the current press stroke is N degrees is the angular velocity when the crank angle in the previous four strokes is N degrees. When the error falls below the lower limit of the allowable error based on the average value, an error signal j is generated. When either the error signal i or the error signal j occurs, the output relay 12 is energized via the OR gate 11, and measures such as an emergency stop are taken. Furthermore, when the device is operating normally, the angular velocity for each crank angle takes a roughly constant value over the entire press stroke, so the error signals i, j
does not occur, and a write operation is performed following the comparison operation. In the current operation example, the count value of the counter 8 is [0.0], and the count value of the counter 2 is N, so the crank angle at the current press stroke is stored at address N in the area M1 of the memory 5. is N
The angular velocity in degrees is memorized. Then, each time the encoder 1 generates a pulse a, the above operation is repeated while the crank angle increases by 1 degree. In the above example, the output of the counter 2 is differentiated to detect the angular velocity d, but as shown in Fig. 3, a tachogenerator 1 is attached to the crankshaft.
3 may be provided, and the angular velocity d may be detected by the tachometer generator 13. The example shown in Fig. 3 has exactly the same configuration and operation as the example shown in Fig. 1 except that the angular velocity is detected by the tachometer generator 13, so the same components are denoted by the same reference numerals. Duplicate explanations will be omitted. Also, in the above example, the average value of the angular velocity for each crank angle for 4 strokes was calculated, but simply calculate the angular velocity for each crank angle in the current press stroke by calculating the average value of the angular velocity for each crank angle for 4 strokes. The angular velocity of the same crank angle may be compared, and in this case, the counter 8 and the average value calculation circuit 9 are not necessary, and the memory 5 only needs to be in a single region M1.

【effect】

As explained above, according to the present invention, the angular velocity of the crankshaft is detected for each crank angle and stored in memory, and the current angular velocity is greatly different from the angular velocity at the same crank angle in the previous press cycle. Since it is determined that a speed abnormality has occurred when a speed abnormality occurs, it is possible to immediately deal with the speed abnormality without the need for a watchman to be stationed at all times.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention.
FIG. 2 is a time chart within one crank angle, and FIG. 3 is a block diagram of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Encoder, 2...Counter, 3...Differential circuit, 4...Sampling circuit, 5...Memory, 6...Upper limit comparison section, 7...Lower limit comparison section, 8...
... Counter, 9 ... Average value calculation circuit, 10 ... Setting device, 13 ... Tachometer generator.

Claims (1)

[Claims for Utility Model Registration] A speed detection means for detecting the angular velocity of the crankshaft, a sampling circuit for sampling the angular velocity detected by the speed detection means for each crank angle, and an angular velocity sampled for each crank angle. storage means for storing at least one press stroke for each crank angle; and one press stroke for each crank angle stored in the storage means.
An average value calculation means for calculating an average value of angular velocities over a press stroke, a setting device in which permissible error data of angular velocity is set, and one press stroke for each crank angle calculated by the average value calculation means. The upper limit of the allowable error for each crank angle is calculated based on the average value of angular velocities over a period of minutes and the allowable error data set in the setting device, and the angular velocity sampled for each crank angle is calculated for each crank angle. an upper limit comparison unit that generates an error signal when the upper limit of the allowable error for each crank angle is exceeded; The lower limit of tolerance for each crank angle is calculated based on the tolerance data set in the setting device, and the angular velocity sampled for each crank angle exceeds the lower limit of tolerance for each crank angle. a lower limit comparator which generates an error signal in the event of an error.