JP2000202853A - Method and apparatus for setting stop standard position of table driving mechanism for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exactly set at a stop standard position by moving a table in forward or reverse direction in the state that engagement of a platen side mold with a table side mold is disengaged, monitoring a driving current or the like of a motor, and using a position where an absolute value of the current or the like becomes small as the standard position of the table. SOLUTION: An injection molding machine rotates a rotary table 1 at a pitch of 180 deg., and molds and takes out a product. Thus, a plurality of table side molds 3a, 3b are mounted at a pitch of 180 deg. on the table 1, and one mold 3a is engaged with the other mold 3b in association with a mold clamping operation due to a rise of the table 1 or a fall of a platen 4. In this case, a driving current or a load of a servo motor for driving the table 1 is monitored, and a position where absolute values of these values become small is used as a stop standard position of the table 1. Thus, a positional deviation between a guide post 5 and a guide bush 6 is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a table of an injection molding machine for performing an injection molding operation by moving a table provided with a plurality of table side dies and sequentially fitting the table side dies to a platen side die. The present invention relates to a method and a device for setting a reference position for stopping a driving mechanism.

[0002]

2. Description of the Related Art A plurality of table-side molds are provided on a table which moves linearly, and the table is reciprocated to position one of the table-side molds at a position corresponding to the platen-side mold, thereby clamping the molds. And a rotary injection molding machine using a rotary table (hereinafter, referred to as a rotary table) in place of the shuttle table.

FIG. 3A is a plan view schematically showing the periphery of a rotary table 1 in a vertical rotary injection molding machine.

Rotary table 1 formed in a disk shape
Is mounted so as to be rotatable around one of three tie bars 2 supporting a platen 4 for mounting a platen side mold, and is driven to rotate at a predetermined pitch by a servo motor or the like as a driving source. ing.

In the example shown in FIG. 3A, the rotary table 1 is rotated by 180 °.
Forming and taking out the product by rotating at the pitch 2
The setting when performing the stage type injection molding operation is shown, and the rotary table 1 has 180 °
The table-side mold 3a and the table-side mold 3b are attached at a pitch. In the state shown in FIG. 3 (a), the table-side mold 3a is on the molding stage side, and the table-side mold is on the product take-out stage side. The mold 3b is located.

A table side mold located on the molding stage side
3a is the platen 4 due to the mold clamping operation of the injection molding machine performed by raising the rotary table 1 or lowering the platen 4.
Is filled with a molten resin from an injection cylinder (not shown) erected on the platen 4 and then opened by the lowering of the rotary table 1 or the raising of the platen 4. To return to the initial position, the rotary table 1 rotates 180 °, the table-side mold 3a moves to the product take-out stage side, and the table-side mold 3b moves to the molding stage side. The robot or the like arranged on the side performs an operation of taking out the product remaining in the table side mold 3a.

The table-side mold 3a and the table-side mold 3b are alternately positioned immediately below the platen-side mold by rotation of the rotary table 1 by 180 ° in the forward and reverse directions. The work will be repeated.

However, the gear train of the table driving mechanism for driving the rotary table 1 has some backlash. Further, since the rotary table 1 has a large mass, a large inertial force acts. Therefore, even if the position control of the servo motor or the like serving as a drive source is accurately performed so that the rotary table 1 can be rotated forward and reverse at a 180 ° pitch, the rotary table 1 moves by inertia within the backlash section and stops. And the forward and reverse rotation is not necessarily
There is no guarantee that it will be performed at a 180 ° pitch.

For example, in the initial stage of the operation start or when the temperature is low, the grease or the like applied to the table driving mechanism or the rotary sliding portion of the rotary table 1 is cold and has high viscosity.
Due to this viscosity, the rotation of the rotary table 1 is braked during inertial movement in the backlash section, and the actual rotation angle of the rotary table 1 may be less than 180 °. In addition, when a considerable time has elapsed since the start of the work, or in a situation where the temperature is high, the rotary table 1 overruns the backlash section due to inertia due to a decrease in the viscosity of grease, and the actual rotation angle becomes 180 °. ° may be exceeded.

The stop position of the rotary table 1 is shown in FIG.
As shown in the figure, when closing the mold, the table side mold 3a,
The guide posts 5 at the four corners of 3b should be set to exactly coincide with the centers of the guide bushes 6 serving as the guide holes at the four corners of the platen side mold. However, when the above-described phenomenon occurs and the rotation stop position of the rotary table 1 fluctuates, as shown in FIGS. 3 (c) and 3 (d), the guide posts 5 of the table side dies 3a and 3b Comes into contact with the guide bush 6 of the platen side mold, and the guide post 5 and the guide bush 6 are worn.

If the guide post 5 or the guide bush 6 is worn, the final positioning work between the table-side dies 3a and 3b and the platen-side dies will not be performed accurately, and the dies due to the interference between the cavities and the core will not work. Problems such as damage and deviation of the product shape at the parting line occur.

Further, even if the fluctuation of the rotation stop position of the rotary table 1 due to a change in grease viscosity or the like can be eliminated, the backlash itself in the gear train of the table drive mechanism cannot be eliminated.

Therefore, even when the drive source such as the servomotor is stopped, the rotary table 1 itself can rotate with inertia by the backlash, and the platen side mold and the table side mold 3a or the table side mold 3a can rotate. At the stage of adjusting the stop position of the rotary table 1 to be fitted with the mold 3b, there is a possibility that the setting of the stop position is biased.

Since the deviation of the setting of the stop position leads to problems such as damage to the mold and deviation of the product shape at the parting line, in order to minimize the adverse effect of the backlash of the table drive mechanism itself, it is necessary to perform the following steps. It is necessary to sort the potential backlash amount of the table drive mechanism in a safe direction and set the stop position of the table drive mechanism at the most appropriate position.

[0015]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an injection molding method capable of accurately setting a stop reference position as a reference for stopping a table driving mechanism at the most appropriate position in consideration of the influence of backlash. It is an object of the present invention to provide a method and a device for setting a reference position for stopping a table driving mechanism of a machine.

[0016]

SUMMARY OF THE INVENTION The present invention comprises a platen for mounting a platen-side mold, and a table for mounting a plurality of table-side dies each fitted with the platen-side mold. Reciprocating or forward / reverse rotation of each of the plurality of table-side dies to position each of the plurality of table-side dies at a corresponding position on the platen-side dies, thereby performing an injection molding operation. A guide hole provided on one side of the side mold and the table side mold and a guide post provided on the other side corresponding to the hole are fitted to form a platen side mold and a table side mold. While the table is displaced in the normal and reverse directions, the drive current or load of the motor in the table drive mechanism is monitored, and the absolute value of the drive current or load decreases. It achieved the above objects by the location and the stop reference position of the table drive mechanism.

The platen-side mold and the table-side mold are fitted with a guide hole provided on one side and a guide post provided on the other side, and the platen-side mold and the table-side mold are fitted. When the table is disengaged from the table, the table is moved forward and backward to determine the table stop position during forward movement and the table stop position during reverse movement. A similar task was achieved by setting the position.

Further, in an injection molding machine, the rotary table is moved in one direction to position each of the plurality of table-side dies at a corresponding position of the platen-side dies to perform an injection molding operation. Before starting the injection molding operation,
The platen-side mold and the guide hole provided on one side of the table-side mold and the guide post provided on the other side are fitted to fit the platen-side mold and the table-side mold. In the released state, the table is moved in the direction opposite to the one direction to stop the table, and then the table drive mechanism is driven in the direction to move the table in the one direction from that position, and the motor in the table drive mechanism is moved. The above object is achieved by monitoring the drive current or load of the table drive and determining and setting the stop reference position of the table drive mechanism based on the position where the absolute value of the drive current or load becomes large.

The platen-side mold and the table-side mold are fitted with a guide hole provided on one side of the table-side mold and a guide post provided on the other side, and the platen-side mold and the table-side mold are fitted. After the table is moved in the direction opposite to the one direction and the table is stopped in a state where the table is disengaged, the output torque of the motor of the table drive mechanism is limited to such an extent that the table cannot be moved from that position. A similar problem is achieved by driving the table drive mechanism in a direction to move the table in the one direction, and determining and setting a stop reference position of the table drive mechanism based on the position where the table drive mechanism stops.

Further, in an injection molding machine, the table is reciprocated or rotated forward and backward to position each of the plurality of table-side dies at a corresponding position on the platen-side dies to perform an injection molding operation. Before the start of the injection molding operation, the guide holes provided on one side of the platen side mold and the table side mold and the guide posts provided on the other side corresponding to the holes are fitted. With the platen side mold and table side mold disengaged from each other, move the table in the reverse direction to stop the table, and then move the table drive mechanism in the direction to move the table in the forward direction from that position. Driving monitors the drive current or load of the motor in the table drive mechanism, and based on the position where the absolute value of the drive current or load increases, stops the table drive mechanism during forward movement. After determining and setting the reference position, moving the table in the forward direction to stop the table, and then driving the table drive mechanism in the direction to move the table in the reverse direction from that position, driving the motor in the table drive mechanism Monitor the current or load, determine and set the stop reference position of the table drive mechanism at the time of the reverse movement based on the position where the absolute value of the drive current or the load becomes large, and at the time of forward movement or at the time of forward rotation The stop reference position of the table drive mechanism at the time of backward movement or reverse rotation may be individually set.

A guide hole provided on one side of the platen-side mold and the table-side mold and a guide post provided on the other side corresponding to the hole are fitted to each other. After the table is stopped by moving the table in the opposite direction with the mold and the table side mold released, the output torque of the motor of the table drive mechanism is limited so that the table cannot be moved from that position The table drive mechanism is driven in a direction to move the table in the forward direction, and based on the position where the table drive mechanism stops, the stop reference position of the table drive mechanism at the time of the forward movement is determined and set. After the table is stopped by moving the table in the direction, the output torque of the motor of the table drive mechanism is limited so that the table cannot be moved from that position, and the table is moved in the reverse direction. The table drive mechanism is driven in the direction in which the table drive mechanism is stopped, and the stop reference position of the table drive mechanism when moving in the reverse direction is determined and set based on the position where the table drive mechanism is stopped, so that the table drive mechanism moves back and forth during forward or forward rotation. The stop reference position of the table drive mechanism at the time of or during reverse rotation can also be set individually.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an essential part of a rotary injection molding machine according to an embodiment to which a table origin position setting method of the present invention is applied and a control device thereof.

The control device 10 includes a CPU 25 for CNC as a microprocessor for numerical control, a CPU 18 for PMC as a microprocessor for a programmable machine controller, a servo CPU 20 as a microprocessor for servo control, and an A / D converter. A pressure monitor CPU 17 for detecting the injection pressure and the screw back pressure from the pressure detector on the side of the injection molding machine via the device 16 and performing a sampling process;
Information can be transmitted between the microprocessors by selecting mutual input and output via the two.

The PMC CPU 18 has a ROM 13 storing a sequence program for controlling the sequence operation of the injection molding machine.
A RAM 14 used for temporary storage of operation data and the like is connected.A ROM 27 storing a program for controlling the entire injection molding machine and a RAM 28 used for temporary storage of operation data and the like are connected to the CPU 25 for CNC. I have.

Also, a servo CPU 20 and a pressure monitoring CPU
Each of 17 has a ROM 21 storing a control program dedicated to servo control and a RAM 19 used for temporary storage of data, and a ROM 11 storing a control program relating to injection pressure sampling processing and the like, and an R 21 used for temporary storage of data.
AM12 is connected.

Further, the servo CPU 20 is connected to a servo amplifier for driving a servo motor of each axis for table rotation, clamping, injection, screw rotation, ejector, etc. based on a command from the CPU 20. The output from the position / speed detector attached to the servo motor of each axis is
Returned to 0. The current position of each axis is calculated by the servo CPU 20 based on the feedback pulse from the position / speed detector, and is updated and stored in the current position storage register of each axis.

FIG. 1 shows only the servo amplifier 15 for rotating the table, the servomotor M and the position / speed detector P, but all the other axes have the same configuration. However, it is not necessary to detect the current position for the screw rotation type, but only the speed.

The interface 23 is an input / output interface for connecting to a host computer or the like.

The manual data input device 29 with display is CR
It is connected to the bus 22 via the T display circuit 26, so that it is possible to select a graph display screen and function menus, perform various data input operations, etc., and provide numeric keys for numeric data input and various function keys. Have been.

The nonvolatile memory 24 is a memory for storing molding data for storing molding conditions, various set values, parameters, macro variables, and the like relating to the injection molding operation.

With the above configuration, the PMC CPU 18 controls the sequence operation of the entire injection molding machine, and the CNC CPU 25
The movement command is distributed to the servo motors of each axis based on the operation program of the controller and the molding conditions of the non-volatile memory 24, and the servo CPU 20 uses the movement commands distributed to each axis and the position / speed detector. Based on the detected position and speed feedback signals, as shown in FIG. 2, servo control such as conventional position loop control, speed loop control, and current loop control is performed, and so-called digital servo processing is performed. Then, the servo motors of each axis are drive-controlled.

The observer 30 shown in FIG. 2 loads the servo motor M for rotating the table for each speed loop cycle based on the torque command (current command) obtained in the speed loop process and the actual speed feedback signal. This is for estimating the torque. Since the observer 30 is conventionally known and used, a detailed description thereof will be omitted.

The peripheral structure of the rotary table 1 in the main body of the rotary injection molding machine is the same as that of the conventional example shown in FIG.

Next, the principle of setting the reference position for stopping the table driving mechanism will be described with reference to FIG.

FIG. 4 shows the relationship between the backlash between the servomotor M serving as the drive source of the table drive mechanism and the rotary table 1 and the guide post 5 of the table side mold 3a.
FIG. 4 is a conceptual diagram showing a simplified relationship between the contact and the guide bush 6 of the platen side mold.

In FIG. 4, the operations of the servo motor M, the table driving mechanism, and the rotary table 1 are simplified by replacing them with linear motions. Block A is the output shaft of the servo motor M, and block B is the rotary table 1. And lower die 3a and guide post 5, block C are upper die and guide bush
Equivalent to 6.

The backlash between the rotary table 1 and the servo motor M, that is, the total backlash in the table driving mechanism is collectively indicated by a, and the play between the guide post 5 and the guide bush 6 is also shown. Indicated by b. Needless to say, guide post 5 and guide bush 6
Between the rotary table 1 and the servo motor M
It is much smaller than the backlash between a. The guide post 5 and the guide bush 6 have almost no play in order to accurately position the platen-side mold and the table-side mold, for example, the accuracy of Saddle-eye is guaranteed with an accuracy of 1/100 millimeter order. Because there is.

Further, the table side mold 3a has four guide posts 5, and the platen side mold also has four guide bushes 6, each of which has an unavoidable mounting position error due to processing. There is. Therefore, in a state where the four guide posts 5 are actually inserted into the four guide bushes 6, the position of the table-side mold 3a is restrained with respect to the platen-side mold beyond the above-mentioned hammer-eye accuracy. .
The play b between the guide post 5 and the guide bush 6 shown in FIG. 4 is substantially the play of the table side mold 3a with respect to the platen side mold, and its value is extremely small.

On the other hand, since a power transmission mechanism composed of a plurality of members such as a gear train is interposed in the table drive mechanism, the total sum a of mechanical backlash in the table drive mechanism is necessarily the aforementioned play. greater than b.

In FIG. 4A, the servo motor M shown in FIG.
FIG. 3C shows a state in which the rotary table 1 is rotated to the limit in the counterclockwise direction with the drive source, that is, a state corresponding to FIG. 3C. In this state, the state between the servo motor M and the rotary table 1 is shown. The backlash, that is, the backlash a in the table drive mechanism is all distributed counterclockwise with respect to the rotary table 1, that is, to the left in FIG. 4 (a). Further, the play b between the guide post 5 and the guide bush 6 is all distributed clockwise with respect to the guide post 5, that is, to the right in FIG. 4 (a).

In this state, even if the servo motor M is driven in a direction in which the rotary table 1 is rotated clockwise, since the backlash a exists in the table driving mechanism, little resistance acts on the servo motor M. The load on the servo motor M is very light. This is the servo motor M shown in FIG.
Corresponds to the section from the rotational position X to Y.

When the servo motor M is further driven, the backlash a in the table driving mechanism is eliminated. As a result, as shown in FIG.
Drive force directly rotates the large-mass rotary table 1 via the table drive mechanism, and the servo motor M
The load on the device increases rapidly. This is the portion of the rotational position YY of the servo motor M shown in FIG.

Then, the rotary table 1 rotates clockwise so that the guide post 5 hits the inner wall on the opposite side of the guide bush 6 as shown in FIG. When the play b is all distributed counterclockwise with respect to the guide post 5, that is, completely to the left in FIG. 4C, the movements of the servo motor M, the table driving mechanism, and the rotary table 1 are forcibly stopped. . This is the position of the rotation position Z of the servo motor M shown in FIG.
This corresponds to the state shown in FIG.

Then, when the servo motor M is driven again in a direction for rotating the rotary table 1 in the counterclockwise direction from this state, a phenomenon completely opposite to the above occurs. First, the clockwise direction with respect to the rotary table 1, that is, Until the backlash a in the table drive mechanism allocated to the right side in FIG. 4C is eliminated, the load on the servo motor M is very light as shown in sections X ′ to Y ′ in FIG. Become.

Then, when the backlash a is eliminated and the driving force of the servo motor M is directly transmitted to the rotary table 1, that is, at the position of Y'-Y 'in FIG. The load on the device increases rapidly.

Finally, the rotary table 1 rotates counterclockwise so that the guide post 5 hits the inner wall of the guide bush 6 as shown in FIG. The movement of the servo motor M, the table drive mechanism, and the rotary table 1 is forcibly stopped when the play b is all clockwise with respect to the guide post 5, that is, when the play b is completely allocated to the right side in FIG. Will be. This is the position of the rotation position Z 'of the servo motor M shown in FIG. 5, and corresponds to the state of FIG. 3 (c).

First, consider the case where the table driving mechanism is driven to move the rotary table 1 clockwise, that is, rightward from the state of FIG.

In this case, in order to prevent interference between the left end of the guide post 5 and the inner wall of the guide bush 6, the servo motor M is rotated from the state shown in FIG. 4A to the state shown in FIG. It is enough.

Needless to say, this condition is a sufficient condition for preventing interference between the left end of the guide post 5 and the inner wall of the guide bush 6, and is not a necessary condition.

That is, actually, the servo motor M is
Even if the rotary table 1 is stopped in front without rotating to the state of (b), there is a possibility that the rotary table 1 is positioned at an appropriate position by the inertial movement of the rotary table 1, but the inertial movement amount of the rotary table 1 itself is It is not obvious. Therefore, finally, the appropriate stop position of the servo motor M is at least before the state of FIG.
It can be said that it is just before the position of YY in FIG.

The section before the position of Y in FIG. 5 during the clockwise rotation is, in short, the section from X to Y in FIG.

Next, a case is considered in which the table driving mechanism is driven to move the rotary table 1 counterclockwise, that is, to the left from the state of FIG.

In this case, in order to prevent interference between the right end of the guide post 5 and the inner wall of the guide bush 6, it is sufficient to rotate the servo motor M from the position Z in FIG. 5 to the position Y'-Y '. It is. As before, this is a sufficient condition, not a requirement.

As described above, the servo motor M is connected to the Y'-
Even if the rotary table 1 is stopped without rotating to the position of Y ', there is a possibility that the rotary table 1 is positioned at an appropriate position by the inertial movement of the rotary table 1, but the inertial movement amount of the rotary table 1 itself is Finally, it can be said that the appropriate stop position of the servomotor M is at least before the position of Y′-Y ′ in FIG.

During rotation in the counterclockwise direction, Y'-Y 'in FIG.
In short, the section before the position of
It is a section from X 'to Y'.

Accordingly, an injection molding machine or a shuttle table which reciprocates by rotating the rotary table 1 clockwise and counterclockwise to position the table-side molds 3a and 3b relative to the platen-side mold. In the case of the injection molding machine using the above, in the case of performing one table drive mechanism in the forward and reverse rotation directions, that is, in the case where the drive control of the rotary table 1 is performed by setting the stop reference position of the servo motor M, the above described Two conditions, namely, setting the stop reference position of the servo motor M to the section from X to Y in FIG. 5, and setting the stop reference position of the servo motor M to X ′ in FIG.
It is necessary at the same time to set the section from to.

The overlapping section satisfying these two conditions is shown in FIG.
In short, the position where the load on the servo motor M is low both when the motor rotates forward and when the motor rotates in the reverse direction (the position where the absolute value of the load decreases) is the reference for stopping the servo motor M. It is only necessary to set the position. And when operating the injection molding machine continuously,
The correction amount α is determined in consideration of the rotational speed of the rotary table 1 and the amount of movement due to the inertia of the rotary table 1 according to the speed pattern and the like, and the servo motor M is controlled at the position α before the set stop reference position. When stopped, the rotary table 1 moves to some extent by inertia from the position where the servomotor M (table driving mechanism) stops, and the guide post 5 and the guide rod 6 stop at the corresponding positions.

In the case of the present embodiment, the observer 30 shown in FIG.
By sequentially reading the estimated load obtained at every predetermined cycle, and displaying the estimated load on the screen of the manual data input device 29 with a display in association with the current position of the servo motor M, a graph display similar to that of FIG. 5 can be obtained. Figure 2
5 by sequentially reading the current command value output from the speed loop at predetermined intervals and displaying it on the screen of the manual data input device 29 with a display corresponding to the current position of the servo motor M. You can get the display.

Therefore, the operator refers to these graphs and visually observes a section from Y ′ to Y in FIG. 5, that is, a section where the load of the servo motor M is reduced both in the forward rotation and in the reverse rotation. Check and set an appropriate position in that section as the stop reference position of the servo motor M.
It may be set to 0.

Of course, a manual data input device with a display
It is also possible to display a graph using an oscillograph or the like instead of 29.In the case of an injection molding machine that does not have appropriate display means, perform the same work using an oscillograph or the like. Can be.

Further, the position most suitable as the reference position for stopping the servomotor M is the center of the section from Y 'to Y in FIG. 5, that is, the positional relationship between the upper die C and the servomotor M.
This is the position of the servo motor M when the relationship shown in FIG.

Accordingly, in the case of the control device 10 which can accurately grasp the relationship between the change in the load or drive current of the servomotor M and the current position by the manual data input device 29 with a display as in this embodiment, After confirming the position of the servo motor M corresponding to Y 'and the position of the servo motor M corresponding to Y, further add both values and divide by 2 to obtain the stop reference position of the servo motor M. The optimum position (Y '+ Y) / 2 can be easily obtained.

Further, a graph XYYZ showing a change in drive current and load when moving in the clockwise direction and a graph X'- showing a change in drive current and load when moving in the counterclockwise direction.
Since Y'-Y'-Z 'has a perfect mirror image relationship, as a result, the value of (Y' + Y) / 2 is equal to the value of (Z '+ Z) / 2.

Therefore, instead of obtaining (Y ′ + Y) / 2, the table stop position Z when the rotary table 1 is moved clockwise and the table stop when the rotary table 1 is moved counterclockwise By calculating the position Z 'on the display and implementing the equation of (Z' + Z) / 2, the optimum position (Z '+ Z) / 2 = (Y ′ + Y) / 2 can be easily obtained.

At the table stop positions Z and Z ', there is a clear criterion that the rotation of the servomotor M is mechanically stopped by the interference between the guide post 5 and the guide bush 6, so that the proper stop reference position It is extremely easy to detect the position required for the calculation for obtaining the position.

Therefore, the method of obtaining the stop reference position using the arithmetic expression of (Z '+ Z) / 2 is performed when the reduction ratio of the table drive mechanism is large, that is, when the servomotor is operated by the resistance.
It is also suitable when it is difficult to detect the change points Y and Y 'of the load and the drive current because the change of the load and the drive current of M is small. Also, when there are many gears in the table drive mechanism and the backlash between the gears is eliminated in order, the load and drive current of the servo motor M change stepwise, that is, unlike FIG. And the rise of YY and Y'-
It is also suitable for a case where it is difficult to identify the positions of the changing points Y and Y 'of the load and the drive current because the rise of Y' is stepwise. Further, the present invention is also very suitable in a case where the operation for obtaining the stop reference position is completely automated by the processing on the control device 10 side.

The correction of the stop reference position by the automatic processing using the control device 10 will be described later in detail.

On the other hand, in an injection molding machine in which the rotary table 1 is rotated only in one of the clockwise and counterclockwise directions to position the table-side dies 3a and 3b with respect to the platen-side dies, It is not necessary to consider the situation when 1 is rotated in the opposite direction.

Therefore, for example, in the case of an injection molding machine in which the rotary table 1 is rotated only clockwise to position the table-side molds 3a and 3b with respect to the platen-side mold, the rotary table 1 is rotated counterclockwise. After moving and stopping in the state as shown in FIG. 4 (a), the servo motor M is driven in a direction to rotate the rotary table 1 clockwise from that position, and manual data input with a display is performed in the same manner as described above. Monitor the change in the load or drive current of the servo motor M with the device 29 or an oscillograph, etc., and observe the initial position where the load or drive current suddenly increases, that is, FIG.
The position of YY in FIG. 5 corresponding to the state of FIG. 5 is obtained and set as a stop reference position, the value thereof, and a rotary table for continuous operation.
The target stop position of the servo motor M may be determined and set in consideration of the amount of movement due to the inertia of the rotary table 1 according to the rotation speed of the rotary table 1 or its speed pattern.

After the rotary table 1 is moved counterclockwise and stopped in the state shown in FIG. 4 (a), the rotary table 1 cannot be rotated clockwise from the position shown in FIG. 4 (a). In addition, if the output torque of the servo motor M is limited to such an extent that backlash in the table drive mechanism can be eliminated and the servo motor M is driven in a direction in which the rotary table 1 is rotated clockwise, the servo motor M
Since the motor stops automatically at the position 4 (b), that is, the position YY in FIG. 5, this position is set as a stop reference position, and further, the target stop position of the servo motor M is considered in consideration of the value and the inertia of the rotary table 1. Can be determined and set.

Incidentally, even in the case of an injection molding machine in which the rotary table 1 is rotated forward and reverse to position the table-side molds 3a and 3b with respect to the platen-side mold, the servos for the normal rotation and the reverse rotation are used. When individually determining and setting the stop reference position of the motor M, similarly to the case of an injection molding machine that performs the positioning operation by rotating the rotary table 1 only in one of the clockwise direction and the counterclockwise direction. When rotating the rotary table 1 in one of the directions, it is not necessary to consider another rotation direction.

Accordingly, after the rotary table 1 is moved counterclockwise and stopped in the state as shown in FIG. 4A, the servo motor M is driven in a direction for rotating the rotary table 1 clockwise from that position. Monitor the change in the load or drive current of the servo motor M, and set the first position where the load or drive current suddenly increases as the stop reference position for clockwise rotation, and conversely, the rotary table
After moving 1 in the clockwise direction and stopping it, the servomotor M is driven from that position in a direction to rotate the rotary table 1 in a counterclockwise direction, and the servomotor M is driven by the manual data input device 29 with a display or an oscillograph. The change of the load or the drive current may be monitored, and the first position where the load or the drive current suddenly increases may be set as the stop reference position in the counterclockwise rotation.

FIGS. 6 and 7 show the outline of the stop reference position determination processing for automatically obtaining the stop reference position of the table drive mechanism using the above-mentioned equation (Z '+ Z) / 2. It is a flowchart. It is assumed that the rough positioning operation of the table-side mold 3a with respect to the platen-side mold has already been completed before starting this processing.

PMC CPU that has started the stop reference position determination processing
First, in a state in which the mold is completely opened, that is, in a state in which the guide post 5 is completely retracted from the guide bush 6, the rotary table 1 is rotated 180 ° forward and reverse by a predetermined number of times M times. Is repeated to stabilize the viscosity of grease and the like applied to the table drive mechanism and the rotary table 1 to allow each part of the machine to fully adapt, and then place the rotary table 1 in the initial position, that is, the stage before starting this processing. (Step S1 to Step S6).

At this stage, the state of grease applied to the table drive mechanism and the rotary sliding portion of the rotary table 1 is the same as that in the continuous operation, and is stable.

However, since the positioning operation of the rotary table 1 and the table-side dies 3a and 3b performed at this stage is a rough operation, the positioning operation is performed as shown in FIGS. 3 (c) and 3 (d). Furthermore, there is a high possibility that only a degree of accuracy that barely maintains the fitting between the guide bush 6 and the guide post 5 in a state where the bias is generated between the guide bush 6 and the guide post 5 is high.

Therefore, the PMC CPU 18 further performs a process for obtaining a stop reference position of the table driving mechanism.

First, the PMC CPU 18
Or the platen 4 is lowered, and the guide post 5 and the guide bush 6 are fitted together in a state where the parting surface between the platen-side mold and the table-side mold 3a is not brought into close contact (step S7).

Next, the PMC CPU 18 rotates the rotary table 1 in the counterclockwise direction with the driving torque of the table rotation servomotor M limited so as not to damage each part of the mechanism (step S8, step S8). S9).

However, the processing of steps S8 and S9 is a preparatory operation until it gets tired. At this stage, the current position of the servo motor M corresponding to the stop position of the rotary table 1 is not read. This is because the table stop position at this stage may be different from the value of the table stop position Z 'in the counterclockwise direction in FIG.

For example, it is assumed that the position of the guide post 5 is shifted counterclockwise with respect to the guide bush 6 at the time when the first rough positioning operation is performed. Guide post 5
The end of the guide bush 6 and the opening of the guide bush 6 are chamfered.
It is possible to force the guide post 5 into the guide bush 6 by the half mold clamping operation in.

Therefore, the guide post 5 and the guide bush 6
At this stage, the positional relationship between the two is apparently as shown in FIG. 4 (a).

However, in such a situation, that is, in a situation where the guide post 5 is forced into the guide bush 6 with the position of the guide post 5 shifted counterclockwise with respect to the guide bush 6, A strong pressing force acts between the guide post 5 and the guide bush 6, and a strong stress also acts on the gear train in the table driving mechanism.

Under such circumstances, even if the driving torque of the table rotation servomotor M is limited to allow the table drive mechanism and the servomotor M to substantially rotate in the reverse direction,
At that time, there is no guarantee that the rotary table 1 can be returned to a desired position by removing the pressing force acting between the guide post 5 and the guide bush 6 and the stress generated in the table driving mechanism. This is because the inertial mass of the rotary table 1 is large and the table drive mechanism has a certain amount of frictional resistance.

Therefore, if the value of the table stop position in the counterclockwise direction at this time is read, it means that the value is on the left side of the original table stop position Z 'as shown in FIG. Is an inappropriate value for the table stop position Z '.

Needless to say, the possibility that the guide post 5 is properly positioned with respect to the guide bush 6 at the stage when the first rough positioning work is performed, or that the guide post 5 is There is a possibility that the positioning is shifted, in such a case, the table stop position may be read at this stage and set as the value of Z ', but the first rough positioning work was performed It is not obvious what the positional relationship between the guide post 5 and the guide bush 6 is at the stage.

Therefore, in consideration of the case where the position of the guide post 5 is displaced in the counterclockwise direction with respect to the guide bush 6, this preliminary operation should always be executed.

Next, the PMC CPU 18 rotates the rotary table 1 clockwise until it stops, in the same manner as described above, with the drive torque of the table rotation servomotor M limited so as not to damage each part of the mechanism. (Step S10, Step S11), read the current position of the table rotation servomotor M corresponding to the stop position of the rotary table 1,
The value is stored in the stop position storage register A (step
S12).

The current position of the servo motor M at this time is shown in FIG.
Is equivalent to the rotation angle Z.

The determination as to whether or not the rotary table 1 has stopped is made in steps S9 and S11 and in step S14 to be described later.
By determining whether or not the value of the position deviation accumulated in the position loop has exceeded the set value, or by determining whether or not the value of the speed feedback in the speed loop has become equal to or less than the set value. Do.

Next, the PMC CPU 18 rotates the rotary table 1 in the counterclockwise direction with the drive torque of the table rotation servomotor M limited to such a degree that the components of the mechanism are not damaged in the same manner as described above. (Step S13,
In step S14, the current position of the table rotation servomotor M corresponding to the stop position of the rotary table 1 is read, and the value is stored in the stop position storage register B (step S15).

The current position of the servo motor M at this time is shown in FIG.
Of the rotation angle Z ′.

Then, based on the values of the table stop positions Z and Z ′ stored in the stop position storage register A and the stop position storage register B, the PMC CPU 18 described above (Z ′ +
The value of the stop reference position O 'of the table drive mechanism is obtained by executing the equation (Z) / 2 (step S16). In this embodiment, the stop reference position O 'is set as the origin of the table driving mechanism.

Then, according to the rotational speed of the rotary table 1 and its speed pattern when the injection molding machine is continuously operated, the amount of movement of the rotary table 1 due to inertia in the backlash of the table driving mechanism is taken into consideration. The correction amount α may be set, the table drive mechanism (servo motor M) may be stopped and positioned at a position α before the stop reference position. For example, as shown in FIG.
Is rotated 180 ° in the forward and reverse directions, the position before the origin O ′ obtained as the stop reference position by the correction amount α is set as the stop target position, and the rotary table 1 is rotated 180 ° from the origin O ′. The position before the set position by the correction amount α may be set as the stop target position. Note that the correction amount α may be different depending on the rotation direction.

[0095]

According to the present invention, the stop reference position of the table driving mechanism can be easily set to the most appropriate position in consideration of the influence of backlash in the table driving mechanism. Furthermore, the mold clamping operation can be performed stably without causing a displacement between the platen side mold and the table side mold, and the mold is damaged due to the interference between the cavity and the core, and the parting line is damaged. It is possible to prevent molding problems such as deviation of the product shape.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a rotary injection molding machine and a control device thereof according to an embodiment to which a position shift removing method of the present invention is applied.

FIG. 2 is a functional block diagram schematically showing position loop control, speed loop control, and current loop control by a servo CPU.

FIG. 3 is a plan view showing a main part of a rotary injection molding machine and problems of the related art.

FIG. 4 is a conceptual diagram showing a working principle for obtaining a stop reference position of a table driving mechanism.

FIG. 5 is a simplified graph showing the relationship between the rotation position of a table rotation servomotor, load, and drive torque.

FIG. 6 is a flowchart illustrating a process of automatically determining a stop reference position of the table driving mechanism.

FIG. 7 is a continuation of the flowchart showing the stop reference position automatic determination process.

[Explanation of symbols]

 Reference Signs List 1 rotary table 2 tie bar 3a table side mold 3b table side mold 4 platen 5 guide post 6 guide bush 10 controller 11 ROM 12 RAM 13 ROM 14 RAM 15 servo amplifier 16 A / D converter 17 CPU for pressure monitor 18 PMC CPU 19 RAM 20 Servo CPU 21 ROM 22 Bus 23 Interface 24 Non-volatile memory 25 CPU for CNC 26 CRT display circuit 27 ROM 28 RAM 29 Manual data input device with display 30 Observer M Servo motor P Position / speed detector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F206 AM19 AR074 JA07 JC02 JL02 JM05 JP13 JP14 JP17 JQ81 JQ88 JT04 JT11 JT32

Claims (7)

[Claims] A platen on which a platen-side mold is mounted; and a table on which a plurality of table-side molds respectively fitted to the platen-side mold are mounted. In an injection molding machine including a table configured to perform an injection molding operation by positioning each of the plurality of table-side dies at a corresponding position on the platen-side die, the platen-side die and the table-side die may be In a state where the guide hole provided on one side and the guide post provided on the other side corresponding to the hole are fitted and the fitting between the platen side mold and the table side mold is released,
While the table is moved in the forward and reverse directions, the drive current or load of the motor in the table drive mechanism is monitored, and the position where the absolute value of the drive current or load becomes smaller is set as the stop reference position of the table drive mechanism. A method for setting a reference stop position of a table driving mechanism of an injection molding machine. 2. A reciprocating or forward / reverse rotation of the table, comprising a platen on which a platen-side mold is mounted and a table on which a plurality of table-side molds respectively fitted with the platen-side mold are mounted. In an injection molding machine including a table configured to perform an injection molding operation by positioning each of the plurality of table-side dies at a corresponding position on the platen-side die, the platen-side die and the table-side die may be In a state where the guide hole provided on one side and the guide post provided on the other side corresponding to the hole are fitted and the fitting between the platen side mold and the table side mold is released,
The table is moved forward and backward to determine a table stop position at the time of forward movement and a table stop position at the time of reverse movement, and an average position of both is obtained as a stop reference position of the table driving mechanism. To set the reference position for stopping the table drive mechanism of the injection molding machine. 3. A platen for attaching a platen-side mold, and a table for attaching a plurality of table-side molds respectively fitted to the platen-side mold, wherein the mold is attached to the platen and the table. An injection molding machine provided with a table that reciprocates or reciprocates or rotates the table to position each of the plurality of table-side molds at corresponding positions on the platen-side mold to perform an injection molding operation. A guide hole provided on one side of the platen-side mold and the table-side mold and a guide post provided on the other side corresponding to the hole are fitted to each other so that the platen-side mold and the table-side mold are fitted. Means for relatively positioning the platen and the table in a state in which the fitting with the mold has been released, and after positioning by the positioning means, the table is moved in reverse and forward to A table drive of an injection molding machine, comprising: means for obtaining a table stop position and a table stop position at the time of reverse movement; and means for obtaining an average position of the two and setting the average position as a stop reference position of a table drive mechanism. Stop reference position setting device for the mechanism. 4. A platen having a platen-side mold attached thereto, and a rotary table having a plurality of table-side molds respectively fitted with the platen-side mold, wherein the table is moved in one direction to move the table in one direction. In an injection molding machine having a table in which each of a plurality of table-side dies is positioned at a corresponding position of a platen-side die to perform an injection molding operation, before starting the injection molding operation, the platen-side die And a guide hole provided on one side of the table side mold and a guide post provided on the other side corresponding to the hole to fit the platen side mold and the table side mold. After the table is moved, the table is moved in the direction opposite to the one direction to stop the table, and then the table drive mechanism is driven from the position to move the table in the one direction to drive the table. Injection molding, wherein the drive current or load of the motor in the moving mechanism is monitored, and the stop reference position of the table drive mechanism is determined and set based on the position where the absolute value of the drive current or load increases. To set the stop reference position of the table drive mechanism of the machine. 5. A platen to which a platen-side mold is attached, and a rotary table to which a plurality of table-side molds respectively fitted with the platen-side mold are attached, and the table is moved in one direction to move the table in one direction. In an injection molding machine having a table in which each of a plurality of table-side dies is positioned at a corresponding position of a platen-side die to perform an injection molding operation, before starting the injection molding operation, the platen-side die And a guide hole provided on one side of the table side mold and a guide post provided on the other side corresponding to the hole to fit the platen side mold and the table side mold. After the table is moved in the direction opposite to the one direction and the table is stopped, the output torque of the motor of the table drive mechanism is limited so that the table cannot be moved. A table for an injection molding machine, wherein the table drive mechanism is driven in the direction in which the table drive mechanism is moved in one direction, and a stop reference position of the table drive mechanism is determined and set based on a position where the table drive mechanism stops. How to set the drive reference stop position. 6. A platen on which a platen-side mold is mounted, and a table on which a plurality of table-side molds respectively fitted with the platen-side mold are mounted, and the table is reciprocated or rotated forward and reverse. In an injection molding machine having a table in which each of the plurality of table-side molds is positioned at a corresponding position of the platen-side mold to perform an injection molding operation, before starting the injection molding operation, The guide hole provided on one side of the mold and the table side mold and the guide post provided on the other side corresponding to the hole are fitted to fit the platen side mold and the table side mold. After the table is moved in the reverse direction, the table is stopped by moving the table in the reverse direction, and then the table drive mechanism is driven in the direction in which the table is moved in the forward direction from that position. The drive current or load of the motor is monitored, and based on the position where the absolute value of the drive current or load increases, the stop reference position of the table drive mechanism at the time of forward movement is determined and set, and the table is moved in the forward direction. After moving and stopping the table, the table drive mechanism is driven in a direction to move the table in the reverse direction from that position, and the drive current or load of the motor in the table drive mechanism is monitored, and the absolute value of the drive current or load is monitored. A stop reference position setting method for a table driving mechanism of an injection molding machine, wherein a reference position for stopping the table driving mechanism when moving in the reverse direction is determined and set based on a position where the value increases. 7. A platen on which a platen-side mold is mounted, and a table on which a plurality of table-side molds respectively fitted to the platen-side mold are mounted. In an injection molding machine having a table in which each of the plurality of table-side molds is positioned at a corresponding position of the platen-side mold to perform an injection molding operation, before starting the injection molding operation, The guide hole provided on one side of the mold and the table side mold and the guide post provided on the other side corresponding to the hole are fitted to fit the platen side mold and the table side mold. When the table is moved in the opposite direction and the table is stopped, the output torque of the motor of the table drive mechanism is limited so that the table cannot be moved from that position. The table drive mechanism is driven in the direction to move the table in the forward direction, and based on the position where the table drive mechanism stops, the stop reference position of the table drive mechanism at the time of the forward movement is determined and set, and the table is moved in the forward direction. After stopping the table, the output torque of the motor of the table drive mechanism is limited so that the table cannot be moved from that position, and the table drive mechanism is driven in a direction to move the table in the reverse direction. A stop reference position setting method for a table driving mechanism of an injection molding machine, wherein a reference position for stopping the table driving mechanism when moving in the reverse direction is determined and set based on the stopped position.