JPH05138705A - Method and device for controlling motor-driven injection molding machine - Google Patents

Abstract

PURPOSE:To realize high maintenance, by a method wherein correct and high- precision control is realized and generation of damage of a movable mechanism part or a defective molded product is prevented. CONSTITUTION:A feedback control system drive-controlling a movable mechanism part 3, for example, a screw movement driving mechanism part 3p of an injection device 3s by a driving motor 2 is constituted. Especially, a position of a movalbe part 4 in the movagble mechanism part 3 is detected directly and a position and/or a speed of the movable part 4 is feedback-controlled so that a detected measured value (the first measured value) Dx becomes coincident with an instruction value Ds established beforehand. Then the position and/or the speed of the movable part 4 obtained by a rotation of the driving motor 2 and the obtained second measured value Dy and first measured value Dx are compared with each other, throgh which when a deflection between the first measured value Dx and second measured value Dy exceeds the established value, abnormality treatment is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and apparatus for an electric injection molding machine having a feedback control system for driving and controlling a movable mechanism portion such as a screw advancing / retreating drive mechanism portion in an injection device by a drive motor.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional controller 50 in an electric injection molding machine. In the figure, reference numeral 51 is an injection device. The injection device 51 has an injection nozzle 52n for injecting a molten resin at the tip, and a hopper 52 for supplying the material to the rear.
A heating cylinder 52 having h is provided, and a screw 53 is loaded inside the heating cylinder 52. Further, the rear end of the screw 53 is coupled to the screw advancing / retreating drive mechanism portion 54. The screw advancing / retreating drive mechanism portion 54 is provided with a ball screw mechanism 55 composed of a ball nut 55n coupled to the rear end of the screw 53 and a ball screw 55b loaded in the ball nut 55n, and a driven gear 56e provided at the rear end of the ball screw 55b and this. A transmission gear mechanism 56 including a drive gear 56d meshed with the driven gear 56e is provided, and the drive gear 56d is attached to the rotation shaft of the servo motor 57. On the other hand, 61 is an injection device 51.
Showing the control system of the detection processing unit 62, the comparison processing units 63, 6
4, a conversion control unit 65, 66, a drive circuit 67 of the servo motor 57, an encoder 68 for detecting the rotation of the servo motor 57 to configure a feedback control system, the detection processing unit 62 is a central control unit including a CPU and the like. 6
Connect to 9.

Thus, the injection device 51 functions as follows in the injection process, for example. First, the central control unit 6
From 9, the shift position of the screw 53 and the speed command value at each shift position are given to the detection processing unit 62. As a result, the drive circuit 67 operates the servo motor 57,
The screw 53 is moved forward via the transmission gear mechanism 56 and the ball screw mechanism 55. The position of the screw 53 is obtained by the encoder 68, and the measured value thereof is given to the detection processing unit 62 and converted into the speed by the conversion processing unit 65, and the converted measured value of the speed is given to the comparison processing unit 63. It On the other hand, since the speed command value is given to the comparison processing unit 63 from the detection processing unit 62, the speed command value and the actual measurement value are compared, and the deviation thereof is converted into the current command value by the conversion processing unit 66. , To the comparison processing unit 64.
Further, the comparison processing unit 64 is provided with the actual measurement value of the drive current flowing through the servo motor 57, the actual measurement value and the current command value are compared, and the deviation thereof is provided to the drive circuit 67. As a result, feedback control is performed so that the measured speed value matches the speed command value. The detection processing unit 62 monitors the position of the screw 53 obtained by the encoder 68, and when the shift position is reached, the speed command value in the next stage is given to the comparison processing unit 63.

On the other hand, 71 is a mold clamping device, which is a fixed mold 72.
The movable platen 7 that supports the fixed plate 73 that supports the movable mold 74
5, the movable platen 75 is coupled to the movable platen advance / retreat drive mechanism unit 76. The movable plate advancing / retreating drive mechanism unit 76 is configured similarly to the screw advancing / retreating drive mechanism unit 54, and 77 is a ball screw mechanism and 78 is a transmission gear mechanism. Further, 79 is a servo motor, and 81 is a control system of the mold clamping device 71. Mold clamping device 7
1 is basically configured and functions similarly to the injection device 51.

[0005]

However, the above-described conventional control device 50 has the following problems to be solved.

First, when performing position control and / or speed control of the movable part such as the screw 53, the position and / or speed of the movable part was obtained from the encoder attached to the servo motor, and therefore it is incorporated in the feedback control system. Ball screw mechanism 55 between the servo motor 57 and the movable part
And 77 and the transmission gear mechanisms 56 and 78, etc., and eventually, the position and / or the position of the movable portion is changed due to backlash of the movable mechanism portion, distortion due to temperature change, etc., and error due to aging due to wear. It is difficult to control speed accurately and accurately.

Secondly, since it is not possible to quantitatively detect the degree of wear due to aging and the occurrence of backlash due to troubles, it is impossible to prevent the failure of the movable mechanism portion or the occurrence of defective products. , High maintenance is not possible.

The present invention solves the problems existing in the prior art as described above, and realizes accurate and high-precision control, and prevents the failure of the movable mechanism and the generation of defective products. It is an object of the present invention to provide a control method and device of an electric injection molding machine that can realize high-level maintenance.

[0009]

A control method for an electric injection molding machine according to the present invention is configured so that a drive motor 2 drives a movable mechanism section 3,
For example, the screw advancing / retreating drive mechanism section 3p of the injection device 3s,
In the feedback control system for driving and controlling the movable plate advancing / retreating drive mechanism part 3q of the mold clamping device 3r, the screw rotation driving mechanism part of the injection device, the ejecting pin advancing / retreating drive mechanism part of the ejecting device, the advancing / retreating drive mechanism part of the nozzle moving device, Movable mechanism part 3
Directly detecting the position and / or speed of the movable part 4 at
The basic feature is that the position and / or speed of the movable part 4 is feedback-controlled so that the detected measured value (first measured value) Dx matches the preset command value Ds. In this case, as a control method according to another embodiment, the position and / or speed of the movable portion 4 is further obtained from the rotation of the drive motor 2 and the obtained second actual measurement value Dy and the first actual measurement value Dx are compared. If the deviation between the first actually measured value Dx and the second actually measured value Dy exceeds the set value, the abnormality processing can be performed.

Further, in the control device 1 for the electric injection molding machine according to the present invention, the position of the movable portion 4 in the movable mechanism portion 3 and / or
Alternatively, a detection function unit that directly detects the speed (first detection function unit)
10 and the actual measurement value obtained from the detection function unit 10 (first actual measurement value)
The basic feature is to include a control function unit 11 that feedback-controls the position and / or speed of the movable unit 4 so that Dx matches the preset command value Ds. In this case, further, the second detection function unit 13 that obtains the position and / or the speed of the movable unit 4 from the rotation of the drive motor 2, the second actual measurement value Dy obtained from the second detection function unit 13, and the first actual measurement value described above. An abnormality processing function unit 14 that compares Dx and performs abnormality processing when the deviation between the first actually measured value Dx and the second actually measured value Dy exceeds a set value can be provided.

[0011]

According to the control method and apparatus 1 of the electric injection molding machine according to the present invention, first, the movable part 4, for example, the injection device 3s.
The position and / or speed of the screw 4s that moves back and forth from the screw advancing / retreating drive mechanism section 3p is directly detected by the detection function section (first detection function section) 10. Then, the actual measurement value (first actual measurement value) Dx obtained from the detection function unit 10 is given to the control function unit 11. The control function unit 11 uses the first measured value Dx
And a preset command value Ds are compared to obtain the deviation. Therefore, this deviation is given to the drive circuit of the drive motor 2, for example, and feedback control is performed so that the first actual measurement value Dx matches the command value Ds. In this case, the feedback control system is the screw 4 that is the controlled object.
Since the first measured value Dx obtained by directly detecting the position and / or speed of s is used, an error due to backlash or secular change of the ball screw mechanism or the transmission gear mechanism existing between the drive motor 2 and the screw 4s. The control is performed to eliminate the.

Further, the position and / or speed of the screw 4s indirectly obtained by the rotation of the drive motor 2 is obtained from the second detection function unit 13. The actual measurement value obtained from this becomes the second actual measurement value Dy, and the abnormality processing function unit 14 compares the first actual measurement value Dx and the second actual measurement value Dy to obtain the deviation thereof, and the deviation exceeds the preset value. Troubleshoot abnormalities such as issuing an alarm. In this case, if the deviation is equal to or less than the set value, the error existing in the movable mechanism portion such as the ball screw mechanism between the drive motor 2 and the screw 4s is small, but on the other hand,
If the deviation exceeds the set value, it means that the error of the movable mechanism unit has increased. Therefore, it is possible to monitor the quantitative increase state of errors that occur due to aging and troubles,
In addition, if the set value exceeds the abnormal value, abnormal processing, for example, by issuing an alarm, it is possible to replace parts and prevent the occurrence of defective products due to such causes. It becomes possible to perform high-level maintenance.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the structure of a control device for an electric injection molding machine according to the present invention will be described with reference to FIG.

In the figure, M is an electric injection molding machine, and in particular, the injection device 3s and the mold clamping device 3r are extracted and shown in order to facilitate the description. The injection device 3s has a heating cylinder 21 having an injection nozzle 21n for injecting a molten resin at the tip and a hopper 21h for supplying a material to the rear, and the screw 4s constituting the movable part 4 is provided inside the heating cylinder 21. To load. Further, the rear end of the screw 4s is coupled to the screw advancing / retreating drive mechanism portion 3p which constitutes the movable mechanism portion 3. The screw advancing / retreating drive mechanism section 3p includes a ball screw mechanism 22 composed of a ball nut 22n coupled to the rear end of the screw 4s and a ball screw 22b loaded in the ball nut 22n, and a driven gear 23e provided at the rear end of the ball screw 22b and this. Drive gear 23 meshing with driven gear 23e
The drive gear 23d is attached to the rotary shaft of the servomotor 2s (drive motor 2).

On the other hand, 25 indicates a control system of the injection device 3s. 10s is a scale that constitutes a detection function unit (first detection function unit) 10 that can directly detect the position of the screw 4s, and includes a conversion processing unit 26 that converts the position into a speed, a detection processing unit 27 that detects a shift position, Further, it is connected to the input side of the comparator 28. The servo motor 2s is connected to the output side of the drive circuit 29 and
The input side of is connected to the output side of the comparison processing unit 32. The current detection value obtained by detecting the drive current flowing from the drive circuit 29 to the servo motor 2s is fed back to one input side of the comparison processing section 32, and the output side of the conversion processing section 31 is connected to the other input side. .. Furthermore, the conversion processing unit 3
One input side of 1 is connected to the output side of the comparison processing section 30, the output side of the conversion processing section 26 described above is connected to one input side of the comparison processing section 30, and the other input side is It is connected to the output side of the detection processing unit 27 described above. Then, the other input side of the detection processing unit 27 is connected to the central control unit 35 including a CPU and the like. On the other hand, 13s is an encoder for detecting the rotation of the rotary shaft of the servo motor 2,
It is connected to the other input side of the above-mentioned comparator 28 via the conversion processing unit 33. The encoder 13s and the conversion processing unit 33 configure the second detection function unit 13. The output side of the comparator 28 is connected to the central control unit 35, and the central control unit 35 is connected to the alarm generation unit 34.
With the above, the abnormality processing function unit 14 is configured.

Next, the function of the injection device 3s, as an example, the function in the injection step will be described.

First, from the central control unit 35, the screw 4s
The shift position and the speed command value at each shift position are given to the detection processing unit 27. As a result, the drive circuit 29
Operates the servo motor 2s to move the screw 4s forward via the transmission gear mechanism 23 and the ball screw mechanism 22. The position of the screw 4s is directly detected by the scale 10s, the detected first measured value Dx is given to the detection processing unit 27, and is converted into the first measured value Dx representing the speed by the conversion processing unit 26 for comparison processing. It is given to the part 30. In the comparison processing unit 30, the speed command value Ds given from the detection processing unit 27 is compared with the first measured value (speed) Dx, and the deviation is converted into a current command value by the conversion processing unit 31, and then the comparison process is performed. Assigned to the part 32. On the other hand, the measured value of the drive current flowing through the servo motor 2s is given to the comparison processing unit 32, the measured value is compared with the current command value, and the deviation is given to the drive circuit 29. This allows
Feedback control is performed so that the first measured value (speed) Dx matches the command value Ds. The feedback control system constitutes the control function unit 11. Further, the detection processing unit 27 monitors the position of the screw 4s by the first measured value (position) Dx obtained from the scale 10s, and when the shift position is reached, the speed command value in the next stage is compared with the comparison processing unit 30.
Given to.

Therefore, in the control method according to the present invention, the first measured value Dx obtained by directly detecting the position of the screw 4s to be controlled is used. Therefore, the ball screw mechanism 22 existing between the servo motor 2s and the screw 4s is used. Control is performed to eliminate an error due to backlash of the transmission gear mechanism 23, secular change, or the like.

On the other hand, the encoder 13s detects the rotational speed (rotational position) of the servomotor 2s, and the conversion processing unit 3
3 is given. In the conversion processing unit 33, the position of the screw 4s is indirectly obtained, the second measured value (position) Dy is obtained, and the second measured value Dy is given to the comparator 28. Since the first actual measurement value (position) Dx described above is given to the comparator 28, the comparator 28
Compares the first measured value Dx with the second measured value Dy, obtains a deviation thereof, and the deviation is given to the central controller 35. The central control unit 35 is preset with a set value for determining whether or not the error is an abnormal value. If the error exceeds the set value, an abnormal process, that is, an abnormal detection signal is issued. The alarm is given to the alarm generation unit 34 to turn on an abnormality occurrence lamp or the like to issue an alarm.

Therefore, it is possible to monitor the quantitatively increasing state of the error generated due to secular change or trouble. Also,
If the error increases abnormally, the parts can be replaced based on the abnormal processing, and the defective molding due to such a cause can be prevented and sufficient maintenance can be performed.

On the other hand, the mold clamping device 3r is similarly constructed and functions. The mold clamping device 3r includes a fixed plate 37 that supports the fixed mold 36 and a movable plate 39 that supports the movable mold 38. The movable plate 39 is coupled to the movable plate advancing / retreating drive mechanism section 3q. Note that the other configurations are the same as those on the injection device 3s side. Therefore, the same parts of the mold clamping device 3r as those on the injection device 3s side are designated by the same reference numerals to clarify the configuration thereof, and detailed description thereof will be omitted. The movable platen 3 is used in the mold clamping device 3r.
If 9 is replaced with the screw 4s on the injection device 3s side, other configurations and functions become the same as those on the injection device 3s side described above.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, as the movable mechanism unit 3, the screw advancing / retreating drive mechanism unit 3p of the injection device 3s and the movable plate advancing / retreating drive mechanism unit 3q of the mold clamping device 3r are illustrated. The present invention can be similarly applied to other movable mechanism parts such as the ejector pin advance / retreat drive mechanism part and the advance / retreat drive mechanism part of the nozzle moving device. In addition, the detailed configuration, method, and the like can be arbitrarily changed without departing from the scope of the present invention.

[0024]

As described above, the control method and apparatus for the electric injection molding machine according to the present invention directly detects the position and / or speed of the movable part in the movable mechanism part by the detection function part,
The control function unit feedback-controls the position and / or speed of the movable unit so that the detected actual measurement value (first actual measurement value) matches the preset command value. Play.

Since a movable mechanism portion such as a ball screw mechanism or a transmission gear mechanism existing between the drive motor and the movable portion is also incorporated in the feedback control system, backlash existing in the movable mechanism portion, distortion and wear due to temperature change, etc. It is possible to eliminate an error due to secular change, etc., and to realize accurate and highly accurate control of the position and / or speed of the movable part that is the control target.

Further, the second detection function unit obtains the position and / or speed of the movable portion from the rotation of the drive motor, the abnormality processing function unit compares the obtained second actual measurement value with the first actual measurement value, and If the deviation between the first measured value and the second measured value exceeds the set value, abnormal processing is performed, so that it is possible to quantitatively detect the degree of wear due to aging, and also to detect the occurrence of backlash due to trouble. Therefore, it is possible to realize a high level of maintenance such as the prevention of malfunction of the movable mechanism and the occurrence of defective products.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing a control device of an electric injection molding machine according to the present invention,

FIG. 2 is a block configuration diagram showing a control device of an electric injection molding machine according to a conventional technique,

[Explanation of symbols]

 1 control device 2 drive motor 3 movable mechanism part 3s injection device 3p screw advancing / retreating drive mechanism part 3r mold clamping device 3q movable plate advancing / retreating drive mechanism part 4 movable part Dx measured value (first measured value) Ds command value Dy second measured value 10 Detection Function Section (First Detection Function Section) 11 Control Function Section 13 Second Detection Function Section 14 Abnormal Processing Section

Claims (6)

[Claims] 1. A method for controlling an electric injection molding machine comprising a feedback control system for driving and controlling a movable mechanism section by a drive motor, wherein the position and / or speed of the movable section in the movable mechanism section is directly detected, and the measured value is detected. The method for controlling an electric injection molding machine is characterized in that the position and / or the speed of the movable part is feedback-controlled so that the above-mentioned value agrees with a preset command value. 2. The movable mechanism section includes a screw advance / retreat drive mechanism section of an injection device, a movable plate advance / retreat drive mechanism section of a mold clamping device, a screw rotation drive mechanism section of an injection device, a projecting pin advance / retreat drive mechanism section of a ejector, and a nozzle movement. The control method for the electric injection molding machine according to claim 1, wherein the forward / backward drive mechanism section of the apparatus is one or more. 3. A control method for an electric injection molding machine comprising a feedback control system for driving and controlling a movable mechanism section by a drive motor, wherein the position and / or speed of the movable section in the movable mechanism section is directly detected and detected. The second measured value obtained by feedback-controlling the position and / or speed of the movable part so that the measured value matches the preset command value, and also by obtaining the position and / or speed of the movable part from the rotation of the drive motor. And a first actual measurement value are compared with each other, and if the deviation between the first actual measurement value and the second actual measurement value exceeds a set value, abnormality processing is performed, and a method for controlling an electric injection molding machine. 4. A control device for an electric injection molding machine, comprising a feedback control system for drivingly controlling a movable mechanism section by a drive motor, and a detection function section for directly detecting the position and / or speed of the movable section in the movable mechanism section, Make sure that the measured value obtained from the detection function unit matches the preset command value,
A control device for an electric injection molding machine, comprising a control function unit for feedback-controlling the position and / or speed of a movable part. 5. The movable mechanism section includes a screw advance / retreat drive mechanism section of an injection device, a movable plate advance / retreat drive mechanism section of a mold clamping device, a screw rotation drive mechanism section of an injection device, a protruding pin advance / retreat drive mechanism section of an ejector, and a nozzle movement. The control device for the electric injection molding machine according to claim 4, wherein the control device is one or more of the advancing / retreating drive mechanism part of the device. 6. A control device for an electric injection molding machine, comprising a feedback control system for driving and controlling a movable mechanism section by a drive motor, wherein a first detection function section for directly detecting the position and / or speed of the movable section in the movable mechanism section. And a control function unit that feedback-controls the position and / or speed of the movable unit so that the first measured value obtained from the first detection function unit matches a preset command value; The second detection function section for obtaining the position and / or speed is compared with the second measurement value and the first measurement value obtained from the second detection function section, and the deviation between the first measurement value and the second measurement value exceeds the set value. A control device for an electric injection molding machine, which is provided with an abnormality processing function unit that performs abnormality processing.