CN113414955A - Screw rotating speed control method for improving plasticizing quality of injection molding machine - Google Patents

Screw rotating speed control method for improving plasticizing quality of injection molding machine Download PDF

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CN113414955A
CN113414955A CN202110873681.2A CN202110873681A CN113414955A CN 113414955 A CN113414955 A CN 113414955A CN 202110873681 A CN202110873681 A CN 202110873681A CN 113414955 A CN113414955 A CN 113414955A
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screw
rotating speed
injection molding
molding machine
plasticizing
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CN113414955B (en
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谢鹏程
朱金柏
赵梓良
丁玉梅
杨卫民
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Beijing University of Chemical Technology
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Beijing University of Chemical Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/76—Measuring, controlling or regulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76494—Controlled parameter
    • B29C2945/76595—Velocity
    • B29C2945/76605—Velocity rotational movement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76655—Location of control
    • B29C2945/76658—Injection unit
    • B29C2945/76665—Injection unit screw

Abstract

The invention discloses a screw rotating speed control method for improving the plasticizing quality of an injection molding machine, which is characterized in that a current displacement value of a screw is acquired through a displacement sensor arranged at the tail end of the screw, a screw structure parameter and an initial process parameter set value are read by an injection molding machine controller and are substituted into a screw rotating speed control function calculation model, a screw rotating speed control scheme of the rotating speed about the real-time screw displacement is obtained, and the screw rotating speed control scheme is transmitted to a plasticizing motor servo control system of the injection molding machine to control the rotating speed of the screw in the current period in real time, so that the uniformity of the plasticizing quality of a melt is realized. The method for controlling the rotating speed of the screw for improving the plasticizing quality of the injection molding machine is beneficial to improving the plasticizing quality of plastic melt, improving the uniformity of the melt and reducing the number of times of mold testing caused by equipment or material replacement.

Description

Screw rotating speed control method for improving plasticizing quality of injection molding machine
Technical Field
The invention belongs to the field of injection molding, and particularly relates to a method for setting a screw rotating speed value in a plasticizing process of an injection molding machine.
Background
The plastic has the characteristics of light weight, good chemical stability and the like, is widely applied to various fields, and injection molding is one of the main processing methods of the plastic. Today the precision of plastic articles places higher demands on the injection moulding process, and the quality of the plasticised material is a prerequisite for ensuring the precision of the injection moulded articles. In the plasticizing process, the screw rod rotates and retreats axially, the effective length of the screw rod is continuously reduced, so that the difference between the thermal history and the shearing history of the materials participating in the plasticizing at different moments is caused, and the uniformity of the melt in the metering chamber is reduced. The rotation speed setting of the screw has direct influence on the temperature and pressure distribution of the melt, so that a practitioner can improve the plasticizing quality by setting the rotation speed value of the screw in a segmented manner in the plasticizing process, but the traditional method for determining the injection molding process parameters mainly adopts a trial and error method, namely, the process parameters are determined according to the limited experience of related personnel, and then the trial and error evaluation is continuously carried out, and finally the proper rotation speed value of the screw is determined. However, in actual production, the number of times of mold testing of specific products is large due to the diversity of equipment and materials, and the process parameter determination time is long. Therefore, a method for controlling the screw rotation speed is required to overcome the above difficulties and obtain a suitable set value of the screw rotation speed quickly.
Disclosure of Invention
The invention discloses a screw rotating speed control method for improving the plasticizing quality of an injection molding machine, which is characterized in that a current displacement value of a screw is acquired through a displacement sensor arranged at the tail end of the screw, a screw structure parameter and an initial process parameter set value are read by an injection molding machine controller and are substituted into a screw rotating speed control function calculation model, a screw rotating speed control scheme of the rotating speed about the real-time screw displacement is obtained, and the screw rotating speed control scheme is transmitted to a plasticizing motor servo control system of the injection molding machine to control the rotating speed of the screw in the current period in real time, so that the uniformity of the plasticizing quality of a melt is realized. The method for controlling the rotating speed of the screw for improving the plasticizing quality of the injection molding machine is beneficial to improving the plasticizing quality of plastic melt, improving the uniformity of the melt and reducing the number of times of mold testing caused by equipment or material replacement.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention relates to a screw rotating speed control method for improving the plasticizing quality of an injection molding machine.
A screw rotating speed control method for improving the plasticizing quality of an injection molding machine is characterized by comprising the following four steps (S1-S4):
s1: and starting and initializing the injection molding machine, reading the equipment information document by the injection molding machine controller, and acquiring the relevant parameters of the injection molding machine and the screw.
S2: the displacement sensor connected with the screw rod can acquire data of the current position of the screw rod in real time, and the data are input into the injection molding machine controller after being amplified and subjected to analog-to-digital conversion by the sensor control circuit.
S3: the user pre-adjusts a set of injection molding process parameters which can stabilize the quality of the product, including but not limited to plasticizing stroke, screw rotation speed, screw back pressure, barrel temperature, reading equipment control system parameter k (the screw rotation speed can be set into the number of sections), and input material performance parameters.
S4: and (3) in an injection molding machine controller, substituting all parameters obtained in the process into a screw rotating speed control function calculation model to obtain a screw rotating speed control equation n (x), namely calculating a screw rotating speed value required by the real-time position of the screw, converting the screw rotating speed value into a control signal, transmitting the control signal to a plasticizing servo motor, and controlling the rotating speed of the screw in real time. Substituting the parameters obtained in the above process into the calculated screw rotation speed control equation n (x) as follows:
Figure BDA0003189576080000021
in the formula, memory
C1＝B2m-(A1B3+A2B2)p
Figure BDA0003189576080000031
C3＝-4A1B1B2PH
C4＝2A1A2
Figure BDA0003189576080000035
Figure BDA0003189576080000036
Figure BDA0003189576080000032
Wherein m is a constant and is only related to the structural parameters of the equipment and the initial process parameters set by a user, the value of the constant directly determines the size of the energy consumption value of the melt,
Figure BDA0003189576080000033
p is back pressure; eta is the apparent viscosity of the melt; d is the diameter of the screw; h3The length of the screw homogenizing segment; phi is the helix angle of the homogenization section; λ is the material thermal conductivity;
Figure BDA0003189576080000034
the temperature of the inner wall of the machine barrel corresponds to the screw homogenizing section; t ismThe temperature of the melt in the homogenization section; the units are international units.
And calculating a rotating speed control curve in the plasticizing process in an injection molding machine controller. Sampling and coding the obtained control curve, outputting the control curve to a controller of a screw rotating speed control servo motor, and finally obtaining the most appropriate screw rotating speed under the real-time screw position, namely, in the screw plasticizing process, rotating and retreating along the axial direction, and in the screw groove melting process of plastics entering a screw feeding section at different moments, changing the screw rotating speed to ensure that the obtained energy is kept consistent, thereby improving the uniformity of plasticizing quality.
The invention provides a screw rotating speed control method for improving the plasticizing quality of an injection molding machine, which has the advantages that:
(1) compared with the prior art, the technical scheme is favorable for improving the plasticizing quality of the plastic melt in the injection molding process and improving the melt plasticizing uniformity.
(2) The number of times of die testing caused by restarting or replacing the die after shutdown is greatly reduced, and the material waste is reduced.
Drawings
FIG. 1 is a schematic flow chart of an implementation of a screw rotation speed control method for improving plasticizing quality of an injection molding machine;
FIG. 2 is a schematic diagram of a screw rotation speed control device for improving the plasticizing quality of an injection molding machine.
Detailed Description
The present invention is further illustrated by the following specific embodiments. The following description is only a few embodiments, and any non-inventive substitutions or modifications based on the embodiments of the present invention may be made to other embodiments within the scope of the present invention. In addition, the technical features mentioned in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention relates to a screw rotating speed control method for improving the plasticizing quality of an injection molding machine.
A screw rotating speed control method for improving the plasticizing quality of an injection molding machine mainly comprises the following four steps (S1-S4):
s1: starting and initializing the injection molding machine, reading an equipment information document by an injection molding machine controller, obtaining relevant parameters of an injection molding machine table and a screw, wherein the diameter of the screw is 45mm, the length-diameter ratio is 20, the groove depth of a homogenizing section is 2.7mm, the helix angle of a helix edge of the homogenizing section is 17 degrees and 40 degrees,
s2: the displacement sensor connected with the screw rod can acquire data x of the current position of the screw rod in real time, and the data x is amplified and subjected to analog-to-digital conversion by the sensor control circuit and then input into the injection molding machine controller.
S3: the user adjusts a set of injection molding process parameters capable of stabilizing the quality of the product according to preset conditions, including but not limited to a plasticizing stroke of 5D-5 x 45-225 mm, a screw rotation speed, an initial screw rotation speed of 40rpm, a screw back pressure of 6MPa, a barrel temperature of 200 ℃, a reading device control system parameter k-5 (the screw rotation speed can be set into sections), and input materialsThe material performance parameter is that the viscosity of the PP material is 6x10 at 200 DEG C6PaS。
S4: in an injection molding machine controller, substituting various parameters obtained in the process into a screw rotating speed control function calculation model to obtain a screw rotating speed control equation n (x), namely calculating a screw rotating speed value required by the real-time position of a screw, namely n (x), and calculating by using the parameters to obtain a control curve approximation equation:
Figure BDA0003189576080000051
wherein:
Figure BDA0003189576080000052
x 'is the backward distance of the screw, x' belongs to (0-3) D, and D is the diameter of the screw.
And sampling, quantizing and coding the relational expression to convert the relational expression into a control signal, further transmitting the control signal to a plasticizing servo motor, and controlling the rotating speed of the screw rod in real time. The calculation mode of substituting each parameter obtained in the process into the calculated screw rotating speed control equation n (x) is as follows:
Figure BDA0003189576080000053
in the formula, memory
C1＝B2m-(A1B3+A2B2)p
Figure BDA0003189576080000054
C3＝-4A1B1B2PH
C4＝2A1A2
Figure BDA0003189576080000055
Figure BDA0003189576080000063
Figure BDA0003189576080000061
Wherein m is only related to the structural parameters of the equipment and the initial process parameters set by a user, the value of m directly determines the size of the energy consumption value of the melt,
Figure BDA0003189576080000062
p is back pressure; eta is the apparent viscosity of the melt; d is the diameter of the screw; h3The length of the screw homogenizing segment; phi is the helix angle of the homogenization section; λ is the material thermal conductivity; t isbL3The temperature of the inner wall of the machine barrel corresponds to the screw homogenizing section; t ismThe temperature of the melt in the homogenization section; the units are international units.
And calculating a rotating speed control curve in the plasticizing process in an injection molding machine controller. And sampling and coding the obtained control curve, outputting the control curve to a controller of the screw rotating speed control servo motor, and finally obtaining the most appropriate screw rotating speed under the real-time screw position. In the plasticizing process, the screw rotates and retreats along the axial direction, so that the energy obtained by the plastic entering the screw feeding section at different moments in the melting process is kept consistent, the uniformity of the plasticizing quality is improved, through experimental verification, the rotating speed of the screw is changed in real time compared with the constant rotating speed of the screw in the injection molding process, the quality repetition precision variance of a product is reduced to 29.48 from 42.90, and the impact strength is improved by about 10.8% in the aspect of sample performance.

Claims (3)

1. A method for improving the rotational speed control of the screw rod of the injection molding machine plastifying quality, the apparatus is formed and mainly includes injection molding machine plastifying unit, screw rod displacement transducer, sensor controller, plastify servomotor, servomotor controller and injection molding machine controller, etc., characterized by, including the following four (S1-S4) steps:
s1: and starting and initializing the injection molding machine, reading the equipment information document by the injection molding machine controller, and acquiring the relevant parameters of the injection molding machine and the screw.
S2: the displacement sensor connected with the screw rod can acquire data of the current position of the screw rod in real time, and the data are input into the injection molding machine controller after being amplified and subjected to analog-to-digital conversion by the sensor control circuit.
S3: a user pre-adjusts a group of injection molding process parameters capable of stabilizing the quality of a product, including but not limited to a plasticizing stroke, a screw rotating speed, a screw back pressure, a machine barrel temperature, a reading device control system parameter k (the screw rotating speed can be set into the number of sections), and input material performance parameters;
s4: and (3) in an injection molding machine controller, substituting all parameters obtained in the process into a screw rotating speed control function calculation model to obtain a screw rotating speed control equation n (x), namely calculating a screw rotating speed value required by the real-time position of the screw, converting the screw rotating speed value into a control signal, transmitting the control signal to a plasticizing servo motor, and controlling the rotating speed of the screw in real time.
2. The method for controlling the rotating speed of the screw for improving the plasticizing quality of the injection molding machine according to claim 1, wherein the optimum rotating speed value n (x) of the screw at the real-time position x of the screw is obtained by the following formula:
Figure FDA0003189576070000011
in the formula, memory
C1＝B2m-(A1B3+A2B2)p
Figure FDA0003189576070000012
C3＝-4A1B1B2PH
C4＝2A1A2
Figure FDA0003189576070000021
Figure FDA0003189576070000022
Figure FDA0003189576070000023
Wherein m is a constant and is only related to the structural parameters of the equipment and the initial process parameters set by a user, the value of the constant directly determines the size of the energy consumption value of the melt,
Figure FDA0003189576070000024
p is back pressure; eta is the apparent viscosity of the melt; d is the diameter of the screw; h3The length of the screw homogenizing segment; phi is the helix angle of the homogenization section; λ is the material thermal conductivity;
Figure FDA0003189576070000025
the temperature of the inner wall of the machine barrel corresponds to the screw homogenizing section; t ismThe temperature of the melt in the homogenization section; the units are international units.
3. The method of claim 2, wherein during the plasticizing process, the screw is rotated and moved backward along the axis, and during the melting process, the rotational speed n (x) of the screw is changed to make the energy obtained by the screw consistent, thereby improving the uniformity of the plasticizing quality.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114670408A (en) * 2021-12-30 2022-06-28 阿托斯(上海)液压有限公司 Low back pressure control method and device for injection cylinder retraction storage of injection molding machine
CN116619712A (en) * 2023-07-17 2023-08-22 广东伊之密高速包装系统有限公司 Shaft positioning system of injection molding machine and control method thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3797808A (en) * 1970-10-22 1974-03-19 Cincinnati Milacron Inc Plastication control system for injection molding machines
US4094940A (en) * 1974-01-21 1978-06-13 Usm Corporation Injection molding machine controls
JPH11334885A (en) * 1998-05-27 1999-12-07 Sekisui Chem Co Ltd Material supply amount control method
US20110298146A1 (en) * 2010-02-09 2011-12-08 Noriyuki Akasaka Device and Method for Plasticization Control of Electric Injection Molding Machine
CN108215105A (en) * 2018-01-29 2018-06-29 海天塑机集团有限公司 A kind of method and system for improving injection repeatable accuracy

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3797808A (en) * 1970-10-22 1974-03-19 Cincinnati Milacron Inc Plastication control system for injection molding machines
US4094940A (en) * 1974-01-21 1978-06-13 Usm Corporation Injection molding machine controls
JPH11334885A (en) * 1998-05-27 1999-12-07 Sekisui Chem Co Ltd Material supply amount control method
US20110298146A1 (en) * 2010-02-09 2011-12-08 Noriyuki Akasaka Device and Method for Plasticization Control of Electric Injection Molding Machine
CN108215105A (en) * 2018-01-29 2018-06-29 海天塑机集团有限公司 A kind of method and system for improving injection repeatable accuracy

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114670408A (en) * 2021-12-30 2022-06-28 阿托斯(上海)液压有限公司 Low back pressure control method and device for injection cylinder retraction storage of injection molding machine
CN114670408B (en) * 2021-12-30 2023-06-16 阿托斯(上海)液压有限公司 Low back pressure control method and device for injection cylinder rollback storage of injection molding machine
CN116619712A (en) * 2023-07-17 2023-08-22 广东伊之密高速包装系统有限公司 Shaft positioning system of injection molding machine and control method thereof
CN116619712B (en) * 2023-07-17 2023-10-17 广东伊之密高速包装系统有限公司 Shaft positioning system of injection molding machine and control method thereof

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