CN114474634A

CN114474634A - Optimized design of cooling system of round cover injection mold

Info

Publication number: CN114474634A
Application number: CN202210058495.8A
Authority: CN
Inventors: 殷燕芳; 李玉华; 陈艳山
Original assignee: Wuhan Polytechnic University
Current assignee: Wuhan Polytechnic University
Priority date: 2022-01-19
Filing date: 2022-01-19
Publication date: 2022-05-13

Abstract

The invention discloses an optimized design of a cooling system of a round cover injection mold, which comprises the following steps: according to dome shape characteristic to carry out the structure to mould and cut apart, corresponding division is 3 discrete cooling units, 2 kinds of cooling water channels are formulated to every cooling unit, make up into 8 kinds of whole cooling system design proposals with discrete cooling water channel, and the dome 3D model that will Solidworks draw is directed into Moldflow software and is carried out the mould flow analysis, includes: analyzing the position of a pouring gate, analyzing a forming window and filling, establishing a gating system and a cooling system by using a modeling tool, and performing cooling analysis on 8 cooling system schemes, wherein the results comprise: the optimal cooling system scheme is obtained by comparing analysis results of the temperature of a cooling medium of the loop, the flow rate of the loop, the temperature of the wall of the loop, the time for reaching the ejection temperature, the average temperature of a plastic part and the temperature curve of the plastic part, and an optimization method is provided for the design of the cooling system of the circular cover injection mold.

Description

Optimized design of cooling system of round cover injection mold

Technical Field

The invention relates to the technical field of injection mold design, in particular to an optimized design of a cooling system of a round cover injection mold.

Background

In the injection molding production of plastic, the temperature of a mold directly influences the quality and efficiency of a plastic part, molten plastic is injected into the mold and solidified into the plastic part to be removed from a mold cavity, and the temperature is reduced by a cooling system in the mold; the cooling effect of a cooling system is related to a number of factors, including: the geometric shape of the plastic part, the layout of the cooling water channel, the cooling medium, the plastic part material, the mold temperature, the flow rate of the cooling medium and the like are difficult to measure by an experimental method, so that more and more enterprises select a mold flow analysis technology to obtain the prediction information, the design scheme of the cooling system is optimized, the number of mold testing times is reduced, the production efficiency is improved, the mold cost is reduced, and the product quality is improved.

An existing round cover injection molding part comprises an inner layer and an outer shell, as shown in figure 3, the average wall thickness is 3mm, and the appearance quality requirement of the plastic part cannot have the defects of flash, jet flow marks, depressions, cracks, size change and the like; the plastic part has certain mechanical property requirements, and cannot deform too much to ensure assembly.

And (3) realizing the simulation of the cooling process of the plastic melt in the mold by using MoldFlow software, predicting various problems possibly occurring in the cooling process, perfecting a design scheme and obtaining an optimized cooling system design.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the defects of the prior art, the optimized design of the cooling system of the round cover injection mould is provided, and the molding quality of the plastic part is improved.

The above object of the present invention is achieved by the steps of:

the method comprises the following steps: the plastic part structure is divided into 3 parts according to the shape characteristics of the round cover: the upper end surface and the outer circumferential surface belong to the shell and are formed by a cavity arranged in the fixed die; the inner surface belongs to the inner layer and is molded by a core disposed on a movable mold.

Step two: the cooling system of dome injection mould is located cover half and movable mould respectively, and the corresponding 3 discrete cooling units that divide into: a cooling unit A matched with the upper end surface, a cooling unit B matched with the outer circumferential surface and a cooling unit C matched with the inner surface; the cooling unit A and the cooling unit B are disposed on the fixed mold part, and the cooling unit C is disposed on the movable mold part.

Further, 2 cooling water channels are prepared for each discrete cooling unit, 6 cooling water channels of 3 units are A1, A2, B1, B2, C1 and C2, and the cooling water channels are mutually combined into 8 cooling system schemes.

Step three: A3D model is established for the plastic part by using Solidworks modeling software, the proportion of the three-dimensional model is 1: 1, the three-dimensional model is stored as a format 'round cover, stl' file which can be identified by Moldflow software, the file is imported into the Moldflow software to divide a double-layer grid, the divided grids are counted, and grid defect diagnosis and grid defect repair are carried out, so that the quality optimization of the grids reaches the Moldflow analysis standard.

Step four: analyzing the gate position, namely selecting the analysis type as the gate position, selecting the material type and setting process parameters according to the shape and production environment requirements of the dome part, and confirming, analyzing and calculating to obtain the optimal gate position result; the position is on the top surface of the round cover, and the result is determined by combining various factors as the actual design pouring gate position, and the mold pouring system is designed by adopting a direct pouring gate mode.

Preferably, the material is chosen to be Generic PP, setting process parameters to select default parameters.

Step five: modeling window analysis, exporting the result and putting the result into a report document, and analyzing the result' quality (modeling window): analysis of the XY plot "determines the optimal injection time.

Step six: and (4) establishing a pouring system by using a modeling tool on a Moldflow platform, performing filling analysis, putting a derived result into a report document, and judging a filling effect.

Preferably, if the filling judgment fails to reach the standard, the gating system optimization is carried out, the next step is carried out until the standard is reached, and a file is stored and named as scheme 1; this file was then replicated 7 times and named scheme 2-scheme 8.

Step seven: and opening the file scheme 1, creating a cooling system, carrying out cooling analysis, exporting results, putting the exported results into a report document, reading information values in various results, judging the cooling effect, and storing the file.

The cooling system is created in 2 ways: one method is that a cooling water channel model is drawn based on Solidworks software according to the shape and the size of a designed cooling water channel, and the model is stored as an stl file, is imported into Moldflow software to divide grids and participate in analysis; one method is that a cooling water channel model is directly created on a Moldflow platform by using a modeling tool according to the shape and the size of a designed cooling water channel, and meshing participation analysis is carried out.

Further, according to the schemes 2 to 8, the cooling analysis operation in the seventh step is repeated, the exported results are respectively put into the report documents, the information values in all the results are read, the cooling effect storage files are judged, and 8 report documents are compared and evaluated.

Preferably, the cooling analysis results of schemes 1 to 8 include: loop cooling medium temperature, loop flow rate, loop reynolds number, loop wall temperature, time to ejection temperature-plastic part, plastic part average temperature, plastic part temperature curve.

Furthermore, the temperature curve of each grid unit of the plastic part model can be checked by using the two-dimensional XY diagram of the plastic part temperature curve, the temperature difference of the upper surface and the lower surface of the plastic part is determined, and the occurrence of warping is predicted and corrected to reduce warping deformation.

Preferably, the analysis result-cooling analysis result determination is based on:

(1) loop cooling medium temperature: the temperature variation range is less than 3 ℃;

(2) loop wall temperature: the temperature of the cooling liquid can not be higher than the inlet temperature of the cooling liquid by more than 5 ℃;

(3) average temperature of plastic part: well below the material ejection temperature;

(4) plastic part temperature curve: evaluated in conjunction with the cooling bed factor of the fill analysis;

(5) time to reach ejection temperature-plastic: the cooling of the round cover is uniform, and the time is as short as possible;

(6) the temperature of the plastic part: the temperature variation on each mould surface should be within 10 ℃;

(7) loop flow rate: the maximum flow rate in each loop was < 5 times the average flow rate.

Preferably, the cooling purpose of the final optimization scheme is specifically as follows: the cooling time in the injection molding cycle is short, the surface temperature of the injection molding piece is uniform, and the cooling effect is good.

The optimal design scheme is that 3 discrete cooling units correspond to the optimal final result of the combination of 6 cooling water channel models, and the synchronous and uniform cooling treatment of the whole circular cover product is realized; when the cooling water channel model is designed in a combined mode, the cooling water channel model is matched with the whole mold structure, the reasonability of the arrangement positions of water channels is considered, and meanwhile, all factors such as the connection and installation of external water pipes of the water channel inlets and outlets and the coordination of staff operation are comprehensively analyzed.

Compared with the prior art, the optimized design of the cooling system of the dome injection mold is the optimized design of the cooling system established on the Moldflow software platform, the feasibility judgment of a mold cooling water channel can be rapidly carried out, the advantages and disadvantages of the design of the cooling system of the dome injection mold can be simulated and analyzed, the optimal design scheme of the cooling system and the cycle time IPO calculated from the target mold temperature can be obtained, the molding cycle can be effectively reduced, the efficiency can be greatly improved, and an effective optimization method is provided for the design of the cooling system of the dome injection mold.

Drawings

FIG. 1 is a flow chart of the method of the present invention.

Fig. 2 is a cooling system creation flow diagram.

Fig. 3 is a schematic structural diagram of a plastic part.

Fig. 4 is a graph of optimal injection times in a fill analysis.

Fig. 5 is a schematic view of the cooling circuit design of the cooling unit a.

Fig. 6 is a schematic view of the cooling circuit design of the cooling unit B.

Fig. 7 is a schematic view of the cooling circuit design of the cooling unit C.

Fig. 8 is a grid cell temperature profile for cooling system solution 1.

Fig. 9 is a grid cell temperature profile for cooling system solution 8.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

As shown in fig. 1-9, the present invention provides an optimized design of a cooling system for a dome injection mold, comprising the following steps:

the method comprises the following steps: dividing the dome structure into: the upper end surface and the outer circumferential surface belong to the shell and are formed by a cavity arranged in the fixed die; the inner surface belongs to the inner layer and is molded by a core disposed on a movable mold.

Step two: the cooling system of dome injection mould is located cover half and movable mould respectively, and the corresponding 3 discrete cooling units that divide into: the cooling unit A is matched with the upper end face, the cooling unit B is matched with the outer circumferential face, and the cooling unit C is matched with the inner surface; the cooling unit A and the cooling unit B are disposed on the fixed mold part, and the cooling unit C is disposed on the movable mold part.

Further, 2 cooling water channel models are prepared for each discrete cooling unit, 6 cooling water channel models of 3 units are A1, A2, B1, B2, C1 and C2, and are mutually combined into 8 cooling system schemes, as shown in Table 1.

Table 1:

cooling system	Water channel combination	Cooling circuit	Cooling system	Water channel combination	Cooling circuit
						Scheme 1	A1B1C1	4 are provided with	Scheme 5	A2B1C1	4 are provided with
Scheme 2	A1B1C2	5 are provided with	Scheme 6	A2B1C2	5 are provided with
						Scheme 3	A1B2C1	5 are provided with	Scheme 7	A2B2C1	5 are provided with
Scheme 4	A1B2C2	6 are	Scheme 8	A2B2C2	6 are

Step three: A3D model is built for a dome by using Solidworks modeling software, the three-dimensional model is stored as a dome-stl file at a ratio of 1: 1, double-layer mesh division is carried out by importing the three-dimensional model into Moldflow software, the value of the mesh density of the whole model is defined as 1mm, and the divided meshes are counted and the mesh defect diagnosis is carried out.

Preferably, the model mesh quality comprises: no free edge, no multiple edge, no unit crossing, a connected region of 1, an aspect ratio of less than 8, and a unit matching rate of greater than 85%.

Further, in the grid defect diagnosis result, the defects which do not meet the model analysis requirement are repaired, the repaired grid is counted, and the statistical result is shown in table 2.

Table 2:

step four: analyzing the pouring gate position, selecting the analysis type as 'pouring gate position', selecting the material type as Generic PP according to the shape of the round cover part and the requirement of production environment, setting process parameters and selecting default parameters, analyzing and calculating to obtain the optimal pouring gate position on the top surface of the round cover, and designing a mold pouring system by adopting a direct pouring gate mode for the actual pouring gate position.

The performance parameters of the material Generic PP in the fourth step include: the recommended mold surface temperature is 40 deg.C, melt temperature is 240 deg.C, maximum shear stress is 0.25MPa, and maximum shear rate is 100000s^-1The ejection temperature is 101 ℃, the melt temperature ranges from 220 ℃ to 260 ℃, and the mold temperature ranges from 20 ℃ to 60 ℃.

Step five: modeling window analysis, exporting the result and putting the result into a report document, and analyzing the result' quality (modeling window): analysis of the XY plot "determined the optimal injection time to be 0.5382 s.

Step six: a casting system is established on a Moldflow platform by using a modeling tool, filling analysis is carried out, a derived result is put into a report document, the filling effect is judged by comparing the result, the parameters of the filling result meet the balance requirement, and a file is saved and named as scheme 1; this file was then replicated 7 times and named scheme 2-scheme 8.

The cooling system is created in the following way: and directly creating a cooling water channel model on the Moldflow platform by using a modeling tool according to the shape and the size of the designed cooling water channel, and dividing a grid to participate in analysis.

The cooling analysis results of the schemes 1 to 8 include: loop cooling medium temperature, loop flow rate, loop reynolds number, loop wall temperature, time to ejection temperature-plastic part, plastic part average temperature, plastic part temperature curve.

As shown in fig. 8, the temperature profile of the plastic part in the cooling analysis result of the scheme 1 shows the temperature conditions of the selected 4 grid cells (T8388, T75532, T98262, T64903) on the dome model; as shown in fig. 9, the temperature profile of the plastic part in the cooling analysis result of the scheme 8 shows the temperature conditions of the selected 4 grid cells (T8388, T75532, T98262, T64903) on the dome model; in the graph, the X axis represents the thickness change, the Y axis represents the temperature of the plastic part, the temperature values of two end points on the curve are checked, the temperature difference of the upper surface and the lower surface of the corresponding position of the grid unit can be determined, the warping condition is judged, and the warping can be reduced due to the small temperature difference.

By adopting the technical scheme, after the cooling analysis of the schemes 1 to 8 is finished, the scheme 8 can be determined as an optimal cooling system design scheme, the cooling liquid temperature and cavity temperature result abstracts of the cooling analysis are displayed in the analysis log, and the cavity temperature result abstracts are shown in table 3; cooling system design scheme 8 shows that the cooling time is short in the injection molding cycle, the surface temperature of the injection molding piece is uniform, the cooling effect is good, and the purpose of optimally designing the cooling system is achieved.

Table 3:

surface temperature-maximum of parts	55.30℃
		Part surface temperature-minimum	31.99℃
Part surface temperature-average value	42.44℃
		Temperature-maximum of cavity surface	51.78℃
Temperature-minimum of cavity surface	28.36℃
		Temperature-average value of cavity surface	38.68℃
Average die outside temperature	28.64℃
		Cycle time	58.26s

Compared with the traditional method, the method greatly reduces the development cost of a developer, greatly shortens the development period, is equivalent to the improvement and improvement of the design on the cooling water channel model optimization, tests and analyzes the system through simulation before the specific implementation of the project, uses the simulation technology to timely verify the correctness of the cooling scheme in the design period, reduces the unnecessary errors generated in the design and model test stages, and improves the product quality.

While there have been shown and described what are at present considered the fundamental principles of the invention and its essential features, it is to be understood that the invention is not limited by the details of the foregoing description, since various modifications and changes may be made therein without departing from the spirit and scope of the invention.

Claims

1. The utility model provides a dome injection mould cooling system optimal design which characterized in that:

(1) the plastic part structure is divided into according to the shape characteristics of the round cover: the upper end surface and the outer circumferential surface are formed by a cavity of the fixed die, and the inner surface is formed by a core of the movable die; the corresponding cooling system of the dome injection mold is divided into 3 discrete cooling units: a cooling unit A disposed on the upper end surface, a cooling unit B disposed on the outer circumferential surface, and a cooling unit C disposed on the inner surface;

(2) 2 cooling water channel models are made for each discrete cooling unit, and 6 cooling water channels of 3 units are mutually combined to form 8 cooling system schemes;

(3) establishing a dome 3D model based on Solidworks software, outputting the model as a dome-stl file, importing the file into Moldflow software to divide a double-layer mesh, and optimizing the mesh quality;

(4) analyzing the position of a pouring gate on a Moldflow platform, setting the type of materials and relevant parameters of an injection machine, exporting the analysis result and putting the analysis result into a report document;

(5) performing modeling window analysis on a Moldflow platform, and putting a derived result into a report document;

(6) filling analysis is carried out on a Moldflow platform, and a result is exported and put into a report document;

(7) performing simulation calculation on 8 cooling system schemes in the cooling stage of the injection molding process by adopting a numerical simulation method on a Moldflow platform, and putting a derived result into a report document;

(8) and analyzing the modular flow analysis results of the 8 cooling system schemes, selecting a water channel combination scheme with good effect as an optimal cooling system design scheme, and achieving the purpose of optimal design of the cooling system.

2. The method according to claim 1, wherein the step (1) of dividing the plastic part structure is a disassembly process of the part product based on the characteristics, so that each part of the product can be designed with a corresponding cooling water channel to obtain effective cooling.

3. The method according to claim 1, wherein the 6 cooling water channel model designs in the step (2) are all designed according to the design principle requirements of the aperture size and the hole position relationship of the water channel.

4. The method as claimed in claim 1, wherein in the step (3), grid defect diagnosis and grid defect repair are performed on the divided finite element grid, so that the quality of the divided finite element grid meets the standard requirement of the Moldflow analysis.

5. The method according to claim 1, wherein the gating system structure is designed according to the result derived from the gate position analysis in the step (4), the optimal injection time is determined according to the result derived from the molding window analysis in the step (5), and the feasibility of relevant parameter design is checked according to the derived result by simulating the filling process of the dome through the filling analysis in the step (6).

6. The method according to claim 1, wherein the cooling analysis process parameter settings of different cooling system schemes in the step (7) are consistent, one cooling system scheme is introduced into each analysis, and the report documents of 8 cooling system schemes are subjected to result analysis comparison.

7. The method as claimed in claim 1, wherein the analysis result in the step (7) comprises: loop cooling medium temperature, loop flow rate, loop wall temperature, time to reach ejection temperature-plastic part, plastic part maximum temperature, plastic part average temperature, plastic part temperature curve.

8. The method according to claim 1, wherein the method for selecting the optimal cooling water channel in step (8) is specifically as follows: the cooling time in the injection molding cycle is short, and the surface temperature of the injection molding piece is uniform.

9. The method according to claim 1, wherein the optimal design scheme is a combined end result of 3 discrete cooling units corresponding to 8 cooling system schemes, and realizes synchronous and uniform cooling treatment of the whole circular cap product; when the cooling water channel model is designed in a combined mode, the cooling water channel model is matched with the whole mold structure, the reasonability of the arrangement positions of water channels is considered, and meanwhile, all factors such as the connection and installation of external water pipes of the water channel inlets and outlets and the coordination of staff operation are comprehensively analyzed.