CN100418731C

CN100418731C - Method of determining a hold pressure control start pressure for resin injection molding

Info

Publication number: CN100418731C
Application number: CNB038016966A
Authority: CN
Inventors: 小高光一; 铃木贤一; 汤浅明博
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2002-03-26
Filing date: 2003-03-11
Publication date: 2008-09-17
Anticipated expiration: 2023-03-11
Also published as: WO2003080307A3; GB2396840A; KR20040097118A; CA2467594A1; JP2003276070A; GB2396840B; JP3778441B2; GB0409755D0; CN1791500A; WO2003080307A2

Abstract

A hold pressure control start pressure for resin injection molding is determined by finding a pressure (Ps) at which a pressure curve (H) representing the pressure on a resin melt inside the mold cavity forms a valley (J) occurring first after a peak of the pressure curve, and setting the thus found pressure (Ps) as a hold pressure control start pressure that is used for performing pressure control during a subsequent resin molding operation. Since the hold pressure control start pressure is determined on the basis of the pressure curve, it is essentially possible to obtain a setting pressure value for such hold pressure control start pressure through a single run of test injection molding process.

Description

Be identified for the method for initial pressure of the control that keep-ups pressure of resin injection moulding

Technical field

The present invention relates to the improvement in the method for initial pressure of the control that keep-ups pressure that is identified for the resin injection moulding.

Background technology

Japanese patent application publication No. discloses a kind of injection control apparatus that is used for injection (mo(u)lding) machine for the file of (putting down) 4-48339, it is designed to like this, that is: pass by when the resin pressure in being filled in mould surpasses predetermined pressure or after the start injection operation in the scheduled time, control begins to keep-up pressure.Use is arranged on pressure sensor in this mould can measure resin pressure in this mould.

Investigation according to the inventor carries out has been found that: disclosed technology is not entirely satisfactory in above-mentioned Japanese open source literature, still also has two problems to have to be solved.A problem is easily to determine predetermined pressure, and another problem is: because bigger pressure variation or fluctuation take place, therefore be difficult to measure the resin pressure in this mould.Below with reference to Fig. 6 A and 6B and Fig. 7 these problems are described in further detail.

Fig. 6 A and 6B are the conventional illustration curve maps of two kinds of different modes that is used for determining predetermined pressure that adopts.In the curve map shown in Fig. 6 A and the 6B, trunnion axis is represented after the start injection process time in the past, and vertical axis is illustrated in the pressure in this mould.

In Fig. 6 A, the pressure curve of representing with " a " shows: because too high injection speed, huge crest appears at the final stage of injection process.Pressure curve with " b " expression among Fig. 6 shows: because the injection speed that reduces, the crest that appears at the injection process final stage is lower than the crest of pressure curve " a ".The pressure curve of with dashed lines " A " expression is represented the optimum pressure curve.In theory, can determine best pressure curve " A " by retest injection process under such condition, this condition is: the crest that appears at an injection process final stage is lower than the crest of previous injection process, as the pressure curve as shown in Fig. 6 A " a " and " b " know show.From the viewpoint of mould protection, such process is not preferred, because during the retest injection process, this mould will bear excessive pressure loading.

Fig. 6 B represents different processes, wherein in order to protect mould, prevents that to be enough to be reduced to the injection speed that produces crest pressure from beginning this test injection process, knows just as the pressure curve " c " shown in Fig. 6 B to show.In the implementation of ensuing test injection process, improve injection speed slightly, thereby obtain pressure curve with " d " expression.Like this, can repeat this test injection process, little by little improve injection speed simultaneously, up to obtaining the optimum pressure curve " A " that imaginary line is represented.This process need is repeatedly carried out the test injection operation, so efficient is very low.

Fig. 7 represents the exemplary that traditional pressure sensor is provided with.As shown in this Fig, pressure sensor 104 embeds moveable die 102 like this, that is: basically in the face of being limited to the center of the die cavity 103 between moveable die 102 and the fixed mould 101.In injection process, process hot flow path 106 and inwardly projecting orifice or cast gate (gate) 107 make the molten resin that flows out from injection nozzle 105 flow to die cavity 103.In a period of time behind start injection, the unexpected fluctuation of the resin of fusing experience turbulent flow (can comprise the generation of whirlpool and the collision of molten resin) and cavity pressure (that is: the resin pressure in the die cavity).This pressure oscillation makes cavity pressure mensuration be difficult to realize.Therefore, must consider the installation site of pressure sensor.

Therefore, the method that the purpose of this invention is to provide a kind of initial pressure of the control of can determining easily, fast and efficiently to keep-up pressure.

Summary of the invention

According to the present invention, a kind of method of initial pressure that is identified for the control that keep-ups pressure of resin injection moulding is provided, it comprises the following steps: when carrying out injection speed control, carry out the test injection process, to obtain the pressure curve under this condition, that is: this pressure curve comprises the crest that cavity pressure drew that takes place owing to the final stage in this test injection process; Find a pressure, at this pressure place, this pressure curve is formed on the trough that occurs for the first time after this crest; And the pressure that will find like this is set at the initial pressure of the control that keep-ups pressure, and it can be used in and carry out pressure control in resin forming operating process subsequently.

Because on the basis of this pressure curve, determine this initial pressure of control that keep-ups pressure, so can carry out the test injection forming process by single in fact, the setting pressure of the initial pressure that obtaining is used to keep-up pressure controls.This this process has significantly reduced the man-hour of this test injection process.

Preferably this cavity pressure is measured in the position that the molten resin in the die cavity that injects die assembly from cast gate can steady flow.Before the remainder of this die cavity, fill the part be positioned near this die cavity this cast gate with molten resin, and become stable very soon at the cavity pressure (being the pressure of molten resin) of this mould cavity part office.Being used for the pressure sensor of measurement mode cavity pressure is positioned at this cavity section, and preferably is positioned at the center of this cavity section.

In a preferred form of the present invention, this die cavity has the cavity section and this cavity section that are positioned near this cast gate and has the space bigger than this cast gate.This cavity section has: the first area that is right after this cast gate downstream position; Become the second area of the major part of this die cavity away from this cast gate and one; And the 3rd zone between first area and second area.The position of measurement mode cavity pressure is positioned at the second area of this cavity section, and preferably is positioned at the center of the second area of this cavity section.

Description of drawings

Fig. 1 is the vertical cross section that is used for realizing the die assembly of method of the present invention;

Fig. 2 A is the horizontal sectional drawing of cutting open along the 2A line of Fig. 1;

Fig. 2 B is the curve map that is illustrated in the pressure distribution in a part of mould cavity of cast gate of contiguous this mould;

Fig. 3 is the illustration curve map of this mode, that is: by test injection process according to the present invention determine the to keep-up pressure initial pressure of control;

Fig. 4 is the flow chart of the expression operating sequence that injection (mo(u)lding) machine in use carries out according to the present invention;

Fig. 5 is the curve map of explanation one pressure curve, and this pressure curve is illustrated in the cavity pressure in the process of carrying out the injection moulding operation;

Fig. 6 A and 6B be expression conventional adopt be used for determining to keep-up pressure the curve map of two kinds of distinct methods of initial pressure of control; And

Fig. 7 is the conventional view that is used for pressure sensor is contained in the exemplary that the sensor in the mould is provided with that adopts of expression.

The specific embodiment

Come to describe in further detail a preferred embodiment of the present invention below with reference to the accompanying drawings.

Fig. 1 represents to be used for to realize the profile of the die assembly of method of the present invention.This die assembly 10 comprises moveable die 11 and fixed mould 12.Fixed mould 12 has formation hot flow path 13 and inwardly projecting orifice or cast gate 14 within it.This moveable die 11 and fixed mould 12 are limited with die cavity 15 between them, this die cavity 15 is communicated with injection nozzle 18 by cast gate 14 and hot flow path 13.This fixed mould 12 has the pressure sensor 17 that embeds by this way in it, that is: this pressure sensor 17 is faced the part 16 of the die cavity 15 that is positioned at contiguous cast gate 14 positions.

Shown in Fig. 2 A, cavity section 16 has the big a lot of cross-sectional area of cross-sectional area than cast gate 14, is enough to make the molten resin that flows out from cast gate 14 to be directed to reposefully the major part of die cavity 15 by this cavity section 16.This main cavity section has the volume space that substantially exceeds cavity section 16.In an illustrated embodiment, this cavity section 16 has foursquare cross section.Pressure sensor 17 preferably is arranged on the center of this cavity section 16, as being appreciated that from the description that provides below with reference to Fig. 2 A and 2B.

Fig. 2 B is the curve map of the pressure distribution in the expression cavity section 16, measures by working pressure sensor 17 when changing the position of pressure sensor 17 with respect to cast gate 14 (Fig. 2 A) and can obtain this pressure distribution.Fig. 2 A and 2B are shown as so interrelatedly, that is: the reference axis initial point of the chart shown in Fig. 2 B is consistent with the exit position of the cast gate 14 shown in Fig. 2 A.

At the first area E that is arranged in this cavity section 16 that is right after cast gate 14 downstream portion (Fig. 2 B), the pressure of molten resin fluctuates.This be because: owing at the resin that allows fusing turbulent flow, whirlpool or similar disturbing phenomenon take place when cast gate 14 is emitted the excessive space that enters this cavity section 16 suddenly, so the pressure on molten resin can change a lot along with the position.

In the second area G of cavity section 16 (Fig. 2 B), the pressure of molten resin is shown as rapid decline, and wherein this second area is arranged in away from the position of cast gate 14 and its and merges to the major part of die cavity 15.This be because: the resin of fusing flows into from this cavity section 16 and compares this main cavity section with excessive space with this cavity section 16.

Among the 3rd regional F (Fig. 2 B) of this cavity section 16 in the middle of being located substantially on first area E and second area G, the pressure of molten resin is fluctuation not, and little by little descends with basic even velocity along with the distance of leaving cast gate 14 increases.Can expect: in case the resin of fusing is filled this cavity section 16, the pressure of the molten resin in cavity section 16 will become stable so.According to the pressure distribution among Fig. 2 B, obviously as can be seen, pressure sensor 17 preferably is arranged in the 3rd regional F, especially is arranged on the middle position away from the 3rd regional F of first area E and second area G.

Fig. 3 is the illustration curve map of this mode, that is: by test injection process according to the present invention determine the to keep-up pressure initial pressure of control.When finishing this test injection process, do not carry out injection pressure control, but carry out injection speed control.Pressure curve H at expression molten resin pressure comprises under the condition of the crest that appears at test injection process final stage, implements this test injection process.In the trough J that after this pressure curve H is formed on crest, occurs for the first time, can find the pressure P s on this time point.Then, pressure P s is set at the initial pressure that keep-ups pressure and control, it is used for carrying out pressure control in resin forming operating process subsequently.Because with pressure curve H is that the initial pressure Ps of control that keep-ups pressure is determined on the basis, so can carry out the test injection forming process by single in fact, acquisition is used for the setup pressure value of the initial pressure of this control that keep-ups pressure.

Fig. 4 is the flow chart that the operating sequence of carrying out between the operating period of injection (mo(u)lding) machine according to the present invention is described.

At first step ST01, the injection (mo(u)lding) machine that die assembly 10 (Fig. 1) is housed is set to operate with the injection speed control model.In this injection speed control model, control the screw rod extruded velocity of injection device according to preset program, thereby control the injection speed of this injection (mo(u)lding) machine.

Then, step ST02 start injection process is implemented injection speed control simultaneously.

In injection process, shown in step ST03, working pressure sensor 17 is measured the pressure that flows into the molten resin in the die cavity 15 from cast gate 14.

Judge at step ST04 whether Pact is equal to, or greater than Ps, wherein: Pact represents the actual pressure that records by pressure sensor 17 (Fig. 1) acquisition, and Ps represents according to previous initial pressure with reference to the definite control that keep-ups pressure of figure 3 described modes.When this is judged to be when sure, program proceeds to step ST05, and at this, the injection speed control model is converted to the control model that keep-ups pressure.Subsequently, carry out the control procedure that keep-ups pressure.

When being judged to be of step ST04 negates, program turns back to step ST03, and continues injection process.

Fig. 5 is the curve map of pressure curve that is illustrated in the pressure of the molten resin in the die cavity 15, and this pressure is to observe between the operating period of this injection (mo(u)lding) machine.When carrying out injection speed control, carry out injection process.This injection process continues always, reaches the initial pressure Ps of the predetermined control that keep-ups pressure up to the pressure of the molten resin that obtains by actual measurement, on this basis injection speed is controlled transitions to pressure control (control keep-ups pressure).Coincide well by pressure curve and the optimum pressure curve A shown in Fig. 6 A and the 6B that aforesaid operations obtains.This means: the initial pressure Ps of the control that keep-ups pressure that the method according to this invention is determined is particularly useful.

As described in, the present invention is used for determining that the method for initial pressure of the control that keep-ups pressure of resin injection moulding comprises the following steps: when carrying out injection speed and control, carry out the test injection process, to obtain the pressure curve under this condition, this condition is: this pressure curve comprises because the crest that draws at the cavity pressure of the final stage appearance of this test injection process; Find a pressure, this pressure is the pressure that this pressure curve is formed on the trough place that occurs for the first time after the crest; And the pressure that will find like this is set at the initial pressure of the control that keep-ups pressure, and it is used for carrying out the pressure control in resin forming operating process subsequently.Because with the pressure curve is that the initial pressure of control that keep-ups pressure is determined on the basis,, obtain the setup pressure value of the initial pressure of this control that keep-ups pressure so can carry out the test injection forming process by single in fact.This process has reduced the man-hour of test injection process greatly.

In addition, the method according to this invention can improve the crest pressure in injection speed and reduction or the reduction injection process.The reducing of crest pressure allows the mould that uses rigidity to reduce, thereby die size is reduced.

The method according to this invention, the molten resin in the die cavity that injects die assembly from cast gate can steady flow the position, measure this cavity pressure.Particularly, before the remainder of this die cavity, be positioned at the resin that the cavity section at contiguous this gate location place is melted and fill, and become stable very soon at the cavity pressure (being the pressure of molten resin) of this cavity section.The pressure sensor that is used for the measurement mode cavity pressure is positioned at this cavity section, and preferably is positioned at the central authorities of this cavity section.This set can guarantee stable injection moulding operation.

Industrial applicibility

Adopt above-mentioned setting, the present invention can be advantageously used for and be very easy to and be identified for efficiently The method of the pressure controlled initial pressure of maintenance of resin injection moulding.

Claims

1. method of initial pressure that is identified for the control that keep-ups pressure of resin injection moulding, it comprises the following steps:

(a) when carrying out injection speed control, carry out the test injection process, to obtain the pressure curve under such condition, that is: this pressure curve comprises the crest that cavity pressure drew that takes place owing to the final stage in this test injection process;

(b) find such pressure, at this pressure place, this pressure curve is formed on the trough that occurs for the first time after this crest; And

(c) pressure that will find like this is set at the initial pressure of the control that keep-ups pressure, and it can be used in and carry out pressure control in resin forming operating process subsequently,

Wherein, described cavity pressure is measured in the position of the molten resin steady flow in the die cavity that injects die assembly from cast gate.

2. the method for claim 1, it is characterized in that, described die cavity has the cavity section and this cavity section that are positioned at described gate location place and has the space bigger than described cast gate, and this cavity section has: the first area that is right after this cast gate downstream position; Away from this cast gate and merge to the second area of the major part of this die cavity; And the 3rd zone between first area and second area, and the described position of wherein measuring this cavity pressure is positioned at the second area of this cavity section.

3. method as claimed in claim 2 is characterized in that, the described position of measuring this cavity pressure is positioned at the central authorities of the second area of this cavity section.