JP2009137130A - Die molding method and molding die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding method and an injection molding die allowing a molded product molded in a first die and a second die by injecting material, to be surely taken out of the second die side. <P>SOLUTION: This die molding method is carried out by allowing a fixed die 10 and a movable die 40 to abut on each other to form a cavity 2, bringing the molded product 92 into close contact with the movable die 40 when separating the movable die 40 from the fixed die 10 after injection-molding a molding material MT, and then separating the molded product 92 from the movable die 40 using an eject pin 50. When the movable die 40 is separated from the fixed die 10, a push-out means 30 provided at the fixed die 10 pushes out the molded product 92 toward the movable die 40 side, and mold release resistance force R when the eject pin 50 separates the molded product 92 from the movable die 40 is measured by a load cell 70. The push-out force F of the push-out means 30 is changed according to the mold release resistance force R measured by the load cell 70. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In this invention, the first mold and the second mold are brought into contact with each other to form a cavity, and after the material is injected and molded, when the second mold is separated from the first mold, The present invention relates to a molding method and a molding die in which a molded product is brought into close contact with the second mold, and then the molded product is separated from the second mold by an eject pin.

Conventionally, a cavity is formed by bringing a fixed mold and a movable mold into contact with each other, and after molding the material by injection, the molded product is moved to the movable mold when the movable mold is separated from the fixed mold. An injection molding method is performed in which the molded product is brought into close contact with the mold, and then the molded product is separated from the movable mold by an eject pin.
In the injection molding method, when the movable mold is separated from the fixed mold, the molded product is changed in shape, runner shape, etc. in order to ensure that the molded product is closely attached to the movable mold and separated. Devised to increase the mold release resistance.
On the other hand, in Patent Document 1, an auxiliary projection plate 15 is slidably provided facing the PL surface of a fixed mold for a primary molded product, and can be projected and retracted by a spring 16 so that the primary molded product is movable when the mold is opened. It is described that it is surely moved and held in the cavity 4. That is, a method is described in which an extrusion pin that acts by a spring force is provided on the fixed mold side, and the molded product is securely adhered to the movable mold.

JP-A-8-197578, paragraph (0010)

However, the invention disclosed in Patent Document 1 has the following problems.
That is, due to the secular change of the mold, the surface roughness of the cavity surface deteriorates and the mold release resistance on the fixed mold side increases, so the molded product is fixed when the movable mold and the fixed mold are separated. There was a problem that remained on the mold side.
This problem occurs for the following reasons. That is, among the molded products by the injection molding method, in the injection molding in which the stator of the motor for a hybrid vehicle is molded, the molding material that is the material of the molded product includes, for example, resin materials such as styrene and saturated polyester, alumina A relatively hard mixed material such as glass fiber is included. When such a molding material is molded with a mold, the mixed material in the molding material touches the cavity surface during molding, thereby deteriorating the surface roughness of the cavity surface. The surface roughness of the cavity surface deteriorates as the number of molding shots increases, and the mold release resistance on the fixed mold side gradually increases.
When the mold release resistance increases and the molded product remains in the fixed mold, the molded product is forcibly taken out, and it is difficult to use the molded product as a product. In the injection molding method for molding a stator of a hybrid vehicle motor, since the price per molded product is high, this is a serious problem.

  The present invention has been made in view of the above circumstances, and it is possible to reliably take out the molded product formed by the first mold and the second mold by injecting the material from the second mold side. An object is to provide a mold forming method and a mold.

In order to achieve the above object, a mold forming method and a mold according to the present invention have the following configurations.
(1) The first mold and the second mold are brought into contact with each other to form a cavity, the material is injected and molded, and then the second mold is separated from the first mold. In a mold molding method in which a product is brought into close contact with the second mold, and then the molded product is separated from the second mold by an eject pin, the first mold and the second mold are separated from each other. When the extrusion means provided in the first mold pushes the molded product to the second mold side, the eject pin separates the molded product from the second mold. The mold release resistance force is measured by the mold release resistance measuring means, and the pushing force of the pushing means is changed according to the mold release resistance force measured by the mold release resistance measuring means.

(2) The first mold and the second mold are brought into contact with each other to form a cavity, and after the material is injected and molded, the molding is performed when the second mold is separated from the first mold. In a molding die in which the product is brought into close contact with the second die and then the molded product is separated from the second die by an eject pin, the first die is provided on the first die. Extrusion means for extruding the molded product to the second mold side when the second mold is separated from the second mold, and mold release resistance when the eject pin separates the molded product from the second mold It has a release resistance measuring means for measuring a force, and a control means for changing the pushing force of the pushing means according to the release resistance force measured by the release resistance measuring means.

Next, the operation and effect of the mold forming method and the mold according to the present invention having the above-described configuration will be described.
In the mold molding method of the present invention using the molding mold of the present invention, the first mold and the second mold are brought into contact with each other to form a cavity, the material is injected and molded, and then the second mold is molded. When the mold is separated from the first mold, the molded product is brought into close contact with the second mold, and then the molded product is separated from the second mold by an eject pin. Then, when the first mold and the second mold are separated from each other, the extrusion means provided in the first mold pushes the molded product to the second mold side, and the eject pin pushes the molded product. The release resistance measuring means measures the release resistance force when separating from the second mold, and the pushing force of the pushing means is changed according to the release resistance force measured by the release resistance measurement means. Therefore, when the first mold and the second mold are separated from each other, the molded product was measured by the mold release resistance measuring means. In extrusion force of the extrusion means is varied depending on the type resistance, is pushed out to the second mold side.

By the way, when molding the stator of a hybrid vehicle motor with resin, for example, in addition to a resin material such as styrene and saturated polyester, a mold material containing a relatively hard mixed material such as alumina and glass fiber is injected. There is a case where injection is performed by a molding method and molding is performed using a fixed mold and a movable mold.
In such molding, the mixed material in the mold material touches the cavity surfaces of both molds to roughen the cavity surface. The surface roughness of the cavity surface gradually deteriorates with aging.
The applicant conducted an experiment to analyze this phenomenon in detail. In the experiment, especially when the number of moldings (number of molding shots) increases from tens of thousands to hundreds of thousands, the surface roughness of the cavity surface extremely deteriorates as the number of molding shots increases. It was newly confirmed that the mold release resistance when the product is separated from the fixed mold is considerably increased.
Such deterioration of the surface roughness is assumed to proceed in the same way on both sides of the fixed mold and the movable mold. That is, the mold release resistance force when the molded product is separated from the fixed mold and the mold release resistance force when the molded product is separated from the movable mold by the eject pin are approximately the same magnitude. Conceivable.

Also, through experiments, regarding the mold release resistance when the molded product is separated from the fixed mold, when the magnitude of the mold release resistance when the number of molding shots is the first time is 1, for example, from several thousand times to 10,000 The mold release resistance increases rapidly as the number of molding shots increases, approximately twice as much as the first time before and after the rotation, and approximately five times the first time when tens of thousands of times. The resistance continued to increase with the increase in the number of molding shots, and when it reached hundreds of thousands of times, it was newly found out that its release resistance was actually more than 10 times that of the first time.
In general, in injection molding using a fixed mold and a movable mold, these molds are used up to the number of molding shots exceeding several hundred thousand times as the number of times they can be used.
Under these circumstances, even if an extrusion pin that operates with a constant spring force is provided on the fixed mold side, as in the conventional injection molding method, if the spring is used with the spring force kept constant, it will be fixed. While using the mold and the movable mold, the spring force may be smaller than the resistance to release when the molded product is separated from the fixed mold, which may occur when the number of molding shots is relatively small. .
Then, when the movable mold and the fixed mold are separated from each other, the molded product may remain on the fixed mold side due to the difference from the spring force and the mold release resistance force remaining on the fixed mold side.

On the other hand, in the mold molding method of the present invention using the molding mold of the present invention, the mold release resistance measuring means measures the mold release resistance force when the molded product is separated from the second mold by the eject pin. Since the pushing force by the pushing means is changed according to the measured release resistance, the surface roughness of the cavity surface deteriorates due to secular change, and the release resistance on the first mold side increases. In addition, the molded product can be pushed out to the second mold side by the pushing force overcoming the mold release resistance by the pushing means.
That is, it is considered that the mold release resistance when the molded product is separated from the first mold is substantially the same as the mold release resistance force when the molded product is separated from the second mold by the eject pin.
From this, the mold release resistance on the first mold side continues to increase to about several times, about five times, etc. with respect to the magnitude of the mold release resistance when the number of molding shots is the first time, and several tens of times. If the release resistance when reaching 10,000 times is more than 10 times the initial value, the release resistance force on the second mold side is the same as the release resistance on the first mold side. It is assumed that the trend is increasing.
In the mold forming method of the present invention using the mold of the present invention, the extrusion means measures the mold release resistance force when the eject pin separates the molded product from the second mold by the mold release resistance measuring means. Then, the molded product is pushed out to the second mold side with the pushing force changed according to the measured release resistance.
For this reason, even if the mold release resistance on the first mold side continues to increase to about 2 times, about 5 times, etc. at the time of the first time, the extrusion means does not exceed 10 times. Since the molded product is pushed out to the second mold side with the pushing force changed according to the measured release resistance on the second die side, the molded product inevitably becomes the first by the pushing force of the pushing means. 2 It will be pushed out to the mold side.
Therefore, when the first mold and the second mold are separated from each other, the molded product can be reliably taken out from the second mold side.

(Embodiment)
Hereinafter, an embodiment in which a molding die according to the present invention is embodied will be described in detail with reference to the drawings.
1 and 2 are cross-sectional views illustrating the configuration of an injection mold 1 according to this embodiment. FIG. 1 shows a clamped state during molding, and FIG. 2 shows a mold open state after molding. FIG. 3 is an explanatory diagram showing the P portion in FIG. 2 in an enlarged manner. FIG. 4 is an explanatory view showing an electric control circuit of the injection mold 1 shown in FIG.
In the present embodiment, the injection mold 1 (molding mold) injects resin into the insert member 91 that is a component constituting the stator portion of the motor for a hybrid vehicle by an injection molding method, and the fixed mold 10 (first mold). This is a mold for producing a product 90 obtained by molding a molded product 92 formed by one mold) and a movable mold 40 (second mold). The insert member 91 includes a substantially annular bus bar portion and a plurality of coil portions connected to the bus bar portion on the inner diameter side.

As shown in FIGS. 1 to 4, the injection mold 1 includes a fixed mold 10, an extrusion means 30, a movable mold 40, an eject pin 50, a load cell 70, a control means 80, and the like.
An extrusion means 30 is disposed on the fixed mold 10 side, and an eject pin 50 and a load cell 70 are disposed on the movable mold 40 side. The injection mold 1 is electrically controlled by the control means 80. To work.

First, the control means 80 will be described.
As shown in FIG. 4, the control unit 80 includes a known microcomputer such as an I / O terminal 81, a CPU 82, a RAM 83, and a ROM 84. The microcomputer is loaded with a later-described release resistance force measurement program stored in the ROM 84 or the like, or other program on the CPU 82, so that a predetermined operation, for example, a movable mold mounting plate 41 and an eject pin mounting described later are mounted. The operation of the panel 60, the operation of the load cell 70, the driving of the fluid supply source 25, and the like are performed.

Next, the fixed mold 10 will be described.
The fixed mold 10 is fixed to a fixed mold mounting board 11 having a structure that does not move in the mold opening / closing direction (vertical direction in FIGS. 1 and 2).
The fixed mold 10 includes four work push pins 20 and four push means 30 disposed between each work push pin 20 and the fixed mold mounting board 11.
The workpiece extruding pin 20 is a pin that holds the insert member 91 while being clamped together with the movable die 40 by pressing by the extruding means 30 at the time of mold clamping, and as shown in FIG. 5, the fixed die 10 and the movable die 40. Are arranged on the outer side in the radial direction of the doughnut-shaped cavity 2 formed in contact with each other at a position divided into four equal parts in the circumferential direction. FIG. 5 is a plan view of the fixed mold viewed from the parting surface PL in FIG.

In the present embodiment, the pushing means 30 is a gas cylinder, and is configured to be able to vary the pressing force toward the movable mold 40 according to the flow rate of the working gas. When the mold is clamped, the extruding means 30 presses the work extruding pin 20 toward the movable mold 40 with a predetermined pressing value, while the movable mold 40 and the fixed mold 10 are separated from each other by a predetermined pressing force. The workpiece extruding pin 20 is pressed by changing the pressing value of the molded product 92 to the movable mold 40 side.
Specifically, each extrusion means 30 is connected to four independent fluid supply sources 25 by piping (not shown). This fluid supply source 25 supplies working gas to the extrusion means 30.
Each fluid supply source 25 is electrically connected to the I / O terminal 81 of the control means 80, and controls the flow rate of the working gas to the pushing means 30 to be connected based on the operation command from the CPU 82, This is configured to be supplied to the extrusion means 30. Thus, the pushing means 30 changes the pressing force to the workpiece pushing pin 20 according to the flow rate of the working gas controlled by the fluid supply source 25 to be connected.

Next, the movable mold 40 will be described.
The movable mold 40 is fixed via an intermediate member 42 to a movable mold mounting plate 41 that can move in the mold opening / closing direction (vertical direction in FIGS. 1 and 2). The movable mold 40 moves to the parting surface PL which is a mold clamping position with the fixed mold 10 by the movement in the mold opening / closing direction by the movable mold mounting plate 41 and comes into contact with the fixed mold 10. Yes.
The movable mold 40 has a mounting surface 40a on which the insert member 91 is mounted, and has a central cylindrical portion 43 that protrudes from the mounting surface 40a toward the fixed mold 10 side. As shown in FIGS. 5 and 6, the central cylindrical portion 43 is positioned at the radial center portion of the inserted insert member 91, and the movable mold 40 and the fixed mold 10 abut on the parting surface PL. When this is done, the cavity 2 is formed between the fixed mold 10. FIG. 6 is a plan view of the movable mold as viewed from the parting surface PL in FIG.
At the time of injection molding, a molding material MT, which is a material of the molded product 92, is injected into the cavity 2 from a sprue (not shown) provided on the fixed mold 10 side through a runner 93 and a gate (not shown) to form the molded product 92. (See FIG. 1).
In this embodiment, the mold material MT includes a material including a main material that is a resin material such as styrene or saturated polyester, a sub-material such as alumina or glass fiber, and a release material.

The movable mold 40 is provided with eight rod-like eject pins 50 for separating the molded product 92 from the movable mold 40. Each eject pin 50 is arrange | positioned in the position which divides the cavity 2 into 8 equally in the circumferential direction between adjacent coil parts among the insert members 91 (refer FIG. 6). The eject pin 50 is supported at its lower end 51 by an eject pin mounting board 60 disposed on the inner side of the intermediate member 42.
The eject pin mounting board 60 is connected to a hydraulic cylinder (not shown) that is electrically connected to the I / O terminal 81 of the control means 80, and has a predetermined stroke in the mold opening / closing direction (the vertical direction in FIG. 1 and the like). It is configured to be movable within a range.
When the eject pin mounting board 60 is raised, the eject pins 50 are also raised accordingly, and the molded product 92 that is in contact with the upper end surface 50a of each eject pin 50 is lifted upward to mount the movable mold 40. Separated from the mounting surface 40a. Thereby, the molded product 92 is separated from the movable mold 40.

Next, the load cell 70 (release resistance measuring means) will be described.
Eight load cells 70 are arranged between the lower end 51 of each eject pin 50 and the abutment 61 of the eject pin mounting board 60 in a state where the lower end 51 and the abutment 61 can abut. It is installed.
The load cell 70 is a load cell having a known configuration, and measures the release resistance R when the eject pin 50 separates the molded product 92 (product 90) from the movable mold 40.
Specifically, in the load cell 70, the abutting portion 61 is moved through the load cell 70 until the molded product 92 is lifted from the placement surface 40 a of the movable die 40 due to the elevation of the eject pin mounting plate 60. The pressing force applied to the load cell 70 when the is pressed is measured as the release resistance R.
Each load cell 70 is electrically connected to the I / O terminal 81 of the control means 80, and outputs a measured value Rm of the release resistance R to the RAM 83 of the control means 80.

Next, the manufacturing process of the product 90 using the injection mold 1 will be briefly described.
The insert member 91 is placed at a predetermined position on the placement surface 40 a of the movable mold 40. Thereafter, the movable mold 40 is moved to the parting surface PL with the fixed mold 10 to bring the movable mold 40 and the fixed mold 10 into contact with each other. Thereby, the cavity 2 is formed in the injection mold 1.
Next, the pushing means 30 pushes the workpiece pushing pin 20 toward the movable mold 40 with a predetermined pressing value, and holds the insert member 91 placed on the placement surface 40 a in the cavity 2.
Next, the molding material MT is injected into the cavity 2 through a runner 93 and a gate (not shown) from a sprue (not shown) provided on the fixed mold 10 side at an injection pressure of 10 MPa, for example. Thereby, the mold material MT is filled in a form covering the periphery of the insert member 91 in the cavity 2, and thereafter, the mold material MT in this state is cooled.
Thus, the molding material MT in the cavity 2 becomes a molded product 92 in a molded form, and a product 90 in which the insert member 91 is molded by the molded product 92 is obtained.
Note that the cured molding material MT in the runner 93 and the gate until reaching the cavity 2 is removed from the product 90 in a subsequent process.

Next, a mold forming method according to this embodiment using the injection mold 1 will be described with reference to FIGS.
FIG. 7 is a view showing a state in which the movable mold 40 and the fixed mold 10 are separated from each other in the injection mold 1, and the molded product 92 is moved by the pushing means 30 through the workpiece pushing pins 20. The state after pushing out to the side is shown. FIG. 8 is a flowchart showing the configuration of the release resistance measurement program. FIG. 9 is a table used to calculate the pressing force Fn of each workpiece pushing pin 20.

The mold molding method according to the present embodiment is performed when the movable mold 40 is separated from the fixed mold 10 after the molding material MT is injected into the cavity 2 and molded in the manufacturing process of the product 90 described above. It is premised on an injection molding method in which the product 92 is brought into close contact with the movable mold 40 and then the molded product 92 is separated from the movable mold 40 by the eject pin 50.
In the mold forming method according to the present embodiment, (1) when the movable mold 40 and the fixed mold 10 are separated from each other, the extrusion means 30 provided in the fixed mold 10 moves the molded product 92. Extrusion to the mold 40 side, (2) The load cell 70 measures the release resistance R when the eject pin 50 separates the molded product 92 from the movable mold 40, and (3) the load cell 70 measures. The extrusion value Fn of the pushing force F of the pushing means 30 is changed according to the measured value Rm of the mold release resistance R.

The mold forming method according to this embodiment will be described in detail.
This mold forming method is performed based on the procedure of the mold release resistance measurement program shown in FIG. 8 when repeatedly manufacturing a plurality of products 90 continuously.
In other words, this release resistance measuring program is executed by the control means 80 every time corresponding to the number of products 90 to be manufactured.
The mold release resistance measurement program starts from a state where the movable mold 40 and the fixed mold 10 are clamped after the molded product 92 is molded in the cavity 2 (the state shown in FIG. 1). To be started.

First, in step S10, when the molded product 92 that is in close contact with the movable mold 40 is separated from the movable mold 40 with respect to the previous molded product 92 molded once before, the eight eject pins 50 are respectively provided. The release resistance R received is measured by each load cell 70.
Specifically, the release resistance R received by the eight eject pins 50, that is, the first to eighth eject pins 51, 52, 53, 54, 55, 56, 57, and 58, respectively, is individually received. The eight load cells 70 that abut are measured.
When the previous molded product 92 does not exist, that is, when the molded product 92 to be the product 90 is formed for the first time, for example, a molded product 92 for a test product different from the product 90 is used. It is preferable to measure the release resistance R.

Next, in step S11, each load cell 70 has a measured value Rm (1 ≦ m) of the release resistance R measured by the first to eighth eject pins 51, 52, 53, 54, 55, 56, 57, 58. ≦ 8) is output to the control means 80, and the eight measurement values Rm are read and stored by the control means 80.
In FIG. 9, the measured value Rm is R ₁ measured with the first eject pin 51, R ₂ measured with the second eject pin 52, and the eighth eject pin in the same manner. those measured at 58 is denoted by R _8.

Next, in step S12, the pin release resistance, which is the release resistance force R for the three eject pins 50, is controlled by using the three measured values Rm for one push pin 20. Calculate with 80.
As shown in FIGS. 6 and 9 to be referred to, the three measured values Rm correspond to the four workpiece pushing pins 20 (first, second, third and fourth workpiece pushing pins 21 with respect to the radial direction of the cavity 2. , 22, 23, 24), the measured value Rm received by the eject pin 50 adjacent to the second, fourth, sixth, eighth, eject pins 52, 54, 56, 58 is first selected as the center value. Then, the two measured values Rm received by the eject pin 50 corresponding to the center value and the eject pin 50 adjacent in the radial direction of the cavity 2 are used as adjacent values.
Specifically, the second eject pin 52 that is radially adjacent to the first workpiece pushing pin 21 is adjacent to the first and third eject pins 51 and 53.
Therefore, the measurement value Rm at the second eject pin 52 is the measurement value R ₂ , and the measurement values Rm at the first and third eject pins 51 and 53 are the measurement values R ₁ and R ₂ , respectively. In the calculation of the pin release resistance applied to the workpiece pushing pin 21, the measured values R ₁ , R ₂ , and R ₃ are used.
Similarly, in the calculation of the pin release resistance applied to the second workpiece extrusion pin 22, the measured values R ₃ , R ₄ and R ₅ are used. In the calculation of the pin release resistance applied to the third workpiece extrusion pin 23, the measured value R ₅ , R ₆ , and R ₇ are used to calculate the pin release resistance applied to the fourth workpiece extrusion pin 24, and the measured values R ₇ , R ₈ , and R ₁ are used.
As a method for calculating the pin release resistance, for example, the average value of the three measured values Rm is set as the calculated value Cn, and the measured value as the center value is doubled to the two measured values as adjacent values. There is a method of adding the obtained products and calculating an operation value Cn or the like obtained by multiplying the total at this time by 1/2.

Next, in step S <b> 13, when the control unit 80 separates the movable mold 40 from the fixed mold 10, the pressing force F is pressed when the four workpiece pushing pins 20 are pressed by the respective pushing means 30. The value Fn is determined. The pressing value Fn is set so as to be larger than the calculated value Cn according to the calculated value Cn of the pin release resistance calculated in step S12.
Specifically, the pressing value F ₁ of the first workpiece pushing pin 21 is set larger than the calculated value C ₁ calculated using the measured values R ₁ , R ₂ , and R ₃ . Similarly, the pressing pressure value _{F 2} of the second workpiece push-out pin 22, from the measurement value _{R 3,} R 4, calculated value _{C 2} calculated using the _{R 5,} the pressing pressure value _{F 3} of the third workpiece push-out pin 23, from the measurement value _{R 5,} R 6, _{R 7} calculated value _{C 3} calculated using the pressing pressure value _{F 4} of the fourth work extrusion pin 24, was calculated using the measured values _{R 7, R 8, R 1} operation than the value _{C 4,} both set large.

Next, in step S14, the CPU 82 of the control means 80 commands each fluid supply source 25 to operate based on the pressing value Fn determined in step S13, and the flow rate of the working gas supplied to the pushing means 30 to be connected. To control.
Next, when the movable mold 40 moves away from the fixed mold 10 in step S15, the pressing force F of the pushing means 30 corresponding to the flow rate of the working gas controlled by the fluid supply source 25, that is, in step S13. Each workpiece push pin 20 (first to fourth workpiece push pins 21, 22, 23, 24) is pushed with the determined four pressing values Fn, and the molded product 92 is pushed to the movable mold 40 side. Then, as shown in FIG. 7, the molded product 92 moves away from the fixed mold 10 and in close contact with the movable mold 40, and moves in the mold opening direction (downward in FIG. 7) together with the movable mold 40. To do.
When the movable mold 40 is in the mold open state, the eject pin mounting plate 60 is raised, and the molded product 92 (product 90) is lifted by the eight eject pins 50 and separated from the movable mold 40 (see FIG. 2). .

Next, in step S16, when the product 90 is continuously manufactured, it is determined whether or not the next molded product 92 is continuously formed. When performing shaping | molding continuously, it progresses to YES and performs step S10.
However, if step S15 is performed and the release resistance R received by each of the eight eject pins 50 is measured by each load cell 70, the process proceeds to YES, and step S11 may be performed.
On the other hand, when the next molded product 92 is not continuously molded, the process proceeds to NO, and the execution of the release resistance measuring program is terminated.

By the way, in manufacturing a product in which a stator (corresponding to the insert member 91) of a hybrid vehicle motor is molded with a resin as in the mold forming method according to the present embodiment, for example, a resin material such as styrene or saturated polyester. In addition, there is a case where a molding material containing a relatively hard mixed material such as alumina or glass fiber is injected by an injection molding method and molded with a fixed mold and a movable mold.
In such molding, the mixed material in the mold material touches the cavity surfaces of both molds, and the cavity surfaces become rough. The surface roughness of the cavity surface gradually deteriorates with aging. Such deterioration of the surface roughness is assumed to proceed in the same way on both sides of the fixed mold and the movable mold. That is, the mold release resistance force when the molded product is separated from the fixed mold and the mold release resistance force when the molded product is separated from the movable mold by the eject pin are approximately the same magnitude. Conceivable.
Under this assumption, the applicant measured the release resistance on the movable mold side and analyzed in detail the phenomenon that the surface roughness deteriorates.

The analysis results are shown in FIGS. FIG. 10 shows the relationship between the number of moldings (number of molding shots), the surface roughness Rz of the fixed mold, and the release resistance R when the molded article is separated from the movable mold by the eject pin. The results are shown. FIG. 11 is a graph showing the relationship between the number of molding shots and the release resistance R in FIG. FIG. 12 is a graph showing the relationship between the number of molding shots and the surface roughness Rz in FIG.
The surface roughness Rz is a ten-point average roughness Rz defined in the JIS method. The release resistance force R is the release resistance force R measured when the eject pin 50 separates the molded product 92 from the movable mold 40.
As can be easily understood from FIG. 12, it can be seen that the surface roughness Rz of the fixed mold is deteriorated in proportion to the increase in the number of molding shots. As described above, this is because the mixed material in the mold material touches the cavity surface on the fixed mold side and gradually deteriorates due to secular change. It is considered that the deterioration of the degree Rz is progressing.
On the other hand, when the graph shown in FIG. 11 is seen, the mold release resistance R on the movable mold side is shown, but the increasing tendency of the mold release resistance R is the same on the fixed mold side. Inferred. Under these assumptions, the surface roughness Rz of the cavity surface on the fixed mold side deteriorates as the number of molding shots increases, especially when the number of molding shots increases from tens of thousands to hundreds of thousands of times. It has been newly found that the mold release resistance when the mold is separated from the fixed mold is extremely increased compared to the state up to several thousand times.

Furthermore, regarding the mold release resistance when the molded product is separated from the fixed mold, that is, the mold release resistance force R on the movable mold side, the magnitude of the mold release resistance force R when the number of molding shots is around the first time is set to 1. Sometimes, for example, about twice as many as the first time at the time of several thousand to about 10,000 times, about five times the first time at the time of tens of thousands, etc. The mold release resistance continues to increase as the number of molding shots increases, and after that, when it reaches hundreds of thousands of times, the mold release resistance is actually more than 10 times that of the first time. Also confirmed anew.
Specifically, description will be made using the data shown in FIGS. That is, the release resistance R when the number of forming shots is the first, 10,000 times, 100,000 times, and 400,000 times is 3.92 × 10 ³ (N), 9.8 × 10 ³ (N), and 29.4 × 10 ³ (in this order). N), 49.0 × 10 ³ (N). Assuming that the measured value 3.92 × 10 ³ (N) of the release resistance R at the first time is 1, the number of molding shots increases as the number of molding shots increases approximately 10,000 times to 10,000 times and approximately 7.5 times to 100,000 times. It continues to increase rapidly. When it reaches 400,000 times, it reaches 49.0 × 10 ³ (N), which is more than 12 times.
Thus, the magnitude of the mold release resistance R near the first time and the magnitude of the mold release resistance R exceeding several hundred thousand times are larger than the magnitude of the mold release resistance by more than 10 times. Differences arise.

In general, in the injection molding using a stationary mold and a movable mold as in the mold molding method according to the present embodiment, these molds are used up to the number of molding shots exceeding hundreds of thousands as the number of times they can be used. Is done.
Under these circumstances, even if an extrusion pin that operates with a constant spring force is provided on the fixed mold side, as in the conventional injection molding method, if the spring is used with the spring force kept constant, it will be fixed. While using the mold and the movable mold, the case where the spring force is smaller than the resistance to release when the molded product is separated from the fixed mold may occur when the number of molding shots is relatively small.
Then, when the movable mold and the fixed mold are separated from each other, the molded product may remain on the fixed mold side due to the difference from the spring force and the mold release resistance force remaining on the fixed mold side.

On the other hand, in the mold forming method according to the present embodiment using the injection mold 1 of the present invention, the mold 92 when the molded product 92 (product 90) is separated from the movable mold 40 by the eject pin 50 is used. Since the load cell 70 measures the resistance force R and the pushing force F by the pushing means 30 is changed according to the measured pressing value Fn of the release resistance force F, even if the surface roughness of the cavity surface 2 is changed due to secular change. Even if the degree deteriorates and the mold release resistance on the fixed mold 10 side increases, the molded product 92 can be pushed out to the movable mold 40 side by the pushing force F by the extrusion means 30 that overcomes the mold release resistance.
That is, the mold release resistance when the molded product 92 is separated from the fixed mold 10 is almost the same as the mold release resistance force R when the molded product 92 is separated from the movable mold 40 by the eject pin 50. it is conceivable that.
From this, the mold release resistance on the fixed mold 40 side continues to increase to about several times, about five times, etc. with respect to the magnitude of the mold release resistance when the number of molding shots is the first time. If the release resistance when reaching 10,000 times is more than 10 times the first time, the release resistance R on the movable mold 40 side is also equal to the release resistance on the fixed mold 10 side. It is inferred that the trend is similar.
In the mold forming method according to the present embodiment using the injection mold 1 of the present invention, the extrusion means 30 causes the release force R when the eject pin 50 separates the molded product 92 from the movable mold 40. Is measured each time the molded product 92 is carried out once by the load cell 70, and the molded product 92 is moved to the movable mold 40 side with the pressing force Fn which is greatly changed according to the measured value Rm of the measured release resistance R. Extrude into.
For this reason, even if the mold release resistance on the fixed mold 10 side reaches about twice, about 5 times, or more than 10 times the size at the first time, the extrusion means 30 performs a molding shot. Since the molded product 92 is extruded to the movable mold 40 side with the extrusion value Fn of the pushing force F changed according to the release resistance R on the movable mold 40 side measured every time, the molded product 92 is extruded. The pushing force F of the means 30 inevitably pushes out to the movable mold 40 side.
Therefore, when the movable mold 40 and the fixed mold 10 are separated from each other, the molded product 92 can be reliably taken out from the movable mold 40 side.

Further, in the present embodiment, the product 90 is molded by the fixed mold 10 and the movable mold 40 by injecting resin to the insert member 91 which is a component constituting the stator part of the motor for the hybrid vehicle by an injection molding method. The molded product 92 is molded, and the price per product 90 is high.
According to the mold forming method according to the present embodiment using the injection mold 1, the mold release resistance on the fixed mold 10 side is increased, and the molded product 92 does not remain in the fixed mold 10, forcibly. The molded product 92 is not removed from the fixed mold 10.
Therefore, it is difficult to forcibly take out the molded product 92 remaining in the fixed mold 10 and use the molded product 92 as the product 90, thereby preventing the occurrence of economic loss due to the disposal of the product 90. can do.

(Deformation)
A mold forming method according to this modification using the injection mold 1 of the embodiment will be described with reference to FIGS. 10 and 11 and FIG.
FIG. 13 is a flowchart showing an inspection procedure of the pressing means 30 performed by the mold forming method according to the present modification.
The mold forming method according to this modified embodiment is different from the mold forming method according to the above-described embodiment in a method used to change the pressing force F of the pressing means 30. In the embodiment, the pressing means 30 configured in the injection mold 1 is a gas cylinder. On the other hand, in this modification, the pressing means 30 is configured as a coil spring.
However, the injection mold 1 used in this modification is the same as the injection mold 1 of the present embodiment except that the pressing means 30 is a coil spring and the fluid supply source 25 is not provided.
Therefore, it demonstrates centering on the metal mold | die shaping | molding method which concerns on this modification, and description of the part similar to embodiment is abbreviate | omitted or abbreviate | omitted.

The mold forming method according to this modification will be described in detail.
This mold forming method is based on the inspection of the pressing means 30 shown in FIG. 13 when repeatedly manufacturing a plurality of products 90.
The inspection of the pressing means 30 is performed in consideration of the tendency of the mold release resistance of the fixed mold 10 and the movable mold 40 to increase as the number of molding shots increases and the performance of the coil spring (pressing means 30) to be attached. In practice, for example, it is regularly performed at a frequency of about once a month.
That is, as can be seen from FIGS. 10 and 11 given as an example, the magnitude of the mold release resistance R of the fixed mold 10 and the movable mold 40 is from several thousand shots to about 10,000 times. For example, the rate of increase in the release resistance R accompanying the increase in the number of molding shots is higher than the rate of increase from several thousand to about 10,000 times. Although it tends to be small, it has continued to increase to about 2 times, about 5 times, etc. at the first time, and the mold release resistance when reaching hundreds of thousands of times is more than 10 times the first time It is guessed.
The pressing means 30 is a coil spring having a predetermined spring constant. Generally, in the coil spring, the allowable range of the spring force that can withstand the external force with high reliability as the resistance force applied to the coil spring in the spring force generated from the set spring constant is the set spring. It is thought that it does not reach several times the power.

From the viewpoint of reliability in terms of the performance of such a spring, the allowable range of the number of molding shots that can withstand the increasing release resistance R with the spring force of the coil spring attached to the injection mold 1 is It is considered that the number of molding shots is different when the number is relatively small and when the number is relatively large.
That is, at a time when the number of molding shots is relatively small, for example, the number of molding shots from the first to several thousand, and even after that, even if the spring is replaced with a new spring, the number of molding shots after the spring replacement is tens of thousands of times. Depending on the number of molding shots, there may occur a case where the spring force is smaller than the mold release resistance R when the molded product is separated from the fixed mold 10.
On the other hand, when the number of molding shots is relatively large, the spring force may be smaller than the mold release resistance force R when the number of molding shots is approximately tens of thousands to hundreds of thousands after the spring replacement.
Then, for the coil spring attached when the number of forming shots is the first time, it is necessary to inspect the first pressing means 30 when the number of forming shots reaches several thousand, and then The inspection of the pressing means 30 performed in (1) needs to be performed when the number of molding shots molded after the first inspection reaches tens of thousands.
Furthermore, as the timing of inspections to be performed after the second inspection, inspections are repeatedly performed based on this concept, and the number of molding shots scheduled for molding from the previous inspection to the next inspection is determined next time. As a reference time for inspecting the pressing means 30, a set number k of predicted results of analysis with reference to FIGS. 10 and 11 is set.

The periodic inspection is started in a state where the next molded product 92 is to be molded after the previous molded product 92 is molded as an initial state.
First, in step S20, it is determined whether or not the molding of the previous molded product 92 corresponds to the (k-1) th molding shot. When it corresponds to the (k-1) th time, the process proceeds to YES, and Step S21 is executed. On the other hand, if not applicable and less than the (k−1) th time, the process proceeds to NO, and step S22 is executed to mold the molded product 92 until the number of molding shots reaches the (k−1) th time. Continue repeatedly.
Next, in step S21, after the molding of the (k-1) -th molded product 92 is finished and the next k-th molded product 92 is molded, the molded product 92 in close contact with the movable mold 40 is formed. When each of the load cells 70 is separated from the movable mold 40, the release resistance R received by each of the eight eject pins 50 is measured by each load cell 70. Specifically, the release resistance R received by the eight eject pins 50, that is, the first to eighth eject pins 51, 52, 53, 54, 55, 56, 57, and 58, respectively, is individually received. Measurement is performed using the load cell 70 in contact.

Next, in step S23, the measured value Rm (1 ≦ m ≦ 8) of the release resistance R for eight places measured in step S21 is read.
Next, in step S24, the pin release resistance, which is the release resistance force R for three ejecting pins 50 applied to the three ejecting pins 50, is controlled by the control means 80 using the three measured values Rm. Calculate with.
Note that the selection method for selecting the three measurement values Rm and the calculation method using the three measurement values Rm for obtaining the pin release resistance are, in the embodiment, step S12 in the flowchart shown in FIG. Therefore, the description of the selection method and the calculation method is omitted here.

Next, in step S25, the calculated value Cn of the pin release resistance calculated in step S24 and data indicating the relationship between the number of molding shots and the release resistance R among the results shown in FIG. After collation, the pressing value Fn of the pressing force F by the pushing means 30 is determined.
That is, in FIG. 10 or FIG. 11, the magnitude of the release resistance R when the number of molding shots is k-th is confirmed. The magnitude of the release resistance force R analyzed in advance and the calculated value Cn of the pin release resistance are compared, and each pusher 30 according to each calculated value Cn of the pin release resistance for the four workpiece pushing pins 20. The pressing value Fn of the pressing force F is determined respectively. The pressing value Fn is determined by changing it so as to be larger than the respective calculated values Cn calculated in step S24.
Specifically, the pressing value F ₁ of the first workpiece pushing pin 21 is set larger than the calculated value C ₁ calculated using the measured values R ₁ , R ₂ , and R ₃ . Similarly, the pressing pressure value _{F 2} of the second workpiece push-out pin 22, from the measurement value _{R 3,} R 4, calculated value _{C 2} calculated using the _{R 5,} the pressing pressure value _{F 3} of the third workpiece push-out pin 23, from the measurement value _{R 5,} R 6, _{R 7} calculated value _{C 3} calculated using the pressing pressure value _{F 4} of the fourth work extrusion pin 24, was calculated using the measured values _{R 7, R 8, R 1} operation than the value _{C 4,} both set large.

Next, in step S26, a coil spring having a spring constant corresponding to the pressing value Fn determined in step S25 is selected, and the old coil spring that has been installed until the number of molding shots is kth is replaced with the selected new coil spring. .
However, in the current inspection, if the pressing value Fn determined in step S25 is almost the same as the pressing value Fn determined in the previous inspection performed before this inspection, or the old coil spring has If the spring force is acceptable, there is no need to replace it with a new coil spring.
Thus, the inspection of the pressing means 30 ends.
After inspecting the pressing means 30, molding of the molded product 92 with the number of molding shots after the (k + 1) th time is started, and as described above, the increase tendency due to the increase in the number of molding shots and the performance of the coil spring to be mounted are taken into consideration. The coil spring replaced in step S26 is used up to the set number newly set in step S26.

As described above, in the injection molding using the stationary mold and the movable mold as in the mold molding method according to the present invention, these molds have a number of molding shots exceeding hundreds of thousands as the number of times they can be used. Used up to.
Under such usage circumstances, while the fixed mold and the movable mold are used over a long period of time, the size of the mold release resistance may be doubled, five times, and more than ten times depending on the frequency of molding shots. However, according to the mold forming method according to this modification, the periodic inspection shown in FIG. 13 is performed in which the pressing value Fn by the pressing means 30 is changed according to the increase amount of the release resistance R. The spring having a constant spring force is not used continuously, and the spring force does not become smaller than the mold release resistance force when the molded product 92 is separated from the fixed mold 10. Therefore, when the movable mold 40 and the fixed mold 10 are separated from each other, the molded product 92 is moved to the fixed mold 40 side due to the difference from the spring force and the mold release resistance force remaining on the fixed mold 10 side. There is no fear of remaining.

In addition, this invention is not limited to the said embodiment and modification, A part of structure can also be changed suitably and implemented in the range which does not deviate from the meaning of invention.
For example, in the embodiment and the modification, as a mold forming method, the fixed mold 10 and the movable mold 40 are brought into contact with each other to form the cavity 2, and the molding material MT is injected and molded. The injection molding method for molding the insert member 91 is exemplified.
However, the mold forming method of the present invention is not limited to the injection molding method exemplified in the embodiment and the modified embodiment. For example, the cavity is formed by bringing the first mold and the second mold into contact with each other. In addition, the present invention can be appropriately applied to other mold forming methods such as casting in which molten metal is injected into a cavity and formed.

In the embodiment and the modified embodiment, the injection mold 30 is provided in the fixed mold 10, while the eject pin 50 is disposed in the movable mold 40, so that the molded product 92 remains in the movable mold 40. The mold 1 was illustrated.
However, the molding die may have a configuration in which an eject pin is provided in the fixed die and an extrusion means is provided in the movable die in order to leave the molded product in the fixed die.

Further, in the embodiment, the drive unit that changes the pressing force F by controlling the flow rate of the gas supplied from the fluid supply source 25 is exemplified for the extrusion unit 30.
However, the pushing means may be, for example, a hydraulic cylinder or the like whose pressing force can be changed according to the flow rate of the supplied hydraulic oil, etc., and a driving source that can change the pressing force when the molded product is pushed out to the movable mold side If so, various changes can be made.

In the embodiment and the modification, the load cell 70 is exemplified as the release resistance measuring unit.
However, the mold release resistance measuring means can be variously modified as long as it can measure the mold release resistance force when the molded product is separated from the movable mold.

It is sectional drawing explaining the structure of the injection mold which concerns on embodiment, and shows the clamping state at the time of shaping | molding. It is sectional drawing explaining the structure of the injection mold which concerns on embodiment, and shows the mold open state after shaping | molding. It is explanatory drawing which expands and shows the P section in FIG. It is a circuit diagram explaining the electric control of the injection molding die concerning an embodiment. FIG. 2 is a plan view of a fixed mold viewed from a parting surface PL in FIG. 1. FIG. 2 is a plan view of a movable mold viewed from a parting surface PL in FIG. 1. In the injection mold which concerns on embodiment, it is a figure which shows a mode that a movable mold and a stationary mold separate, and shows the state after pushing a molded article to the movable mold side by the extrusion means. It is a flowchart which shows the structure of a mold release resistance force measurement program. It is a list used for calculation of the pressing force of each work pushing pin. It is a table | surface which shows the result investigated about the relationship with the number of shaping | molding shots, the surface roughness of a fixed metal mold | die, and mold release resistance. 11 is a graph showing the relationship between the number of molding shots and the release resistance R in FIG. 10. It is the graph shown about the relationship between the number of shaping | molding shots in FIG. 10, and surface roughness Rz. It is a flowchart which shows the check procedure of the press means performed with the injection molding method which concerns on a deformation | transformation form.

Explanation of symbols

1 Injection mold (molding mold)
2 cavity 10 fixed mold (first mold)
30 Extrusion means 40 Movable mold (second mold)
50 Eject pin 70 Load cell (Release resistance measuring means)
80 Control means 90 Product 91 Insert member R Release resistance MT Mold material MT (material)

Claims (2)

A cavity is formed by bringing the first mold and the second mold into contact with each other, and after molding the material by injecting the material, when the second mold is separated from the first mold, the molded product is In a mold molding method in which the molded product is brought into close contact with the second mold and then the molded product is separated from the second mold by an eject pin.
When the first mold and the second mold are separated from each other, the pushing means provided in the first mold pushes the molded product toward the second mold;
The release resistance measuring means measures a release resistance force when the eject pin separates the molded product from the second mold,
Changing the pushing force of the pushing means according to the releasing resistance measured by the releasing resistance measuring means,
A mold forming method characterized by the above. A cavity is formed by bringing the first mold and the second mold into contact with each other, and after molding the material by injecting the material, when the second mold is separated from the first mold, the molded product is In a molding die that is brought into close contact with the second die and then separated from the second die by an eject pin,
An extrusion means provided on the first mold, for extruding the molded product toward the second mold when the first mold and the second mold are separated from each other;
A release resistance measuring means for measuring a release resistance force when the eject pin separates the molded product from the second mold;
Control means for changing the pushing force of the pushing means according to the releasing resistance force measured by the releasing resistance measuring means;
A molding die characterized by comprising:

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