JP3372766B2 - Injection molding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine having a partial compression function for compressing a part of resin in a mold molding space, and more particularly, a part of a molded product having a size of less than 0.15 mm. The present invention relates to an injection molding machine capable of forming a partially ultra-thin molded product having an ultra-thin portion.

[0002]

2. Description of the Related Art Molten resin injected and filled in a molding space (cavity) of a mold becomes difficult to flow as the cross-sectional area of a channel of the molten resin becomes smaller. The thickness is 0. When it becomes about several mm,
The molten resin cannot be completely spread over the thin portions.

Therefore, a part of the molded product is set to 0. After the molten resin is injected and filled into the molding space (cavity) of the mold in order to make it as thin as several millimeters, before the resin is solidified, a predetermined part of the resin in the molding space is compressed by, for example, a compression core. A partial compression molding method is known in which a thin portion is partially obtained by compression. However, the thickness of the thin portion that can be achieved by such a partial compression molding method is about 0.
The limit was 16 mm.

By the way, recently, electronic devices have become smaller and more sophisticated, and there has been a demand for a partially ultra-thin molded product in which a part of the molded product has an ultra-thin portion of less than 0.15 mm. Examples of such a partially ultra-thin molded product include a card base of a small memory card called a stamp size memory card.

FIG. 8 is a perspective view showing an example of a card base for the above-mentioned small memory card (stamp size memory card). In the figure, 50 is a thin plate-shaped card base, and its size is 45 × 37 mm in length and width, and the thickness S.
1 (thickness S1 of the main body portion) is S1 = 0.8 mm. An ultra-thin portion 51 having a thickness S3 of S3 = 0.13 mm (vertical and horizontal dimensions of 22 × 14 mm) is provided at an intermediate portion of the card base 50 on one side in the longitudinal direction. The thickness S2 is S around the thin portion 51.
A thin portion 52 having a thickness of 2 = 0.4 mm is provided.
A flash memory or the like is mounted on the ultra-thin portion 51, and the entire thickness thereof is 0.8 mm in a state in which it is completed as a small memory card.

It is difficult to manufacture the card substrate 50 having the ultra-thin portion 51 with the thickness S3 = 0.13 mm as described above by the usual injection molding without partial compression. 9A shows a mold molding space (cavity) 61A having the same shape as the shape of the card base 50 shown in FIG.
When the molten resin is injected and filled from the gate 62 into the mold molding space 61A, the molten resin 63 (shown with dots in the drawing) has an ultra-thin portion as shown in FIG. 9B. The area to be formed (a space having a thickness of 0.13 mm) 64 does not reach at all. Of course, the ultra-thin-wall portion-forming region 64 is formed under extremely high-speed and high-pressure conditions that exceed the injection conditions of normal injection molding.
Although it is possible to force the molten resin 63 to enter, it is difficult to achieve a non-defective product because the internal distortion of the molded product becomes large and the injection mechanism must be extremely large.

Therefore, using the partial compression method, the thickness S3 =
It is conceivable to manufacture the card substrate 50 having the ultrathin portion 51 of 0.13 mm. 10 and 11 are views showing a method of molding the card base 50 by the conventional partial compression method.

That is, as shown in FIG.
Before the injection / filling of the molten resin, the mold molding space (cavity) 61B is set such that the minimum thickness of the molding space is S2 = 0.4 mm. In this state, the molten resin 63 is injected and filled from the gate 62 into the mold molding space 61B. In this case, as shown in (b) of FIG. 10, the molten resin 63 is not yet completely spread in the thin space in the mold molding space 61B depending on the size of the thin space. Often not. So in this case,
The molten resin 63 is forcibly pushed into all of the mold molding space 61B under conditions of higher speed and higher pressure than the injection conditions of normal injection molding.

Next, before the resin 63 in the die molding space 61B is solidified, as shown in FIG. 11, the compression core 65 is driven forward to compress a predetermined portion of the resin 63, whereby the above-mentioned structure is obtained. Attempt to form a part commensurate with the ultra-thin part. Such a method is a conventional method for molding the card substrate 50 by the partial compression method.

[0010]

However, in the molding method using the above-mentioned conventional partial compression method,
It is difficult to achieve the above-mentioned S3 = 0.13 mm as the thickness of the ultra-thin portion by the compression / pushing by the compression core 65, and the value exceeding S3 = 0.13 mm is unavoidable (for example, 0.16 mm). Value). This is because the compression is performed by the compression core 65 after the resin 63 has been completely injected and filled into the mold molding space 61B. In other words, the skin layer that immediately occurs on the outer peripheral side of the filled resin. This is because the compression is performed by the compression core 65 at the time when the outer solidified film, which is referred to as, grows considerably, so that it is difficult to compress it to the target thickness due to the resistance of the skin layer.

Further, as described above, in order to overcome the resistance of the skin layer to make it ultra-thin, a large compression force is required, and a large and powerful compression drive source is required, which is mounted on the movable die plate. The compression mechanism to be used becomes large.

Further, as in the card base body 50 shown in FIG. 8, an ultra-thin portion 51 having S3 = 0.13 mm and S2 =
If there is a thin portion 52 of 0.4 mm and it is attempted to compress it in two stages, two sets of compression drive source and compression mechanism are required.

Furthermore, the molten resin 63 injected into the mold molding space 61B is first filled (wrapped) into a portion having a small flow path resistance (the space of S1 = 0.8 mm), and the flow path resistance is reduced. Of the ultra-thin portion 5 compressed by the compression core 65 as shown in FIG.
A weld line 66 is inevitably generated at 1 '. However, if the weld line 66 is present in the ultra-thin portion 51 ′ that is extremely thin and has the smallest mechanical strength, the weld line 66 may easily crack due to impact or the like.

Therefore, the technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art. The purpose is to remove a part of a molded product from 0.15.
Ultra-thin part less than mm (for example, thickness 0.13m
It is easy to make a partial ultra-thin molded product with an ultra-thin portion of about m.
An object of the present invention is to provide an injection molding machine capable of reliable molding.

[0015]

In order to achieve the above-mentioned object, the present invention executes an injection stroke by feedback control using an electric drive motor as an injection drive source, and compresses a part of resin in a mold molding space. In an injection molding machine having a partial compression function for performing, a compression electric servomotor as a compression drive source, and a rotation → linear conversion mechanism for converting the rotation of the compression electric servomotor into a linear motion,
A compression toggle link mechanism driven by the rotation-to-linear conversion mechanism, a compression first compression bar connected to the output side of the toggle link mechanism, and a forward drive by the first compression bar. A first compression core forming a part of a mold, a second compression bar for compression connected to a crosshead which is an input side of the toggle link mechanism, and forward drive by the second compression bar. A second compression core forming a part of a mold is provided, and it is recognized that the forward position of the screw has reached a position corresponding to a preset compression start timing, and the electric servomotor for compression described above is used. It is configured to start the partial compression stroke.

[0016]

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. 1 to 3 show a first embodiment of the present invention.
FIG. 6A is a schematic operation explanatory view of the injection molding method for a partially ultra-thin molded product by the injection molding machine according to the embodiment, where (a) of each drawing shows a cross section of a main part of the mold mechanism, and b) shows a resin plane in the mold molding space corresponding to (a) of each drawing.

The present embodiment is an application example for molding the card base 50 for the small memory card (stamp size memory card) shown in FIG. 8, and the description of the card base 50 will not be repeated. I will omit it.

1 to 3, 1 is a fixed side mold, 2
Is a movable mold, PL is a mold release surface, 3 is a mold molding space (cavity) formed by the molds 1 and 2 in a mold clamped state,
Reference numeral 4 is a gate, 5 is a first compression core having a rectangular cross-section provided in the movable mold 2, 6 is a second compression core having a rectangular cross-section provided in the movable mold 2, and 7 is It is a molten resin (resin). The first compression core 5 and the second compression core 6 are 2
It has a heavy structure.

Before the injection after the mold clamping, the mold mechanism is in the state shown in FIG. 1A, the first and second compression cores 5 and 6 are in the retracted position, and the mold is The entire molding space 3 is set to have a uniform thickness S1 = 0.8 mm.

At the injection start timing, the molten resin 7 is injected from the gate 4 into the mold molding space 3,
The molten resin 7 begins to be filled in the mold molding space 3. At this time, since the mold molding space 3 is set to a relatively thick space having a uniform thickness, the flow resistance is small, and the molten resin 7 is smoothly and promptly filled into the mold molding space 3, and By providing the single gate 4 at an appropriate position with respect to the mold molding space 3, it is possible to prevent a confluence point of the molten resin 7 (that is, a weld line is generated) in the mold molding space 3. It is considered.

Injection of the molten resin 7 into the mold molding space 3
As the filling progresses, the molten resin 7 is completely spread over the ultra thin portion forming region for forming the ultra thin portion 51,
At a predetermined timing before the injection / filling of the molten resin 7 into the mold molding space 3 is completed, (a) in FIG.
As shown in, the first compression core 5 is driven forward by a predetermined amount. Thus, the molten resin 7 in which the skin layer in the region where the ultra-thin portion is to be formed is not grown is compressed by the first compression core 5, and the ultra-thin portion 51 with the thickness S3 = 0.13 mm is formed. It is formed. Thus, the thickness S3 = 0.
The reason why it is possible to partially compress up to an ultra-thin wall dimension of 13 mm is that the skin layer compresses the molten resin 7 in an ungrown state, so that the resistance from the resin is relatively small, as described above.
As a result, the thickness S3 = 0.1 that could not be achieved before.
Partial compression up to 3 mm is possible, and good thickness dimension accuracy of the ultra-thin portion 51 can be secured. Furthermore, since no weld line is generated in the ultrathin portion 51,
There is also no risk of the ultra-thin portion 51 cracking.

Along with the partial compression by the first compression core 5 as described above, the final stage of injection / filling progresses, and the molten resin 7 is completely spread to every corner of the mold molding space 3, whereby injection is performed.・ Filling is completed. Immediately after this, the second compression core 6 is driven forward by a predetermined amount, whereby the unsolidified resin 7 around the previously formed ultrathin portion 51 is compressed by the second compression core 6. , The aforementioned thickness S2 = 0.4
The thin portion 52 of mm is formed. The partial compression by the second compression core 6 is simply and easily achieved up to the thickness S2 = 0.4 mm, which could be easily achieved in the past, so it is easily and easily achieved even after the injection / filling is completed. To be done. Although S2 is set to 0.4 mm in the present embodiment, the value of S2 can of course be set to a value of about 0.2 mm that can be reliably achieved even by the conventional partial compression.

Next, the mold mechanism of the injection molding machine of this embodiment will be described. 4 to 6 are views showing the structure of the mold mechanism of the injection molding machine of the present embodiment. FIG. 4 is in the state of FIG. 1, FIG. 5 is in the state of FIG. 2, and FIG. Each corresponds to the state of FIG.

4 to 6, 11 is a fixed die plate, 12 is a fixed die (corresponding to the fixed die 1) attached to the fixed die plate 11, 13 is a movable die plate, and 14 is movable. A movable mold (corresponding to the movable mold 2) attached to the die plate 13 is a first compression core (the first compression core 15) that can move forward and backward by a predetermined amount with respect to the movable mold 14. (Corresponding to core 5), 16 is movable mold 1
4 is a second compression core (corresponding to the second compression core 6) capable of moving forward and backward by a predetermined amount.

The movable die plate 13 is constructed so that it can be moved forward and backward relative to the fixed die plate 11 by a die opening / closing driving source and a die opening / closing driving mechanism (not shown). A compression servomotor (compression electric servomotor) 17 is mounted on the movable die plate 13.
The rotation of the motor 17 is transmitted to the pulley 18 via a timing belt (not shown). A rotary holder 19 is rotatably held by the movable die plate 13 via a bearing, and the pulley 18 and the nut body 20 are integrally coupled to the rotary holder 19. A ball screw shaft 21 is screwed into the nut body 20 and is driven forward and backward by the nut body 20.

Reference numeral 22 denotes a toggle link mechanism mounted on the movable die plate 13. One end 22a of the link is pivotally supported on the movable die plate 13 and the other end 22b of the link.
Are rotatably supported by the compression plate 23. Further, one end of the ball screw shaft 21 is integrally coupled to the cross head 22c of the toggle link mechanism 22, and the ball screw shaft 21
The toggle link mechanism 22 is driven by the forward and backward movement of the compression plate 23, which drives the compression plate 23 forward and backward.

Reference numeral 24 denotes a first compression bar, one end of which is integrally connected to the compression plate 23.
The other end side of 4 is inserted through the movable mold 14 so as to be able to move forward and backward so that the first compression core 15 can be driven forward. 25 is a second compression bar, one end of which is integrally connected to the crosshead 22c.
The other end of the compression bar 25 is inserted through the movable mold 14 so as to be able to move forward and backward, and the second compression core 16 can be driven forward. That is, the first compression bar 24 is connected to the output side of the toggle link mechanism 22, and the force corresponding to the enlargement ratio of the toggle mechanism is applied to the first compression core 1.
The second compression bar 25 is applied to the toggle link mechanism 2
The second compression core 16 is connected to the input side of the second compression core 16 by applying a force equivalent to that of the input side of the toggle link mechanism 22 to the second compression core 16.

Next, the operation of the mold mechanism having the above structure will be described. Before the injection after the mold clamping, the mold mechanism is in the state shown in FIG. 4, and at this time, the mold molding space (cavity) has a total thickness of S1 = 0.8.
It is set to be uniform in mm, and the first and second compression cores 15 and 16 are in the retracted position. Although not shown, the first and second compression cores 15 and 16 are biased in the rightward direction in the figure by a spring force, and the tips of the first and second compression cores 15 and 16 are provided. The surface is flush with the release surface PL.

In the above state, when the injection start timing in the molding cycle is reached, the molten resin starts to be injected and filled in the mold by an injection mechanism (not shown) using an electric servomotor as an injection drive source. As a result, the molten resin starts to be filled in the mold molding space from a gate (not shown). The electric servomotor, which is the injection drive source, is controlled by feedback control so that the actually measured speed value of the injection / filling process follows the set speed value. , Injection resin speed) is precisely controlled.

The injection / filling process based on the above velocity feedback control progresses, the molten resin is completely spread over the ultra thin portion formation-scheduled region for forming the ultra thin portion 51, and the die molding is performed. Measured stroke information (measured rotation amount information) from the injection control system that the predetermined timing before the injection and filling of the molten resin into the space was completed
When the compression control system recognizes by the compression control system, the compression control system rotationally drives the compression servomotor 17 by, for example, speed feedback control to move the crosshead 22c forward through the pulley 18, the nut body 20, and the ball screw shaft 21. Thus, the toggle link mechanism 22 is driven in the tension direction. It should be noted that the drive of the toggle link mechanism 22 by the compression servo motor 17 can be made to have a good responsiveness, but if the mechanical delay is in an unacceptable range, the timing for starting the compression servo motor 17 is set. The mechanical delay time may be advanced.

As shown in FIG. 5, the compression servomotor 1
When the toggle link mechanism 22 is driven in the direction in which it is stretched by 7, the first compression bar 2 is pushed through the compression plate 23.
4 is driven forward to drive the first compression core 15 forward, whereby the molten resin in which the skin layer in the region where the ultrathin portion is to be formed is not grown is compressed by the first compression core 15. The ultra-thin portion 51 having the thickness S3 = 0.13 mm is formed. In the present embodiment, the pushing operation of the first compression core 15 by the first compression bar 24 is completed at the point where the toggle link mechanism 22 is completely stretched (that is, the dead point). To obtain a larger compression force. That is, compared with the forward stroke of the crosshead 22c, the first compression bar 24
Although the forward stroke of is extremely small, the partial compression by the first compression core 15 is performed with the force at the timing when the maximum force is obtained by the expansion ratio of the force of the toggle link.

By doing so, the skin layer compresses the molten resin in the ungrown state, and the toggle link mechanism 2
Along with the application of a large compressive force expanded by 2, the thickness S3 = 0.13 which could not be achieved in the past.
The ultra-thin portion 51 of mm can be formed reliably and easily, and it is not necessary to use a large and expensive driving source having power as the driving source of the compression mechanism.

With the above-described partial compression by the first compression core 15, the final stage of injection / filling is in progress.
At the timing when the partial compression by the compression core 15 is almost completed, the molten resin 7 is completely spread to every corner in the mold molding space, and the injection / filling is completed. This state is shown in FIG. 5, and thereafter, the cross head 22c is driven forward by a predetermined amount by the compression servo motor 17.
When the crosshead 22c is driven forward from the state of FIG. 5, as shown in FIG. 6, the second compression core 16 is driven forward by a predetermined amount by the second compression bar 25 directly connected to the crosshead 22c. As a result, the unsolidified resin around the previously formed ultra-thin portion 51 is transferred to the second compression core 16
Are compressed, and the thin portion 52 having the thickness S2 = 0.4 mm is formed.

The partial compression by the second compression core 16 described above can be easily achieved even before in the thickness S2 = 0.4.
Since it only compresses up to mm, the pushing force by the second compression core 16 through the second compression bar 25 directly connected to the crosshead 22c, that is, the expanded force by the toggle link mechanism 22 is not used. However, the partial compression up to the thickness S2 = 0.4 mm can be achieved reliably and easily. Even during the partial compression operation by the second compression core 16, the toggle link mechanism 22 operates due to the forward movement of the crosshead 22c, and the operation after the dead point causes the first compression bar 24 to retract slightly. However, the retreat amount is 0. The value is several orders of magnitude smaller than the stroke that advances about several mm, so there is no problem.

As described above, in the present embodiment, since the single compression drive source (compression servomotor 17) and the single toggle link mechanism 22 perform the partial compression in the two-stage operation, the number of compression drive sources is increased. It is possible to obtain the ultra-thin portion 51 and the thin portion 52 without complicating the compression mechanism. Moreover, in forming the ultra-thin portion 51 that requires a large compression force, the enlargement ratio of the large force by the toggle link mechanism 22 is used, and in forming the thin portion 52 that does not require much compression force, the crosshead is used. Since the compression force is directly obtained from 22c and the magnitude of the compression force is used properly, the card base 50 described above can be molded easily and reliably, and the overall mechanism can be simplified.

In the above description, the partial compression operation by the second compression core 16 uses the forward force of the cross head 22c that causes the toggle link mechanism 22 to operate after the dead point. The partial compression operation by the core 16 may use the forward force of the crosshead 22c that causes the toggle link mechanism 22 to perform an operation before the dead point. In this way, even during the partial compression operation by the second compression core 16, the operation of the toggle link mechanism 22 in the vicinity of the dead point causes the first compression bar 24 to move slightly forward. As described above, the crosshead 22c is 0. Since the amount of advancement of the first compression bar 24 is several orders of magnitude smaller than the stroke of advancing about several mm, the thickness dimension accuracy of the ultra-thin portion 51 is not impaired and there is no problem.

FIG. 7 is a simplified explanatory view of the injection and compression control system of the injection molding machine of this embodiment. In the figure, 17 is the compression servo motor, 31 is a pulse generator for detecting the rotation speed of the compression servo motor 17, 32 is a motor control circuit for driving the compression servo motor 17 by feedback control, and 33 is an injection. Servo motor (injection electric servo motor), 34 is a pulse generator for detecting the rotation speed of the injection servo motor 33, and 35 is a motor control circuit for driving the injection servo motor 33 by feedback control.

The motor control circuit 35 includes a preset speed setting value for the injection / filling stroke and the pulse generator 3.
4 is input, and the motor control circuit 35 speed-feedbacks the injection servomotor 33 so that the measured speed value obtained by appropriately calculating the measured information follows the set speed value. Drive by control. Thereby, the forward speed (in other words, injection resin speed) and position of the screw (not shown) of the injection mechanism are precisely controlled.

Further, the measurement information from the pulse generator 34 is also input to the motor control circuit 32, whereby the motor control circuit 32 recognizes the advance position of the screw (not shown) of the injection mechanism and advances the screw. It is determined whether or not the position (that is, the filling degree of the molten resin into the mold molding space 17) reaches the preset compression start timing, and when the compression start timing is reached, the drive of the compression servomotor 17 is started. To do. Motor control circuit 32
A preset speed setting value for the compression stroke and the measurement information from the pulse generator 31 are input to, and the actual measurement speed value obtained by appropriately calculating the measurement information is used as the set speed value. The motor control circuit 32 drives the compression servomotor 17 by speed feedback control so as to follow. As a result, the forward speed and position of the crosshead 22c are precisely controlled.

As described above, in the present embodiment, the injection servomotor 33 executes the injection stroke by feedback control, and the compression servomotor 17 refers to the injection stroke information in this precisely controlled injection stroke. Since the partial compression process is started, as described above, the above-mentioned ultra-thin portion 51 is reliably formed without losing the timing of compressing the molten resin in the ungrown state of the skin layer. It becomes possible.

[0042]

As described above, according to the present invention, a part of the molded product is an ultra-thin portion having a thickness of less than 0.15 mm (for example, an ultra-thin portion having a thickness of about 0.13 mm). An injection molding machine that can easily and reliably mold ultra-thin molded products can be realized without complicating the mechanism.

[Brief description of drawings]

1 is an injection molding machine according to an embodiment of the present invention,
It is a typical operation explanatory view of the injection molding method of a partially ultra-thin molded product.

FIG. 2 shows an injection molding machine according to an embodiment of the present invention.
It is a typical operation explanatory view of the injection molding method of a partially ultra-thin molded product.

FIG. 3 shows an injection molding machine according to an embodiment of the present invention,
It is a typical operation explanatory view of the injection molding method of a partially ultra-thin molded product.

FIG. 4 is an explanatory diagram showing a configuration of a mold mechanism of the injection molding machine according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a configuration of a mold mechanism of the injection molding machine according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a configuration of a mold mechanism of the injection molding machine according to the embodiment of the present invention.

FIG. 7 is a simplified explanatory diagram of an injection and compression control system of the injection molding machine according to the embodiment of the present invention.

FIG. 8 is a perspective view showing an example of a card base for a small memory card (stamp size memory card).

9 is an explanatory diagram of a case where the card base body of FIG. 9 is manufactured by normal injection molding.

10 is an explanatory diagram of a case where the card base body of FIG. 9 is manufactured by injection molding using a conventional partial compression method.

FIG. 11 is an explanatory diagram of a case where the card base body of FIG. 9 is manufactured by injection molding using a conventional partial compression method.

FIG. 12 is a plan view of a card base for explaining problems with the conventional technique.

[Explanation of symbols]

1,12 Fixed mold 2,14 Movable mold 3 Mold forming space (cavity) 4 gates 5,15 1st compression core 6,16 2nd compression core 7 Molten resin (resin) 11 Fixed die plate 13 Movable die plate 17 Compression servo motor 18 pulley 20 nut body 21 Ball screw shaft 22 Toggle link mechanism 22c crosshead 23 Compression plate 24 First compression bar 25 Second compression bar 31,34 Pulse generator 32 Motor control circuit for compression servo motor 33 Injection Servo Motor 35 Motor control circuit for injection servo motor

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Claims (3)

(57) [Claims] 1. An injection molding machine equipped with an electric servomotor as an injection drive source for performing an injection stroke by feedback control and having a partial compression function for compressing a part of resin in a mold molding space. , A compression electric servomotor as a compression drive source, and rotation for converting the rotation of the compression electric servomotor into a linear motion →
A linear conversion mechanism, a compression toggle link mechanism driven by the rotation-> linear conversion mechanism, a compression first compression bar connected to the output side of the toggle link mechanism, and the first compression bar. A first compression core that is part of a mold that is driven forward by the first compression core, a second compression bar that is connected to the crosshead that is the input side of the toggle link mechanism, and a second compression bar. and recognizes that led to a position corresponding to the second comprises a compression core, the compression start timing forward position of the screw has been set in advance forming a part of the mold which is driven forward by the upper An injection molding machine characterized in that a partial compression process is started by an electric servomotor for compression. 2. The advance of the first compression core by the first compression bar is stopped in the vicinity of a point at which the force expansion ratio of the toggle link mechanism is the largest, according to claim 1. An injection molding machine characterized by. 3. The method according to claim 2, wherein, following the partial compression operation by the first compression core,
An injection molding machine characterized in that the second compression core is moved forward by the second compression bar to partially compress a region different from the region compressed by the first compression core.