JP3179510B2 - Injection molding method and apparatus - 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 method and apparatus for plastics, and more particularly to an injection molding method and a gate cutting method for simultaneously performing product compression molding and gate cutting in an ideal state in a mold during injection molding. Related to the device.

[0002]

2. Description of the Related Art Conventionally, in the injection molding, the gate cutting of a molded product is usually performed by taking out the molded product from a mold after cooling and solidifying, and cutting the gate in a later step. In addition, in injection molding, shrinkage after molding or the like often causes sink marks in molded articles, and often lacks dimensional stability. Therefore, in order to reduce sink marks, a wide range of molding conditions such as a pressure-holding step have been taken, and efforts have been made to find optimum conditions. In addition, in order to prevent sink marks, for example, a partly pressurizing method for partially pressing a portion easily causing sink marks as described in Japanese Patent Publication No. 52-109556 is used, but a molded article having a large wall thickness variation is used. At present, the effect is weak, and cracking distortion and the like occur.

[0003] Further, as disclosed in Japanese Patent Application Laid-Open No. 58-134722, for example, a mold cavity is vibrated by applying ultrasonic waves to reduce sink marks, but sufficient results can be obtained. Did not.

[0004]

Conventionally, in gate cutting of a molded article in injection molding, there are many gate cutting methods in which a molded article is taken out of a mold after cooling and solidifying, and the gate is cut in a later step. Although there is certainty, the number of steps is increased, but the cost is high, and the occurrence rate of defects such as scratches is increased. Also, in the injection molding, shrinkage after molding, etc., due to shrinkage of the molded product, often lacks dimensional stability, aiming at reduction of sink, taking a wide range of molding conditions such as pressure-holding process, Although the partial pressurization method is used to partially push the prone to sink marks,
Since the molding time is prolonged, cost is high and cracking strain is generated. An object of the present invention is to obtain a precise and clean gate cut surface in a mold,
Moreover, it is an object of the present invention to provide an injection molding method and apparatus capable of simultaneously obtaining a molded product having high sinking accuracy without sink marks.

[0005]

In order to solve the above-mentioned problems, in the present invention, a member capable of pushing a molten resin from a mold gate portion into a mold cavity or a core and cutting the gate is used as a mold cavity. Or make it slidable with respect to the core, apply micro vibration to the member after injection filling, soften the plastic near the gate by this vibration energy, and then forcibly displace the member without vibration or applying vibration An injection molding method comprising a product compression step of compressing a product and a gate cutting step of performing gate cutting while applying no vibration or vibration to the member before, after or simultaneously with or after the product compression step after injection filling.

[0006] In addition, the product compression process and the gate cutting process
After the completion of
At least the product surface that has been gate-cut while giving a return movement
Also, by bringing the above members into contact for a short time,
The cut surface is obtained.

In order to cut the gate after the product compression step, the molten resin is pushed into the mold cavity or core from the mold gate and the gate-cuttable slider member is slidable with respect to the mold cavity or core. advance, during the holding pressure process and during pressure holding completion cooled after the gate sealing after injection filling is completed, giving the minute vibration to the slider member, to soften the plastic near the gate by the vibrational energy, then no vibration Alternatively, the slider is compressed while applying vibration to forcibly displace the slider member to compress the product, and then the gate is cut.

[0008] Also, the slider member is forcibly displaced to
After the sheet cutting, the micro-vibration or
The product surface that has been gate-cut while giving a gentle reciprocating motion
At least for a short time
Obtain a cutting surface.

In order to cut the gate simultaneously with the product compression step using the slider member, the molten resin is pushed into the mold cavity or core from the mold gate portion and the gate member is cut by the mold cavity. Alternatively, after the injection filling, the slider member is forcibly moved to perform the product compression and the gate cutting, and the gate-cut product is further given to the slider member with slight vibration or gentle reciprocating motion. The product compression and gate cutting are performed simultaneously so as to finish the gate-cut product surface by contacting the surface at least for a short time.

Further, in order to compress the product after cutting the gate, the molten resin is pushed into the mold cavity or core from the mold gate portion, and a punch member capable of cutting the gate is slid on the mold cavity or core. after rotatably to advance, injection filling, gives a minute vibration to the punch member to soften the plastic near the gate by the vibrational energy, the later forcibly displacing the punching member while applying a vibration-free or vibration The gate is cut, and the punch member is made to protrude into the cavity or the core to perform product compression molding.

[0011] In addition, the punch member is forcibly displaced to
After cutting the sheet, further punch members Small vibration or loose
Applying a gentle reciprocating motion to the product surface that has been gate-cut
It is good to make contact at least for a short time.

In order to cut the gate at the same time as the product compression step using a punch member, a punch member which can be pushed into the mold cavity or core from the mold gate portion to push in the molten resin and cut the gate. After slidable with respect to the mold cavity or core, after injection filling, the punch member is forcibly moved to cut the gate, and the product is pressed into the cavity or core to perform product compression molding. Compression of the product and cutting of the gate are performed simultaneously so that the product is finished by contacting the surface of the product with the gate cut at least for a short time while giving a minute vibration or gentle reciprocating motion.

[0013] In implementing such a method, the slider section
In the case of materials, runner, gate and
Fixed mold to form cavity or core for molding product part
And a part of the runner part in the movable mold and movable mold
To allow the molten resin to be pushed into the cavity or core
In addition, a gate-cuttable slider member is slidably arranged.
The slider member is driven by a cylinder fixed to a movable mold.
An injection molding apparatus adapted to move is used. At this time,
Control is easy if the cylinder is a servo cylinder.

[0014] If with the punch member, runner contact surface, a gate portion and the stationary mold to form a cavity or core for molding the product section and the movable mold, a part of the runner in the movable mold Is formed so that the melted resin can be pushed into the cavity or core, and a gate member is cut to further slidably dispose a punch member that can enter the cavity or core. An injection molding device driven by a fixed cylinder is used.
The cylinder is preferably a servo cylinder.

[0015]

According to the present invention, the molten resin is pushed into the mold cavity or core from the mold gate and the gate-cuttable member is slidable with respect to the mold cavity or core. A product compression step of applying micro vibration to the member after injection filling, softening the plastic in the vicinity of the gate by the vibration energy, and then forcibly displacing the member without vibration or applying vibration to compress the product;
A gate cutting step of performing gate cutting while applying no vibration or vibration to the member before or after or simultaneously with the product compression step after injection filling. For this reason, by compactly driving the member and compressing the product part by vibration energy, a molded product with high dimensional accuracy without sinking can be obtained at the same time, and molding such as pressure holding process that does not require gate cutting in the subsequent process The present invention provides a low-cost injection molding method and apparatus which can meet a wide range of conditions and does not need to partially add an additional apparatus and process.

[0016] Furthermore, product compression process and gate cutting process
After the completion of the test, further micro-vibration or gentle movement
Shorten at least the member to the cut surface of the gate while giving a reverse movement.
Very good game appearance due to sliding contact only for time
A product having a cut surface can be obtained.

More specifically [0017] The slider member of the present invention
According to the invention used, the slider is pressurized into the mold cavity or the core from the mold gate portion and the gate member is cut. During the post-cooling, micro-vibration is performed to soften the plastic in the vicinity of the gate by the vibration energy, and then the slider member is moved to perform product compression molding and gate cutting. Therefore, since the slider member abuts and slides on the gate cut surface, a product having an extremely good gate cut surface in appearance can be obtained. In addition, the slider member is minutely driven and the product portion is compression-molded by vibration energy. shrinkage is obtained without dimensional precise molded products at the same time, moreover does not require the gate cut at a later step, the molding conditions such as a pressure-holding step and widely
In addition, the present invention provides a low-cost injection molding method and apparatus that does not require additional devices and processes to be added partially.

Furthermore, instead of the minute vibration of the slider member, after injection and filling, the slider member forcibly moving the by after performing the product compression molding, performs gate cutting, micro-vibrations or more slider member The same effect can be obtained by giving a gentle reciprocating motion.

[0019] In addition, outgoing using the punch member of the present invention
According to Ming, after entering the mold cavity or core from the mold gate and pushing the melted resin and injection-filling the gate-cuttable punch member, the resin is vibrated minutely to soften the resin near the gate, and thereafter in perform products compression and gate cutting by moving the punch member, further then to add to rush basis product compression molding punch member into the cavity or core, no further shrinkage than invention by the slider member, precise and An injection molding method and apparatus capable of obtaining a beautiful product have been provided.

[0020] Also, instead of micro-vibrating the punch member, after injection and filling, the punch member forcibly moving the by product compression, performs gate cutting and additional product compression molding,
Given the small vibrations or gradual reciprocating further punch member
Thus, a similar effect can be obtained.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described below. FIG. 1 is a sectional view showing a main part of a first injection molding apparatus according to the present invention. Used for the method. FIG. 1 is a cross-sectional view of a single-piece embodiment mold, and FIG.

The mold includes a fixed mold 7 and a movable mold 3, and a cavity or a core for molding the runner section 11, the gate section 1, and the product section 9 on the contact surfaces of the molds 3 and 7. 5 are formed. In the movable die 3, the bushing 6 <br/> slider member (2) having a forming part and gate cuttable edge 18 of the runner 11, which is removably disposed within the movable mold 3 And are slidably assembled. 10 is a sprue, and a runner part 11 is a gate part 1.
And the sprue 10. Bush 8 in fixed mold 7
Are removably arranged to guide the slider member 2.

The inflow molten resin 4 is introduced from the injection molding machine nozzle (not shown ) into the cavity or core 5 through the sprue 10, the runner section and the gate section 1, and the product section 9 is formed. After the resin 4 is filled into the cavity or the core 5 by injection molding, when the slider member 2 is moved downward as viewed in FIG. 1, the resin 4 in the runner portion 11 passes through the gate portion 1 into the cavity or the core 5. When the slider member 2 is pushed in and then moved upward, the gate 18 is cut at the edge 18. The slider member 2 is connected to a servo cylinder rod 16 of a hydraulic servo cylinder 12 fixed to the movable mold 3. A hydraulic servo cylinder 12 driven by a hydraulic servo control device (not shown) and a signal supplied to a servo valve 17 is capable of selectively performing minute vibration, forcible movement, or gentle reciprocating movement of the slider member 2. I have. 13 in FIG.
14 are product ejection pins 1 each having one end fixed to the ejector plate 15 of FIG.
3 and the position of the sprue discharge pin 14 are shown. When micro vibration is not required, a normal hydraulic cylinder may be used instead of the servo cylinder 12.

The present invention an injection molding method using the slider member by will be described. When the injection into the sprue 10 is started from the nozzle tip of the injection molding machine (not shown), the inflow resin 4 flows into the sprue 10, the runner 11 and the gate 1.
To fill the cavity or core 5. At the time of injection and pressure holding, the slider member 2 is held by the hydraulic servo cylinder 12 at the illustrated position. When the filling is completed, the cooling process is started while maintaining the pressure (the plastic shrinks as it is cooled, so that the filling is maintained to compensate for the shrinkage), and the gate portion 1 is cooled and solidified to seal the gate. In general, the cross-sectional area of the gate 1 is smaller than that of any part of the cavity or the core 5, so that the cooling of the gate 1
The gate of the product is cut off after the gate seal is completed (or during the pressure-holding process after injection filling, or during the cooling after the pressure-holding is completed), because the cooling of the product is fast and the effect of holding pressure is lost after the gate sealing. Has no effect on the product.

[0025] During in the gate seal is completed after that is, after the pressure-holding process and pressure holding completion after injection filling cooling, hydraulic servo cylinder 12 by an unillustrated device repeats minute vibration reciprocation. The minute vibration of the hydraulic servo cylinder 12 causes the slider member 2 to minutely vibrate. When the slider member 2 is forcibly pushed into the product portion 9 while giving a minute vibration, the resin 4 is pushed into the cavity or the core through the gate portion 1 and the product portion is compression-molded. The contact surface between the product part 9 and the slider member 2 in the part 5 is locally heated, and the internal stress and distortion of the molding material are alleviated, and the pressurization of the product part 9 and the stable cooling and solidification of the molding material are promoted. Accurate injection molded products can be obtained. The resin at the interface between the gate 1 and the product portion 9 in the cavity or core 5 is heated and softened by the vibration energy.

When the resin at the interface of the gate portion 1 softens, the slider member 2 is forcibly moved upward as shown in FIG. 1 to cut the gate at the edge 18 of the slider member. Since the softening, compressing, and cutting steps of the resin 4 are completed within only a few seconds, the steps can be performed simultaneously with the cooling of the product section 9, and do not impair productivity as compared with conventional molding. After completion of the gate cutting and cooling, the movable mold 3 retreats in the same manner as in normal injection molding, opens the mold, takes out the product part 9 and the runner part 11, and ends the molding process. Before the next mold clamping, the slider member 2 is returned to its original position by a device (not shown) so as to be ready for the next molding.

Furthermore, before opening the mold after the gate cutting, selectively, while the slider member 2 is minutely vibrated by a servo cylinder 12, the surface 19 of the slider member 2 only a short time to cut product face those By contacting and rubbing, the product surface can be further refined. In order to forcibly displace the slider member 2, the runner portion 11 and the sprue 10 are also temporarily cut, but the cut surface of the runner portion 11 and the sprue 10 are abutted and rubbed while slightly vibrating. By doing so, the runner part 1
The molding process can be completed by taking out the sprue 1 and the sprue 10 at the same time. The vibration of the slider member 2 may give a gentle reciprocating motion for a short time.

[0028] Then using the slider member according to the present invention
Another injection molding method will be described. The same mold shown in FIGS. 1 and 2 as the injection molding method described above is used. When the injection into the sprue 10 is started from the nozzle tip of an injection molding machine (not shown), the inflow resin 4 is filled into the cavity or core 5 through the sprue 10, the runner 11 and the gate 1. After the injection filling, the slider member 2 is forcibly moved downward by the hydraulic servo cylinder 12 as seen in FIG. 1 to push the resin 4 toward the product portion 9 side, and the product is pressed. And displace it upwards,
The gate is cut at the edge 18, and after the gate is cut, the hydraulic servo cylinder 12 is driven to cause the slider member 2 to reciprocate minutely for a short time. At the time when the gate is cut, the cut surface of the gate is still soft, and the surface 19 of the slider member 2 is brought into contact with the cut surface of the slider to be rubbed, so that a lapping effect is applied and the cut surface of the gate is glossy. Will be finished.

Since the pushing into the product, the cutting of the gate and the subsequent contacting step are completed within a few seconds, the productivity is not hindered as compared with the conventional injection molding method. In addition, since the gate cutting is performed at the time when the holding pressure can no longer be applied, there is no adverse effect on the molded product. In addition, depending on the type of resin, instead of applying minute vibration to the slider member 2 in the contact step after the gate is cut,
Even if a gentle reciprocating motion is given to the slider member 2 so that the surface 19 of the slider member 2 comes into contact with the gate cut surface, a gate cut surface having a good glossy surface can be obtained. After the product compression molding gate cutting and the subsequent contacting step, the mold is opened in the same manner as ordinary injection molding, and the molded product, the runner part and the sprue in which the resin filled in the cavity or the core 5 is taken out, and the molding step is performed. finish. Before the next mold clamping, the slider member 2 is returned to its original position by a device (not shown) so as to be ready for the next molding.

[0030] FIGS. 3 to 5 in the cross sectional view illustrating a second injection molding apparatus of the present invention, in Figure 3 the punch member 22 is the starting position, FIG. 4 is a position where the punch member 22 has a gate cut,
FIG. 5 shows a state in which the punch member 22 is located at a position where the punch member 22 protrudes into the cavity or the core 25 from the gate portion 21, and is used in the injection molding method using the punch member of the present invention.

[0031] Those in contact surface, the runner portion 31, the cavity or core 25 to form the gate portion 21 and the product portion 29 are formed (these Figures 1 and between the fixed mold 27 and movable mold 23 2), a part of the runner part 31 is formed in the movable mold 23, and a gate cut is performed to further slidably move the punch member 22 which can be inserted into the cavity or the core 5. The arrangement point is the same as that shown in FIGS. 1 and 2 only. The punch member 22 is driven by a hydraulic servo cylinder 32. Reference numerals 33 and 34 denote a product discharge pin and a sprue discharge pin, respectively. The end surface 38 of the punch member 22 forms a part of the runner portion 31 in FIG. 3, forms a gate cut end surface in FIG. 4, and forms a projecting surface into the cavity or the core 5 in FIG. Like the slider member 2 in FIGS. 1 and 2, the punch member 22 can selectively perform minute vibration, forcible movement, or gentle reciprocation by the hydraulic servo cylinder 32. When there is no, a normal hydraulic cylinder may be used.

[0032] The present invention an injection molding method using a punch member by the Explaining, this method slider member
The difference from the injection molding method used is that the punch member 22 further enters the cavity or the core 25 after the gate is cut, and the product portion 29 is further compression-molded.
This is almost the same as the injection molding method using the slider member . That is, at the time of injection, the punch member 22 is held by the hydraulic servo cylinder 32 at the illustrated position. After the injection filling, the hydraulic servo cylinder 32 repeats the minute vibration reciprocating motion by a device not shown. This hydraulic servo cylinder 3
The two reciprocating motions cause the punch member 22 to slightly vibrate. The punch member 22 is forcibly applied while applying a minute vibration.
When the resin is pushed into the product part 29 side, the resin at the interface of the gate part 21 is heated and softened by vibration energy, and then the punch member 22 is forcibly displaced to the position shown in FIG. As further shown in FIG.
5 into which the punch member 22 is inserted.
Was compression molded. By the additional compression molding, the contact surface between the product part 9 and the punch member 22 in the cavity or the core 25 is more locally heated by vibration energy, and the internal stress distortion of the molding material is alleviated, and the stable cooling and solidification of the molding material is promoted. As a result, it is possible to obtain a highly accurate injection molded product without sink marks.

Since the resin softening, cutting and additional compression steps are completed within a few seconds, the productivity is not impaired as compared with the conventional molding. After completion of gate cutting and molding, the movable mold 23 retreats and the mold is opened, the product part 29 and the runner part 31 are taken out in the same manner as in normal injection molding, and the molding step is completed. Before the next die clamping, the punch member 22 is returned to its original position by a device (not shown) so as to be ready for the next molding. Further, after the gate is selectively cut and the additional compression molding is performed, the punch member 22 is applied to the cut product surface for a short time while the punch member 22 is slightly vibrated or gently reciprocated by the servo cylinder 32.
By contacting the side wall 39, the product surface can be further refined.

[0034] Other morphism <br/> out molding method using a punch member of the present invention then, with respect to y de molding method described above, the punch member 22 is advanced when the gate cutting, further cavities or cores 25, except that the product part 29 is additionally compressed and formed .
The same effect as described above can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a first injection molding apparatus used in an injection molding method using a slider member of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view of a main part showing a second injection molding apparatus used in an injection molding method using a punch member of the present invention, in which a punch member 22 is at a starting point position.

FIG. 4 is a cross-sectional view of a main part showing a state where the punch member 22 of FIG. 3 has performed a gate cut.

5 is a cross-sectional view of a main part showing a state where the punch member 22 of FIG. 3 has further protruded into a cavity or a core 25 after gate cutting.

[Explanation of symbols]

 1, 21 Gate part 2 Slider member 3, 23 Movable mold 4 Resin 5, 25 Cavity or core 7, 27 Fixed mold 9, 29 Product part 10, 30 Sprue 11, 31, Runner part 12, 32 Servo cylinder 22, Punch member

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukio Nakamura 4-11-4 Nishikawaguchi, Kawaguchi City, Saitama Prefecture Inside Nippon Kayaku Co., Ltd. (72) Inventor Norinaga Yoneoka 4-11-4 Nishikawaguchi, Kawaguchi City, Saitama Prefecture (56) References JP-A-1-264821 (JP, A) JP-A-52-109556 (JP, A) JP-A-3-53919 (JP, A) JP-A-3-244520 (JP, A) JP-A-3-138121 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/00-45/84 B29C 33/00-33/76

Claims (12)

(57) [Claims] 1. A member, which is capable of pushing a molten resin into a mold cavity or a core from a mold gate and allowing a gate to be cut with respect to the mold cavity or the core, so that the member can be slid with respect to the mold cavity or the core. A small vibration to soften the plastic in the vicinity of the gate by this vibration energy, and then compress the product by forcibly displacing the member without vibration or applying vibration, and a product compression step, after injection filling, the product A gate cutting step in which a gate is cut while applying no vibration or vibration to the member before, after, or simultaneously with the compression step. 2. The product compression step and the gate cutting process
After the end of the process, the member is further subjected to minute vibration or loose
While giving a reciprocating motion,
Characterized in that, at least, the members are brought into contact for a short time.
The injection molding method according to claim 1, wherein 3. A gate seal after injection filling, wherein a molten resin is pushed into a mold cavity or core from a mold gate portion and a gate-cuttable slider member is slidable with respect to the mold cavity or core. During the pressure-holding process after the completion of the pressure-holding and during the cooling after the completion of the pressure-holding, a minute vibration is applied to the slider member, the vibration energy softens the plastic in the vicinity of the gate, and then the slider member is subjected to no vibration or vibration. An injection molding method characterized in that a product is compressed by forcibly displacing and a gate is cut. Wherein it was at least short time contact in the further product surface that is the gate cut while providing small vibrations or gradual reciprocates the slider member after forcibly displaced so gate cutting the slider member Characterized by
Injection molding method of claim 3 Symbol placement that. 5. A slider member capable of pushing a molten resin into a mold cavity or a core from a mold gate portion and slidable with respect to the mold cavity or the core. The product whose gate has been cut by forcibly moving the member to compress the product and cut the gate, and furthermore, contact the surface of the gate-cut product at least for a short time while giving the slider member a minute vibration or a gentle reciprocating motion. An injection molding method characterized by simultaneously performing product compression and gate cutting for finishing a surface. 6. A mold member is inserted into a mold cavity or a core to push in a molten resin, and a gate member capable of being gate-cut is slidable with respect to the mold cavity or the core. , the punch member to give minute vibrations to soften the plastic near the gate by the vibrational energy, the later, no vibration or a forcibly displacing the punch member while applying vibration to the gate cut, further the punch An injection molding method, wherein a product is pressed into the cavity or the core to perform product compression molding. 7. After the gate member is cut by forcibly displacing the punch member, the punch member is brought into contact with the gate-cut product surface for at least a short time while giving a slight vibration or a gentle reciprocating motion to the punch member. Characterized by
Injection molding method of claim 6 Symbol mounting. 8. A punch member which enters the mold cavity or core from the mold gate portion to push in the molten resin, and allows a gate member capable of gate cutting to slide with respect to the mold cavity or core, and after injection filling. The gate was cut by forcibly moving the punch member, and the product was pressed into the cavity or core to perform product compression molding, and the gate was cut while giving the punch member a minute vibration or a gentle reciprocating motion. An injection molding method comprising simultaneously performing product compression and gate cutting in which the product is finished by being brought into contact with the product surface for at least a short time. 9. A fixed mold and a movable mold for forming a cavity or a core for molding a runner portion, a gate portion and a product portion on an abutting surface, and a part of the runner portion is formed in the movable mold. soluble resin can only allow One gate cut pushed into the cavity or the core slider member was slidably disposed, said slider member and to be driven by a cylinder fixed to the movable mold An injection molding apparatus characterized by the above-mentioned. 10. The cylinder is a servo cylinder
Injection molding apparatus according to claim 9 Symbol mounting, characterized in that. 11. A fixed mold and a movable mold for forming a cavity or a core for molding a runner section, a gate section and a product section on an abutting surface, and a part of the runner section is formed in the movable mold. A meltable resin can be pushed into the cavity or core, and a gate member is cut, and a punch member that can protrude into the cavity or core is slidably disposed, and the punch member is fixed to the movable mold. An injection molding apparatus characterized by being driven by a set cylinder. 12. The cylinder is a servo cylinder.
Injection molding apparatus according to claim 11 Symbol mounting, characterized in that.