JPH0353919A - Cutting method of gate - Google Patents

Abstract

PURPOSE:To make cleaning of plastic adhering to a first and/or second member every shot unnecessary, by a method wherein after completion of gate sealing after injection filling, fine vibration is given to the first and/or second member, plastic close to a gate is softened with vibration energy, at a point of time when the plastic is softened sufficiently, the first and/or second member is displaced forcibly and the gate is cut off. CONSTITUTION:When injection is begun into a sprue part 24 through the tip part of a nozzle of an injection molding machine, an inflow resin 1 is filled into a cavity 21 by passing through the sprue part 24, a rubber part 25 and a gate 22. When filling is completed, the injection molding machine is entered into a cooling process while performing dwelling and the gate 22 is cooled, solidified and sealed. When gate sealing is completed, a servocylinder repeats a fine oscillation and reciprocation. The reciprocation oscillates finely a rotary shaft 3 and gate cutting piece 2 through rack gears 8, 8' and pinions 3, 3', through oscillation energy of which the resin at an interface between the cavity 21 and gate 22 is heated for softening. When the resin at the gate 22 is softened, the rotary shaft 3 is rotation-displaced forcibly by a desired quantity and the gate 22 is cut off.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a plasticsox injection molding method, and in particular, in the plasticsox injection molding, the gate, which is the injection port into the cavity, has a side gate 1-, a pinky 1- , Fange-1-, Filmke-1 ``J'' Except for the pin gate, the product part and the runner are usually taken out of the mold while being connected at the gate part, and the game part is removed from the mold in the later process.
・The gate is cut in an ideal state in the mold during molding, and the product part and the runner are separated and taken out. Regarding the method.

(1 branch of Tsuchiki + M) As a conventional gate cutting method, for example, the patent application 1986-2
There is a pending but unpublished method disclosed in No. 49949, in which the member constituting the mold gate part is made slidable with respect to the mold cavity or core, and the gate seal after injection filling is made. After completion (or during the pressure retention process), applying micro vibrations (or reciprocating motion) to the member,
A gate cutting method has been proposed in which the vibration energy softens the plastic near the gate, and when the plastic is sufficiently softened, the member is forcibly displaced and the gate is cut in one step.

(Problems to be Solved by the Invention) The gate cutting method described above has been able to obtain a product with an extremely good appearance because no gate cutting marks remain; however, the members constituting the sliding mold gate part A mold cavity or core that forms a counterpart member, that is, a fixed part on the non-sliding side, that comes into contact with the part during microvibration or reciprocation;
The plastic that forms the sprue or the runner from the sprue to the gate is rubbed between the! This may cause friction between the part and the opposing mold cavity or core, causing problems, or if there is plastic on the non-sliding side of the part.
'W, and the next product was defective, so it was necessary to clean the plastic that had arrived after each use.

An object of the present invention is to provide a gate cutting method that prevents plastic from adhering to the members forming the sprue portion or the runner portion extending from the sprue portion to the gate and the mating non-sliding member.

(Means for Solving the Problems) Therefore, the present invention has solved the above-mentioned problems of the prior art by providing a gate cutting method as described in the claims.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings. FIG. The gate cutting piece 2, which is the first member constituting the mold gate part 22 and the runner part 25 forming the cutting device of .22, is 2{llllI,
It is rotatably attached to a movable side mango 12 which is a movable side mold. The movable side body 12 is removably attached to the identification side body 20 supported on a manufacturing machine (not shown) in a movable side body 19 that can be retracted from the position shown in the figure in order to open the mold. It has a cavity 21 or core for molding. The fixed side mantle 13 is removably disposed within the fixed side main body 20, and cooperates with the movable side mantle 12 to form a mold core or cavity on the abutting side.

23 is a product, 22 is a gate, 24 is a sprue portion, and 25 is a runner portion that connects the sprue portion 24 and the gate 22, and the outside thereof is exposed as a part of the gate cutting piece 2. A surface 2 that comes into sliding contact with this runner portion 25
A cutting piece support 6, which is a second member having a
A bearing 7' is installed in the stationary side mantle 13 and on the stationary side main body 20 so that it can be driven by the gate cutting piece 2, which is a member of It is rotatably supported through.

In the embodiment, the runner part 25 is formed in the gate cutting piece 2 to cut two pieces, but when cutting one piece, only the sprue part 24 can be formed, and the sprue part of the gate cutting piece 2 It goes without saying that 24 and the surface 26 of the cutting piece support 6 can be arranged in abutment. Figure 2 is a sectional view taken along line II■ in Figure 1, with 14' and 15'
, 16' are the eschector plates 27 in FIG.
The positions of the gate runner discharge pin 14, the sprue discharge bin 15, and the product discharge bin 16, which are fixed at one end and pass through the movable main body 19 or the rotating shaft 3, are shown. 11 is a gas vent, and 17 is a cooling water hole. Cutting piece support 6
may be driven synchronously with the gate cutting piece by the rotary shaft 3. The gate cutting piece 2 is fixed to the rotating shaft 3 by a cutting piece fixing key 5, and the rotating shaft 3 is rotatably supported by the movable main body 19 via a bearing 77 and the rotating shaft support 4. Each rotating shaft 3, 3 has a binion 3', 3',
The pinion is meshed with Ranok 8's Rasok Gya 8.8'. The rotation axis 3 rotates the support piece 6, and the game 1
- The cutting piece 6 may be driven/synchronized with the cutting board 1-6. FIG. 3 is a cross-sectional view taken along the line 2 in FIG. The rasok 8 is connected to the Ll throat (not shown) of the cypress cylinder 18 by a hydraulic surf cylinder joint pin 9. The Ura Pressure Rebo cylinder 18 is fixed to the movable main body via the cylinder fixing plate 10, and is driven by a hydraulic power source and a servo valve (not shown), so that the joint pin 9 and the rasokku 8 can be slightly vibrated, and the rasokya 8'. 8
The rotary shaft 3.3 can be rotated with minute vibrations via a pinion 3'3' that meshes with the pinion 3'3'.

A first gate cutting method according to the present invention will be described. When injection starts into the sprue section 24 from the nozzle tip of an injection molding machine (not shown), the inflowing resin 1 passes through the sprue section 24, the runner section 25, and the gates 22, 22, and then flows through the cavities 21, . 21 is filled. After filling is completed, the cooling process begins while maintaining the pressure (plastisox shrinks as it cools, so the filling pressure is maintained to compensate for the shrinkage), and the gate 1-22.22 cools and solidifies, sealing the gate. be done. Generally, the cross-sectional area of the gate 22 is smaller than any other part of the cavity 21, so the cooling of the gate 22 is faster than the cooling of the product part, and the holding pressure effect disappears after the gate is sealed, so even if the gate is cut when the gate sealing is completed, the product will not be produced. ．． has no effect. When the gate sealing is completed, the servo cylinder 18 repeats micro-vibration reciprocating motion by a device not shown. This reciprocating motion of the servo cylinder l8 causes the quadrilateral shaft 3 and the gate cutting piece 2 to be slightly vibrated through the reciprocating gears 8, 8' and pinions 3', 3'. The resin at the interface generates heat and softens.

When the resin of the gate 22 softens, the rotary shaft 3 is forcibly rotated by a desired amount to cut the gate 22.

Note that heat generation due to vibration energy occurs only in the resin part.
Since the amount of heat generated on the cursor surface of the rotating shaft 3 is negligible, the softened portion is rapidly cooled at the same time as the gate is cut.

The softening and cutting process of the resin is completed in just a few seconds, so it can be done at the same time as cooling the product, and does not impede productivity compared to conventional models.

After gate cutting and cooling are completed, the mold is opened in the same way as normal injection molding, and the product and runner are taken out to complete the shaping process.

Furthermore, after turning the rotary shaft 3 by a desired amount to cut the gear I-22, the rotary shaft 3 is further slightly vibrated by the servo cylinder 18 via the rank gear 8' and the pinion 3', and is then cut. The cut surface of the gate can be further cleaned by bringing the mold surface of the rotary shaft 3 into contact with the cut surface of the gate for a short period of time, pressing it and licking it. The vibration of the rotating shaft 3 may provide a gentle reciprocating motion for a short period of time.

Next, the second gate cutting method according to the present invention will be explained. The same mold as in the first gate cutting method is used as shown in FIGS. 1 to 3. When the molten resin starts to be poured into the sprue section 24 from the nozzle tip of the injection molding machine (not shown), the molten resin flows through the sprue section 24, the runner section 25 and the gates I and 2.
2 and fills the cavity 21. When filling is completed, the cooling process begins while maintaining pressure, and when the gate 22 begins to cool and solidify (before the gate 22 is cooled and solidified and sealed), the viscosity of the resin in the gate 22 becomes extremely high. , it is impossible to fill the shrinkage due to holding pressure, but there is a state that is soft enough to cut.

That is, in the injection cycle, in the pressure holding step after completion of injection, the gate 22 usually has the smallest cross-sectional area and is the first to be cooled and solidified. Therefore, after a certain period of time has elapsed after entering the holding pressure step, there is a time period in which the resin becomes too hard to feed into the cavity 21 due to holding pressure, but is soft enough to be cut. During this time period, the rotary shaft 3 is rotated by the servo cylinder 18 to cut the gate 22, and after the gate cutting is completed, the cylinder 18 is driven to cause the rotary shaft 3 to reciprocate and minutely vibrate for a short time. At the time when the gate 22 is cut, the cut surface of the gate is still soft, and by bringing the polished surface of the rotary shaft 3 into contact with the cut surface of the gate 1 and pushing it by one degree, With the addition of the lasoping effect, the cut surface of the gate will be finished with a glossy finish. Since the cutting of the gate 22 and the subsequent abutment process are completed within a few seconds, productivity is not hindered compared to the conventional injection molding method. Further, since gate cutting is performed when the holding pressure is no longer effective, there is no adverse effect on the molded product.

1I Also, depending on the type of resin, instead of applying minute vibrations to the rotary shaft 3 during the contact process after cutting the gate, the member is applied to the rank, and the rotary shaft 3 is gently rotated in a reciprocating manner to apply the gate cassette to the cut surface of the gate. Even if the polished surface of the mold of the shaft is brought into contact with the shaft and pressed and rubbed, it is possible to obtain a gate cut surface with a good glossy surface. After the gate cutting and the subsequent abutting process, the mold is opened in the same way as in normal injection molding, and the molded product and runner are taken out with the resin filled in the cavity 21, and the molding process is completed.

(Effects of the Invention) As explained above, the gate cutting method according to the present invention does not leave gate cutting marks, so it is possible to obtain a product with an extremely good appearance, and it also eliminates the conventional post-finishing process. In addition to advantages such as being able to make the gate larger, the second member, which is the other member that comes into sliding contact with the sprue portion or runner portion of the first member, is driven by/synchronized with the first member to generate minute vibrations or reciprocating motion. Therefore, there is no or almost no relative movement between the two members, so even when the plastic 12 near the gate softens and the gate is cut, both the first and second members remain plastic. There is no longer any problem caused by friction or adhesion of plastics to the first and second members, and therefore there is no need to clean the plastics that adhere every time.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main part of a mold used in the gate cutting method according to the embodiment of the present invention, and FIGS. 2 and 3 are cross sections taken along the lines 1 and 2 in FIG. 1, respectively. Show the diagram. 2... Gate cutting piece (first member), 6... Cutting piece support 1 (second member), 12... Movable side insert (mold cavity or core), 13... Fixed side insert (mold cavity or core), 22...gate (gate part)
, 24... Sprue part, 25... Runner part, 26
...Sliding surface

Claims (4)

[Claims] (1) A first member that constitutes a mold gate portion and a sprue portion or a runner portion, and a surface that slides in contact with the sprue portion or runner portion of the first member and is driven by the first member. / A second member arranged to be synchronously drivable is slidable with respect to the mold cavity or core, and after the gate sealing after injection and filling is completed, the second member is arranged to be able to be driven synchronously.
A minute vibration is applied to the first and/or second member, the vibration energy softens the plastic near the gate, and when the plastic is sufficiently softened, the first and/or second member is forcibly displaced to open the gate. A gate cutting method characterized by cutting. (2) The gate cutting method according to claim 1, wherein after forcibly displacing the member, the member is brought into contact with the cut surface of the cut gate for at least a short period of time while applying minute vibrations to the member. (3) The gate cutting method according to claim 1, wherein after forcibly displacing the member, the member is brought into contact with the cut surface of the cut gate for at least a short period of time while giving a gentle reciprocating motion to the member. . (4) A first member that constitutes a mold gate part and a runner part, and a surface that slides into contact with the sprue part or the runner part of the first member, and is driven/synchronously driven with respect to the first member. a second member arranged so as to be slidable relative to the mold cavity or core, and the first and/or second member is slidably disposed relative to the mold cavity or core; the first and/or second gate.
A method for cutting a gate, wherein the cut surface of the gate is finished by bringing the member into contact with the cut surface of the cut gate for at least a short period of time while applying minute vibrations or a second gentle reciprocating motion to the member.