JPH0549015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a runnerless injection molding apparatus using external heating and equipped with a local heating mechanism for a gate portion.

[Conventional technology]

Conventionally, this kind of runnerless injection molding equipment called a hot runner method generally places a sharp heating element in a runner part formed in a mold to heat raw material resin that accumulates or flows in the runner part. Alternatively, a heater was provided in the outer peripheral mold constituting the runner part to heat the raw resin in the runner part.

[Problem that the invention seeks to solve]

However, in the conventional example described above, the runner is integrally formed with the gate portion leading to the cavity, so it is extremely difficult to control the temperature of the sharp heating element and the heater on the outer periphery of the runner portion.

In other words, if we consider thermal energy for the sole purpose of keeping the raw material resin in the runner warm and melting it, we will not be able to properly control the solidification or semi-solidification of the minute amount of resin that is exposed to the gate, and the molded product will not be able to be opened during the mold opening operation. When taken out, the molten resin flows out from the gate, deteriorating moldability and causing a so-called runny nose phenomenon.

To this end, the inventor has developed a special configuration called Spear System, which heats the gate section partially from the inside or outside, allowing runnerless injection molding to be performed with high precision and efficiency. Technology is in the spotlight.

However, in the case of high-precision, high-precision molding processing, a controller is required to control the temperature, and while the Spear system does not require a particularly large and expensive controller, other runnerless injection molding machines require IC technology, There was a problem in that there was a high dependence on the use of expensive controllers using computer technology and so-called electronic control.

[Means for solving problems]

This invention has been made by focusing on the above-mentioned points, and it is possible to use the conventionally known raw material plasticizing means, injection molding means, and mold structure as they are, and the runner part and cavity in the mold can be used as is. A runner heating means for heating the runner part and a gate heating means for heating the gate part are formed as separate members, and the gate heating means is made of a thermally conductive material. A high annular material is used to form a flow path for the molten resin, which contacts the runner heating means to receive thermal energy transfer from the runner heating means, and is further equipped with a self-heating heating mechanism such as a heater to heat the gate section from the outside. The above-mentioned problems have been solved by simplifying the configuration by allowing localized heating and by making heat control extremely easy.

This makes it possible to simplify temperature control by simplifying or omitting temperature control using a controller such as a computer and obtain high-precision molded products.It also simplifies the configuration, reduces costs, and significantly lowers injection pressure. The purpose of the present invention is to provide a runnerless injection molding device that can perform the following steps.

[Effect]

The thermally molten raw material obtained by the raw material plasticizing means and supplied to the runner section is subjected to heat acting from the outside to the inside by the runner heating means, and the gate section is also heated from the outside to the inside by the gate heating means. It maintains a semi-solid state or a molten state due to the thermal action acting on both sides.

The temperature setting of the runner heating means is as follows:
This is determined in advance before the molding operation in consideration of heat conduction to the gate heating means, which has a self-heating function, and a fixed amount of raw material is intermittently applied to the runner section of the runner and the gate section using normal injection molding means. It is then supplied into the cavity.

Particularly, since thermal energy supplied to the raw material of the gate portion through thermal conduction from the runner heating means is indirectly applied by the annular gate heating means, self-heating of the gate heating means is avoided. The action is significantly less, which allows the material to be in a semi-solid or molten state during each molding operation.
In other words, the gate section maintains either an open or closed state.

Therefore, it is possible to smoothly inject and fill the cavity with molten resin each time an injection molding operation is performed, and even when the molded product in the cavity is taken out in the open state, there is no unnatural dripping from the gate part. The phenomenon is prevented.

Moreover, since the runner part and the gate part are disposed on the same straight line and penetrating each other, the injection pressure can be reduced and the injection molding operation can be carried out efficiently.

〔Example〕

Examples of the present invention will be described below.

In FIG. 1, 1 is a means for thermoplasticizing raw materials; 2 is a means for thermoplasticizing raw materials;
3 is an injection molding means for molten resin, 3 is a mold, especially a runner formed in a fixed mold 4, and 5 is a manifold that forms two or more injection channels, and a heating device such as a necessary number of cartridge heaters. Sources (not shown) are provided where necessary.

A runner heating means 6 is disposed between the manifold 5 and the intermediate mold 8 communicating with the cavity 7, and is housed in a tubular annular housing portion 9.

By the way, this runner heating means 6 does not need to be particularly specified, but it can be selected from either a self-heating type such as a heater or a high-frequency electromagnetic induction coil, or a heat-dependent type such as a heat pipe filled with a heat transfer fluid. It can be used as Self-heating types may require a controller; heat-dependent types require almost no controller at all.

All the embodiments of the present invention shown in FIGS. 1 to 3 use a heat-dependent heat pipe 6a, which is filled with a thermally conductive fluid and is formed in the shape of a double-pipe ring. A runner portion 10 corresponding to a straight hole with a desired diameter R ₁ is formed as a part of the so-called runner 3 .

11 is connected to the runner heating means 6,
The gate heating means includes a gate portion 12 that communicates with the cavity 7, has an annular collar 13 at the base, engages with the tip step portion 14 of the heat pipe 6a, and has a narrow tapered portion 15. A gate 16a of the cavity 7 is opened through a gate hole 16 having a diameter R ₂ smaller than the diameter R ₁ and further through a tapered portion 17 . The runner portion 10 of the heating means 6 and the gate portion 12 of the gate heating means 11 are arranged on the same axis, that is, on the same straight line. The gate heating means 11 is preferably made of copper, a metal such as copper, beryllium, or other material having good thermal conductivity.

At the tip of the gate heating means 11,
A heater H of a heating mechanism is wrapped around the outer periphery and operates constantly or intermittently each time a molding operation is performed to constitute an auxiliary heat source for the gate heating means 11.

Reference numeral 18 denotes a tubular support holder that rigidly supports the runner heating means 6 and gate heating means 11 at the outer circumferential position, one end of which is brought into contact with the manifold 5 by a flange 19, and the other end is bent at a tip end. 2
0 and the inner step 21 engages with the annular flange 13 of the gate heating means 11, and this flange 1
The structure is such that one end of the heat pipe 6a that comes into contact with the heat pipe 9 can collide with the end surface of the manifold 4 and be fixed.

Reference numeral 22 denotes a positioning ring that can be engaged with the flange-like portion 19 of the support holder 18, and is aligned with the stepped portion 25 of the insertion hole 24, which has approximately the same shape as the support holder 18, so as to obtain a minute air gap 23 within the intermediate mold 8. engaged. 26 is a temperature sensor formed by a thermocouple or the like, and is provided near the gate heating means 11.

Reference numeral 27 indicates a movable mold that can form the cavity 7 and can be opened and closed freely, and 28 indicates a holding frame cylinder disposed around the outer periphery of the heater H.

The action will be explained based on the above structure.

First, the raw material to be used is melted by the raw material thermoplasticization means 1 so that it can be injection molded, and the thermal energy of the manifold 5 is generated by the heating source for heat retention provided in the mold, especially the fixed mold 4. is transmitted to the support holder 18 that collides with this, and the heat pipe 6a, which is the runner heating means 6, is maintained at a required temperature by the support holder 18.

At the same time, necessary thermal energy is also supplied to the gate heating means 11, which is a separate member, and is in contact with the runner heating means 6.

After reaching the preset temperature of the gate heating means 11, the molten raw material resin is injected by the injection molding means 2. If the runner 3 bored in the mold 4 is filled with molten resin, the necessary amount is transferred from the runner section 10 of the runner 3 to the cavity 7 through the gate 16a of the gate section 12 by the action of the injection molding means 2. A predetermined volume of resin is filled inside. At this time, the heater H serving as a heating mechanism supplies thermal energy to the gate heating means 11 at all times or during the molding operation, so that the thermal melting state of the raw resin in the gate portion 12 can be controlled with high sensitivity.

Then, after a certain period of time has elapsed and the resin filled in the cavity 7 is cooled and solidified, the movable mold 27 is opened and the molded product is taken out.

Since the above is a single molding cycle, the necessary number of molded products can be obtained by repeating the operation.

By the way, in this embodiment, the heat pipe 6a is used as the runner heating means 6, so the heat source for heating the heat pipe 6a is the mold 4, especially a cartridge heater installed inside the manifold 5. It is possible to absorb the necessary amount of thermal energy by using heat conduction as a heating source, and
This absorbed thermal energy can also be effectively conducted to the gate heating means 11 connected in contact with the tip.

Therefore, the heating temperature of the molten resin in the gate part 12 becomes slightly lower by the gate heating means 11, so that the insufficient amount of heat can be constantly or intermittently replenished as needed by the heater H, and the molten resin in the gate part 12 is heated slightly lower. It is possible to maintain the raw material resin in 12 in an optimal state convenient for molding operations, prevent the molten resin from flowing out from the gate 16a after taking out the molded product, and prevent the dripping phenomenon, allowing subsequent repeated molding operations to be performed with high precision. be able to.

In addition, the runner part 10 and gate part 12 of the runner 3
Since the air gap 23 is formed in a straight line, it has the advantage of requiring low injection pressure.
, which prevents dissipation of temperature and loss of thermal energy, making it possible to perform the molding operation smoothly.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the gate heating means 1 shown in FIG.
1 is not simply brought into contact with one end surface of the runner heating means 6, but the annular collar 13 is expanded slightly and further extended into the runner portion 10 of the runner heating means 6 to form a cylindrical portion 11a, thereby heating the runner. The inside of the means 6 is supported by this cylindrical part 11a so that the inside of the cylindrical part 11a can be used as a runner part 10, and the runner heating means 6 made of a heat pipe 6a is completely held and reinforced from the inside and outside. The purpose of this project is to protect it.

Further, the support holder 18 has a configuration in which the bent tip 20 shown in FIG. An auxiliary holder 18c for the heat pipe 6a with good thermal conductivity is interposed on the contact surface.

Since the other configurations are substantially the same as those of the first embodiment, detailed explanation thereof will be omitted.

Next, another embodiment of the present invention will be described based on FIG.

In this embodiment, the gate heating means 11 and the runner heating means 6 are not brought into direct contact, and a coupling ring 29 having excellent thermal conductivity and wrapped with a heater H ₂ is screwed onto the open end of the support holder 18b. A difference in structure from the previous embodiment in that a hollow pipe 30 is used for reinforcement and in contact with the gate heating means 11 on the inner side of the runner heating means 6 which is interposed and forms the runner part 10. There is.

Further, the support holder 18b that collides with the manifold 5 is provided with a ring 31 and a support tube 32 made of a material with excellent thermal conductivity and supporting the manifold side of the runner heating means 11.

However, similar to the previous embodiment, this embodiment uses a heat pipe 6a to utilize the heat source inside the mold 4 to heat the runner section 10 and gate section 12 from the outside toward the center. The effect is the same.

Therefore, among the configurations of this embodiment, those that are substantially the same as those of the previous embodiment are given the same reference numerals, and since the functions are also the same as those of the previous embodiment, the details thereof will be omitted.

Three embodiments have been described above for this explanation, and the runner heating means 6 that heats the runner portion and the gate heating means 11 that heats the gate portion 12
The gate heating means is made of a highly thermally conductive annular material to form a flow path for the molten resin, and the thermal energy of the gate heating means 11 uses the thermal energy of the runner heating means 6. If it is constructed so that the necessary thermal energy can be supplied by its own heating means,
The configuration of each part does not need to be particularly limited, and can be applied to anything having the above-mentioned technical content.

〔Effect of the invention〕

According to this invention, the runner part and the gate part are connected on the same straight line, and the thermal energy of the runner heating means for heating the runner part is transmitted directly or through another coupling to the gate heating means of the gate part. Because of this, heat conduction and heat distribution are reasonable, and heat is supplied according to the diameter.

The gate heating means is a highly thermally conductive annular material that forms a flow path for the molten resin, and is connected to the runner heating means so as to receive thermal conduction of the thermal energy from the runner heating means. The structure is such that a means is provided to locally heat the raw resin from the outer circumferential side of the gate. That is, the gate section is equipped with a self-heating type heating mechanism equipped with a heater that is energized and generates heat separately from the runner heating means, and is further equipped with a heat-dependent heating mechanism that receives heat from the adjacent runner heating means. The temperature of the gate section, where temperature control is extremely important, can be quickly and precisely controlled with simple operations, enabling high-speed, high-density injection molding. Further, the runner heating means can obtain thermal energy from a heat source within the mold by using a heat-dependent structure such as a heat pump, and the overall structure can be provided simply and at low cost.

Furthermore, according to the present invention, since a super steel metal material can be used for the gate heating means that has both a self-heating type and a heat-dependent type function, other fibers such as glass fibers are not mixed into the molten resin. The wear resistance can be partially improved even if the runner is heated, and the heat conduction from the runner heating means can be formed using a small volume member. High precision injection molding operations can be performed because the desired state, such as molten state, solidified state, or semi-solidified state, can be sensitively controlled depending on the situation.

Furthermore, according to the present invention, a small, small-volume gate heating means is designed and stored in advance, and a runner heating means is prepared each time according to the size of the mold and molding machine. Therefore, the current uneconomical situation in which expensive runner heating means are stocked more than necessary can be significantly improved and waste can be eliminated.

Furthermore, the runner heating means has the advantage that it is possible to use not only a heat-dependent type such as a heat pipe, but also a self-heating type heat source of your choice such as a heater, a cartridge heater, or a high-frequency electromagnetic induction heating coil. .

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and FIGS. 2 and 3 are longitudinal sectional views showing two other examples of the same. 1... Raw material thermoplasticization means, 2... Injection molding means, 3... Runway, 4... Fixed mold, 5... Manifold, 6... Runner heating means, 7... Cavity, 10... Runner part, 11...Gate heating means, 12...Gate part, 29...Coupling, H, _H2 ...Heater as a heating mechanism.

Claims (1)

[Claims] 1. A runnerless injection molding device that allows thermoplasticized raw materials to be injected into a desired cavity through a runner section and a gate section through a runner provided in a mold using an injection means such as a piston. A runner heating means for heating the runner part and a gate heating means for heating the gate part are formed as separate members. It is formed of a cylindrical heat pipe that can raise the temperature by absorbing the thermal energy of the heat source through thermal conduction, and the gate heating means is made of a highly thermally conductive annular material that forms a flow path for the molten resin. A heat transfer-dependent heating mechanism is connected to the runner heating means so as to receive heat transfer of thermal energy from the heating means, and a self-heating heating mechanism is equipped with a heater that is energized and generates heat separately from the runner heating means. A runnerless injection molding apparatus characterized in that the runnerless injection molding apparatus is made up of a combination of parts and is configured to locally heat the resin in the gate part from the outer circumferential side.