JP2005271014A - Multi-cavity metal injection molding die using hot runner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal injection molding die capable of high speed filling where a molten material is filled in a short time without increasing the mold clamping force to be required in a molding die. <P>SOLUTION: The molding die comprises a plurality of hot runner nozzles 7 which allow a manifold 6 to communicate with each cavity 1 as a product part, and comprises a temperature raising timing set means for setting the difference in time to the temperature raising timing of each hot runner nozzle 7, and by differentiating the time at which each hot runner nozzle 7 is opened, molten material is filled into the plurality of cavities 1 as product parts in order. By filling the molten material to be fed in a state of being concentrated on each cavity 1 as a product part, the filling time (injecting time) per cavity 1 as a product part is reduced, the molten material can be filled in a high temperature state where solidification does not occur even without unnecessarily increasing the pressure under which the molten material is injected, and by suppressing the internal pressure of the molten material, high speed injection can be performed without increasing the molding die clamping force to be required in the molding die. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multi-cavity metal injection mold using a hot runner, and relates to a technology of a molding mold that uses a hot runner to mold a multi-cavity metal injection mold such as a magnesium alloy.

  Conventionally, as a multi-cavity molding die in resin molding, for example, there is one described in Patent Document 1. This is a molding device provided with a plurality of valve gate nozzles. Each valve gate nozzle communicates with the mold cavity at the outer end (gate) and communicates with the manifold at the inner end. The gate is opened and closed by the withdrawal of the provided valve pin. The timing for opening the gates of the valve gate nozzles is to open all the valve gate nozzles simultaneously, or to open the valve gate nozzles for each row.

  However, unlike the resin molding, in the metal injection molding, the molten metal of the molten material is high temperature and the solidification temperature is high, so the solidification time in the molding die is as short as 0.1 sec or less. For this reason, in the method using the valve gate nozzle having the above-described valve pin, the metal of the material is solidified in the runner of the molding apparatus, and thus this method has not been used for metal injection molding.

  FIG. 6 shows an example of multi-cavity in conventional metal injection molding, and schematically shows the arrangement of sprues, runners, product cavities, etc. in a four-cavity molding die using a cold runner. .

  In the configuration shown in FIG. 6A, the runner 4 is first branched in two directions from the spru 2 and further branched in two directions, and in the configuration shown in FIG. Branches in four directions.

  6A and 6B, the molten material injected from the injection molding machine is filled into the molding die from the sprue 2 and flows into the product cavity 1 through the runner 4 and the gate 3. An overflow 5 may be provided at the tip of the product cavity 1 to prevent molding defects such as air bleeding and welds.

  In the metal injection molding using this cold runner, since the solidification time of the molten metal is short, it is necessary to fill the molten material at a high speed, and in the multi-cavity molding, the molten material is put into each product part cavity 1. Since it is necessary to consider the filling balance, sufficient arrangement is required for the arrangement and shape of the runner 4.

  Practical use of multi-cavity metal injection molds using hot runners to reduce injection time and increase the temperature of the molten material to be filled, which are issues in multi-cavity metal injection molding using cold runners Has been.

  FIG. 4 shows a four-piece mold using a hot runner, schematically showing the arrangement of hot runners, products, etc. FIG. 5 shows the cross-sectional structure of the hot runner mold. It is.

  4 to 5, in the molding die using the hot runner, the manifold 6 is maintained around the melting point of the metal material to be injected, and the metal material in the manifold 6 is in a molten or semi-molten state. The temperature of the hot runner nozzle 7 is controlled by heating with the heating unit 8, and the metal material in the hot runner nozzle 7 is in a solid state to prevent the molten material from being ejected when the mold is opened.

  At the time of injection molding, the hot runner nozzle 7 is first heated by the heating unit 8 after the mold is tightened, and the gate 3 is opened by melting or semi-molten the solid metal material in the hot runner nozzle 7. To do.

  Next, the molten material is supplied from the injection molding machine, and the product portion cavity 1 is filled with the molten material from the hot runner nozzle 7 through the manifold 6. Thereafter, the hot runner nozzle 7 is also cooled during the cooling time of the product cavity 1, and the gate 3 is closed when the metal material in the hot runner nozzle 7 becomes solid again.

After the metal material of the product part cavity 1 is sufficiently cooled, the molding die is opened, the product is taken out, and one cycle of injection molding is completed.
JP 2002-144379 A

  However, in the conventional metal injection mold using a cold runner and a hot runner, it is necessary to inject the molten material at a high pressure in order to fill the product portion cavity with the molten material in a short time. A force derived from the internal pressure acts in the direction of opening the molding die. This force increases as the internal pressure of the molten material increases and the projected area of the product cavity on the split surface of the mold increases, which causes the mold clamping force to be insufficient. There is a quality problem that burrs are generated by a minute opening on the divided surface.

  The present invention solves the above-described problems, and provides a metal injection mold that enables high-speed filling in which a molten material is filled in a short time without increasing the necessary clamping force in the mold. For the purpose.

  In order to achieve the above object, a metal injection mold for multi-cavity molding according to the present invention according to claim 1 is a molding die for performing multi-cavity injection molding of a metal material, and includes a manifold and a plurality of product parts. It has a plurality of hot runner nozzles communicating with each of the cavities, has a temperature rise timing setting means for setting a time difference in the temperature rise timing of each hot runner nozzle, and varies the time when each hot runner nozzle opens. A plurality of product part cavities are sequentially filled.

  With the above configuration, the filling material (injection time) per product part cavity is shortened by filling the molten material supplied from the injection molding machine through the manifold in a concentrated manner for each product part cavity. The molten material can be filled at a high temperature that does not solidify without increasing the pressure for injecting the molten material more than necessary, and the required mold clamping force of the molding die can be reduced by suppressing the internal pressure of the molten material. High-speed injection can be performed without increasing.

  The multi-cavity metal injection mold of the present invention according to claim 2 has a sensor means for detecting that each product portion cavity is filled with a molten material, and raises the temperature by feeding back the output of the sensor means. In the timing setting means, after the filling of the molten material in the product cavity of the hot runner nozzle with the earlier temperature rise timing, which is preceded by the opening, is completed, the next hot runner nozzle with the later temperature rise timing at which the opening is delayed becomes the nozzle opening temperature. The time difference of the temperature rise timing is adjusted so that the temperature reaches.

  According to a third aspect of the present invention, there is provided a multi-cavity metal injection mold according to the present invention for performing a multi-cavity injection molding of a metal material, wherein a plurality of manifolds communicate with each of a plurality of product portion cavities. The hot runner nozzles have nozzle opening temperature setting means for setting a temperature difference between the nozzle opening temperatures of the hot runner nozzles, and the hot runner nozzles are sequentially opened to a plurality of product section cavities at different times. It is to be filled.

  The multi-cavity metal injection mold of the present invention according to claim 4 has a sensor means for detecting that each product part cavity is filled with a molten material, and a nozzle opening for feeding back the output of the sensor means. In the temperature setting means, after the filling of the molten material in the product cavity of the hot runner nozzle with the high nozzle opening temperature preceded by the opening is completed, the next hot runner nozzle with the low nozzle opening temperature that opens slowly opens. The temperature difference between the nozzle opening temperatures is adjusted.

  As described above, according to the multi-cavity metal injection mold using the hot runner of the present invention, the molten material supplied from the injection molding machine through the manifold is concentrated and filled in each product part cavity. By filling the molten material in a high temperature state in which the filling time (injection time) per product part cavity is shortened and the molten material is not solidified without increasing the pressure for injecting the molten material more than necessary. In addition, by suppressing the internal pressure of the molten material, high-speed injection can be performed without increasing the necessary clamping force of the molding die.

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
The basic configuration of the molding die in the present embodiment is the same as that shown in FIGS. In the present embodiment, temperature rising timing setting means (not shown) for setting a time difference in the temperature rising timing of each hot runner nozzle 7 is provided in the molding die. The temperature rise timing setting means controls the start / stop of the heating unit 8 of each hot runner nozzle 7 and has a timer or the like.

  FIG. 1 shows a schematic graph for setting temperature raising conditions for a plurality of hot runner nozzles 7 in the case of four-piece picking as an example of multiple picking. In FIG. 1, a plurality of hot runner nozzles 7 will be described with reference numerals 1) to 4).

  Here, the time difference of the temperature rise timing at which heating of each heating unit 8 is started in the temperature rise timing setting means is set as follows. That is, after the filling of the product cavity 1 of the hot runner nozzle 1) is completed, the hot runner nozzle 2) reaches the nozzle opening temperature and the filling of the product cavity 1 of the hot runner nozzle 2) is started, and the hot runner nozzle After the filling of the product part cavity 1 of 2) is completed, the hot runner nozzle 3) reaches the nozzle opening temperature and the filling of the product part cavity 1 of the hot runner nozzle 3) is started, and the product of the hot runner nozzle 3) After the filling of the part cavity 1 is completed, the hot runner nozzle 4) reaches the nozzle opening temperature and filling of the product part cavity 1 of the hot runner nozzle 4) is started.

  With this setting, each hot runner nozzle 1) to 4) is heated up sequentially with the time difference set by the temperature raising timing setting means, and a deviation occurs when each hot runner nozzle 1) to 4) reaches the nozzle opening temperature. .

  The molding machine starts injection at the same time as the hot runner nozzle 1) that has started to rise in temperature reaches the nozzle opening temperature. Since only the hot runner nozzle 1) is opened at the start of injection, only the product portion cavity 1 corresponding to the hot runner nozzle 1) is filled with the molten material.

  After starting the temperature increase of the hot runner nozzle 1), the hot runner nozzles 2), 3) and 4) increase in temperature sequentially at a predetermined time difference. Next to the product cavity 1 corresponding to the hot runner nozzle 1), The product cavity 1 corresponding to the hot runner nozzle 2), the product cavity 1 corresponding to the hot runner nozzle 3), and the product cavity 1 corresponding to the hot runner nozzle 4) are sequentially filled during a series of injection operations. Will be.

(Embodiment 2)
The conditions for opening the hot runner nozzle 7 include the temperature of the molten material and the pressure applied by injection. The higher the temperature of the molten material, the easier it is to open, the lower the difficulty of opening, and the higher the applied pressure. Since it is easy to open and it becomes difficult to open as it is low, the time when the hot runner nozzle 7 is opened can be controlled by a combination of temperature and pressure.

  Therefore, nozzle opening temperature setting means (not shown) for setting a temperature difference between the nozzle opening temperatures of the hot runner nozzles 7 is provided in the molding die. The nozzle opening temperature setting means controls the start / stop of the heating unit 8 of each hot runner nozzle 7 and has a temperature sensor and the like.

  FIG. 2 shows a schematic graph for setting the temperature condition of the hot runner nozzle 7 in the case of four pieces as an example of multiple pieces. Here, the nozzle opening temperature is set at a predetermined temperature difference, the hot runner nozzle 7 having a high nozzle opening temperature is opened at a low pressure, and the hot runner nozzle 7 having a low nozzle opening temperature is set at a high pressure. Open.

  In FIG. 2, the plurality of hot runner nozzles 7 will be described with reference numerals 1) to 4), respectively. The set temperature of the hot runner nozzle 1) is the highest, and the hot runner nozzle 2), the hot runner nozzle 3), and the hot runner nozzle 4) are set so that the temperature decreases in this order. In this case, the hot runner nozzle 1) opens when the pressure is PA, and the hot runner nozzle 2), hot runner nozzle 3), and hot runner nozzle 4) open when the pressure is PB, PC, and PD, respectively. At this time, the pressure becomes PA <PB <PC <PD.

  When molding is started with the hot runner nozzles 1) to 4) set at this temperature, when the injection pressure from the molding machine exceeds the nozzle opening pressure PA of the hot runner nozzle 1), the product cavity of the hot runner nozzle 1) 1 starts filling. The hot runner nozzle 2) opens when the injection pressure that rises as the hot runner nozzle 1) is filled reaches the nozzle opening pressure PB of the hot runner nozzle 2), and the product cavity 1 of the hot runner nozzle 2) Filling is started.

  Similarly, the hot runner nozzle 3) opens when the injection pressure that rises as the filling of the product cavity 1 of the hot runner nozzle 2) reaches the nozzle opening pressure PC of the hot runner nozzle 3), and the hot runner nozzle 3 ) Filling of the product part cavity 1 is started. Similarly, the hot runner nozzle 4) starts filling when the injection pressure that rises as the filling of the product cavity 1 of the hot runner nozzle 3) reaches the nozzle opening pressure PD of the hot runner nozzle 4). When the filling of the product part cavity 1 of the nozzle 4) is completed, the series of injection operations of the molding machine is completed.

(Embodiment 3)
FIG. 3 is a schematic diagram when the sensor of the multi-cavity metal injection mold according to Embodiment 1 and Embodiment 2 of the present invention is installed, and the same components as those in FIG. To do.

  In FIG. 3, a sensor 9 such as a pressure sensor or a temperature sensor is provided in the overflow 5 at the tip of the product part cavity 1 in order to sense that the molten material has been filled in the product part cavity 1.

According to this configuration, the filling timing of each product part cavity 1 can be grasped by the measurement by the sensor 9.
For this reason, by feeding back the output of the sensor 9 to the temperature rise timing setting means, for example, after the filling of the molten material in the product cavity 1 of the hot runner nozzle 1) with the earlier temperature rise timing preceded by the opening is completed, the opening is opened. It is possible to reliably adjust the time difference of the temperature rising timing so that the next hot runner nozzle 2) whose temperature rising timing is late and the next hot runner nozzle 2) reaches the nozzle opening temperature.

  Alternatively, by feeding back the output of the sensor 9 to the nozzle opening temperature setting means, for example, after the filling of the molten material in the product cavity 1 of the hot runner nozzle 1) having a high nozzle opening temperature preceded by the opening is completed, the opening is opened. It is possible to reliably adjust the temperature difference between the nozzle opening temperatures so that the next hot runner nozzle 2), which is delayed and has a low nozzle opening temperature, opens.

The graph which shows typically the temperature rising condition setting of the several hot runner nozzle in Embodiment 1 of this invention The graph which shows the relationship between the nozzle opening temperature of the several hot runner nozzle in Embodiment 2 of this invention, and nozzle opening pressure Simplified layout of sensors such as pressure sensors in Embodiment 3 of the present invention Simplified layout of sprue, runner and product cavity in multi-cavity metal injection mold using conventional hot runner Schematic sectional view of manifold and nozzle in multi-cavity metal injection mold using conventional hot runner (A), (b) is a simplified layout of sprue, runner, and product cavity in a multi-cavity metal injection mold using a conventional cold runner, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Product part 2 Sprue 3 Gate 4 Runner 5 Overflow 6 Manifold 7 Hot runner nozzle 8 Hot runner nozzle heating unit 9 Sensor 10 Fixed side mold plate 11 Fixed side mold mounting plate

Claims (4)

A mold for injection molding of a large number of metal materials, which has a plurality of hot runner nozzles communicating with the manifold and each of the plurality of product section cavities, and provides a time difference in the temperature rise timing of each hot runner nozzle. A multi-cavity metal injection mold using a hot runner, characterized in that it has a temperature rising timing setting means for setting, and fills a plurality of product part cavities sequentially at different times when each hot runner nozzle opens. . A hot runner nozzle product having a temperature rise timing setting means having a sensor means for detecting that a molten material is filled in each product part cavity and feeding back the output of the sensor means and having an early temperature rise timing. The temperature difference of the temperature rise timing is adjusted so that the next hot runner nozzle with a slow temperature rise timing after the completion of filling of the molten material in the partial cavity reaches the nozzle opening temperature. A multi-cavity metal injection mold using the hot runner described in 1. A mold for injection molding of a large number of metal materials, which has a plurality of hot runner nozzles that communicate with the manifold and each of the plurality of product section cavities, and the temperature difference between the nozzle opening temperatures of each hot runner nozzle A multi-cavity metal injection mold using a hot runner, characterized in that it has a nozzle opening temperature setting means for setting a plurality of product part cavities sequentially at different times when each hot runner nozzle opens. Type. A hot runner nozzle product having a high nozzle opening temperature preceded by an opening in a nozzle opening temperature setting means that has sensor means for detecting that each product portion cavity is filled with molten material and feeds back the output of the sensor means. The temperature difference of the nozzle opening temperature is adjusted so that the next hot runner nozzle having a low nozzle opening temperature, which is delayed in opening, is opened after the filling of the molten material in the partial cavity is completed. Multi-cavity metal injection mold using the described hot runner.

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