JP2003145258A - Method and apparatus for molding metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for molding a metal by which molding cycle time is reduced to a great extent, the scattering of a mold- lubricant to the outside is prevented, and the aggravation of a working environment is prevented. SOLUTION: In the method for molding the metal, between the mold-clamping process S1 of a mold in which the mold 1 is closed and injection-pressure increase (solidifying) processes S3 of a molten metal, a gate-melting process for heating a hot runner 21 to melt the plug (metallic material) of a gate 27, a mold-lubricant coating process for spraying the lubricant onto the wall surface of a cavity 10, and a material-metering process are simultaneously carried out in parallel to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal forming method and apparatus suitable for forming a metal such as a magnesium alloy by using an injection molding machine and a hot runner.

[0002]

2. Description of the Related Art Generally, a thixomolding device is provided with an injection mechanism and a mold clamping mechanism, and a solid raw material obtained by chipping a metal such as magnesium alloy fed from a hopper is screwed into a cylinder heated to a predetermined temperature. It is transported by and heated to a liquid state or semi-molten state, and by applying a shearing force with this rotating screw, thixotropic property in the solid-liquid coexisting state (sol is simply given a mechanical impact without changing the temperature) And the gel are reversibly converted), this metal material is charged at the tip of the cylinder and then injected into the molding die,
Molded into metal molded products after holding pressure and cooling.

By the way, the conventional magnesium alloy forming step in this thixomolding apparatus is, as shown in FIG. 3, a mold clamping step 1-gate melting step 2-injection / pressure increasing (solidification) step 3-measuring step 4 A mold cycle including a mold opening step 5-product take-out step 6-release agent applying step 7-air blowing step 8 is adopted, and the solidifying step and the measuring step are performed in parallel. That is, first, a mold clamping process for closing the mold is performed. Next, a gate melting step 2 of heating the hot runner in order to melt the plug (metal material) at the tip of the nozzle of the hot runner is performed. When it becomes possible to inject by the gate melting step 2, a molten or semi-molten metallic material is injected, and an injection / pressure increasing (solidifying) step 3 is performed to increase the pressure to prevent sink marks due to solidification shrinkage. Then, the weighing process 4 for weighing the material for the next injection is performed. The metal material filled in the mold during the material measurement is deprived of heat by the mold and solidifies. When the metal material is completely solidified and the product can be taken out, a mold opening step 5 for opening the mold is performed. Next, the product take-out step 6, the release agent applying step 7, and the air blowing step 8 are performed to complete the molding cycle. In this case, the measuring step is a step that requires a relatively long time among the above-mentioned steps, so that it is started together with the start of the solidification step in time for the end of the mold clamping step.

However, if the measuring step is started in parallel with the solidifying step, a waiting time is required from the end of the measuring step to the progress of each step and the end of the mold clamping step.
In the thixomolding method, injecting the metal material into the molding die in a state where the apparent viscosity is reduced by expressing the thixotropic property in the cylinder is the best way to obtain a good quality metal molded product. It is a condition. However, as described above, if a waiting time occurs after the metering process is completed and before injection, the thixotropic property developed in the solid-liquid coexisting metal material charged in the cylinder is lost, and the viscosity becomes high. There is a problem that the quality of the metal molded product is deteriorated by being injected in the state of being injected.

As a solution to this problem, Japanese Patent Laid-Open No.
There is known a metal forming method using a thixomolding device according to JP-A-01-25852. This method
The start time of the measuring process is set so that the end time of the mold clamping process and the end time of the measuring process coincide with each other, and the metal material after the measuring process is immediately injected into the mold after the mold clamping process. By doing so, the waiting time described above is eliminated. However, in this method, the mold release agent application step is provided after the mold opening step and before the mold clamping step, and since the material measurement and the mold release agent application are performed at the same time with the mold opened, the injection is performed. The molten metal material may drip from the tip of the nozzle and adhere to the nozzle touch surface or the metal mating surface, resulting in insufficient nozzle touch or insufficient mold clamping, and there is a risk of flashing during injection. In addition, the release agent itself scatters to the outside of the mold, drips, and the like, and the working environment deteriorates.

Further, in the metal forming method according to the above publication,
The mold release agent coating process, which requires a relatively long working time, is performed in parallel with the measuring process, but it is provided independently of the processes other than the measuring process, which does not lead to shortening of the molding cycle time. There is. In this case, the effect of shortening the solidification time by using the hot runner is offset, and a sufficient shortening of the cycle time cannot be expected.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present invention focuses on the fact that a mold release agent coating step, a metering step, and a gate melting step can be performed in parallel. It is an object of the present invention to provide a metal forming method and an apparatus thereof, which can significantly reduce the time, prevent the release agent from scattering to the outside, and prevent the deterioration of the working environment.

[0008]

The present invention provides a metal forming method and an apparatus therefor according to each of the claims as a means for solving the above problems. Claim 1
The metal forming method described in 1. is a metal forming method using a thixomolding method, between a mold clamping step and a metal material injection / pressurization step, and a gate melting step of heating a hot runner. , The release agent applying step and the material measuring step are performed in parallel.
The cycle time of the molding cycle can be shortened. Also,
Since the release agent can be applied while the molding die is closed, it is possible to prevent the release agent from scattering outside the die and improve the working environment.

According to a second aspect of the present invention, there is provided a metal forming method in which, after a mold opening step of opening a forming die, a step of taking out a metal formed product and an air blowing step to the forming die are also performed in parallel. As a result, the cycle time of the molding cycle can be further shortened.

According to a third aspect of the present invention, there is provided a metal forming apparatus in which a mold closing means closes a mold and a mold opening means opens the mold, and a metal mold in which a metal material is closed. Injection and pressure increasing means for injecting into the inside, gate melting means for heating the hot runner to melt the solidified metal material at the nozzle tip of the hot runner, and cavity wall of the closed mold A mold releasing agent coating means for spraying a mold releasing agent, a measuring means for measuring a metal material by a moving amount of a screw, and a control means for controlling the operation of each means described above are provided. After the mold is clamped and before the metal material is injected and the pressure is increased, the control means controls the gate melting means, the release agent applying means, and the measuring means so as to operate in parallel at the same time. This claim 3
Is an apparatus invention for carrying out the method invention of claim 1, and its operation and effect are the same as those of claim 1.

According to a fourth aspect of the present invention, there is provided a metal forming apparatus which operates an ejector pin to take out a metal formed product from a molding die, and air blows into the molding die to form a cavity and a material supply path. An air blow means for cleaning the wall surface is further provided, and after the molding die is opened, the control means causes the product take-out means and the air blow means to operate in parallel at the same time. This Claim 4 is an apparatus invention for carrying out the method invention of Claim 2, and its operation and effect are the same as those of Claim 2.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A metal forming method and an apparatus therefor according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the entire configuration of a thixomolding apparatus (metal forming apparatus) used in the metal forming method of the present invention. Thixomolding equipment (metal forming equipment)
Has a molding die 1 including a fixed die 11 and a movable die 12. The molding die 1 forms a cavity 10 for molding a metal material such as a magnesium alloy by clamping a fixed die 11 and a movable die 12.

An electrically-operated mold driving mechanism (not shown) is provided for the movable mold 12 so that it can be moved forward and backward with respect to the fixed mold 11. Further, the movable die 12 is provided with an ejector pin 15 and a drive mechanism 16 for taking out a molded product after molding from the mold.

The fixed mold 11 is provided with a hot runner 21 which communicates with the cavity 10. Hot runner 2
A gate 27 is formed in a portion communicating with the cavity 10 of No. 1, and the hot runner 21 is entirely surrounded by a heating source 28. The hot runner 21 is connected to an injection cylinder 26 of the injection mechanism 2 provided outside the fixed mold 11 via an injection nozzle 20.
The screw 22 is arranged in the injection cylinder 26, and the heating mechanism 23 is provided on the outer periphery of the injection cylinder 26. Further, a hopper 24 for supplying a metal material is provided in communication with the inside of the injection cylinder 26, and a screw drive mechanism 25 for driving the screw 22 is installed adjacent to the injection cylinder 26. Therefore, the metal material supplied from the hopper 24 is changed to the injection cylinder 26.
The inside of the hot runner 2 is conveyed by the rotation of the screw 22, melts during the conveyance, and the molten metal is discharged from the injection nozzle 20 to the hot runner 2
1 to be supplied into the cavity 10.

Further, in the thixomolding apparatus of the present invention, the material supply passage 19 of the fixed mold 11 communicates with the outside of the fixed mold 11 so that the mold release agent can be sprayed when the molding die 1 is clamped. The release agent supply path 13 is
It is formed in communication with the fixed mold 11. Release agent supply path 13
Is connected to the release agent supply device 29 and supplies the release agent by, for example, a piston method. A blocking pin 14 that opens and closes the release agent supply passage 13 is provided in the fixed mold 11 so as to be able to move forward and backward.

The operation control of the thixomolding apparatus of the present invention is basically performed by the machine controller 30. That is, the release agent supply device 29 is connected by the release agent supply device controller 31 connected to the machine controller 30.
The hot runner controller 32, which is also connected to the machine controller 30, controls the heating source 28 of the hot runner 21 and manages its temperature. Further, the machine controller 30 includes a screw drive mechanism 25 and an injection cylinder 26.
The operations of the outer peripheral heating mechanism 23, the mold driving mechanism (not shown), the driving mechanism 16 of the ejector pin 15, the shutoff pin 14 of the release agent supply passage 13, and the like are also controlled.

Next, the metal forming method of the present invention using the thixomolding apparatus having the above-mentioned structure, that is, the operation of the thixomolding apparatus will be described with reference to the flowchart of FIG. First, in step S1, the mold driving mechanism is driven to bring the movable mold 12 into contact with the fixed mold 11 to clamp the molding die 1 (mold clamping step).

Next, in step S2, a mold release agent injection nozzle (not shown) is introduced into the mold release agent supply path 13, and the mold release agent supply device 29 causes the injection nozzle and the mold release agent supply path 13 to flow. A mold release agent is sprayed onto the contact surface of the metal material to be supplied, which is formed by the wall surface of the cavity 10, to form a lubricant film of the mold release agent on the wall surface (mold release agent applying step). At the same time, in this step S2, in order to melt the solidified plug (metal material) of the gate 27, which is the tip of the hot runner 21, the hot runner 21 is controlled by the heating source 28 controlled by the hot runner controller 32.
Is heated to melt the gate (gate melting step). Furthermore,
In this step S2, the metal material is measured using the injection mechanism 2 (measurement step). The measurement of the metallic material is performed by driving the screw 22 by the screw drive mechanism 25 and moving the screw 22 from a predetermined position (retracting amount). This moving amount changes depending on conditions such as the weight of the metal molded product. That is, in step S2, the release agent applying step, the gate melting step, and the measuring step are performed in parallel.

Then, in step S3, the screw 22 is moved forward by the screw drive mechanism 25, the molten metal material is injected from the gate 27 of the hot runner 21, and the cavity 10 is filled with the required amount of molten metal. In this case, pressure is increased in order to prevent sink marks due to solidification shrinkage of the molten metal (injection / pressure increase (solidification) step). After the filling, the molding die 1 is cooled to solidify the molten metal. In this case, the release agent supply passage 13 is naturally closed by the forward movement of the blocking pin 14.

After the molten metal is completely solidified, in step S4, the mold driving mechanism is driven to move the movable mold 12 to the fixed mold 1.
The mold is released from 1 and the mold is opened (mold opening step). Next, in step S5, the drive mechanism 16 installed in the thixomolding device is operated to eject the ejector pin 1
5 is ejected and the molded product is taken out from the mold (product taking-out step). At the same time, in this step S5, air blow is performed by an air blow nozzle (not shown) connected to the air pressure source to remove burrs and the like adhering to the wall surfaces of the cavity 10 and the material supply passage 19 and clean the wall surface. Yes (air blow process). Then, the mold is clamped again and the next molding cycle is started. The series of molding cycles are controlled by the machine controller 30.

Next, the experimental results comparing the cycle times of the molding cycle of the present invention shown in FIG. 2 and the conventional molding cycle of FIG. 3 will be described. In the conventional molding cycle, the mold clamping process 1 …………………… 3 seconds Gate melting process 2 ……………… 3 seconds Injection / pressurization (solidification) process 3 …… 3 seconds Material metering process 4 ... ……………… 11 seconds Mold opening step 5 …………………… 4 seconds Product removal step 6 ……………… 4 seconds Release agent application step 7 ……………… 10 seconds Air blow Process 8 was 6 seconds and the cycle time was 44 seconds.

On the other hand, in the molding cycle of the present invention, the mold clamping step S1 ……………………………………………… 3 seconds Gate melting step, material measuring step, release material coating step S2 …… 11 seconds Injection / pressurization (solidification) step S3 …………………………………… 3 seconds Mold opening step S4 ……………………………………………… ...... 4 seconds Product removal process, air blow process S5: 4 seconds, and the cycle time is 25 seconds, which is almost half the cycle time of the conventional molding cycle.

Next, the function and effect of the present invention will be described.
In general, gate melting cannot be performed unless the molding die is closed for safety. Therefore, the gate melting step can be performed only after the mold clamping step and before the injection / pressurization (solidification) step. In general, only the material measurement can be performed as the composite operation during this period, but if the method of applying the release agent with the molding die closed is used, the release agent application step can also be the composite operation. . Moreover, the material measuring process and the mold release agent applying process have a remarkably long cycle time as compared with other processes, and by performing these combined operations (parallel operation), the cycle time of the molding cycle can be greatly extended. Can be shortened.

Further, in the molding cycle of the present invention, since the mold release agent is sprayed after the mold is clamped, the split surfaces of the fixed mold and the movable mold are immediately in contact with each other, and are separated from each other. No mold agent is attached. Further, since the mold is clamped, the cavity and the material supply path are in a closed state separated from the outside, so that it is possible to prevent the release agent from adhering to an unnecessary portion and the release agent from scattering to the outside. This makes it possible to prevent deterioration of the working environment, suppress wasteful consumption of the release agent, and use the undiluted solution itself without water for diluting the release agent. Therefore, it is possible to prevent the temperature from being lowered due to the adhesion of the release agent to the molding die, and it is possible to secure the excellent bathing property for a metal material having a small heat capacity, for example, a magnesium alloy.

As described above, in the metal forming method and apparatus of the present invention, a magnesium alloy is particularly suitable as the metal material, but the metal material is not limited to this. Further, in the above configuration, the case where the release agent supply passage is provided in the fixed mold is described as an example, but the point is that the release agent is supplied in the state where the molding die is closed. It suffices if it can be performed, and it may be provided in a movable type. The type of the release agent can be applied without particular selection, such as an oil-based lubricant, and the release agent can be diluted or a solvent other than water can be used. Further, as a method for attaching the release agent, a method by suction can be appropriately adopted in addition to the method by spraying.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a thixomolding apparatus used in a metal forming method according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a forming cycle of the metal forming method according to the embodiment of the present invention.

FIG. 3 is a flowchart of a conventional molding cycle.

[Explanation of symbols]

1 ... Mold 10 ... Cavity 11 ... Fixed type 12 ... Movable 13 ... Release agent supply path 2 ... Injection mechanism 20 ... Injection nozzle 21 ... Hot runner 22 ... Screw 23 ... Heating mechanism 24 ... Hopper 25 ... Screw drive mechanism 26 ... Cylinder 27 ... Gate 28 ... Heating source 29 ... Release agent supply device 30 ... Machine controller 31 ... Release agent supply device controller 32 ... Hot runner controller

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B22D 21/04 B22D 21/04 B (72) Inventor Ryuichi Onoda 1-chome, Showa-cho, Kariya city, Aichi stock Within DENSO

Claims (4)

[Claims] 1. A chipped metal material is conveyed by a screw into a hot runner heated to a predetermined temperature, heated to a semi-molten or liquid state, charged at the tip of the hot runner, and then placed in a molding die. In the metal forming method of injecting, cooling, and forming into a metal formed product, there is a hot process between the mold clamping process of closing the mold and the injection / pressure increasing process of injecting the metal material into the mold and increasing the pressure. The gate melting process that heats the hot runner to melt the solidified metal material at the nozzle tip of the runner, the mold release agent application process that sprays the mold release agent on the cavity wall of the molding die, and the measurement of the metal material A metal forming method characterized in that the measuring step is performed in parallel. 2. The method according to claim 1, wherein after the mold opening step of opening the molding die, a product take-out step of taking out the metal molded article and an air blowing step to the molding die are also performed in parallel. Metal forming method. 3. A chipped metal material is conveyed by a screw into a hot runner heated to a predetermined temperature, heated to a semi-molten or liquid state, charged at the tip of the hot runner, and then placed in a molding die. In a metal forming apparatus that injects, cools, and forms a metal formed article, the metal forming apparatus includes mold clamping and mold opening means for performing mold clamping for closing the mold and opening the mold for opening the mold. Injection and pressure increasing means for injecting metal material into a closed mold and increasing pressure, gate melting means for heating the hot runner to melt the solidified metal material at the nozzle tip of the hot runner, and closing The releasing agent application means for spraying the releasing agent on the cavity wall surface of the formed molding die, the measuring means for measuring the metal material by the moving amount of the screw, and the operation of each means described above are controlled. And a control means for controlling the molding die after the molding die is clamped by the mold clamping / mold opening means, and injecting a metal material into the molding die by the injection / pressure increasing means, A metal forming apparatus, characterized in that the gate melting means, the release agent applying means, and the measuring means are simultaneously operated in parallel by the control means before the pressure is increased. 4. A product take-out means for actuating an ejector pin to take out a metal molded article from a molding die, and an air blow for blowing air into the molding die to clean walls such as cavities and material supply paths. Means for opening the mold by the mold clamping / mold opening means, and then causing the product extracting means and the air blowing means to operate simultaneously in parallel by the control means. Item 4. The metal forming apparatus according to item 3.