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Plastic molding mold related technology development
Published:2015-04-08
A heat treatment and surface treatment
Although simple to simplify the mold production process is difficult, but according to a variety of molding conditions, faster and more stable production of high performance metal mold is feasible. At the same time, also built from overseas for mold making ordering system.

Moreover, the heat treatment should be re-evaluated in the past die. On the reality of the situation is concerned, mold making, although not completely avoid the heat treatment, but a considerable part of the plastic mold from heat-treated to non-heat-type conversion is possible.

1.1 heat-treated and non-heat-type classification type
Generally composed of molded resin, which decided to choose the number and die casting mold material. That glass fiber in the resin (hereinafter referred to as GF) number and the number of die-casting is an important factor in mold material selection. According to past practice, you can contain 35% GF as the criterion, the number of die-cast into 500,000 (times) than heat-treated and 500 000 (times) the following non-heat-treated.

For example, 300,000 times less if the molding with a resin comprising 30% GF, under the conditions of the pre-hardened steel 30-32HRC treatment of embodiment N, and If a resin containing 35% GF was 500,000 times molding, In the implementation of pre-hardened steel 40HRC N and PVD coating conditions, even without the use of heat-type material, but also achieve the target number of die-casting. Of course, containing 40% -50% GF 700,000 times resin casting mold, they shall be the base material for high-hardness heat treatment, and the need for complex N and PVD processing, Japan Fujio industrial companies to carry out a lot of mold such a treatment.

1.2 heat treatment conditions and the quality of the mold
Heat treatment is performed in a mold to produce quenching and tempering in the deformation, therefore, meet the quality requirements heat treatment should be quickly cooled as much as possible, which is required to resist deformation as slowly as possible contradictions between the cold, to meet the above two requirements is very difficult.

Mold materials in addition to having a good cutting performance, but also the need to reduce the size of the deformation in the heat treatment step. Recently the forging die steel PD613 and HPM31 improvement, developed into SLD-Magic and DCMX two materials. Compared with the JIS SKD11, improved performance of these steels have been greatly improved. Plastic molding die, because the main flame is carried out to strengthen the molding resin, so in addition to considering its wear resistance and corrosion resistance, the need to take full account of aging caused by the change in the molding.

Because of the wear resistance and hardness is proportional, so the metal mold material used in steel hardness 60HRC. Also, note that the material will become brittle and hard, it is possible for mold damage, you should consider its ductility (also known as malleable), therefore, the general control of the material hardness 56-58HRC. And, when the need to consider the corrosion resistance, in principle, the use of M (martensite) stainless steel. The focus on the corrosion resistance of the heat treatment, can not reduce the corrosion resistance of the precipitation of carbides. The need to avoid more than 450 ℃ temperature tempering.

However, in order to implement N after heat treatment and plating treatment, high temperature tempering is appropriate disposal.

In order to prevent aging changes, there is a need for a low temperature treatment, i.e., tempering should be the precipitation of carbides at a temperature of not less than 400 ℃ performed.

1.3 Development of non-heat-treated mold material
In Japan, the production of plastic molding dies, although faced with lower costs and shorten delivery time, improve the quality of the pressure, but in the use of pre-hardened plastic mold steel additional surface modification of the conditions, even without heat treatment can also be used to meet Claim. According to the survey showed that the current materials convert heat from pre-hardened steel surface hardness 40HRC a modified non-heat-type mold is increasing rapidly. Expected a few years later, pre-hardened steel hardness about 40HRC increase from now to about 45HRC, making it a non-heat-type mold material.

In the context of globalization, the mold industry, the Japanese domestic mold companies in order to survive, we must take some countermeasures. Paying particular attention to an important indicator of the cost, delivery and product quality in order to compete with overseas manufacturing mold. Application of non-heat treated type material pre-hardened steel additional surface modification will generally hardness 40HRC. However, the limited scope of such disposal. Therefore, if the rush to pre-hardened steel hardness increased to about 45HRC, may be difficult to meet the global demand for about 48HRC hardness of non-heat-treated materials.

In order to achieve the stated objectives, the development of the hardness of the steel mill house must organize a set of pre-hardened steel. The high hardness of the material of the cutting, machining and other problems of the resolution time, the process will be about pre-hardened steel non-heat treated type of practical application.

2 by laser welding repair welding of metal mold Precision Technology
In the past, mold surfacing weld repair, generally using W inert gas shielded arc welding (TIG welding for short). However, in recent years, due to the pulsed laser welding. Advent of welding machines, making it more subtle, sophisticated mold repair possible. In Japan, the laser welding welding machine had its maneuverability and precision machining for jewelry. But is now widely used in plastics, die casting, stamping die repair. Because you can mold parts, wear department, and pinhole defects within an accuracy of 0.01mm surfacing repair, repair it as an effective means to expand their market, demand is high, so that the mold manufacturers and those who are entrusted with the processing industry have introduced this technology and equipment.

Patch 2.1 Features Technology
Compared with the general TIG welding, laser welding. Welding with a low heat input welding without preheating and post-weld treatment characteristics, making subtle precision surfacing in the past can not be carried out. Welding possible.

Because TIG welding torch is the side with high-calorie melt the workpiece and surfacing materials, while surfacing welding with welding speed, high welding strength and so on. However, because of a large heat input, the workpiece deformation, resulting in secondary undercut and stress; and, because of burrs (flash) and more, resulting in machining, EDM long time, rising costs and other issues. In addition, for small parts (e.g. pin-shaped needle tip, groove-like bottom and side, etc.), TIG welding is not appropriate.

Conversely, laser welding. Welding is a pulsed laser irradiation point, the thermal effect on the workpiece is very small, does not cause deformation of the workpiece, two undercuts damage. Can be confirmed by a subsidiary of the microscope while surfacing welding parts, while the laser welding operation. Further, since the distance between the microscope's focus and continuous adjustment of the laser focus, allowing for surfacing welding portion accurately irradiated. Of course, compared to TIG welding, if using a large number of laser welding, the welding has the disadvantage of slow. However, high precision laser welding, and can reduce the subsequent finishing time and cost can be combined with a narrow groove bottom hole, inside corners and other small parts surfacing. Butt-welding, it can be considered that the laser welding repair plastic molding with the best technical mold.

With a change in plastic molding, die casting, stamping die repair and design, in addition to alteration, correction, as well as mechanical parts, precision parts surfacing welding, TIG welding and other undesirable (e.g. two undercut pinholes ) welding repair, and a variety of metals. welding.

2.2 surfacing methods and use
Taking into account the surfacing. Weld material, shape and adjustment of the laser pulse width, frequency number, the beam diameter (diameter of focus), thereby setting the optimum welding. Welding conditions. Due to continued focus on the microscope and laser focal distance adjustment, it is easy to carry out condition setting. First, in order to prevent fusion of the repair part bad, is performed without using wire laser welding portion is irradiated only for. Then insert the tip of the wire, to carry out a small amount of melted welding; surfacing then normal, until a bad weld surfacing layer without pinholes.

3 Rapid Prototyping Process
3.1 Summary of Rapid Prototyping
The so-called rapid prototyping, three-dimensional shape is a solid object with a thin layer stacked may be treated to achieve accumulation of the physical shape of the body shape. Concrete is high-precision, short delivery time, production of metal molds for the target, were developed Metal Laser Sintering technology and precision machining composite processing technology.

The basic principle of this technology are:
1) First, the three-dimensional computer-aided design to define the shape of the final shape of the three-dimensional parts.
2) Secondly, thereby calculating three-dimensional shape data intervals cut sheet outline shape processing, in order to thin out the data.
3) based on the data sheet, side by CO2 laser sintered powder material into a sheet the actual shape, side molding, and has terminated the lower engagement by laser sintering after repeatedly cutting contour surface finishing.
4) The material is cured, sliced repeatedly stacked data, the same physical shape component parts on the computer until the definition.
3.2 injection molding metal mold to achieve rapid prototyping technology
In this metal laser-sintering method, you can achieve the impossible in the original mold in a single processing technology, so you can expect short delivery time and cost of metal molds. In the processing method, you can freely form the internal structure, but also constitute a three-dimensional temperature control loop can be expected to improve the accuracy and shorten the injection molding of high technology features a metal mold and molding technology innovation molding cycle.

Fe-based powder material used in the present technique steel powder as a main component. The use of Ni powder and Cu-based powder is a mixed powder molding was developed no microcracks, the maximum bending strength, hardness and metal mold generally used the same steel S50C. Surface of the sample size precision machining made up ± 0.03mm, surface finish 20μm R2.

Using this technique in the gate bushing provided inside pipes, shorten the cooling time, the injection molding engineering to achieve a high cycling, resist the rise of the metal mold temperature, thus avoiding molding accident, and to improve the die life.

3.3 plastic mold new technologies related Japan will cheap plastic molding transfer to China and South Korea with a metal molds. China's production of molds exist some problems, mainly poor appearance of molded plastic products, because the design of the study of mold plastic pyrolysis gas extraction and pumping mechanism is not sufficient. And, if the use of cheap materials and recycling materials, impurities affected the thermal decomposition occurs more gas, but also easily lead to bad product appearance.

Someone using a composite metal laser-sintering machine, but it is recommended to use dual channel mode, resulting in reducing the plastic injection molding cycle. Due to the use of local low-density layer from the metal attracts and vacuum pyrolysis gas gap, promote filling resin, after molding under the conditions of high pressure air jetted promote pyrolysis gas is discharged, the low-density layer clogging occurs removed impurities, which will help to improve product quality.

EOS direct metal recommends modeling techniques. Switzerland Ecoparts companies using DMLS repair damaged metal mold technology development, thereby effectively repair damage to the mold. Compared with the overall manufacturing cost can be reduced, saving time. Ultra-high tensile strength maraging steels up 1900MPa, hardness of 55HRC, the industry has recently been trying to apply it die casting mold and injection mold liner components.

Sintermask company using the generated masking sectional shape, with 10kW infrared lamp, developed laminate molding at high speeds the molten thermoplastic resin. The maximum size for modeling 300mm × 200mm × 800mm; as long as the polyamide material, each able to 100μm thick, 700mm per hour speed modeling; if a large number of individual thumb shape parts can be manufactured 3000, reaching every 10 seconds or less productivity.
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