Japanese mold attempts to "surpass" the rapid response of Chinese molds

Japan's mold industry is in trouble because of the hollowing out of domestic industries, the rise of China's mold industry and the impact of the economic downturn caused by the Lehman incident. In this context, the number of mold manufacturers in Japan has decreased from more than 8,000 in 2000 to more than 5,000 in 2008. Mold production has also fallen by half, from about 1 million units in 2002 to more than 500,000 units in 2009. . In this environment, Japan's mold makers and machine tool manufacturers who have worked hard to get out of their difficulties and create new charm for customers are also eye-catching.

According to Luo Baihui, head of the International Die and Metals and Plastics Industry Suppliers Association, in recent years, China's mold companies have enjoyed a reputation for high-efficiency and low-cost operations worldwide, not only because of their low prices and short lead times, but also the level of mold technology in China. Rapid progress. Japanese companies attempt to deliver products to the market faster than Chinese companies in terms of 1 ultra-precision, 2 long-life, 3 high-speed, so as not to lose the opportunity to sell products. Finding Chinese mold manufacturers that are both technically and financially reliable and making full use of their low price advantage to reduce their own costs. This practice will expand in Japanese companies in the future.

In order to shorten the processing time before the mold was completed, the Japanese Matsuno Mold Manufacturing Co., Ltd. used a 5-axis synchronous control machining center (MC) to complete the mold at a higher speed than before, and shortened the lead time before supplying the product to customers. Matsuno Mould (headquarters: Higashiosaka, Osaka Prefecture) used only half of the original time to manufacture molds for molded plastic car audio panels. Compared with the general-purpose MC with 3-axis control, the mold cutting (tilt) freedom of the 5-axis synchronous control MC increases, and the attitude of the tool such as the ball end mill can be more flexibly set. In this way, the tool can reach the deeper part of the hole that can not be cut by the general-purpose MC. Therefore, the tool can be formed by direct cutting. With the original electric discharge machining, it cannot be molded.

The reason why the company uses the 5-axis synchronous control MC to process the die is to reduce the EDM that takes more time than cutting. In the past, when a mold for molding a car audio panel was manufactured, usually a general-purpose MC was used to cut the graphite and copper electrodes required for electric discharge machining, and the other general-purpose MC was used to roughen the mold. Then, the electrode after cutting is used to perform electric discharge machining on the rough-processed mold. In this way, not only the electrode cutting time is much longer than the rough machining of the die, but also the electrical discharge machining takes a long time. In addition, the electric discharge machining also forms a hardened layer on the surface of the mold, and it is necessary to perform grinding through a post process.

In order to shorten the processing time, Matsuno Mold uses 5-axis synchronous control MC to handle the mold as much as possible through cutting. With this approach, the shape of the electrodes is simplified and the proportion of electrical discharge machining is reduced. As a result, it takes only about 150 hours in total from the processing time of the new type of car audio die, together with the production of CAM data and preparation time. It took about 300 hours. Moreover, the shortening of the processing time can also reduce the processing cost of the mold, "a piece of mold is expected to reduce about 3%."

Matsuno's goal in the future is "no discharge machining." If you can completely remove the electrical discharge machining, you can at least save the electrode. Because it is possible to replace three machines (two general-purpose MCs and one electric discharge machine) with one 5-axis synchronous control MC, the cost of the machine tool can also be reduced. But also can save the customer required electrode inspection work. In addition, since the number of times the workpiece is fixed on the machine tool (the number of processing preparations) is only required once, the mold can be completed with high accuracy.

However, there are also problems. When using 5-axis control MC to prepare complex CAM data, the car audio die "needs an operator to complete 80 hours." And the type of tool will increase. However, in spite of this, this method is still effective for improving the speed before delivery.

Otsuka has developed a portal-type MC "MCR-H (Hyper)" with a view to shortening the delivery period, and has trial-produced molds for the side panels of automobiles. By cutting the mold at high speed and with high precision, the burden of manual grinding operations is reduced. As a result, the mold finishing time was reduced to 60%.

Otsuka obtained the real-vehicle data of the 2L displacement class model from Japanese automakers, and then produced the mold based on these data. Although automakers will not use the molds in mass production, Otsuka still tests prototypes.

The MC used for cutting uses a linear motor on the X-axis and Y-axis, which increases the maximum cutting feed speed to 30m/min. It is also equipped with a “Thermo-Friendly Concept” function that corrects the effects of residual heat while minimizing heating. In this way, the mold surface still achieved excellent machining accuracy despite cutting the mold at a high speed.

The material of the mold is gray cast iron FC250 with a size of 3345×805×1290mm. Using a ball end mill with a diameter of 30 mm at a speed of 30,000 rpm, a cutting feed rate of 21 m/min, a cutting amount of 0.35 mm, and a cycle feed (PickFeed, trajectory distance from the center of an adjacent tool) of 0.35 In the cutting conditions of mm, the mold surface was processed. Afterwards, light artificial sanding was performed.

With the above measures, Daxie reduced the processing time including MC cutting and manual grinding to 28 hours and 52 minutes. It takes about 45 hours for the current machining method to be carefully ground after manual cutting with a ball screw MC. In this way, the total processing time of the mold was shortened to 128 hours and 5 minutes.