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大型模具加工问题

Problem of large mold processing

加工问题

Processing problems

1.巨大的尺寸和重量

1. large size and weight

在加工大型模具时，如何应付其自身的巨大尺寸和重量是加工企业面临的一大挑战。大型模具的加工往往需要大量的劳动力、专用设备和多次调试装夹，而加工精度也受到多方面潜在因素的影响而不易保证。

How to cope with its huge size and weight is a major challenge for processing enterprises when processing large molds. The processing of large mold often requires a large number of labor, special equipment and multiple debugging and clamping, and the processing precision is also affected by many potential factors and is not easy to guarantee.

2.购置成本问题

2. the cost of purchase

加工生产各类大型模具直接相关的最大费用就是机床的购置成本。能够生产大型模具的机床是相当昂贵的，尤其是在复杂工艺安排下，需要使用多台机床才能完成从模具粗加工到精加工的全部工序。这样的先期高投入成本也是很多企业进入这一市场的最大障碍。由此，我们可以看出，如果可以在一台合适的机床上实现大型模具的粗加工和精加工，甚至仅需一次调试装夹，那么很多问题将迎刃而解，加工精度也可以得到保证。

The biggest cost directly related to the manufacture and manufacture of large molds is the purchase cost of machine tools. The machine tool that can produce large mold is very expensive, especially in the complex process arrangement, it is necessary to use multiple machine tools to complete the whole process from the die rough to the finishing. Such a high pre investment cost is also the biggest obstacle for many enterprises to enter the market. As a result, we can see that if the rough machining and finishing of a large mold can be realized on a suitable machine tool, and even only one debugging clamp is needed, many problems will be solved and the machining precision can be guaranteed.

加工中心

machining center

1.铸铁床身结构，机床主轴具有散热功能

1. Cast iron bed structure, machine tool spindle with heat dissipation function

铸铁材料具有很高的刚性和散热特性，因而是制造机床结构件最稳定的材料。对于铣削大型零件用的任何机床，首先需要具有非常结实的铸铁结构，并装备有具有散热功能的主轴。

Cast iron has high rigidity and heat dissipation characteristics, so it is the most stable material for manufacturing machine tool structural parts. For any machine tool used for milling large parts, it is first necessary to have a very strong cast iron structure and equipped with a spindle with heat dissipation function.

就机床的主轴而言，它必须采用内置冷却技术，从轴承外面来冷却主轴，保证在长时间加工过程中，主轴本身不会被烧坏或不会因热膨胀而造成精度损失。这些因素是非常重要的，因为大型模具的加工需要消耗很长的时间，同时在重切削条件下，这会增加模具的热量和应力。所以，机床的结构部件必须具有良好的刚性和散热特性，这是加工出大型优质模具的前提。因此，必须最大程度地限制加工过程中机床的振动，并快速扩散加工过程中产生的热量。选择合适的加工机床和刀具可以实现成本和周期的双赢。

As far as the spindle of the machine is concerned, it must use the built-in cooling technology to cool the spindle from the outside of the bearing to ensure that the spindle itself will not be burnt out or caused by thermal expansion during the long processing. These factors are very important because the processing of a large mold takes a long time, and in heavy cutting conditions, it will increase the heat and stress of the die. Therefore, the structural parts of machine tools must have good rigidity and heat dissipation characteristics, which is the premise for processing large quality moulds. Therefore, the vibration of machine tools must be limited to the maximum extent and the heat generated during the machining process can be rapidly diffused. Choosing the right machine tools and tools can achieve a win-win cost and cycle.

2.热稳定技术

2. thermal stabilization technology

由于加工时间过长，环境温度的影响也是必须要考虑的。例如，在普通机床上加工大型模具，当环境温度变化10℃时，将会导致机床立柱发生6℃的温度变化，从而引起主轴角板平行度发生0.07mm的变化。因此，机床的设计必须考虑到环境温度的效应，避免环境温度影响到加工零件的精度。

Because of the long processing time, the influence of environmental temperature must also be considered. For example, a large mold is processed on a common machine tool. When the temperature of the environment changes 10 degrees C, it will lead to a temperature change at 6 degrees centigrade on the column of the machine tool, which causes the change of the parallelism of the main axis angle plate to occur 0.07mm. Therefore, the design of machine tools must take into account the effect of ambient temperature and avoid the influence of ambient temperature on the accuracy of machined parts.

3.速度

3. speed

对于一台行程能够快速移动的大型模具加工中心来说，大型模具加工机床的主轴转速应至少达到20000r/min，金属的切削速度应满足762～20000mm/min。

For a large mold machining center which can move quickly, the spindle speed of the machine tool should be at least 20000r/min, and the cutting speed of metal should be 762 to 20000mm/min.

4.精度

4. precision

精度控制始终贯穿于模具加工的各个阶段，如果需要在一台加工中心上实现对大型模具的粗加工和精加工，那么必须严格控制机床的定位精度和重复定位精度。大型模具专用的加工中心，一般其定位精度可以达到±1.5μm，重复定位精度应达到±1μm。同时，其节距精度应保持在5μm之内。

Precision control is always run through every stage of die processing. If it is necessary to realize the rough machining and finishing of a large mold at a machining center, it is necessary to strictly control the positioning accuracy and repeatability of the machine tool. In general, the positioning accuracy of large mold special machining center can reach + 1.5 m, and the repeatability of positioning accuracy should reach 1 m. At the same time, the pitch precision should be kept within 5 m.

5.反馈分辨率

5. feedback resolution

对于高精度曲面加工，机床自身的反馈分辨率对于检测加工零件的精度是十分重要的。采用标准的1μm反馈分辨率，通常所获得的结果并不十分理想。如果分辨率能够达到0.05μm，那么其精加工结果几乎没有任何瑕疵。而且，通过对机床分辨率、标尺反馈和小节距滚珠丝杠的控制可进一步提升零件表面的加工质量。

For high precision surface machining, the feedback resolution of machine tools is very important for detecting the accuracy of machining parts. Using the standard 1 m feedback resolution, the results usually obtained are not very satisfactory. If the resolution can reach 0.05 micron m, there will be almost no defect in the finishing process. Moreover, the machining quality of parts can be further improved by controlling the resolution of machine tools, the feedback of scale and the control of ball screws.

6.主轴

6. spindle

大型模具加工中心上使用的主轴必须达到进行粗加工、半精加工和高质量精加工的要求，而且作为一个参考标准，其能够实现的表面加工质量应该控制在2μm的水平。通常，对于模具闭合面和分型线部分的精加工十分重要，但在传统工艺下，许多模具制造商不得不采用手工抛光的方式，以弥补刀具加工精度不足的问题。因为，大型加工机床的造价昂贵，如果为此项工序购置多功能机床，显然是不切合实际的。

The spindle used in a large mold machining center must meet the requirements of rough machining, semi finishing and high quality finishing, and as a reference standard, the quality of the surface machining should be controlled at the level of 2 m. Usually, it is very important to finish machining the closed and parting parts of the die, but in the traditional process, many mould makers have to use manual polishing to make up the problem of the cutting precision of the tool. Because the cost of large machine tools is expensive, it is obviously not practical to purchase multi-function machine tools for this process.

此外，合理的主轴设计必须能够最大程度地延长刀具的使用寿命，使其能够在加工周期内以低振动、低温升的状态持续工作。例如，在大型模具加工中心上加工汽车仪表板模具时，如采用16mmCBN镶刀片精加工刀具，加工速度可以达到8m/min，使用寿命超过30h，可以将加工表面质量控制在0.336～3.2μm。由此可知，考虑到加工大型模具时的刀具成本增加，采用专门设计的大型模具加工机床，不仅可以延长刀具使用寿命，而且可以大量节约加工每付模具的刀具使用成本。

In addition, the reasonable design of the spindle must be able to extend the service life of the tool to the maximum extent so that it can work continuously in the condition of low vibration and low temperature in the processing cycle. For example, when machining a vehicle dashboard mold at a large mold machining center, the processing speed can reach 8m/min and the service life exceeds 30h, and the quality of the processing surface can be controlled from 0.336 to 3.2 mu m, such as 16mmCBN inserting blade finishing tool. Therefore, considering the increase of cutting tool cost in processing large mold, the use of a specially designed large mold machining machine can not only prolong the service life of the tool, but also save a lot of cutting tool cost.

7.可移动的多轴加工头

7. movable multi axis machining head

由于模具尺寸和重量的限制，一般装夹工件需要花费很长的时间。因此，采用3轴联动加工中心不仅减少了工件的调试装夹次数，而且又不影响机床的加工精度，从而使车间加工大型模具的生产能力大大提高。

Due to the limitation of die size and weight, it usually takes a long time to clamp workpiece. Therefore, the use of 3 axis machining center not only reduces the number of debugging and clamping of the workpiece, but also does not affect the machining precision of the machine tool, so that the production capacity of the large mold is greatly improved.

可移动的多轴加工头可以用于加工结构特别复杂的大型模具，按可变几何形状设计的加工头可允许3轴联动加工，仅需一次装夹工件，便可铣削加工型腔

A movable multi axis machining head can be used for a large mold with a very complex structure. A machined head designed by a variable geometry allows 3 axes to be machined. The machining cavity can be milled with only one clamping piece.