The problem of weld mark is not always thinking about adjusting the process. We must learn to repair the mold and solve the problem thoroughly.

当塑件表面质量由于有熔接痕达不到设计要求时，技术人员通常先会从熔料温度、注射速度、压力、流量、模具温度等方面入手解决。而这些都通过设备来实现，参照成型条件标准小幅度调整，逼近理想值。

When the surface quality of the plastic parts can not meet the design requirements, the technicians usually start with the temperature of the melt, the injection speed, the pressure, the flow rate, the temperature of the mould and so on. These are achieved through equipment, with reference to the standard of forming conditions to be adjusted in a small way to approximate the ideal value.

显然，熔料温度、流动速度、压力、流量、模具温度这些可以通过设备来调整的项目是比较容易实现的，一方面调整起来方便，另一方面可以多次反复。困难的在于当以上手段已经无法解决时，就不得不通过修改模具的方法来实现预期效果，这也是要论述的重点。

Obviously, the melting temperature, the flow speed, the pressure, the flow rate, the mold temperature can be easily realized by the equipment which can be adjusted by the equipment. On the one hand, it is easy to adjust, and on the other hand, it can be repeated many times. The difficulty is that when the above methods have been unable to solve, we have to modify the mold to achieve the desired effect, which is the key point to be discussed.

需要修改模具的情形可能有以下几种：

It may be possible to modify the molds in the following ways:

熔接痕处夹有气泡，需要在对应的分型面增设排气孔；

There are bubbles on the weld marks, and the exhaust holes should be added to the corresponding parting surfaces.

熔接痕深度始终超差，需要调整塑件也即模具型腔的厚度；

The depth of weld line is always very poor, so the thickness of the mold cavity is needed to be adjusted.

熔接痕的位置偏向塑件中部，需要调整浇口的位置。

The position of weld marks is biased towards the middle part of the plastic parts, so the location of the gate needs to be adjusted.

下面对以上3 种情形的改善工艺分别进行叙述：

The following 3 improvements are described below:

1. 熔接痕处气泡的形成是由于当两股熔料汇流时，所包围的气体没有及时排除，而留在了塑件内部，在熔接痕表面形成凹坑，可以通俗地称之为“困气”。

1. the formation of bubbles at the weld line is due to the absence of the gas that surrounds the two strands of molten material, and remains in the interior of the plastic parts, forming a pit on the surface of the weld line, which can be popularly known as "trapped gas".

究其原因，可能是对应位置的分型面研配过紧，以致气体无法排出；也可能是合模后，型腔高度尺寸过度不均匀（塑件壁厚相差较大）造成。

The reason is that it may be that the distribution of the corresponding position is too tight, so that the gas can not be discharged,www.hebibanjia.cnwww.luohebanjia.cnwww.zhoukoubanjia.cnwww.xinyangbanjia.com.cn www.shangqiubanjia.cnwww.zhumadianbanjia.cn and the height of the cavity is too uneven (the difference of the wall thickness of the plastic parts is larger).

2. 针对前一种情况，常通过增加或增大排气槽来改善，以目前国内应用最广泛的PP料为例，根据PP料的溢料间隙为0.03 mm这一参数，为避免溢料形成飞边，排气槽间隙为0.01~0.02mm最理想。

2. for the previous situation, it is often improved by adding or increasing the exhaust slot, taking the most widely used PP material at present as an example. According to the parameter of the gap of 0.03 mm, the gap of the exhaust slot is the best for avoiding the spillover to form the flench and the gap of the exhaust slot is 0.01~0.02mm.

为便于模具加工和成型过程中型腔的清理，排气槽的位置多数情况会选择开在定模的分型面上，并尽量开设在型腔的最后充满处。对于型腔高度尺寸过度不均匀的情形，只能通过“补焊”和“打磨”的方法来调整型腔尺寸，这是难度最大，也是模具技术人员在调试中最怕遇到的，它的调整方法和下面要讲到的熔接痕高度始终超差的调整方法一致。

In order to facilitate the cleaning of the medium cavity in the die processing and molding process, most of the position of the exhaust slot is chosen on the mold surface and is opened at the end of the cavity as far as possible. For the oversize of the cavity, the size of the cavity can only be adjusted by "repair welding" and "grinding", which is the most difficult and the most feared in the debugging of the mold technicians. Its adjustment method is consistent with the adjustment method of the end of the weld mark.

3. 当通过调整设备工艺参数和开排气槽的方法皆无法改善或消除塑件由于熔接痕导致质量不良时，很可能不得不调整型腔的尺寸, 当然需要对塑件相应处的厚度进行准确的测量之后，在设计允许的范围内作业。

3. when the process parameters of the equipment and the method of opening and exhaust can not improve or eliminate the poor quality of the plastic parts due to the weld marks, it is very likely to have to adjust the size of the cavity. Of course, the thickness of the plastic parts should be measured accurately and work within the allowable range of the design.

保险杠塑件的壁厚在不同部位并不是一个等值，而是一个渐变的量，其原因是考虑到塑件的具体形状及熔融塑料的流动性，渐变的壁厚有利于成型。壁厚通常在2.60~3.50mm。

The wall thickness of the bumper plastic parts is not an equal value at different parts, but a gradual change. The reason is that the concrete shape of the plastic parts and the fluidity of the molten plastic are taken into account. The thickness of the gradient is beneficial to the molding. The thickness of the wall is usually at 2.60~3.50mm.

模具型腔尺寸的修改分两种情况：一种是增大型腔尺寸，另一种是减小型腔尺寸。

The modification of mold cavity size can be divided into two cases: one is to increase the size of the cavity and the other is to reduce the size of the cavity.

对于第一种情况实现起来较容易，根据检测数据直接对模具型腔的相应部位实施打磨即可。第二种情形就比较复杂，为了达到减小型腔尺寸的目的，首先需要在模具型腔面上堆焊，然后打磨。

For the first case, it is easier to realize, and directly grinding the corresponding parts of the mold cavity according to the test data. The second case is more complicated. In order to reduce the size of the cavity, it is necessary to weld on the mold cavity surface and then polish it.

下面具体介绍减小模具型腔尺寸的方法：

The following is a detailed description of how to reduce the die cavity size.

从工作的难易程度上，首先考虑选择在动模上进行“补焊”和“打磨”会比在定模上容易得多。

From the point of difficulty, the first thing to consider is that it is much easier to choose "welding" and "polishing" on moving dies.

由于注射模的定模型腔面质量直接影响到塑件外观，而焊接过程中有大量的热产生，没有充分的工艺措施保证时，这些热量往往会改变型腔面的组织成分，导致型腔面硬度不同，进而影响塑件外观，实践中要尽量避免定模型腔面的修改。

Because the quality of the cavity surface of the fixed model of the injection mould directly affects the appearance of the plastic parts, and there is a large amount of heat produced during the welding process. When there is no sufficient technological guarantee, these heat often change the composition of the cavity surface, which leads to the different hardness of the cavity surface, and then affects the exterior of the plastic parts. In practice, the model cavity should be avoided as far as possible. The modification of the surface.

动模型腔面修改的一般步骤如下：

The general steps of the modification of the cavity surface of the dynamic model are as follows:

通过在型腔面贴胶的方法试模，大致得出型腔需要增减的厚度；

The thickness of the mold cavity needs to be increased by testing the mold on the cavity surface.

实施“补焊”和“打磨”作业；

The operation of "repairing welding" and "grinding" is carried out.

再次试模，根据成型效果调整型腔面的尺寸。

Try the mold again and adjust the size of the cavity surface according to the molding effect.

其中第二步是难点和关键, 以下是型腔面修补的详细过程：

The second step is difficulty and key. The following is the detailed process of cavity surface repair.

选定和母材相匹配的焊接材料，并确定焊接范围，预留并保护好打磨基准。

Select the welding material matching the base material and determine the welding range, reserve and protect the grinding standard.

分区交替堆焊，注意不要从头焊到尾，以免内应力造成模具型腔面裂损。

The area alternation surfacing should not be welded to the tail, so as to avoid the internal stress causing the crack of the mold cavity surface.

对照预留基准，开始打磨，注意做好周边相关部位的保护。

Compare the reserved benchmark, start grinding, and pay attention to the protection of relevant peripheral parts.

测量补焊面的高度，达到要求之后，将基准空位焊满，完成型腔面的修改。

After measuring the height of the weld surface and meeting the requirement, the reference blank is welded to complete the modification of the cavity surface.