1. The height of the grinding needle needs to be ground for both the top needle and the embedded needle. First, use a color pen and caliper to draw an approximate height on the needle, leaving some margin, and then manually cut it with a cutting piece. Grinding the height requires the use of self-made fixtures, such as most mold rooms, which are specifically used for grinding the height of the needle. The shape may be slightly different, but the function is the same. It is recommended to prepare a higher one for grinding the top needle and a shorter one for grinding the embedded needle. There are various specifications of V-shaped grooves cut on it, which can be used for positioning when clamping the needle. When using it, it can be lying down or vertical, that is, it can be ground at the bottom of the grinding wheel or on the side of the grinding wheel. Pay attention to burning the knife, as the heat dissipation performance of the needle is not good. If you don't pay attention, even though it has been worn down to the number, the height will be reduced, and if it is worn too hard, it may deform.

2. There are usually only a few types of rubber grinding positions, such as grinding steps, slopes, R-joint slopes, etc. The following are several ways to grind rubber positions:

① Self made fixture grinding position, as shown in the picture: In addition to the fixture mentioned above, a self-made fixture is also needed, which is somewhat similar to side repair. Inside, a conical thin needle is locked with a screw, and the height can be adjusted. When grinding the needle, it is used to press against the center position of the needle, so consistency can be maintained when grinding multiple needles. Because plastic molds often grind needles, making this fixture can improve a lot of efficiency.

② The method of directly grinding the glue position with a magnetic table is also commonly used. You need to make a meson and attack a tooth yourself. When using it, clamp the cup head of the needle to facilitate manual rotation of the needle during grinding. In addition, two stoppers are needed, and the thickness of the stoppers is determined by the diameter of the needle. The thickness only needs to be slightly higher than the radius. Before grinding, the side stoppers need to be leveled with a calibration gauge. In addition, whether it is a detailed or rough magnetic table, it is impossible for every part to have the same magnetic properties. This is due to the structure of the magnetic table. Therefore, when directly grinding the needle on the magnetic table, it is necessary to use the needle to test several parts and choose the parts with stronger magnetic properties, which will have a much better effect.

③ The tool of punch molding machine and needle grinder has been introduced in the previous article. Here is a brief explanation. When using it, a slight adjustment can grind circular needles. However, if it is the grinding position, it is necessary to compare the table so that the rotation center of the tool is at the same height as the center of the needle.

④ Attention should be paid to the vise. It can be found that there is also a V-shaped groove on the vise, so the vise can also be used to grind the height of the needle. If grinding the rubber position, attention should be paid to the strength. When clamping the needle, it should not be too loose or too tight, so that it can rotate and be used to grind the rubber position with low accuracy. Similarly, any tool with a right angle and V-shaped groove can be used to grind needles within a certain range.

3. Common types of grinding needles

① Conventional needle inlay, as shown in the picture: Conventional needle inlay is nothing more than grinding steps, slopes, chamfers, R, etc. It is just a combination of these methods. Generally speaking, the straight body is the sealing position, and only the sealing position needs to be ground. Special needle inlay also uses inclined sealing, which requires grinding and matching at the same time.

② Cone shaped copper workers for discharge are mainly used for discharge machining of submerged rubber joints. Most of them are machined with lathes to produce this type of copper rod, and some places are ground with grinders. Some factories directly discharge and connect it, so there is not much requirement for the diameter of the small end. As long as it is smaller than the drawing, it is enough. When discharging, prepare some commonly used on/off gauges and drive it to the required diameter. Some factories cannot connect it because it is to prevent wire drawing and other defects when automatically cutting the gate. This processing method requires grinding the small diameter accurately. If grinding is used, a punch or needle grinder needs to be used in conjunction with a sine magnetic table.

③ The teat needle, as shown in the figure, has been made. The teat mold is a kind of mold with characteristics. Most of the materials are silica gel and silicone glue. The mold embryo is round and rotated. Usually, it is the first mock examination with six points. The inverted button on the teat is ejected with gas assistance. This type of needle has multiple specifications based on the length of the baby's birth time, such as 0.5, 0.4, 0.3, 0.2, etc., which are determined by the baby's inhalation volume. Due to the small diameter of the front end, this type of needle often bends and needs to be replaced frequently. When making the needle, it cannot be completely made according to the drawing, and it needs to be ground and matched at the same time. It is recommended to first grind the slope sealing position, balance the cup head and the template on the mold, and then grind the front end sealing position. As for the length, it is not important because the diameter is too small, and it cannot be penetrated or inserted. When using it, simply cut off the front end, so first grind out a section of the front end, install it on the mold to see how many high-quality products there are, and then grind it to the number, so as to match this type of needle well.

④ Bottle cap breathable needle, as shown in the picture: There are many small breathable holes on the bottle cap. When making the mold, needles need to be inserted because the diameter is too small, such as 0.2. When making beer, these needles often break and need to be replaced frequently. Therefore, more spare parts can be made. For needles with small diameters that need to be pierced, we can only find a solution on the needle, such as materials, etc. However, when we grind them, we can tilt the angle moderately, which is based on our feeling. It is slightly different from ordinary chamfering. We can tilt two different angles, and the data can be pieced together to ensure the diameter of the breathable hole and the function of the breathable hole.

⑤ The inner needle of the needle valve type hot runner is equipped with a gas assisted needle, which is specifically used for sealing and is currently one of the best ways to achieve good sealing effects. These needles require some special treatment, such as material hardness, titanium plating, etc., mainly to ensure that they can work normally at high temperatures without being easily damaged. When designing and grinding the needle, the thermal expansion and contraction of the steel material need to be considered, and the tolerance requirements are relatively high. Moreover, after special treatment, the magnetic properties are usually not very good, and it is usually repaired by specialized hot runner companies, but occasionally they are also made by themselves. When grinding this type of needle, special attention should be paid.