Due to the special requirements of the product, the demoulding direction of a certain part is inconsistent with the mold opening direction of the injection machine. Side parting and core pulling are required to successfully eject the product. There are two types of side parting and core pulling mechanisms: row position and inclined top.
picture
1. Position
1. Calculation of row position and stroke (take the following figure as an example):
In order to ensure the smooth demoulding of the product, the distance of the row movement must be sufficient. Generally, the minimum distance at which the product can be demoulded plus 2~3mm is the minimum stroke:
picture
2. The row positions of the rear mold adopt the structural form of pressure block + oblique pin + slingshot as shown in the figure (sometimes when the width of the row position exceeds 100 and it is inconvenient to use this structure, the T block structure can be considered), but when the row position When it is located in the direction of heaven and earth, and is limited by the position of the back needle and the size of the mold base, it is not necessary to press the block, and the original template can be used.
picture
3. The relationship between the bottom and top surfaces of the row position and the bottom and top surfaces of the front and rear molds is shown in the figure:
picture
4. Regardless of whether there is sealant on the side of the row, both sides must be sloped. The general value is 3~5° on one side. However, when two rows with vertical movement directions are combined, the angle is 45°. If there are rows on all four sides of the product that fit together, you should consider extending one of the rows by one ear during design to ensure accurate positioning.
picture
5. The ratio of row height to thickness should be at most 1, otherwise the row movement will be affected by the flipping moment, causing movement failure. The general requirement is L≧1.5H.
picture
6. The tilt pin angle of the row position is generally 15°~25°, and the maximum cannot exceed 25°. The tilt pin angle is 2° smaller than the row position. Generally, try not to use small tilt pins to ensure the smooth movement of the row position.
7. The oblique pin hole is 1/64" larger than the single side of the oblique pin, about 0.4. When the oblique pin passes through the row, enough space must be left for it on the template.
8. Determination of the position of the oblique pin in the row: The oblique pin should be placed in the middle of the row as much as possible. The specific size requirements are as shown in the figure:
picture
9. The mating surface between the chicken shovel and the row is required to exceed 2/3 of the height of the row, and the screws used for shoveling the chicken should be as large as possible. The following picture shows two different structures of the chicken shovel. Try to avoid using the structure in Figure b.
picture
10. The length of the slingshot in row position should be determined to ensure sufficient space for the slingshot to prevent the slingshot from failing.
Set the stroke of the row to M, the total length of the slingshot to L, and assume that the spring is compressed by 40%. After the row is completely withdrawn, the slingshot is still preloaded by 10%, then:
(40%-10%)L=M
L=（10/3）M
The slingshot space is 0.6L
But when L is too small, in order to prevent the slingshot from failing, it is often necessary to increase the length of the slingshot.
11. When the row position completely wraps the side of the product, in order to prevent the plastic parts from being damaged during the row position, a side top device needs to be set up on the row position. Its structural form is as shown in the figure: In the design, the selection should be based on whether the mold space is sufficient. For a suitable structure, it is recommended to use the structure shown in Figure A.
picture
12. In order to make the movement of the row smooth, there should be no sharp corners that hinder the movement. Generally, the periphery should be rounded with R3~R5.
13. When the slingshot needs to be installed under the row position, the size requirements are as shown in the figure. To prevent the screws from being caught by the slingshot, refer to the table when selecting the slingshot and screws.
picture
14. Large rows should be cooled separately, and wear-resistant blocks should be mounted on the rows or shovels. At this time, there should be a gap of 0.5 between the rows and the shovels, as shown in the figure.
picture
15. When it is necessary to set a limit groove on the front mold row, the structure is as shown in the figure. h is determined according to the row stroke (the size of the limit block is attached). The limit block must be tightened with at least M3/8" screws.
picture
Sometimes, if the current mold line position is too small, the T block is not used for guidance, but the limit block is used directly for guidance and positioning.
16. On the front mold row, the T block and T slot have a clearance of 0.3~0.5 on one side, and only one side is the mating surface. as the picture shows:
picture
17. Calculation of the slingshot length of the front mold row.
Set the row stroke M, the total length of the slingshot L, compression 40%, 10% pre-pressure after the row is completely withdrawn, row angle α, and total row height H, then:
(40%-10%)Lsina=M
L=10M/3sina
At the same time, it should be checked: 0.3Lcosa<1/2H, otherwise the angle a should be increased, but the maximum should not exceed 25°. Sometimes to prevent failure, the L dimension is often increased.
18. The row position of the front mold needs to be hooked.
19. The row position of the front mold is changed to T block on the row position, and T slot is opened on the shovel chicken.
picture
20. The front mold row position generally requires the installation of wear-resistant blocks, as shown in the figure. At this time, there is a gap of 0.5mm between the front mold bevel mating surface and the row position.
picture
21. The protrusion of the front mold row from the front mold shall not exceed 1/2 of the total length of the row, as shown in the figure.
picture
22. The internal extraction position of the front mold. Sometimes the product needs to be set with the internal extraction position of the front mold, as shown in the figure. At this time, in order to avoid the problem of too much clearance on the A board, the T block is often made on the row position and the T slot is opened on the chicken shovel.
23. When a "V"-shaped oil groove is set up on the row, it should be inclined in the direction of the row movement, and the "O"-shaped oil grooves should be interlocked. The depth of the oil groove should be 0.5~1.00mm. The sides of the oil groove should not be connected to prevent oil leakage. .
24. Parts that move with each other on the rows need to be quenched. For example, limit blocks, pressure strips, etc.
