Method for milling a split two-part gate bushing

Abstract

The application discloses a split gate bush, characterized in that the split gate bush comprises an upper bush body and a lower bush body, a circular truncated cone-shaped inner cavity is formed in each of the upper bush body and the lower bush body, the diameter of the inner cavity of the discharge end of the upper bush body is greater than or equal to the diameter of the inner cavity of the feeding end of the lower bush body, the upper bush body and the lower bush body are detachably matched together, the inner cavity of the discharge end of the upper bush body is connected with the inner cavity of the feeding end of the lower bush body, a gate is arranged at the discharge end of the lower bush body, and the matching gap between the upper bush body and the lower bush body is not greater than 2 filaments. The application further discloses a manufacturing method of the split gate bush. The application has the advantages of high smoothness of the inner cavity, no polishing treatment of the inner cavity in the manufacturing process, relatively low manufacturing cost, and removal of air bubbles in plastic raw materials in the injection molding process.

Description

[0001] This application is a divisional application of the invention entitled "Split-type sprue sleeve and its manufacturing method", filed on February 8, 2018, with application number 2018101296063. Technical Field

[0002] This invention relates to the field of molds, and more particularly to a split-type sprue bushing and its manufacturing method. Background Technology

[0003] The gate of an injection mold is the channel connecting the main runner and the cavity. It has the smallest cross-sectional area in the entire runner system, but it plays a crucial role in reducing the apparent viscosity of the melt and improving its flowability. Currently, the one-piece gate bushing (as shown in the attached image) is commonly used in three-plate molds. Figure 1 As shown), the three-plate mold has extremely strict requirements on the smoothness of the inner cavity (3) of the one-piece sprue bushing (if the surface is rough, it will cause the sprue to be difficult to break and the demolding to be poor when the plastic product is molded. At the same time, it will easily cause pressure loss of the injection molding machine during the pouring process, and even cause the product to have marks and burns). The current one-piece sprue bushings are all made of raw material parts (the structure of the raw material parts is shown in the attached figure). Figure 2 (As shown). Currently, the machining methods for internal cavities are ball end milling and electrical discharge machining (EDM). The internal cavity milled by ball end milling is relatively smooth (and can be used directly), while the internal cavity obtained by EDM must undergo chemical or physical polishing treatment (currently, chemical polishing is the most commonly used).

[0004] Currently, the diameter of the integrated sprue bushing used in three-plate molds is generally within 4mm, while the length is over 35mm (generally not exceeding 40mm). Therefore, if milling is used on the raw material, only ball end mills with a diameter of less than 4mm can be used. However, the effective milling depth of most ball end mills with a diameter of less than 4mm is less than 25mm (the ball end mill itself has a limited length (the actual milling length of the ball end mill is less than or equal to its own length). If the length of the ball end mill is too long, the milling process will produce a large error due to "eccentricity," which is problematic in actual production. The milling length of a 3mm (diameter) ball end mill is 25mm, the milling length of a 2mm (diameter) ball end mill is 25mm, and the milling length of a 1mm (diameter) ball end mill is 14mm. Therefore, ball end mills can only process raw materials into semi-finished products. For the remaining unmilled parts, companies generally use electrical discharge machining (EDM). However, EDM will leave iron slag residue on the surface of the inner cavity (3) (the presence of iron slag will make the surface of the inner cavity rough). In order to remove the iron slag on the surface, the inner cavity (3) of the integrated sprue bushing must be chemically polished, which is more complicated. Summary of the Invention

[0005] To address the above-mentioned problems, this invention proposes a split-type sprue sleeve and its manufacturing method.

[0006] The technical solution adopted in this invention is as follows:

[0007] A split-type sprue sleeve includes an upper sleeve body and a lower sleeve body. Both the upper and lower sleeve bodies have frustum-shaped inner cavities. The diameter of the inner cavity at the discharge end of the upper sleeve body is greater than or equal to the diameter of the inner cavity at the feed end of the lower sleeve body. The upper and lower sleeve bodies are detachably fitted together. The inner cavity at the discharge end of the upper sleeve body is connected to the inner cavity at the feed end of the lower sleeve body. A sprue is provided at the discharge end of the lower sleeve body. The fitting gap between the upper and lower sleeve bodies is no more than 2 mils.

[0008] In this solution, the ball end mills used for machining the split-type sprue bushing have milling lengths of 25mm (2mm and 3mm diameter ball end mills) and 14mm (1mm diameter ball end mill). Furthermore, the widest diameter of the inner cavity of the upper section of the bushing is less than 4mm, and the total length of the upper section is no more than 25mm, while the total length of the lower section is no more than 14mm. The total length of the split-type sprue bushing provided in this solution is approximately 35mm. Therefore, in this solution, the sprue bushing is divided into two sections. Since both sections can be machined using ball end mills, the smoothness of the inner cavity of the split-type sprue bushing can be effectively guaranteed, eliminating the need for further chemical polishing. Meanwhile, there will inevitably be a gap between the upper and lower sleeve sections. In this solution, the gap between the upper and lower sleeve sections is guaranteed to be less than 2 mils. During the injection molding process, there will be some residual air bubbles in the plastic raw material. These air bubbles will escape through this gap when passing through the split sprue sleeve, thereby further improving the quality of the plastic parts.

[0009] Optionally, the upper and lower sleeve sections are joined together by threads.

[0010] Threaded connections are convenient and quick.

[0011] Optionally, the upper sleeve and the lower sleeve are connected together by tenon joint.

[0012] The tenon joint mentioned here is not the tenon joint as understood in traditional woodworking. The tenon joint in woodworking requires tenons and mortises and is fixed together by the friction between the two parts. However, the tenon joint in this solution is achieved by the interlocking of the concave and convex parts set in the upper and lower sleeves.

[0013] Optionally, the upper sleeve is a T-shaped cylindrical sleeve, and the lower sleeve is a cylindrical sleeve.

[0014] Optionally, the diameter of the widest end of the inner cavity of the upper sleeve is 3mm to 4mm, the gate is a frustum-shaped gate, and the diameter of the narrowest end of the gate is 0.4mm, and the diameter of the widest end of the gate is 1mm; the length of the upper sleeve is not longer than 25mm, and the length of the lower sleeve is not longer than 14mm.

[0015] A method for manufacturing a split-type sprue sleeve includes the following steps:

[0016] S1: Cut the sleeve material into upper sleeve material and lower sleeve material;

[0017] S2: Then, make matching threads at the connection between the upper sleeve material and the lower sleeve, or make tenons and mortises at the connection between the two.

[0018] S3: Use a ball end mill to shape mill the upper and lower sleeve material parts;

[0019] S4: After milling, assemble the two together.

[0020] Optionally, the upper sleeve material can be milled first using a ball end mill with a diameter of 3mm, and then the upper sleeve material can be milled again using a ball end mill with a diameter of 2mm.

[0021] Optionally, the lower sleeve material can be milled first using a ball end mill with a diameter of 1mm or 2mm, and finally the frustum-shaped gate can be milled using a ball end mill with a diameter of 1mm.

[0022] The beneficial effects of this invention are: high smoothness of the inner cavity, no need to polish the inner cavity during the manufacturing process, relatively low manufacturing cost, and the ability to remove air bubbles in the plastic raw material during the injection molding process. Attached image description:

[0023] Figure 1 This is a simplified schematic diagram of an integrated gating sleeve structure;

[0024] Figure 2 It is a simplified schematic diagram of the raw material component structure;

[0025] Figure 3 This is a schematic diagram of the connection relationship in Example 1;

[0026] Figure 4 This is a simplified structural diagram of Example 1;

[0027] Figure 5 This is a simplified diagram illustrating the connection relationship in Example 2;

[0028] Figure 6 This is a simplified structural diagram of Example 2.

[0029] The labels in the attached figures are as follows: 1. Upper sleeve, 2. Lower sleeve, 3. Inner cavity, 4. Mortise, 5. Tenon, 6. Thread. Detailed implementation method:

[0030] The present invention will now be described in detail with reference to the accompanying drawings.

[0031] Example 1:

[0032] As attached Figure 3 and appendix Figure 4 As shown, the device includes an upper sleeve 1 and a lower sleeve 2. Both the upper sleeve 1 and the lower sleeve 2 have a frustum-shaped inner cavity 3. The diameter of the inner cavity at the discharge end of the upper sleeve 1 is greater than or equal to the diameter of the inner cavity 3 at the feed end of the lower sleeve 2. The upper sleeve 1 and the lower sleeve 2 are detachably fitted together by threads 6. The inner cavity at the discharge end of the upper sleeve 1 is connected to the inner cavity at the feed end of the lower sleeve 2. The discharge end of the lower sleeve 2 is provided with a frustum-shaped gate 201. The fitting clearance between the upper sleeve and the lower sleeve is no more than 2 threads. The diameter of the inner cavity at the feed end of the upper sleeve 1 is 3.95 mm, the diameter of the inner cavity at the discharge end of the upper sleeve is 3.37 mm, the diameter of the narrowest end of the frustum-shaped gate is 0.4 mm, and the diameter of the widest end of the gate is 1 mm. The length of the upper sleeve is no more than 25 mm, and the length of the lower sleeve is no more than 14 mm.

[0033] Example 2:

[0034] As attached Figure 5 and appendix Figure 6 As shown, a split-type sprue sleeve includes an upper sleeve 1 and a lower sleeve 2. Both the upper sleeve 1 and the lower sleeve 2 have a frustum-shaped inner cavity 3. The diameter of the inner cavity at the discharge end of the upper sleeve 1 is greater than or equal to the diameter of the inner cavity 3 at the feed end of the lower sleeve 2. The upper sleeve 1 and the lower sleeve 2 are detachably fitted together by tenons 4 and mortises 5, respectively. The inner cavity at the discharge end of the upper sleeve 1 is connected to the inner cavity at the feed end of the lower sleeve 2. The lower sleeve 2 has a frustum-shaped gate 201 at its discharge end. The clearance between the upper sleeve and the lower sleeve is no more than 2 mm. The inner diameter of the feed end of the upper sleeve 1 is 3.95 mm, the inner diameter of the discharge end of the upper sleeve is 3.37 mm, the diameter of the narrowest end of the frustum-shaped gate is 0.4 mm, and the diameter of the widest end of the gate is 1 mm. The length of the upper sleeve is no more than 25 mm, and the length of the lower sleeve is no more than 14 mm.

[0035] This invention also provides a method for processing a split-type gate sleeve, comprising the following steps:

[0036] S1: Cut the sleeve material into upper sleeve material and lower sleeve material;

[0037] S2: Then, make matching threads at the connection between the upper sleeve material and the lower sleeve, or make tenons and mortises at the connection between the two.

[0038] S3: First, use a ball end mill with a diameter of 3mm to mill the upper part of the sleeve material, then use a ball end mill with a diameter of 2mm to mill the upper part of the sleeve material; first, use a ball end mill with a diameter of 1mm or 2mm to mill the lower part of the sleeve material, and finally use a ball end mill with a diameter of 1mm to mill the frustum-shaped gate.

[0039] S4: After milling, assemble the two together.

[0040] The above description is merely a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural transformations made based on the description and drawings of the present invention, whether directly or indirectly applied to other related technical fields, are similarly included within the scope of protection of the present invention.

Claims

1. A method for milling a split two-section sprue bushing, characterized in that, The split two-section sprue sleeve includes an upper sleeve and a lower sleeve. Both the upper and lower sleeves have frustum-shaped inner cavities. The diameter of the inner cavity at the discharge end of the upper sleeve is greater than or equal to the diameter of the inner cavity at the feed end of the lower sleeve. The upper and lower sleeves are detachably fitted together. The inner cavity at the discharge end of the upper sleeve is connected to the inner cavity at the feed end of the lower sleeve. A sprue is provided at the discharge end of the lower sleeve. The fitting gap between the upper and lower sleeves is no more than 2 mils. The diameter of the widest end of the inner cavity of the upper sleeve is 3mm to 4mm. The gate is a frustum-shaped gate, and the diameter of the narrowest end of the gate is 0.4mm, and the diameter of the widest end of the gate is 1mm. The length of the upper sleeve is no more than 25mm, and the length of the lower sleeve is no more than 14mm. The processing includes the following steps: S1: Cut the sleeve material into an upper sleeve material and a lower sleeve material; S2: Then, make matching threads at the connection between the upper sleeve material and the lower sleeve, or make tenons and mortises at the connection between the two. S3: Then use a ball end mill to mill the upper and lower sleeve raw materials; S4: After milling, assemble the two together; First, use a ball end mill with a diameter of 3mm to mill the upper part of the sleeve material, and then use a ball end mill with a diameter of 2mm to mill the upper part of the sleeve material. First, use a ball end mill with a diameter of 1mm or 2mm to mill the lower section of the sleeve material, and finally use a ball end mill with a diameter of 1mm to mill the frustum-shaped gate; The upper and lower sleeve sections are joined together by threads. Alternatively, the upper and lower sleeves can be connected together using mortise and tenon joints.

2. The milling method for a split two-section sprue bushing as described in claim 1, characterized in that, The upper sleeve is a T-shaped cylindrical sleeve, and the lower sleeve is a cylindrical sleeve.

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