Display back cover injection mold

Abstract

The utility model relates to injection mold technical field discloses a kind of display rear cover injection molds, including rear mould and front mould, and front mould and rear mould cooperate to form the injection cavity of display rear cover, and the working surface of front mould is equipped with non-appearance window forming area, and non-appearance window forming area is provided with opening forming area and glue inlet, and glue inlet and opening forming area between are provided with glue resistance convex rib, and glue resistance convex rib extends along the periphery of opening forming area and is arranged. Such design, by setting glue resistance convex rib between glue inlet and opening forming area, to form annular buffer area, glue resistance convex rib continues to block high-pressure melt to the penetration of opening forming area edge parting surface in subsequent pressure maintaining stage, to transfer the risk of easy overflow material from window parting line to controllable area, to solve the problem that display rear cover is prone to burr in hole position after injection molding, without doing inverted mould, and then the development cost of mould can be saved.

Description

Technical Field

[0001] This utility model relates to the field of injection mold technology, and in particular to an injection mold for a display back cover. Background Technology

[0002] In injection molding, high-flow-rate engineering plastics are prone to melt front retention during the mold filling stage, which can easily lead to the formation of burrs in areas with thin walls or abrupt structural changes. Specifically, when the melt flows through areas where the cross-sectional area suddenly decreases or the flow direction changes abruptly, the flow velocity at the leading edge slows down significantly due to the surge in resistance. The melt front is subjected to the high pressure and shearing action of the subsequent melt, causing non-uniform changes in temperature and viscosity. The high-temperature, low-viscosity retained melt is highly likely to penetrate into the microscopic gaps under pressure, forming burrs.

[0003] In existing plastic mold designs, the injection point is preferentially far away from the window and hole positions. However, when the space of the appearance part design does not allow for this, it is difficult to solve the problem of burrs at the product holes. The melt filling path at the product holes often induces turbulence or jetting, which aggravates the instability and energy dissipation of the melt front and significantly increases the risk of stagnant melt invading the parting surface gap.

[0004] When the melt overflows into the gap of the parting surface around the window, it can easily form flash with obvious visual defects, which seriously damages the appearance quality of the product and the cleanliness of the window area. Removing such flash in post-processing not only increases the process cost, but also poses a risk of scratching the surface of the back cover of the display. Summary of the Invention

[0005] The main purpose of this utility model is to provide an injection mold for a display back cover, which aims to improve the shortcomings of the prior art and solve the problem that burrs easily appear at the holes after the display back cover is injection molded.

[0006] To achieve the above objectives, this utility model proposes a display back cover injection mold, comprising:

[0007] Post-model kernel;

[0008] The front mold core and the rear mold core cooperate to form an injection cavity for the back cover of the display. The working surface of the front mold core is provided with a non-appearance window forming area. The non-appearance window forming area is provided with an opening forming area and a glue inlet. A glue-blocking rib is provided between the opening forming area and the glue inlet. The glue-blocking rib extends along the outer periphery of the opening forming area.

[0009] Optionally, the cross-section of the adhesive-resistant rib is in the shape of an equilateral trapezoid.

[0010] Optionally, the height of the adhesive-resistant rib is 0.5mm to 1.0mm.

[0011] Optionally, the height of the adhesive-resistant rib is 0.8 mm.

[0012] Optionally, the bottom width of the adhesive-resistant rib is 0.5mm to 1.0mm.

[0013] Optionally, the bottom width of the adhesive-resistant rib is 0.8 mm.

[0014] Optionally, the front mold core is provided with two opposing strip-shaped protrusions, one of which is located at the upper edge of the injection cavity, and the other of which is located at the lower edge of the injection cavity.

[0015] Optionally, the diameter of the glue inlet is 5mm to 7mm.

[0016] Optionally, the diameter of the glue inlet is 6mm.

[0017] Optionally, the depth of the glue inlet is 0.5 mm.

[0018] Beneficial Effects: The display back cover injection mold proposed in this utility model includes a rear mold core and a front mold core. The front and rear mold cores cooperate to form the injection cavity of the display back cover. The working surface of the front mold core has a non-appearance window forming area. An opening forming area and a gate are provided in the non-appearance window forming area. A blocking rib is provided between the opening forming area and the gate, and the blocking rib extends along the outer periphery of the opening forming area. This design, by providing a blocking rib between the gate and the opening forming area to form an annular buffer area, continuously prevents high-pressure melt from penetrating to the edge parting surface of the opening forming area during the subsequent holding pressure stage. This transfers the risk of overflow from the window parting line to a controllable area, thereby solving the problem of burrs easily appearing at the hole positions after injection molding of the display back cover. This improves the product yield of the display back cover and ensures the stability of product dimensions. Secondly, this design eliminates the need for an inverted mold, thus saving mold development costs. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a three-dimensional structural diagram of the front mold core disclosed in this application;

[0021] Figure 2 for Figure 1 A magnified view of a section at point A in the middle;

[0022] Figure 3 This is a top view of the front mold core disclosed in this application.

[0023] Explanation of icon numbers:

[0024] 1. Front mold core; 11. Non-exterior window forming area; 12. Opening forming area; 13. Glue gate; 14. Glue-blocking rib; 15. Strip-shaped protrusion.

[0025] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0028] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0029] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Additionally, the technical solutions of various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0030] As an important component of electronic products, the monitor back cover serves multiple functions, including structural support, electromagnetic shielding, heat dissipation assistance, and aesthetic decoration. Its typical characteristics include large size, relatively thin wall thickness, high surface quality requirements, and often include complex mounting holes, snap-fit ​​structures, and internal reinforcing ribs.

[0031] To achieve efficient and low-cost mass production, thermoplastic injection molding is the main process for manufacturing display back covers. In the injection molding process, high-flow-rate engineering plastics are prone to melt front retention during the mold filling stage, which can easily form burrs in thin-walled or structurally abrupt areas of the product. Specifically, when the melt flows through areas where the cross-sectional area suddenly decreases or the flow direction changes abruptly, the flow velocity at the leading edge slows down significantly due to the surge in resistance. The leading melt is continuously subjected to the high pressure and shearing action of the subsequent melt, resulting in non-uniform changes in temperature and viscosity. The high-temperature, low-viscosity retained melt is very likely to penetrate into the microscopic gaps under pressure, forming burrs.

[0032] In existing plastic mold designs, the injection point is preferentially far away from the window and hole positions. However, when the space of the appearance part design does not allow for this, it is difficult to solve the problem of burrs at the product holes. The melt filling path at the product holes often induces turbulence or jetting, which aggravates the instability and energy dissipation of the melt front and significantly increases the risk of stagnant melt invading the parting surface gap.

[0033] When the melt overflows into the parting surface gap around the window, it easily forms flash with obvious visual defects, which seriously damages the appearance quality of the product and the cleanliness of the window area. Post-processing to remove such flash not only increases process costs, but also poses a risk of scratching the surface of the display back cover.

[0034] Secondly, to suppress burr formation, traditional mold designs often necessitate the use of special structures such as inverted molds. These designs adjust the mold opening direction or add cavity layers to keep the critical parting surface away from the window or appearance surface. However, inverted mold structures are far more complex than conventional molds in terms of slider, ejection, hot runner, and cooling system design, requiring extremely high manufacturing precision and significantly increasing debugging difficulty. This directly leads to a longer mold development cycle, a significant increase in initial investment costs (mold fees), and may increase the difficulty and cost of maintenance during subsequent mass production.

[0035] Based on this, the present application provides an injection mold for a display back cover, see [link to relevant documentation]. Figures 1-3 As shown, the injection mold for the back cover of the display includes a rear mold core (not shown in the figure) and a front mold core 1. The front mold core 1 and the rear mold core cooperate to form an injection cavity for the back cover of the display. The working surface of the front mold core 1 is provided with a non-appearance window forming area 11. The non-appearance window forming area 11 is provided with an opening forming area 12 and a glue inlet 13. A glue-blocking rib 14 is provided between the opening forming area 12 and the glue inlet 13. The glue-blocking rib 14 extends along the outer periphery of the opening forming area 12.

[0036] Specifically, by setting a blocking rib 14 between the injection port 13 and the opening molding area 12, an annular buffer area is formed. The blocking rib 14 continuously blocks the high-pressure melt from penetrating to the edge parting surface of the opening molding area 12 during the subsequent holding pressure stage, thereby transferring the risk of overflow from the window parting line to a controllable area. This solves the problem of burrs easily appearing at the hole position after injection molding of the display back cover, thereby improving the product yield of the display back cover and ensuring the stability of product dimensions. Secondly, this design eliminates the need for an inverted mold, thus saving mold development costs.

[0037] In one embodiment of this application, the cross-section of the adhesive-resistant rib 14 is in the shape of an equilateral trapezoid.

[0038] Specifically, during injection molding, the front mold core 1 and the rear mold core surround the injection cavity forming the back cover of the display. The working surface of the front mold core 1 is provided with a resisting rib 14 corresponding to the resisting groove of the back cover of the display. After injection molding, the inclined side wall surface (draft surface) of the resisting rib 14 forms the side of the resisting groove of the back cover of the display. The cross-section of the resisting rib 14 is in the shape of an equilateral trapezoid, and the bottom width of the resisting rib 14 is greater than the top width of the resisting rib 14. The groove opening width of the resisting groove of the back cover of the display after injection molding is greater than the bottom width of the resisting groove. This design significantly reduces the frictional resistance when the back cover of the display after injection molding is ejected from the front mold core 1, avoids possible scratches, tears or deformation during demolding, ensures the structural integrity of the back cover of the display, and improves the product yield.

[0039] In one embodiment of this application, the height of the adhesive-resistant rib 14 is 0.5 mm to 1.0 mm. Preferably, the height of the adhesive-resistant rib 14 is 0.8 mm.

[0040] In one embodiment of this application, the bottom width of the adhesive-resistant rib 14 is 0.5 mm to 1.0 mm. Preferably, the bottom width of the adhesive-resistant rib 14 is 0.8 mm.

[0041] In one embodiment of this application, the front mold core 1 is provided with two oppositely arranged strip-shaped protrusions 15, one of the two strip-shaped protrusions 15 is located at the upper edge of the injection cavity, and the other of the two strip-shaped protrusions 15 is located at the lower edge of the injection cavity.

[0042] Specifically, the injection-molded back cover of the display has a mounting groove formed on its surface corresponding to the area of ​​the strip-shaped protrusion 15, which is used to install a shock-absorbing component made of silicone rubber.

[0043] Silicone rubber's main chain consists of Si-O bonds with high bond energy, giving it excellent weather resistance, oxidation resistance, and resistance to various chemical media (such as weak acids, weak alkalis, alcohols, and salt spray). This results in a longer service life for shock absorbers made of silicone rubber, reducing maintenance costs for display devices. Secondly, silicone rubber's molecular chains are highly flexible, allowing it to quickly recover its original shape and maintain a high resilience after long-term compression or cyclic loading. Its low compression set ensures that shock absorbers maintain preload and damping effect during long-term use, preventing performance degradation due to plastic deformation. Furthermore, silicone rubber exhibits excellent high and low temperature stability, typically maintaining stable elastic modulus and damping properties within a temperature range of -60℃ to 200℃. This ensures reliable operation of shock absorbers in extreme temperature environments, avoiding performance failures caused by low-temperature embrittlement or high-temperature softening common in shock absorbers made of ordinary rubber.

[0044] In one embodiment of this application, the diameter of the glue inlet 13 is 5mm to 7mm, preferably 6mm, and the depth of the glue inlet 13 is 0.5mm.

[0045] To further illustrate this point, this application also provides a method for assembling the shock absorber and the monitor back cover, as follows:

[0046] First, set the pressure holding time on the assembly fixture to 7 seconds. Next, peel off the adhesive backing on the shock absorber and place it into the positioning groove of the bottom mold. Then, place the monitor back cover into the bottom mold groove, press the start button, and the upper mold will press down and hold the pressure for 7 seconds. The holding pressure is 4-5 kg / F. After the pressure holding time reaches 7 seconds, the cylinder will automatically retract, and the shock absorber and the monitor back cover will be properly bonded.

[0047] It should be noted that the assembly fixture in the embodiments of this application is an existing device. This application does not involve structural improvements to the assembly fixture. The structure of the assembly fixture can be as disclosed in the utility model patent with patent publication number CN222933382U, entitled "Automatic Assembly Fixture for Plastic Shell Support Pad". Therefore, this application will not describe the specific structure of the assembly fixture here.

[0048] In this embodiment, the display back cover may be made of polycarbonate or acrylonitrile-styrene-acrylate copolymer.

[0049] Specifically, polycarbonate (PC) maintains good toughness at low temperatures and has good creep resistance. Using polycarbonate to make the back cover of the display can give the back cover good impact resistance and deformation resistance, thereby effectively resisting mechanical stress during transportation, installation and use, greatly reducing the risk of breakage and significantly extending the service life.

[0050] Acrylonitrile-styrene-acrylate copolymer (ASA) maintains good rigidity and dimensional stability while possessing impact resistance. Its toughness is relatively less affected by low-temperature environments. The weather resistance of acrylonitrile-styrene-acrylate copolymer (ASA) enables it to effectively resist degradation caused by outdoor ultraviolet radiation, damp heat, and other factors, avoiding material embrittlement, pulverization, and strength reduction. Using acrylonitrile-styrene-acrylate copolymer (ASA) to make the back cover of a monitor can ensure the long-term structural stability of the back cover under harsh climatic conditions.

[0051] To further illustrate this point, this application also provides the injection molding process for the display back cover, as detailed below:

[0052] Step 1: Use PC or ASA material for injection molding via hot runner needle valve. The gate is located on a non-surface surface of the product. The gate 13 is a columnar channel with a diameter of 6mm and a depth of 0.5mm.

[0053] Step 2: Set the mold opening stroke to 380mm and the injection molding machine clamping force to 260 tons;

[0054] Step 3: During the mold closing stage, apply a holding pressure of 50MPa, control the temperature of the front mold at 70℃, control the temperature of the rear mold at 80℃, and the molding cycle is 55 seconds.

[0055] Step 4: Open the mold with a mold opening distance of 380mm, and use a robotic arm to remove the injection-molded display back cover plastic part.

[0056] Step 5: Place the rubber strip into the positioning slot of the assembly fixture to ensure its position is fixed.

[0057] Step 6: Place the monitor back cover into the designated cavity of the assembly fixture.

[0058] Step 7: The operator presses the start button with both hands, driving the cylinder to push the pressure block to perform the pressing action, and presses the rubber strip into the mounting groove of the monitor back cover through the push block;

[0059] Step 8: Press the rubber strip with a constant pressure of 5 kg and maintain the pressure for 7 seconds.

[0060] Step 9: After the pressure holding is completed, the cylinder drives the pressure block to retract 5mm to the initial position.

[0061] Step 10: Remove the assembled part and perform the following tests in sequence:

[0062] (a) Check if the rubber strip is properly pressed in place;

[0063] (b) Check whether the appearance of the monitor back cover meets the appearance standards.

[0064] Step 11: Place the inspected and qualified monitor back cover into a packaging bag for packaging.

[0065] In summary, the display back cover injection mold proposed in this utility model includes a rear mold core and a front mold core 1. The front mold core 1 and the rear mold core cooperate to form an injection cavity for the display back cover. The working surface of the front mold core 1 is provided with a non-appearance window forming area 11. The non-appearance window forming area 11 is provided with an opening forming area 12 and a glue inlet 13. A glue-blocking rib 14 is provided between the opening forming area 12 and the glue inlet 13. The glue-blocking rib 14 extends along the outer periphery of the opening forming area 12. This design, by setting a blocking rib 14 between the injection port 13 and the opening molding area 12, forms an annular buffer area. The blocking rib 14 continuously blocks the high-pressure melt from penetrating to the edge parting surface of the opening molding area 12 during the subsequent holding pressure stage, thereby transferring the risk of overflow from the window parting line to a controllable area. This solves the problem of burrs easily appearing at the hole positions after injection molding of the display back cover, thereby improving the product yield of the display back cover and ensuring the stability of product dimensions. Secondly, this design eliminates the need for an inverted mold, thus saving mold development costs.

[0066] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A display back cover injection mold, characterized in that, include: Post-model kernel; The front mold core and the rear mold core cooperate to form an injection cavity for the back cover of the display. The working surface of the front mold core is provided with a non-appearance window forming area. The non-appearance window forming area is provided with an opening forming area and a glue inlet. A glue-blocking rib is provided between the opening forming area and the glue inlet. The glue-blocking rib extends along the outer periphery of the opening forming area.

2. The injection mold for the display back cover according to claim 1, characterized in that, The cross-section of the adhesive-resistant rib is in the shape of an equilateral trapezoid.

3. The display back cover injection mold according to claim 1, characterized in that, The height of the adhesive-resistant rib is 0.5mm to 1.0mm.

4. The injection mold for the display back cover according to claim 1, characterized in that, The height of the adhesive-resistant rib is 0.8 mm.

5. The injection mold for the display back cover according to claim 1, characterized in that, The bottom width of the adhesive-resistant rib is 0.5mm to 1.0mm.

6. The display back cover injection mold according to claim 4, characterized in that, The bottom width of the adhesive-resistant rib is 0.8mm.

7. The injection mold for the display back cover according to claim 1, characterized in that, The front mold core is provided with two opposing strip-shaped protrusions, one of which is located at the upper edge of the injection cavity, and the other of which is located at the lower edge of the injection cavity.

8. The injection mold for the display back cover according to claim 1, characterized in that, The diameter of the glue inlet is 5mm to 7mm.

9. The injection mold for the display back cover according to claim 1, characterized in that, The diameter of the glue inlet is 6mm.

10. The injection mold for the display back cover according to claim 1, characterized in that, The depth of the glue inlet is 0.5 mm.

Images