A micro-stress mold core and a mold comprising the micro-stress mold core

Abstract

The present invention provides a micro-stress mold core and a mold including the micro-stress mold core, belonging to the field of mold structure. The micro-stress mold core of the present invention comprises a mold core body, the mold core body comprises a mounting surface for mounting the mold core body, a mold cavity surface for setting a product mold cavity, and a side surface arranged on the periphery of the mounting surface and the mold cavity surface, wherein the mounting surface is provided with a reinforcement structure, the mounting surface is also provided with a mold core heating expansion positioning guide structure, the reinforcement structure and the mold core heating expansion positioning guide structure are both provided with heating expansion expansion slots, and a mold core expansion gap is provided between the side surface and the mounting plate. The beneficial effect of the present invention is: minimizing product deformation caused by mold core warping.

Description

Technical Field

[0001] The invention relates to a mold structure, in particular to a mold for achieving mold temperature balance. Background Art

[0002] In an injection mold, the mold core is a key precision part in the center of the mold. It is a very important part in the mold, and its structure directly determines the fineness of the product. The mold core will have thermal expansion during the heating process. If the heat is unbalanced, it will cause the mold core to expand and warp. For products that require precision processing, its deformation directly affects the accuracy of the product. However, no mold core currently takes this situation into consideration. Therefore, a micro-stress mold core is urgently needed to solve the product deformation caused by micro-strain such as thermal expansion deformation of the mold core.

[0003] In addition, the existing mold core only has one set of heating pipes and cooling pipes, which are uniformly controlled by the controller and cannot maintain mold temperature balance. This structure has the following defects:

[0004] (1) The temperature of the mold cavity near the heating tube rises quickly and is high, while the temperature of the mold cavity far from the heating tube rises slowly and is low, which is not conducive to the flow of the injection liquid. In addition, the core steel will expand when heated. The higher the temperature, the greater the shrinkage after cooling, which can easily cause product deformation due to uneven shrinkage of the mold.

[0005] (2) The cooling temperature of the product surface cannot be controlled. The low-temperature area of ​​the product surface cools first, and the high-temperature area cools later, which will affect the appearance quality of the product and easily cause the product to warp and deform.

[0006] In addition, the water outlet and water inlet of the cooling pipe in the prior art are both arranged on one side of the mold, and the cooling pipe is relatively long in the mold, which is not conducive to cooling. The temperature difference between the water inlet pipe and the water outlet pipe is relatively large, thereby aggravating the imbalance of the mold temperature. Summary of the invention

[0007] In order to solve the problems in the prior art, the present invention provides a micro-stress mold core and also provides a mold including the micro-stress mold core.

[0008] The micro-stress mold core of the present invention includes a mold core body, and the mold core body includes a mounting surface for mounting the mold core body, a mold cavity surface for setting a product mold cavity, and side surfaces arranged on the periphery of the mounting surface and the mold cavity surface, wherein the mounting surface is provided with a reinforcement structure, and the mounting surface is also provided with a mold core heating expansion positioning guide structure, the reinforcement structure and the mold core heating expansion positioning guide structure are both provided with heating expansion expansion grooves, and a mold core expansion gap is provided between the side surface and the mounting plate.

[0009] The present invention is further improved in that the reinforcement structure includes reinforcement ribs arranged around the mounting surface and integrally formed with the side surface, and reinforcement bones arranged inside the reinforcement ribs.

[0010] The present invention is further improved in that the mold core heating expansion positioning guide structure includes positioning ribs arranged at the transverse center and the longitudinal center of the installation surface, and the positioning ribs are protruding from the surface of the reinforcement structure.

[0011] The present invention is further improved in that the mold core heating expansion positioning guide structure also includes a plurality of positioning columns arranged on the reinforcing ribs.

[0012] The present invention is further improved in that the core body is provided with more than one temperature zone, each temperature zone is provided with a set of heating device, cooling device and temperature measuring device for detecting the temperature of the product cavity corresponding to the temperature zone, and the heating device and cooling device in each temperature zone are individually controlled by a controller.

[0013] The present invention is further improved, the heating device is a heating tube, the cooling device is a cooling pipe with cooling water inside, the water inlet of the cooling pipe is arranged on one side of the core body, and the water outlet is arranged on the other side of the core body opposite to the water inlet.

[0014] The present invention is further improved in that the number of the heating tubes and the cooling tubes are both multiple, the heating tubes and the cooling tubes are arranged at intervals, and the temperature measuring devices, cooling tubes and heating tubes are at equal distances from each other.

[0015] The present invention is further improved in that the vertical distance between the temperature measuring device and the product mold cavity, the distance between the temperature measuring device and the cooling pipe, and the distance between the temperature measuring device and the heating pipe are equal.

[0016] The present invention is further improved in that the distance between the heating tube and the mounting surface of the mold core body is equal to the distance between the heating tube and the mold cavity of the mold core body product.

[0017] The present invention also provides a mold including the micro-stress mold core, comprising an insulation support plate and a mounting plate, wherein one side of the insulation support plate is provided with an installation groove corresponding to the mold core heating expansion positioning guide structure, the mold core heating expansion positioning guide structure of the micro-stress mold core is fixed in the installation groove, the mounting plate is provided with an accommodating groove for accommodating the mold core body and the insulation support plate, and the outer side of the mounting plate is provided with a water inlet pipe and a water outlet pipe connected to the cooling pipe.

[0018] Compared with the prior art, the beneficial effects of the present invention are: minimizing product deformation caused by core warping and achieving precision processing of products; by dividing the mold into zones and embedding a temperature measuring device, each zone controls the mold temperature separately, thereby ensuring mold temperature balance, and is not restricted by product size, shape, structure, and wall thickness, thereby avoiding thermal expansion deformation of the core due to unbalanced heat, and also avoiding warping deformation of the product due to unbalanced product cavity temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the mold structure of the present invention;

[0020] Figure 2 It is a schematic diagram of the structure of the front mold core and mold cavity surface;

[0021] Figure 3 for Figure 2 BB section view;

[0022] Figure 4 for Figure 3 Enlarged view of part C;

[0023] Figure 5 and Figure 6 for Figure 2 AA section view;

[0024] Figure 7 and Figure 8 This is a schematic diagram of the front mold core installation surface;

[0025] Fig. 9 It is a schematic diagram of the partitioning of another embodiment of the front mold core. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0027] like Figure 1-Figure 6 As shown, as an embodiment of the present invention, the mold of the present invention includes a front mold core 3, a rear mold core 4, and a product mold cavity 5 arranged between the front mold core 3 and the rear mold core 4. In this example, a heating device 16, a cooling device 15 and a temperature sensor 17 for detecting the temperature of the product mold cavity corresponding to the temperature zone are arranged on the front mold core 3. The front mold core of this example is arranged in a 1-to-2 manner, that is, two front mold cores 3 are arranged in one mold.

[0028] like Figure 3-5 , Figure 7As shown, the front mold core 3 of the present invention includes a mold core body 301, the mold core body 301 includes a mounting surface 3012 for mounting the mold core body 301, a mold cavity surface 3011 for setting a product mold cavity for injection molding a product 19, and a side surface 3013 arranged on the periphery of the mounting surface 3012 and the mold cavity surface 3011, wherein the mounting surface 3012 is provided with a reinforcement structure, the mounting surface 3012 is also provided with a mold core heating expansion positioning guide structure, the reinforcement structure and the mold core heating expansion positioning guide structure are both provided with a heating expansion expansion expansion groove 305, and a mold core expansion gap d is provided between the side surface 3013 and the mounting plate (in this case, the front mold core, then the mounting plate is the A plate 7). The width of the mold core expansion gap d in this example is 0.01mm, and the width of the mold core expansion gap d is calculated based on the expansion coefficient of the material of the front mold core 3 and the required mold temperature, and different mold core materials have different expansion gaps. The mold core material of this example is preferably a steel material with fast heat conduction, high corrosion resistance, high toughness and tensile strength, so as to minimize the warping of the mold steel.

[0029] If the heating expansion expansion slot 305 and the core expansion gap d are not provided, then due to installation restrictions, when the front core 3 is heated and expanded, the front core 3 will be arched toward the product cavity, thereby affecting the appearance of the injection molded product 19 in the product cavity 5. The micro-stress core of this example can well avoid this micro-strain phenomenon of the front core 3.

[0030] like Figure 7 As shown, the reinforcement structure of this example includes a reinforcement rib 304 arranged around the installation surface and integrally formed with the side surface, and a reinforcement bone 302 arranged inside the reinforcement rib 304. The reinforcement bones 302 are arranged in a crisscross pattern to connect the reinforcement ribs 304 at both ends, which can improve the rigidity of the steel and make the core body 301 as thin as possible, thereby reducing the absorption and conduction of energy of the core body 301, making the mold temperature heating faster and the temperature easier to control, avoiding the situation where the energy accumulated in the core causes the product cavity temperature to increase significantly after the heating stops. The core body 301 of this example achieves a lightweight design without affecting the rigidity. It saves raw materials.

[0031] The mold core heating expansion positioning guide structure of this example includes positioning ribs 303 arranged at the lateral center and the longitudinal center of the mounting surface 3012, so as to fix the center position of the entire front mold core 3 and avoid the phenomenon of deviation from the center due to the contraction of the mold core body 301. The positioning ribs 303 are arranged on the surface of the reinforcement structure to fix the front mold core 3 as a fixed structure.

[0032] The core heating expansion positioning guide structure of this example also includes four positioning columns 306 arranged on the reinforcing ribs 304. The positioning columns 306 are arranged at the four corners of the core body 301, and combined with the positioning ribs 303, so as to limit the middle and four corners of the core body 301. Preferably, the positioning columns 306, the positioning ribs 303 and the heating expansion expansion slots 305 are arranged symmetrically with the positioning ribs 303 as the central axis, which is more conducive to the balance of contraction after thermal expansion of the core body 301. It avoids the micro deformation of the core caused by the unbalanced contraction after heating thermal expansion, and then causes the surface deformation of the injection molded product 19.

[0033] like Figure 2 , Figure 7 and Figure 8 As shown, the higher the temperature of the core body 301 is, the greater the shrinkage is. Therefore, the unbalanced heating of the core body 301 will also cause micro-strain of the core body 301. Therefore, in order to keep the temperature of the core body 301 and the product cavity balanced in this example, two temperature zones are set on each front core 3 in this example, and a total of four temperature zones are set on the two front cores 3. Each temperature zone is provided with a set of heating devices 16 (the first heating device 1601, the second heating device 1602, the third heating device 1603, and the fourth heating device 1604), a cooling device 15 and a temperature sensor 17. The heating device 16 and the cooling device 15 in each temperature zone are individually controlled by the controller. The number of rear cores 4 in this example is also 2, and each rear core 4 is provided with two cooling zones (not shown in the figure, the installation method of the cooling device is the same as the setting method of the front core 3), and each cooling zone is provided with a set of cooling devices 15, and the cooling devices in each cooling zone are individually controlled by the controller.

[0034] The heating device 16 of this example is a heating pipe, and the cooling device 15 is a cooling pipe with a cooling medium therein. The cooling medium of this example can be water or other liquid medium that absorbs heat.

[0035] like Figure 1-Figure 6As shown, the heating device 16 of this example is arranged on the front mold core. Therefore, this mold is also provided with a heat insulation support plate 6 on the top surface of the front mold core 3 to prevent heat loss. One side of the heat insulation support plate 6 is provided with a mounting groove corresponding to the mold core heating expansion positioning guide structure, and the mold core heating expansion positioning guide structure of the microstress mold core is fixed in the mounting groove. The A plate 7 is provided with a receiving groove for accommodating the mold core body 301 and the heat insulation support plate 6. The heat insulation support plate 6 is fixed on the bottom surface of the A plate 7. The water inlet 1501 of the cooling pipe is arranged on one side of the mold, and the water outlet 1502 of the cooling pipe is arranged on the other side of the mold. The water inlet 1501 and the water outlet are both arranged on the A plate 7 and are connected to the cooling pipe in the front mold core 3. The cooling water enters from one side of the mold and flows out from the other side, which greatly shortens the time that the cooling water stays in the cooling pipe, so that more cooling water passes through per unit time and the cooling efficiency is better. The cooling channels are arranged in parallel in the mold core, and the water flow reaching the vicinity of the product cavity is basically consistent, which is conducive to maintaining mold temperature balance.

[0036] A flow channel plate 9 is provided on the top surface of the A plate 7, and the top surface of the flow channel plate 9 is a panel 10. The rear mold core 4 of this example is fixed on the B plate 8, and two square irons 11 are provided on both sides between the bottom plate 14 and the B plate 8. An ejector bottom plate 13 is fixed on the bottom plate between the two square irons, and an ejector panel 12 is provided on the ejector bottom plate 13. Two ejectors pass through the B plate 8 and are connected to the product mold cavity.

[0037] Of course, the temperature zone in this example can also be set on the rear mold core 4, so that the front mold core 3 and the rear mold core 4 can simultaneously realize the heating and cooling functions. The temperature zone can also be set on the rear mold core 4, and the cooling zone can be set on the front mold core 3, so that the heating device on the rear mold core 4 heats the product mold cavity 5, and the cooling devices of the front and rear mold cores cool the product. In this case, the heat insulation support plate is set on the side with the heating device.

[0038] A plurality of temperature zones are used for heating or cooling respectively, and each temperature zone and cooling zone is controlled separately, and a separate temperature sensor 17 is provided, which can accurately control the temperature of the product cavity so that the temperature difference can be controlled within 2 degrees Celsius, thereby ensuring the micro-stress of the core body 301 and preventing its thermal expansion deformation, which is beneficial to maintaining the mold temperature balance of the product cavity and preventing the injection molded product 19 from warping and deformation caused by unbalanced heating and cooling.

[0039] like Fig. 9As shown, the micro-stress core of this example is particularly suitable for the processing of high-precision products. As one of the embodiments, if the product is a flat arc shape, this example can divide the front core 3 and the rear core into 8 zones (the vertical line is the dividing line of each zone) according to the shape of the product cavity, so as to control the temperature of each temperature zone separately, avoiding the prior art that the cooling pipe and the heating pipe are horizontally set, and the distance from the product cavity 5 is too different, so that the product mold temperature is too different, the product cavity temperature is different, resulting in different molten liquid fluidity and shear rate during injection molding, and the quality of the product cannot be guaranteed; the cooling is not synchronized to cause the product to warp and deform. The present invention is particularly suitable for product cavities with complex three-dimensional shapes. The partitions are set according to the shape of the product, so that the temperature difference of each area of ​​the product can be guaranteed. The scheme of the present invention is not limited by the size, shape, structure, and wall thickness of the product. It can process thin-walled products greater than or equal to 0.5 mm without causing warping and deformation of the product.

[0040] The mounting surface 3012 of the front mold core 3 in this example can also be processed into a non-planar structure according to the shape of the product, as long as the surface of the reinforcing structure is in horizontal contact with the surface of the heat insulation support plate 6. Of course, the surface of the heat insulation support plate 6 in this example can also be adapted to the surface of the mounting surface 3012 of the front mold core, and the heat insulation effect is better.

[0041] like Figure 5-8 As shown, in this example, the number of heating pipes and cooling pipes in each temperature zone is multiple, and the heating pipes and cooling pipes are arranged at intervals, which is conducive to controlling the balance of temperature difference.

[0042] The temperature sensor 17, the cooling pipe and the heating pipe are at equal distances from each other, preferably forming an equilateral triangle. The distance between the temperature sensor 17 and the product mold cavity, the distance between the temperature sensor 17 and the cooling pipe, and the distance between the temperature sensor 17 and the heating pipe are equal. Thus, the mold temperature measured by the temperature sensor 17 is more accurate. The design reason for the equal distances at multiple points is that during the heating or cooling process, the front mold core 3 (steel) will have energy accumulation and heat conduction time when it is hot or cold, so the temperature sensor 17 is set at the mean value of the distance between the cooling pipe and the heating pipe and the surface of the product mold cavity, so that the test results of heating, cooling, and mold cavity surface (i.e., the surface temperature of the workpiece) are more accurate.

[0043] In this example, the distance x between the heating tube and the top surface of the front mold core is equal to the distance y between the heating tube and the cavity surface of the front mold core. The measurement is more accurate. Similarly, in this example, the distance between the cooling pipe in the front mold core and the top surface of the front mold core and the cavity surface of the front mold core is equal.

[0044] By dividing the mold into zones and embedding temperature measuring devices, each zone can control the mold temperature independently, effectively ensuring the mold temperature balance, regardless of product size, shape, structure, and wall thickness. It can process products of various shapes and ensure their quality and appearance.

[0045] like Figure 3 and Figure 4 As shown, in the design of the A plate in this example, the thermal expansion phenomenon of the steel material of the front mold core 3 is fully considered. Therefore, there is a core expansion gap d of 0.01mm between the outer periphery of the front mold core and the A plate. However, the front mold core 3 in this example is a one-to-two arrangement, and the runner is arranged between the two front mold cores 3. Therefore, in order to avoid the branch runner between the runner and the gate interfering with the micro-strain of the front mold core 3, a bridge insert 18 is provided on the A plate 7 in this example. The bridge insert 18 is arranged above the core expansion gap d between the A plate 7 and the front mold core 3. The branch runner of the runner and the gate is arranged above the bridge insert 18. The bridge insert 18 is matched with the gap of the front mold core 3, so as not to interfere with the thermal expansion and contraction of the front mold core 3. In addition, it can also effectively prevent the molten liquid from flowing into the core expansion gap d and blocking the core expansion gap d.

[0046] The specific implementation modes described above are preferred implementation modes of the present invention, and are not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to the specific implementation modes, and all equivalent changes made according to the present invention are within the protection scope of the present invention.

Claims

1. A micro stress mold core, Features: The mold core body comprises a mounting surface for mounting the mold core body, a cavity surface for setting a product cavity, and a side surface arranged on the periphery of the mounting surface and the cavity surface, wherein the mounting surface is provided with a reinforcement structure, the mounting surface is also provided with a mold core heating expansion positioning guide structure, the reinforcement structure and the mold core heating expansion positioning guide structure are both provided with heating expansion expansion slots, and a mold core expansion gap is provided between the side surface and the mounting plate, The reinforcement structure includes a reinforcement rib arranged around the mounting surface and integrally formed with the side surface, and a reinforcement bone arranged inside the reinforcement rib; The mold core heating expansion positioning guide structure includes positioning ribs arranged at the horizontal center and the longitudinal center of the installation surface, and the positioning ribs are protruding from the surface of the reinforcing structure. The mold core heating expansion positioning guide structure also includes a plurality of positioning columns arranged on the reinforcing ribs.

2. The micro-stress mold core according to claim 1, Features: The core body is provided with more than one temperature zone, each temperature zone is provided with a set of heating device, cooling device and temperature measuring device for detecting the temperature of the product cavity corresponding to the temperature zone, and the heating device and cooling device in each temperature zone are individually controlled by a controller.

3. The micro-stress mold core according to claim 2, Features: The heating device is a heating tube, the cooling device is a cooling pipe with cooling water inside, the water inlet of the cooling pipe is arranged on one side of the core body, and the water outlet is arranged on the other side of the core body opposite to the water inlet.

4. The micro-stress mold core according to claim 3, Features: The number of the heating tubes and the cooling tubes are both multiple, the heating tubes and the cooling tubes are arranged at intervals, and the temperature measuring devices, the cooling tubes and the heating tubes are at equal distances from each other.

5. The micro-stress mold core according to claim 3, Features: The vertical distance between the temperature measuring device and the product mold cavity, the distance between the temperature measuring device and the cooling pipe, and the distance between the temperature measuring device and the heating pipe are equal.

6. The micro-stress mold core according to claim 3, Features: The distance between the heating tube and the mounting surface of the mold core body is equal to the distance between the heating tube and the mold cavity of the mold core body product.

7. A mold comprising the micro-stress core according to any one of claims 2 to 6, Features: It includes a heat-insulating support plate and a mounting plate, wherein one side of the heat-insulating support plate is provided with a mounting groove corresponding to the core heating expansion positioning guide structure, the core heating expansion positioning guide structure of the micro-stress core is fixed in the mounting groove, the mounting plate is provided with a receiving groove for accommodating the core body and the heat-insulating support plate, and the outer side of the mounting plate is provided with a water inlet pipe and a water outlet pipe connected to the cooling pipe.

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