Thick workpiece mold pressing mold

Abstract

The invention belongs to the technical field of plastic processing, and particularly relates to a thick workpiece mold pressing mold. The thick workpiece mold pressing mold comprises a male mold body, a female mold body and a runner, the male mold body comprises a first contact face, the female mold body comprises a second contact face, the distance between the first contact face and the second contact face is h1, when the female mold body and the male mold body move to the preset distance h1, a closed cavity is formed by the female mold body and the male mold body, and melt is injected into the cavity through the runner; and after injection is completed, the runner is closed, the female die and the male die are closed until the gap is zero, a movable push plate is arranged in the female die and can achieve the effect of hindering the jetting phenomenon when melt is jetted out of the runner, and when the initial position between the push plate and the female die is zero, the position, corresponding to the glue injection opening, of the push plate is sunken inwards. According to the mold pressing mold, pressure maintaining pressure does not need to be provided by a runner during mold pressing forming, a melt injection mechanism is prevented from being damaged, and the service life of the mold is prolonged; the internal shrinkage cavity phenomenon of the obtained thick workpiece is improved; and a push plate is arranged in the female die, so that the injection effect generated when melt enters a cavity is prevented, air involved in a workpiece is reduced, meanwhile, the internal stress of the workpiece is reduced, and the problem of cracking of a thick workpiece is effectively solved.

Description

[0001] This application is a divisional application, the parent patent application number is: CN202411367198.7, the application date is: 2024-09-29, and the name is: A thick part molding die and operation method. Technical Field

[0002] The present application belongs to the field of plastic processing technology, and specifically relates to a molding die and an operating method. Background Art

[0003] The compression molding process uses the characteristics of each stage in the resin curing reaction to realize product molding, that is, the molding plasticization, flow and filling the mold cavity, and the resin solidification. In the process of the molding material filling the mold cavity, not only the resin flows, but also the reinforcing filler flows with it. Therefore, the molding pressure of the compression molding process is higher than other process methods, which belongs to high-pressure molding.

[0004] The injection molding process is a method in which completely molten plastic material is stirred by a screw at a certain temperature, injected into a mold cavity with high pressure, and then cooled and solidified to obtain a molded product.

[0005] In order to realize the molding processing of thick parts, the original injection molding machine is improved in the prior art. The patent with patent number CN202110724003.X discloses a thick part injection mold, including: a cavity, one of the side walls of the cavity is a movable push block, and the volume of the cavity can be changed by moving the push block, a push rod, one end of the push rod is connected to the push block and is located outside the cavity, a pin plate, the pin plate is connected to the other end of the push rod, and a buffer structure and / or a cavity compression structure.

[0006] In the above-mentioned injection molding process, the mold structure is complex and the hot runner is required to provide a higher holding pressure and a longer holding time to meet the molding requirements of the parts, which has a great impact on the life of the injection molding machine, and shrinkage holes will still appear inside the parts. For compression molding, as the thickness increases, the processing process becomes more difficult, and shrinkage holes will still appear in the parts.

[0007] Therefore, there is an urgent need to provide a compression mold that can improve the shrinkage cavity phenomenon of thick parts during the compression molding process. Summary of the invention

[0008] In order to overcome the problem of internal shrinkage cavities in the molding process of existing compression molds, the purpose of this application is to provide a compression mold for thick parts and an operation method to improve the shrinkage cavities of thick parts during the compression molding process, which is specifically achieved through the following technical solutions: A thick part molding die, characterized in that it includes a punch, a die, and a runner, the punch includes a first contact surface, the die includes a second contact surface, the distance between the first contact surface and the second contact surface is h1, when the die and the punch move to a preset h1 distance, the die and the punch form a closed cavity, the melt is injected into the cavity through the runner, after the injection is completed, the runner is closed, and the die and the punch are closed until the gap is 0.

[0009] Optionally, the flow channel includes an injection channel and an injection channel, and the injection channel is perpendicular to the injection channel.

[0010] Optionally, a movable push plate is provided inside the concave mold, and the minimum distance between the initial position of the push plate and the punch is ≥ 0, and the push plate can play an effect of hindering the injection phenomenon when the melt is ejected from the runner.

[0011] Optionally, when the initial position between the push plate and the concave mold is 0, the position of the push plate corresponding to the glue injection port is recessed inward.

[0012] Optionally, a limit block for limiting the displacement distance of the push plate is provided at the bottom of the die.

[0013] Optionally, the limit block is detachably connected to the bottom of the die.

[0014] Optionally, the limit block is height adjustable.

[0015] Optionally, the push plate is provided with a position adjustment device, and the push plate is driven to move in the cavity by the position adjustment device.

[0016] Optionally, the position adjustment device includes a connecting mechanism and an adjusting mechanism, and the connecting mechanism connects the push plate and the adjusting mechanism.

[0017] Optionally, the connecting mechanism includes a connecting rod, one end of which is fixedly connected to the push plate.

[0018] Optionally, the connecting mechanism includes a connecting plate and a sliding column, the connecting plate can move along the direction of the sliding column, and the connecting plate is fixedly connected to the connecting rod and the adjusting mechanism.

[0019] Optionally, the adjusting mechanism includes an oil cylinder, one end of the connecting rod is fixedly connected to the oil cylinder, and the oil cylinder drives the connecting rod to move, thereby driving the push plate to move.

[0020] Optionally, the adjusting mechanism includes an oil cylinder, and the connecting plate is fixedly connected to the connecting rod and the oil cylinder. The oil cylinder drives the connecting plate to move, thereby driving the connecting rod and the push plate to move.

[0021] Optionally, the oil cylinder is provided with an electrically controlled one-way valve, and the electrically controlled one-way valve enables the oil cylinder to generate resistance to the movement of the push plate toward the direction of the die.

[0022] Optionally, the adjustment mechanism includes a limit rod, a spring, and a first limit column, the first limit column is fixed on the punch, one end of the spring is fixed on the die, and the other end is fixed to the limit rod, providing a force to the limit rod in the direction of the first limit column, one end of the limit rod is hinged to the connecting plate, and the other end is provided with a limit protrusion, the force provided to the first limit column by the limit protrusion and the spring, so that when the mold is opened, due to the resistance of the limit protrusion and the first limit column, the connecting plate is driven to move along the sliding column, and then the push plate is driven to move, and when the mold opening distance reaches a certain degree, the limit protrusion is separated from the first limit column.

[0023] Optionally, a second limiting column is also included, which is fixed on the die. The second limiting column can make the limiting protrusion and the first limiting column contact each other when the mold is closed and meet the requirement that when the mold is opened, due to the resistance of the limiting protrusion and the first limiting column, the connecting plate is driven to move along the sliding column, thereby driving the push plate to move.

[0024] Optionally, the limiting protrusion includes a third contact surface and a fourth contact surface, the angle between the third contact surface and the limiting rod is an obtuse angle, and the angle between the fourth contact surface and the limiting rod is an acute angle.

[0025] The present application also provides an operating method for a thick-worked part molding die, comprising the following steps: the die and the punch are closed to a preset h1 position, the melt enters the cavity through the runner, and after the injection is completed, the runner is closed, the melt injection mechanism no longer provides holding pressure, and the die and the punch are closed until the gap is 0.

[0026] Optionally, the die and the punch are closed to a preset h1 position, the melt enters the cavity through the runner, and after injection is completed, the runner is closed, the melt injection mechanism molding machine no longer provides injection holding pressure, and the die and the punch are closed until the gap is 0; when a thick workpiece needs to be demolded, the thick workpiece is pushed out by moving the push plate.

[0027] Optionally, the die and the punch are closed to a preset h1 position, and the push plate is moved to an initial position, the minimum distance between the initial position and the punch is ≥ 0, and the push plate can prevent the melt from ejecting from the runner. The melt enters the cavity through the runner. After the injection is completed, the runner is closed, and the melt injection mechanism molding machine no longer provides injection holding pressure. The die and the punch are closed to a gap of 0; when a thick workpiece needs to be demolded, the thick workpiece is pushed out by moving the push plate.

[0028] Compared with the prior art, the beneficial effects of the present application are as follows: the compression mold does not require a runner to provide holding pressure during compression molding, thereby avoiding damage to the melt injection mechanism and increasing the service life of the mold; the internal shrinkage phenomenon of the resulting thick workpiece is improved; a push plate is provided inside the die to prevent the injection effect when the melt enters the cavity, reduce the air drawn into the workpiece, and at the same time reduce the internal stress of the workpiece, effectively improving the problem of cracking of thick workpieces. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the structure of the compression mold described in Example 1; Figure 2 for Figure 1 Cross-sectional view along AA direction; Figure 3 for Figure 2 A partial enlarged view of the D area in the middle; Figure 4 This is a schematic cross-sectional structural diagram of the molding die described in Example 2; Figure 5 This is a schematic cross-sectional structural diagram of the molding die described in Example 3; Figure 6 This is a schematic diagram of the structure of the compression mold described in Example 4; Figure 7 for Figure 6 Cross-sectional view along direction BB; Figure 8 This is a schematic diagram of the molding die structure described in Example 6; Fig. 9 for Figure 8 Cross-sectional view along CC direction; Fig.10 This is a schematic diagram of the structure of the adjustment structure of Example 6; In the figure, the reference numerals are: 1-punch, 101-first contact surface, 2-die, 201-second contact surface, 3-flow channel, 301-injection channel, 302-injection channel, 4-cavity, 5-push plate, 6-glue injection port, 7-limiting block, 8-connecting rod, 9-connecting plate, 10-sliding column, 11 oil cylinder, 12-limiting rod, 13-limiting protrusion, 14-third contact surface, 15-fourth contact surface, 16-spring, 17-second limiting column, 18-first limiting column. DETAILED DESCRIPTION

[0030] The specific implementation methods of the present application are described in detail below through examples, but the specific implementation of the present application does not serve as a limitation on the technical solution of the present application. Any non-substantial changes such as replacing common technical solutions in the field with the technical solutions described in the examples of the present application are within the scope of protection of the present application.

[0031] It should be noted that, unless otherwise specified, the words and directional nouns such as "first", "second", "third", "fourth", "upper", "lower" in this application are only used as a way to describe the structure, and are not limitations on the technical solution of this application. Those skilled in the art should understand that "fixed" or "fixed connection" in this application includes direct fixation and indirect fixation, and those skilled in the art can set it according to actual needs as long as it does not affect the realization of the structural function. Example 1

[0032] like Figure 1 , Figure 2 , Figure 3 A thick workpiece molding die shown in the figure includes a punch 1, a die 2, and a runner 3. The punch 1 includes a first contact surface 101, and the die 2 includes a second contact surface 201. The distance between the first contact surface 101 and the second contact surface 201 is h1. When the die 2 and the punch 1 move to a preset distance h1, the die 2 and the punch 1 form a closed cavity 4. The distance h1 is determined according to the thickness of the required workpiece. In short, h1 is positively correlated with the thickness of the required workpiece. A technician in this field can obtain a better h1 value through a smaller number of tests in this way. At this time, the mold is in a semi-closed state, and the melt is injected into the cavity 4 through the runner 3. In order to better improve the shrinkage phenomenon of the workpiece, the melt in the cavity 4 is filled. After the injection is completed, the runner 3 is closed, and the die 2 and the punch 1 are closed until the gap is 0. At this time, the runner 3 does not provide a holding pressure, and the pressure for part molding comes entirely from the closing pressure between the die 2 and the punch 1.

[0033] In this embodiment, the runner 3 includes an injection channel 301 and an injection channel 302 . The injection channel 301 is perpendicular to the injection channel 302 . Compared with the traditional straight runner 3 , it is more convenient to install and to transport the external melt into the injection channel 301 .

[0034] In this embodiment, a hot runner is selected to inject the melt, which is beneficial to the transportation of the melt. In other embodiments, a cold runner can also be selected, and the corresponding position and length of the runner 3 are adjusted to adapt to the mold to ensure that the melt will not be cooled in the runner 3 during the flow. During the melt transportation process of the cold runner, a material rod will be formed at the injection port 6 due to cooling between the molding of every two parts, and the formed material rod will be taken out as the molded parts are taken out. Example 2

[0035] like Figure 4 A thick workpiece molding die is shown, and the parts that are the same as those in Example 1 are no longer repeated. The difference is that a movable push plate 5 is provided inside the die 2, and the minimum distance between the push plate 5 and the punch 1 at the initial position is ≥ 0, and the push plate 5 can play the role of hindering the injection phenomenon when the melt is ejected from the runner 3.

[0036] In this embodiment, the initial position between the push plate 5 and the die 2 is 0, and the push plate 5 is recessed inwardly corresponding to the position of the injection port 6. After the melt enters the cavity 4 through the injection channel 302, it is sprayed at the recessed portion of the push plate 5, which can effectively avoid the spraying effect and prevent too much air from being drawn into the melt. When the melt is just sprayed out, a certain distance is created between the push plate 5, which is conducive to moving the push plate 5 toward the bottom of the die 2 through the pressure of the melt.

[0037] In this embodiment, a limit block 7 is provided at the bottom of the die 2 for limiting the displacement distance of the push plate 5. The limit block 7 is detachably connected to the bottom of the die 2. In other embodiments, a height-adjustable limit block 7 may also be provided, as long as the function of preventing the push plate 5 from continuing to approach the bottom of the die 2 can be achieved through the height of the limit block 7. The volume of the cavity 4 can be changed by cooperating with the height of the limit block 7 and the distance between the first contact surface 101 and the second contact surface 201. In addition, the limit block 77 can also protect the bottom of the die 2 and increase the service life of the mold. Example 3

[0038] like Figure 5 A thick workpiece molding die is shown, and the parts that are the same as those in Example 2 are not repeated here, except that the side of the push plate 5 facing the punch 1 is flat and the initial position between the push plate 5 and the die 2 is greater than 0. Example 4

[0039] like Figure 6 , Figure 7 The thick workpiece molding die shown includes all the structures of Example 2, except that the push plate 5 is provided with a position adjustment device to drive the push plate 5 to move in the cavity 4, and the position adjustment device includes a connecting mechanism and an adjustment mechanism, and the connecting mechanism connects the push plate 5 and the adjustment mechanism.

[0040] In the present embodiment, the connecting mechanism is a connecting rod 8, one end of which is fixedly connected to the push plate 5, and the other end is fixedly connected to the cylinder 11. It should be noted that since the cylinder 11 in the present embodiment only serves to eject the workpiece, in other embodiments, those skilled in the art may choose other power devices, or may choose not to install the cylinder 11 and manually eject the workpiece.

[0041] In this embodiment, the movement of the cylinder 11 is controlled by the electro-hydraulic reversing valve. When the mold is in the open state, the electro-hydraulic reversing valve is energized, and the cylinder 11 drives the push plate 5 to move toward the punch 1 through the connecting rod 8. After the push plate 5 of the cavity 4 is pushed out, the electro-hydraulic reversing valve loses power and is in a neutral functional state. The mold is then closed to a set distance. At this time, the mold is in an incompletely closed state. At this time, the flow channel 3 injects melt into the cavity 4. The pressure of the melt pushes the push plate 5 of the cavity 4 upward until the push plate 5 contacts the limit block 7. The electro-hydraulic reversing valve is still in a neutral functional state. After the melt is injected, the mold continues to be closed, and the upper and lower molds of the mold are tightened. The plastic melt is compacted and begins to cool and solidify; the electro-hydraulic reversing valve is still in a neutral functional state. After cooling is completed, the mold is opened, the electro-hydraulic reversing valve is energized, the workpiece is ejected, and a molded part is obtained.

[0042] In other embodiments, the oil cylinder 11 may also be provided with an electrically controlled one-way valve. When the melt is injected into the cavity 4 and pushes the push plate 5 upward, the electrically controlled one-way valve causes the oil cylinder 11 to generate resistance to the movement of the push plate 5 toward the direction of the die 2. The existence of the electrically controlled one-way valve enables the melt to maintain pressure during the injection process, which is beneficial to preventing the formation of shrinkage holes in the melt during the molding process. Example 5

[0043] A thick workpiece molding die includes all the structures of Example 4, the difference being that the connecting mechanism includes a connecting plate and a sliding column 10, the connecting plate is fixedly connected to a connecting rod 8 and an oil cylinder 11, the two ends of the connecting rod 8 are respectively connected to a push plate 5 and a connecting plate, the connecting plate is connected to the mold through a sliding column 10, and moves along the direction of the sliding column 10.

[0044] In this embodiment, the connecting rod 8 and the cylinder 11 are located on the same side of the connecting plate. The cylinder 11 is arranged in the horizontal direction of the mold, which effectively saves the overall space of the mold and is easy to install. The cylinder 11 drives the connecting plate to move, thereby driving the connecting rod 8 and the push plate 5 to move. In other embodiments, the cylinder 11 can also be set at other positions, as long as it can realize the function of driving the push plate 5 to move. Those skilled in the art know how to realize its function. The specific working process has been described in Example 4 and will not be repeated here. Example 6

[0045] like Figure 8 , Fig. 9 , Fig.10A thick workpiece molding die shown in the figure includes a connecting mechanism and an adjusting mechanism. The connecting mechanism includes a connecting plate and a connecting rod 8. The connection relationship of the connecting mechanism is the same as that of Example 5. The adjusting mechanism includes a limiting rod 12, a spring 16, and a first limiting column 18. The first limiting column 18 is fixed on the punch 1. One end of the spring 16 is fixed on the die 2, and the other end is fixed to the limiting rod 12, providing a force to the limiting rod 12 in the direction of the first limiting column 18. One end of the limiting rod 12 is hinged to the connecting plate, and the other end is provided with a limiting protrusion 13. The force provided to the first limiting column 18 by the limiting protrusion 13 and the spring 16 makes it possible for the connecting plate to move along the sliding column 10 due to the resistance of the limiting protrusion 13 and the first limiting column 18 when the mold is opened, thereby driving the push plate 5 to move. When the mold opening distance reaches a certain degree, the limiting protrusion 13 is separated from the first limiting column 18.

[0046] In this embodiment, the second limiting column 17 is arranged on the outside of the die 2. The second limiting column 17 can make the limiting protrusion 13 and the first limiting column 18 contact each other when the mold is closed and meet the requirements of opening the mold. Due to the resistance of the limiting protrusion 13 and the first limiting column 18, the connecting plate is driven to move along the sliding column 10, and then the push plate 5 is driven to move.

[0047] In this embodiment, the limiting protrusion 13 includes a third contact surface 14 and a fourth contact surface 15 . The angle between the third contact surface 14 and the limiting rod 12 is an obtuse angle, and the angle between the fourth contact surface 15 and the limiting rod 12 is an acute angle.

[0048] The following is a brief description of the detailed working process of this embodiment: During the mold closing process, in the previous working process, the adjustment mechanism drives the push plate 5 to eject the workpiece. At this time, the connecting plate is located below the sliding column 10 and contacts the die 2. The limiting protrusion 13 is located between the second limiting column 17 and the first limiting column 18. As the die 2 gradually moves toward the punch 1, the connecting plate drives the limiting rod 12 to move with the movement of the die 2, and the limiting protrusion 13 gradually moves toward the first limiting column 18. When the fourth contact surface 15 contacts the first limiting column 18, the die 2 is still moving toward the punch 1, and the action force between the fourth contact surface 15 and the first limiting column 18 is small. Since the limiting rod 12 is hinged to the connecting plate, under the pressure of the connecting plate, the limiting rod 12 will briefly make a pendulum motion, and then re-contact the limiting column under the tension of the spring 16. After that, the mold is in a semi-closing state to form a closed cavity 4.

[0049] During the semi-closing process, since the push plate 5 is fixedly connected to the push plate 5 and the connecting plate, the push plate 5 is located at the position closest to the punch 1. As the melt is injected, the pressure of the melt pushes the push plate 5 to move away from the punch 1, and then the connecting plate is above the sliding column 10. At this time, the limiting protrusion 13 is still below the first limiting column 18, and the third contact surface 14 is in contact with the first limiting column 18.

[0050] During the mold opening process, the die 2 moves in the direction away from the punch 1, but at this time the third contact surface 14 contacts the first limit post 18 to prevent the connecting plate from moving with the movement of the die 2. Therefore, the connecting plate remains relatively still, while the die 2 is constantly moving, and the limiting rod 12 and the limiting column hindering action push the connecting rod 8 and the push plate 5 to eject the workpiece. When the connecting plate is located below the sliding column 10 and contacts the die 2, the die 2 is still moving. Since the pulling force of the die 2 is much greater than the resistance between the limiting rod 12 and the limiting column and the stroke of the die 2 is far, the die 2 drives the connecting plate and the limiting rod 12 to continue to move. The limiting protrusion 13 breaks through the obstruction of the first limit post 18 under the action of the mold pulling force and continues to move toward the direction of the second limit post 17. Finally, the mold stops moving, and the limiting rod 12 stops moving under the pulling force of the spring 16 and the hindering action of the second limit post 17. The limiting protrusion 13 is located between the second limit post 17 and the first limit post 18.

[0051] It should be noted that the components used in the above embodiments can be selected or replaced by those skilled in the art according to their needs, without exceeding the protection scope of this application.

Claims

1. Thick workpiece molding die, characterized in that: It includes a punch, a die, and a runner, the punch includes a first contact surface, the die includes a second contact surface, the distance between the first contact surface and the second contact surface is h1, when the die and the punch move to a preset distance h1, the die and the punch form a closed cavity, the melt is injected into the cavity through the runner, after the injection is completed, the runner is closed, and the die and the punch are closed until the gap is 0; a movable push plate is provided inside the die, and the push plate can play an effect of hindering the injection phenomenon when the melt is ejected from the runner, when the initial position between the push plate and the die is 0, the position of the push plate corresponding to the injection port is recessed inward.

2. The thick workpiece molding die according to claim 1, characterized in that: A limit block for limiting the displacement distance of the push plate is provided at the bottom of the concave die.

3. The thick workpiece molding die according to claim 2, characterized in that: The limiting block is detachably connected to the bottom of the concave mold.

4. The thick workpiece molding die according to claim 2, characterized in that: The limit block is height adjustable.

5. The thick workpiece molding die according to claim 1, characterized in that: The push plate is provided with a position adjusting device, and the push plate is driven to move in the cavity by the position adjusting device.

6. The thick workpiece molding die according to claim 5, characterized in that: The position adjustment device comprises a connecting mechanism and an adjusting mechanism, wherein the connecting mechanism connects the push plate and the adjusting mechanism.

7. The thick workpiece molding die according to claim 6, characterized in that: The connecting mechanism comprises a connecting rod, one end of which is fixedly connected to the push plate.

8. The thick workpiece molding die according to claim 7, characterized in that: The connecting mechanism comprises a connecting plate and a sliding column. The connecting plate can move along the direction of the sliding column. The connecting plate is fixedly connected to the connecting rod and the adjusting mechanism.

9. The thick workpiece molding die according to claim 7, characterized in that: The adjusting mechanism comprises an oil cylinder, one end of the connecting rod is fixedly connected to the oil cylinder, and the oil cylinder drives the connecting rod to move, thereby driving the push plate to move.

10. The thick workpiece molding die according to claim 8, characterized in that: The adjusting mechanism comprises an oil cylinder. The connecting plate is fixedly connected to the connecting rod and the oil cylinder. The oil cylinder drives the connecting plate to move, thereby driving the connecting rod and the push plate to move.

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