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, and the female die and the male die are closed until the gap is zero. 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 patent application number of the parent case is: CN202411367198.7, the application date is: September 29, 2024, and the title is: A Molding Die for Thick Workpieces and an Operating Method. Technical Field

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

[0003] The compression molding process utilizes the characteristics of each stage in the resin curing reaction to achieve the molding of products, that is, the compression molding plasticizes, flows, and fills the mold cavity, and the resin cures. During the flow process of the compression molding material filling the mold cavity, not only does the resin flow, but the reinforcing filler also needs to flow accordingly. Therefore, the molding pressure of the compression molding process is higher than that of other process methods, belonging to high-pressure molding.

[0004] The injection molding process is a method in which, at a certain temperature, the plastic material is completely melted by screw stirring and injected into the mold cavity under high pressure, and after cooling and curing, the molded product is obtained.

[0005] To achieve the molding and processing of thick workpieces, in the prior art, the original injection molding machine is improved. The patent with the patent number CN202110724003.X discloses a thick workpiece injection mold, including: a cavity, one side wall of the cavity is a movable push block, and the volume of the cavity can be changed by the movement of 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 thimble plate, the thimble plate is connected to the other end of the push rod, a buffer structure and / or a cavity compression structure.

[0006] In the above injection molding process, the mold structure is complex and requires the runner to provide a relatively high holding pressure and a relatively long holding time to meet the molding requirements of the workpiece, which has a great impact on the service life of the injection molding machine, and shrinkage holes still occur inside the workpiece; for compression molding, as the thickness increases, the processing process becomes increasingly difficult, and shrinkage holes still occur in the workpiece.

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

[0008] In order to overcome the problem of shrinkage holes inside the workpiece during the molding process of the existing compression mold, the purpose of this application is to provide a compression mold for thick workpieces and an operating method to improve the shrinkage hole problem during the compression molding process of thick workpieces, which is specifically achieved through the following technical solutions: A thick workpiece compression mold, characterized in that it includes a male mold, a female mold, and a runner. The male mold includes a first contact surface, the female mold includes a second contact surface, and the distance between the first contact surface and the second contact surface is h1. When the male and female molds move to a preset distance of h1, the female and male molds form a closed cavity, and the melt is injected into the cavity through the runner. After injection is completed, the runner is closed, and the female and male molds are closed until the gap is 0.

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

[0010] Optionally, a movable ejector plate is provided inside the female mold. The initial position of the ejector plate and the male mold has a minimum distance ≥0, and it can meet the requirement that when the melt sprays out from the runner, the ejector plate can prevent the spraying phenomenon.

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

[0012] Optionally, a limit block for restricting the displacement distance of the ejector plate is provided at the bottom of the female mold.

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

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

[0015] Optionally, the ejector plate is provided with a position adjusting device, and the position adjusting device drives the ejector plate to move in the cavity.

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

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

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

[0021] Optionally, the oil cylinder is provided with an electronically controlled one-way valve, and the electronically controlled one-way valve causes the oil cylinder to generate a resistance for the ejector plate to move towards the female mold.

[0022] Optionally, the adjusting mechanism includes a limiting rod, a spring, and a first limiting post. The first limiting post is fixed on the punch. One end of the spring is fixed on the die, and the other end is fixed to the limiting rod, providing a force to the limiting rod in the direction of the first limiting post. One end of the limiting rod is hinged to the connecting plate, and the other end is provided with a limiting protrusion. Due to the resistance between the limiting protrusion and the first limiting post when the mold is opened, the connecting plate is driven to move along the sliding post, and then the push plate is driven to move. When the mold opening distance reaches a certain degree, the limiting protrusion is separated from the first limiting post.

[0023] Optionally, it further includes a second limiting post. The second limiting post is fixed on the die. The second limiting post can make the limiting protrusion and the first limiting post contact each other when the mold is closed and satisfy that when the mold is opened, due to the resistance between the limiting protrusion and the first limiting post, the connecting plate is driven to move along the sliding post, and then the push plate is driven 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 operation method for a thick workpiece molding die, including the following steps: The die and the punch are closed to a preset h1 position. The melt enters the cavity through the runner. After injection is completed, the runner is closed, and the melt injection mechanism no longer provides a holding pressure. The die and the punch are closed to a gap of 0.

[0026] Optionally, the die and the punch are closed to a preset h1 position. The melt enters the cavity through the runner. After injection is completed, the runner is closed, and the melt injection mechanism (molding press) no longer provides an injection holding pressure. The die and the punch are closed to a gap of 0. When the thick workpiece needs to be demolded, the thick workpiece is pushed out by the movement of the push plate.

[0027] Optionally, the die and the punch are closed to a preset h1 position. The push plate moves to the initial position. The minimum distance between this initial position and the punch is ≥0, and it can satisfy that when the melt sprays out from the runner, the push plate can play a role in hindering the spraying phenomenon. The melt enters the cavity through the runner. After injection is completed, the runner is closed, and the melt injection mechanism (molding press) no longer provides an injection holding pressure. The die and the punch are closed to a gap of 0. When the thick workpiece needs to be demolded, the thick workpiece is pushed out by the movement of the push plate.

[0028] Compared with the prior art, the beneficial effects of the present application are as follows: When the compression mold is used for compression molding, there is no need for a runner to provide a pressure-holding pressure, which can avoid damage to the melt injection mechanism and improve the service life of the mold; the shrinkage cavity phenomenon inside the obtained thick workpiece is improved; a push plate is provided inside the female mold to prevent the jet effect when the melt enters the cavity, reduce the air involved inside the workpiece, and at the same time reduce the internal stress of the workpiece, effectively improving the problem of cracking of the thick workpiece. Brief Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of the compression mold described in Embodiment 1; Figure 2 It is Figure 1 A sectional view taken along the direction of A-A; Figure 3 It is Figure 2 A partial enlarged view of the D area in Figure 4 It is a schematic sectional structure diagram of the compression mold described in Embodiment 2; Figure 5 It is a schematic sectional structure diagram of the compression mold described in Embodiment 3; Figure 6 It is a schematic structural diagram of the compression mold described in Embodiment 4; Figure 7 It is Figure 6 A sectional view taken along the direction of B-B; Figure 8 It is a schematic structural diagram of the compression mold described in Embodiment 6; Figure 9 It is Figure 8 A sectional view taken along the direction of C-C; Figure 10 It is a schematic structural diagram of the adjustment structure in Embodiment 6; In the figure, the reference numerals are: 1 - male mold, 101 - first contact surface, 2 - female mold, 201 - second contact surface, 3 - runner, 301 - injection channel, 302 - injection passage, 4 - cavity, 5 - push plate, 6 - glue injection port, 7 - limit block, 8 - connecting rod, 9 - connecting plate, 10 - sliding column, 11 - oil cylinder, 12 - limit rod, 13 - limit projection, 14 - third contact surface, 15 - fourth contact surface, 16 - spring, 17 - second limit post, 18 - first limit post. Detailed Description of the Embodiment

[0030] The following elaborates on the specific implementation manners of the present application in detail through embodiments. However, the specific implementation of the present application does not limit the technical solution of the present application. Any non-substantive changes such as common technical solution replacements in the art using the technical solution described in the embodiments of the present application fall within the protection scope of the present application.

[0031] It should be noted that, unless otherwise specified, terms such as "first", "second", "third", "fourth", "upper", and "lower" in this application are only used as ways to describe the structure and do not limit the technical solutions of this application. Those skilled in the art should understand that "fixing" or "fixed connection" in this application includes direct fixing and indirect fixing. As long as the realization of the structural function is not affected, those skilled in the art can set it according to actual needs. Embodiment 1

[0032] As Figure 1 、 Figure 2 、 Figure 3 shown, a thick part compression mold 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 the 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 part. Simply put, h1 is positively correlated with the thickness of the required part. Those skilled in the art can obtain a better value of h1 through fewer test times in this way. At this time, the mold is in a semi-closed mold state, and the melt is injected into the cavity 4 through the runner 3. To better improve the shrinkage cavity phenomenon of the part, the melt in the cavity 4 is filled until it is full. After 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 pressure holding pressure, and the pressure for part forming completely comes 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, which is more convenient for installation and for the external melt to be transported into the injection channel 301 compared with the traditional straight runner 3.

[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 position and length of the corresponding runner 3 are adjusted to adapt to the mold to ensure that the melt will not cool in the runner 3 during the flowing process. During the transportation of the melt in the cold runner, a material rod will be formed at the glue injection port 6 due to cooling between the molding of every two parts. The formed material rod will be taken out as the molded part is taken out. Embodiment 2

[0035] As Figure 4 shown, a thick part compression mold, the same parts as in Embodiment 1 will not be described again. The difference is that a movable push plate 5 is provided inside the die 2. The initial position of the push plate 5 and the minimum distance from the punch 1 are ≥0, and it can meet the effect that the push plate 5 can prevent the spraying phenomenon when the melt sprays out from the runner 3.

[0036] In this embodiment, the initial position between the ejector plate 5 and the female mold 2 is 0. The position of the ejector plate 5 corresponding to the glue injection port 6 is recessed inward. After the melt enters the cavity 4 through the injection channel 302, it is sprayed on the recess of the ejector plate 5, which can effectively avoid the spraying effect and prevent excessive air from being involved in the melt. When the melt just sprays out, a certain distance between the melt and the ejector plate 5 is beneficial to moving the ejector plate 5 towards the bottom of the female mold 2 through the pressure of the melt.

[0037] In this embodiment, a limit block 7 is provided at the bottom of the female mold 2 to limit the displacement distance of the ejector plate 5. The limit block 7 is detachably connected to the bottom of the female mold 2. In other embodiments, a limit block 7 with adjustable height can also be set, as long as the function of hindering the ejector plate 5 from continuing to approach the bottom of the female mold 2 through the height of the limit block 7 can be achieved. The volume of the cavity 4 is changed by the cooperation of 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 7 can also play a role in protecting the bottom of the female mold 2 and improving the service life of the mold. Embodiment 3

[0038] As Figure 5 shown in a thick part compression mold, the same parts as in Embodiment 2 will not be described in detail. The difference is that the surface of the ejector plate 5 facing the male mold 1 is a plane and the initial position between the ejector plate 5 and the female mold 2 is greater than 0. Embodiment 4

[0039] As Figure 6 、 Figure 7 shown in a thick part compression mold, which includes all the structures of Embodiment 2. The difference is that the ejector plate 5 is provided with a position adjusting device to drive the ejector plate 5 to move in the cavity 4. The position adjusting device includes a connecting mechanism and an adjusting mechanism, and the connecting mechanism connects the ejector plate 5 and the adjusting mechanism.

[0040] In this embodiment, the connecting mechanism is a connecting rod 8. One end of the connecting rod is fixedly connected to the ejector plate 5, and the other end is fixedly connected to the oil cylinder 11. It should be noted that since the oil cylinder 11 in this embodiment only plays a role in ejecting the part, those skilled in the art can choose other power devices in other embodiments, or can also choose not to install the oil cylinder 11 and manually eject the part.

[0041] In this embodiment, the movement of the oil cylinder 11 is controlled by an electro-hydraulic directional valve. When the mold is in the open state, the electro-hydraulic directional valve is energized. The oil cylinder 11 drives the push plate 5 to move towards the punch 1 through the connecting rod 8. After the cavity 4 and the push plate 5 are pushed out, the electro-hydraulic directional valve is de-energized and in the middle position function state. Then the mold is closed to the set distance. At this time, the mold is not completely closed. At this time, the runner 3 injects the melt into the cavity 4. The pressure of the melt pushes the cavity 4 and the push plate 5 to move upward until the push plate 5 contacts the limit block 7. The electro-hydraulic directional valve is still in the middle position function state. After the melt injection is completed, the mold continues to close, clamping the upper and lower molds of the mold tightly. The plastic melt is pressed and compacted and starts to cool and solidify. The electro-hydraulic directional valve is still in the middle position function state. After cooling, the mold is opened, the electro-hydraulic directional valve is energized, and the workpiece is ejected to obtain the molded workpiece.

[0042] In other embodiments, an electro-controlled check valve can also be provided for the oil cylinder 11. When the melt is injected into the cavity 4 and pushes the push plate 5 to move upward, the electro-controlled check valve causes the oil cylinder 11 to generate a resistance force for the push plate 5 to move towards the female mold 2. The presence of the electro-controlled check valve enables the melt to maintain pressure during the injection process, which is beneficial to preventing the phenomenon of shrinkage holes in the melt during the molding process. Embodiment 5

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

[0044] In this embodiment, the connecting rod 8 and the oil cylinder 11 are located on the same side of the connecting plate. The oil cylinder 11 is arranged in the horizontal direction of the mold, effectively saving the overall space of the mold and facilitating installation. The oil 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 oil cylinder 11 can also be arranged in other positions as long as it can achieve the function of driving the push plate 5 to move. Those skilled in the art know how to achieve its function. The specific working process has been described in Embodiment 4 and will not be elaborated here. Embodiment 6

[0045] As Figure 8 、 Figure 9 、 Figure 10A thick workpiece compression mold shown in the figure includes a connection mechanism and an adjustment mechanism. The connection mechanism includes a connection plate and a connecting rod 8. The connection relationship of the connection mechanism is the same as that in Embodiment 5. The adjustment mechanism includes a limit rod 12, a spring 16, and a first limit post 18. The first limit post 18 is fixed on the convex mold 1. One end of the spring 16 is fixed on the concave mold 2, and the other end is fixed to the limit rod 12, providing a force to the limit rod 12 in the direction of the first limit post 18. One end of the limit rod 12 is hinged to the connection plate, and the other end is provided with a limit protrusion 13. Due to the resistance between the limit protrusion 13 and the first limit post 18, when the mold is opened, the connection plate is driven to move along the sliding column 10, and then the push plate 5 is driven to move. When the mold opening distance reaches a certain extent, the limit protrusion 13 is separated from the first limit post 18.

[0046] In this embodiment, a second limit post 17 is arranged outside the concave mold 2. The second limit post 17 can make the limit protrusion 13 and the first limit post 18 contact each other during mold closing and satisfy that when the mold is opened, due to the resistance between the limit protrusion 13 and the first limit post 18, the connection 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 limit protrusion 13 includes a third contact surface 14 and a fourth contact surface 15. The included angle between the third contact surface 14 and the limit rod 12 is an obtuse angle, and the included angle between the fourth contact surface 15 and the limit rod 12 is an acute angle.

[0048] The detailed working process of this embodiment is briefly described below: During the process of mold closing, in the previous working process, due to the adjustment mechanism driving the push plate 5 to eject the workpiece, at this time, the connection plate is located below the sliding column 10 and contacts the concave mold 2. The limit protrusion 13 is located between the second limit post 17 and the first limit post 18. As the concave mold 2 gradually moves towards the convex mold 1, the connection plate drives the limit rod 12 to move along with the movement of the concave mold 2, and the limit protrusion 13 gradually moves towards the first limit post 18. When the fourth contact surface 15 contacts the first limit post 18, the concave mold 2 is still moving towards the convex mold 1. The acting force between the fourth contact surface 15 and the first limit post 18 is small. Due to the hinge between the limit rod 12 and the connection plate, under the pressure of the connection plate, the limit rod 12 will briefly perform a pendulum motion and then re-contact the limit post under the pulling force of the spring 16. After that, the mold is in a semi-closed state, forming a closed cavity 4.

[0049] During the semi-closing mold process, since the ejector plate 5 is fixedly connected between the ejector plate 5 and the connecting plate, the ejector plate 5 is located at the position closest to the punch 1 at this time. With the injection of the melt, the pressure of the melt pushes the ejector plate 5 to move away from the punch 1, and then the connecting plate is above the slide post 10. At this time, the limit protrusion 13 is still below the first limit post 18, and the third contact surface 14 contacts the first limit post 18.

[0050] During the mold opening process, the female mold 2 moves away from the punch 1. However, at this time, the contact between the third contact surface 14 and the first limit post 18 hinders the movement of the connecting plate along with the movement of the female mold 2. Therefore, the connecting plate remains relatively stationary while the female mold 2 is continuously moving. Through the blocking effect of the limit rod 12 and the limit post, the connecting rod 8 and the ejector plate 5 are pushed to eject the workpiece. When the connecting plate is in contact with the female mold 2 below the slide post 10, the female mold 2 is still moving. Since the pulling force of the movement of the female mold 2 is much greater than the resistance between the limit rod 12 and the limit post and the stroke of the female mold 2 is relatively long, the female mold 2 drives the connecting plate and the limit rod 12 to continue moving. Under the action of the pulling force of the mold, the limit protrusion 13 breaks through the obstruction of the first limit post 18 and continues to move towards the second limit post 17. Finally, the mold stops moving. The limit rod 12 stops moving under the blocking action of the second limit post 17 and the pulling force of the spring 16. The limit protrusion 13 is located between the second limit post 17 and the first limit post 18.

[0051] It should be noted that for the components used in the above embodiments, those skilled in the art can select or replace them according to their needs, which does not exceed the protection scope of this application.

Claims

1. Thick workpiece molding die, characterized in that: The invention comprises a punch, a die, and a runner, wherein the punch comprises a first contact surface, the die comprises 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 arranged inside the die, the push plate is provided with a position adjustment device, the push plate is driven to move in the cavity by the position adjustment device, the position adjustment device comprises a connecting mechanism and an adjustment mechanism, the connecting mechanism connects the push plate and the push plate to move in the cavity ... The plate and the adjustment mechanism, 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 makes the connecting plate move along the sliding column due to the resistance of the limit protrusion and the first limit column when the mold is opened, and then the push plate is driven to move. When the mold opening distance reaches a certain degree, the limit protrusion is separated from the first limit column.

2. The thick workpiece molding die according to claim 1, characterized in that: It also includes a second limiting column, 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 requirements 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.

3. The thick workpiece molding die according to claim 1, characterized in that: The limiting protrusion comprises 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.

4. The thick workpiece molding die according to claim 1, characterized in that: The flow channel comprises an injection channel and an injection channel, and the injection channel is perpendicular to the injection channel.

5. The thick workpiece molding die according to claim 1, characterized in that: The minimum distance between the initial position of the push plate and the punch is ≥ 0, and the push plate can prevent the melt from ejecting when it is ejected from the flow channel.

6. The thick workpiece molding die according to claim 5, characterized in that: When the initial position between the push plate and the concave mold is 0, the position of the push plate corresponding to the injection port is concave inward.

7. 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.

8. The thick workpiece molding die according to claim 7, characterized in that: A limit block for limiting the displacement distance of the push plate is provided at the bottom of the die, and the limit block is detachably connected to the bottom of the die.

9. The thick workpiece molding die according to claim 8, characterized in that: The limit block is height adjustable.

10. The thick workpiece molding die according to claim 1, characterized in that: The connecting mechanism comprises a connecting rod, one end of which is fixedly connected to the push plate.

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