Injection molding method for ball core of ball valve, ball valve injection molding method, and ball core of ball valve

Abstract

An injection molding method for a ball core of a ball valve, a ball valve injection molding method, and a ball core of a ball valve. The injection molding method comprises the steps: performing first injection molding to form an inner-layer ball, the outer diameter of the inner-layer ball being smaller than an outer diameter of a standard ball core; based on the inner-layer ball, performing second injection molding to form an outer-layer ball coating, to obtain a standard ball core. The ball core obtained by the two-step injection molding process used by the present solution, first allows the inner-layer ball to cool and set before injection molding the outer-layer ball coating. After the inner-layer ball is set, even if the roundness is affected due to uncontrollable shrinkage characteristics of the material, this can be compensated by the outer-layer ball coating formed in the second injection molding. Since the thickness of the outer-layer ball coating is smaller relative to the total thickness of the ball core, even if the outer-layer ball coating shrinks after cooling, the degree of shrinkage is smaller, and has less impact on the roundness of the ball core, thus achieving the purpose of obtaining a ball core having greater surface roundness.

Description

Injection molding method of ball core of ball valve, injection molding method of ball valve and ball core of ball valve

[0001] The present application claims priority to the Chinese patent application No. 202411384096.6, filed on September 30, 2024, and entitled "Injection molding method of ball core of ball valve, injection molding method of ball valve and ball core of ball valve", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of valve processing methods, and in particular to an injection molding method of a ball core of a ball valve, an injection molding method of a ball valve and a ball core of a ball valve. BACKGROUND

[0003] An electric ball valve is a device that controls the on-off state of a ball valve through an electric actuator. Its working principle is to rotate the ball core in the valve body through the control of the electric actuator, thereby switching the passage state of the fluid. The electric ball valve is composed of a valve body and a controller. The valve body includes a valve shell and a ball core rotatably installed in the valve shell. The controller drives the ball core in the valve body to rotate to realize the valve switching function.

[0004] In the injection molding process of the valve body of the related electric ball valve, the ball core is first injection molded, and then the ball core is placed in the molding mold of the valve shell. The valve shell is directly injection molded on the basis of the ball core, and the ball core is located in the valve shell after the valve shell is molded. Therefore, the quality of the inner surface of the valve shell is actually determined by the quality of the outer surface of the ball core, that is, the roundness of the surface of the ball core determines the roundness of the inner surface of the valve shell. The related ball core is a one-time injection molded structure. Due to the uncontrollable characteristics of the cooling shrinkage degree of the plastic material, different positions of the ball core material are prone to different degrees of cooling shrinkage after injection molding and cooling, which in turn causes the problem that the roundness of the surface of the ball core is difficult to guarantee. The roundness of the inner surface of the valve shell injection molded on the basis of the ball core is also affected. The combination of the two ultimately leads to a large rotation resistance of the ball core in the valve shell after molding, which leads to higher requirements for the output torque of the controller. Moreover, the fit of the ball core and the valve shell after rotation is not high enough, which affects the sealing performance of the valve body. In high-pressure fluid application scenarios, the valve body is prone to internal leakage.

[0005] The high leakage rate and frequent replacement problem caused by the insufficient roundness of the ball core in the traditional ball valve injection molding process not only increases resource waste, but also aggravates the environmental burden due to the high scrap rate. SUMMARY

[0006] The purpose of the present disclosure includes, for example: to provide an injection molding method of a ball core of a ball valve, an injection molding method of a ball valve and a ball core of a ball valve, which can solve the above-mentioned problems existing in the prior art.

[0007] To achieve the above object, the application adopts the following technical scheme:

[0008] In one aspect, the application provides a method for injection molding a ball core of a ball valve, comprising the steps of:

[0009] primary injection molding an inner layer ball, the outer diameter of the inner layer ball being smaller than that of a standard ball core;

[0010] secondary injection molding an outer layer ball cover on the inner layer ball to obtain a standard ball core.

[0011] In an optional embodiment, the radial thickness of the outer layer ball cover is 1.5-2 mm.

[0012] In an optional embodiment, the outer surface of the inner layer ball is provided with positioning portions

[0013] In an optional embodiment, the positioning portions are positioning protrusions and / or positioning grooves.

[0014] In an optional embodiment, the positioning portions are circular, square, oval, olive-shaped or arc-shaped strips.

[0015] In an optional embodiment, the outer surface of the inner layer ball is provided with a plurality of the positioning portions, which are dot-matrix distributed on the outer surface of the inner layer ball.

[0016] In an optional embodiment, the positioning portions are arc-shaped strips, and are arranged perpendicularly to the rotation direction of the ball core.

[0017] In an optional embodiment, the outer layer ball cover can completely cover the positioning portions.

[0018] In an optional embodiment, the inner layer ball has a central hole corresponding to the communication hole of the ball core, and the central hole has the same size as the communication hole of the standard ball core.

[0019] In an optional embodiment, when the outer layer ball cover is secondary injection molded, the mold is preheated to 60-70℃.

[0020] In another aspect, the application provides a method for injection molding a ball valve, comprising the steps of:

[0021] forming a ball core by using the above-mentioned method for injection molding a ball core;

[0022] attaching heat insulation paper to the surface of the ball core corresponding to the glue injection port of the valve shell mold;

[0023] placing the ball core with the attached heat insulation paper into the valve shell mold, and aligning the heat insulation paper with the glue injection port of the valve shell mold, and then starting injection molding of the valve shell.

[0024] In an optional embodiment, the area of the heat insulation paper is greater than or equal to the area of the glue injection port, and the center of the heat insulation paper is aligned with the center of the glue injection port.

[0025] In an optional embodiment, the edge of the heat insulation paper is greater than or equal to 3mm from the edge of the glue injection port.

[0026] In an optional embodiment, the heat insulation paper is a Teflon film or a polyimide film.

[0027] In an optional embodiment, the heat insulation paper is adhered to the ball core by using temperature-resistant epoxy glue or phenolic resin glue.

[0028] In another aspect, a ball core is provided, which is manufactured by the injection molding method described above, and the ball core comprises an inner layer ball and an outer layer ball covering the outer surface of the inner layer ball, and the outer layer ball is a structure that is secondarily injection molded on the outer surface of the inner layer ball and is integrated with the inner layer ball.

[0029] In an optional embodiment, the surface where the inner layer ball and the outer layer ball contact is provided with a positioning structure.

[0030] The beneficial effects of the present application include: the injection molding method of a ball core of a ball valve, the ball valve injection molding method, and the ball core of the ball valve, which is formed by a two-time injection molding process, an inner layer ball with a smaller outer diameter than the standard ball core is first injection molded, and after the inner layer ball is cooled and shaped, the inner layer ball is placed in a mold to injection mold an outer layer ball, the outer layer ball covers the outer surface of the inner layer ball, and the two are combined to obtain a structure that meets the design of the standard ball core size. The ball core obtained by the two-time injection molding process in the present application, after the inner layer ball is cooled and shaped and then the outer layer ball is injection molded, even if the problem of poor roundness caused by uncontrollable shrinkage characteristics of the material, the outer layer ball can be compensated by the second injection molding. Since the thickness of the outer layer ball is smaller relative to the thickness of the entire ball core, even if the outer layer ball shrinks after cooling, the degree of shrinkage is smaller, and the effect on the roundness of the ball core is smaller, thereby achieving the purpose of obtaining a ball core with a higher roundness of the outer surface, thereby reducing the rotational resistance between the ball core and the valve shell.

[0031] In the case of a ball core with higher roundness obtained by the injection molding method based on the present application, when the valve shell is injection molded based on the ball core, the roundness of the inner circular surface of the valve shell can also be better guaranteed, thereby reducing the resistance of the ball core rotating in the valve shell and reducing the output torque requirement of the controller. In addition, since the ball core can maintain a higher fit after rotating relative to the valve shell, the sealing performance of the valve body can be improved, and the problem of internal leakage of the valve body can be improved.

[0032] In the present disclosure, the twice injection molding process can significantly improve the yield rate and reduce the generation of waste. In addition, since the thickness of the outer layer of the ball is smaller relative to the thickness of the entire ball core, even if the outer layer of the ball shrinks after cooling, the degree of shrinkage is smaller and has less impact on the roundness of the ball core. The roundness of the outer surface of the ball core can be effectively improved, the service life of the valve body can be prolonged, the replacement frequency caused by leakage or wear can be reduced, thereby reducing resource consumption and pollution to the environment caused by discarded valve bodies. BRIEF DESCRIPTION OF DRAWINGS

[0033] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] Fig. 1 is a structural schematic diagram of a ball core according to an embodiment of the present application;

[0035] Fig. 2 is a sectional view of the ball core according to an embodiment of the present application;

[0036] Fig. 3 is an exploded schematic diagram of the ball core according to an embodiment of the present application;

[0037] Fig. 4 is a schematic diagram of one of the embodiments of the inner layer of the ball according to an embodiment of the present application;

[0038] Fig. 5 is a schematic diagram of another embodiment of the inner layer of the ball according to an embodiment of the present application;

[0039] Fig. 6 is a structural schematic diagram of a valve body according to an embodiment of the present application;

[0040] Fig. 7 is an exploded schematic diagram of the valve body according to an embodiment of the present application;

[0041] Fig. 8 is a structural schematic diagram of the valve body combined with a controller according to an embodiment of the present application.

[0042] In the drawings:

[0043] 1 - ball core; 11 - inner layer of the ball; 111 - positioning portion; 12 - outer layer of the ball; 13 - ball; 14 - ball handle; 141 - inner handle; 142 - outer handle; 15 - communication hole; 2 - valve shell; 21 - water inlet and outlet; 3 - heat insulation paper; 4 - controller; 5 - valve body. DETAILED DESCRIPTION

[0044] In order to make the technical problems solved by the present application, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present application will be further described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0045] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances.

[0046] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0047] The electric ball valve is a device for controlling the on-off state of the ball valve by the electric actuator. Its working principle is to realize the rotation of the ball core in the valve body by the control of the electric actuator, so as to switch the passage state of the fluid. Referring to FIG. 8, the electric ball valve is composed of a valve body and a controller 4. The valve body includes a valve shell 2 and a ball core rotatably installed in the valve shell 2. The controller 4 drives the ball core in the valve body to rotate to realize the valve switching function.

[0048] In the injection molding process of the valve body of the related electric ball valve, the ball core is first injection molded, and then the ball core is placed in the molding mold of the valve shell, and the valve shell is secondarily injection molded on the basis of the ball core. After the valve shell is formed, the ball core is located in the valve shell. Therefore, the quality of the inner surface of the valve shell is actually determined by the quality of the outer surface of the ball core, that is, the roundness of the surface of the ball core determines the roundness of the inner surface of the valve shell. The related ball core is a one-time injection molded structure. Due to the uncontrollable cooling shrinkage of the plastic material, different positions of the ball core material are prone to different degrees of cooling shrinkage after injection molding and cooling, which further leads to the problem that the roundness of the surface of the ball core is difficult to guarantee. The roundness of the inner surface of the valve shell injection molded on the basis of the ball core is also affected. The combination of the two finally leads to the great rotation resistance of the ball core in the valve shell after molding, which leads to higher requirements for the output torque of the controller. Moreover, the fitting degree of the ball core and the valve shell after rotation is not high enough, which affects the sealing performance of the valve body. In the high-pressure fluid application scenario, the problem of internal leakage of the valve body is prone to occur.

[0049] In the ball core structure, it includes a ball 13 and a ball handle 14 connected to one side of the ball, the ball handle 14 extends out of the valve shell for connecting with the controller. The ball 13 is internally provided with a communication hole 15 for communicating the water inlet and outlet port 21 of the valve shell, when the ball core rotates to the communication hole 15 deviates from the water inlet and outlet port, the ball valve is closed; when the ball core rotates to the communication hole 15 aligns with the water inlet and outlet port, the ball valve is conducted.

[0050] In order to overcome the above technical problems, in combination with FIGS. 1-3, the embodiment provides a injection molding method of the ball core 1 of the ball valve, comprising the steps of:

[0051] S1. One injection molding inner layer ball 11, the outer diameter size of the inner layer ball 11 is smaller than the outer diameter size of the ball core 1 to be prepared (that is, the outer diameter size of the inner layer ball 11 is smaller than the outer diameter size of the standard ball core 1);

[0052] S2. The outer layer ball 12 is twice injection molded on the basis of the inner layer ball 11 to obtain the ball core 1 (that is, the standard ball core 1).

[0053] The injection molding method of the embodiment at least needs to provide two sets of molds, for example, a first mold and a second mold, the first mold has a first cavity, the size of the first cavity is smaller than the outer diameter size of the ball core 1 to be prepared (that is, the outer diameter size of the standard ball core 1), the inner layer ball 11 can be obtained after injection molding and cooling in the first cavity, the outer diameter size of the inner layer ball 11 is smaller than the outer diameter size of the standard ball core 1; the second mold has a second cavity, the size of the second cavity is equal to the outer diameter size of the standard ball core 1, the inner layer ball 11 is placed in the second cavity, the standard ball core 1 can be obtained after injection molding and cooling in the second cavity.

[0054] Optionally, the inner layer ball 11 has a center hole corresponding to the communication hole 15 of the ball core 1, the center hole has the same size as the communication hole 15 of the standard ball core 1.

[0055] The center hole of the inner layer ball 11 after molding is exactly matched with the size of the communication hole 15 of the standard ball core 1, so the outer layer ball 12 after molding does not need to cover the center hole of the inner layer ball 1. Based on this, in the second mold for making the outer layer ball 12, a mold core matching the size of the center hole can be directly provided, when the inner layer ball 11 is installed, the center hole can be firmly and reliably clamped on the mold core of the second mold.

[0056] It can be understood that the center hole of the inner layer ball 11 constitutes the communication hole 15 of the ball core 1.

[0057] In order to improve the uniformity of the outer layer 12, ensure that the outer layer 12 can completely cover the outer surface of the inner layer 11, in the first mold, a mold core corresponding to the size of the communication hole 15 of the ball core 1 is arranged, so that the inner layer 11 molded by the first mold has the communication hole 15; in the second mold, a mold core corresponding to the standard size of the communication hole 15 is also arranged, when the inner layer 11 is placed in the second mold, the communication hole 15 at the center of the inner layer 11 can be directly aligned with the mold core of the second mold for clamping and fixing, so that the inner layer 11 can be stably and reliably fixed in the second mold, and the problem of offset of the gel impacting the inner layer 11 during injection molding is improved; in particular, the mold core of the second mold supports the inner layer 11 from the middle, so that the inner layer 11 is fixed in the center of the second cavity, and the inner layer 11 and the cavity wall of the second cavity maintain uniform spacing, so that the gel entering the second cavity during injection molding can uniformly cover the outer periphery of the inner layer 11, so as to obtain the outer layer 12 with uniform thickness.

[0058] The injection molding method of the ball core 1 of the embodiment adopts a two-time injection molding process, first, an inner layer 11 with a smaller outer diameter than the standard size of the ball core 1 is molded by one-time injection molding, after the inner layer 11 is cooled and shaped, the inner layer 11 is placed in a mold for injection molding of the outer layer 12, the outer layer 12 covers the inner layer 11, and the combination of the two can obtain a structure that meets the standard size of the designed ball core 1. The ball core 1 obtained by the two-time injection molding process, after the inner layer 11 is cooled and shaped and then the outer layer 12 is injection molded, even if the roundness of the inner layer 11 is poor due to the uncontrollable shrinkage characteristics of the material, it can be compensated for by using the two-time injection molding of the outer layer 12 to restore good roundness. Since the thickness of the outer layer 12 is smaller relative to the thickness of the entire ball core 1, even if the outer layer 12 shrinks after cooling, the degree of shrinkage is smaller, so the overall roundness of the ball core 1 is less affected, thereby achieving the purpose of obtaining a ball core 1 with a higher roundness of the outer surface, thereby reducing the rotational resistance between the ball core and the valve shell.

[0059] In the case of a ball core 1 with higher roundness obtained by the injection molding method based on the scheme, when the valve shell 2 is injection molded based on the ball core 1, the roundness of the inner circular surface of the valve shell 2 can also be better guaranteed, thereby reducing the resistance of the ball core 1 rotating in the valve shell 2, and reducing the requirement for the output torque of the controller; in addition, since the ball core 1 can maintain a higher fit after rotating relative to the valve shell 2, the sealing performance of the valve body can be improved, and the problem of leakage in the valve body can be improved.

[0060] It should be understood that the ball 13 includes the inner layer 11 and the outer layer 12 wrapped outside the inner layer 11.

[0061] Optionally, the ball handle 14 is connected with at least one of the inner sphere 11 and the outer sphere 12, and the connection manner includes but is not limited to one-piece forming, bonding, or threaded connection.

[0062] For example, in some embodiments, the ball handle 14 is connected with only the inner sphere 11; in other embodiments, the ball handle 14 is connected with only the outer sphere 12; in yet other embodiments, the ball handle 14 is connected with both the inner sphere 11 and the outer sphere 12.

[0063] Optionally, the ball handle 14 includes an inner handle 141 and an outer handle 142, the inner handle 141 is connected with the inner sphere 11, and the outer handle 142 is connected with the outer sphere 12, and the outer handle 142 is sleeved or wrapped outside the inner handle 141.

[0064] Optionally, the connection manner of the inner handle 141 with the inner sphere 11 includes but is not limited to one-piece forming or bonding.

[0065] Optionally, the connection manner of the outer handle 142 with the outer sphere 12 includes but is not limited to one-piece forming or bonding.

[0066] Optionally, the radial thickness of the outer sphere 12 is 1.5mm~2mm, for example, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, etc., which is not limited herein.

[0067] The inventor has found that controlling the radial thickness of the outer sphere 12 within the range of 1.5mm~2mm is more reasonable, which can better cope with the shrinkage of the plastic material during cooling and the adverse effects on the shape of the ball core 1. After injection molding, the plastic material will undergo cooling and shrinkage, and the thickness of the outer sphere 12 directly affects the degree of shrinkage. A thinner outer sphere 12 (such as 1.5mm~2mm) has a smaller impact on the overall roundness of the ball core 1, because even if the outer sphere 12 shrinks to a certain extent, due to its limited thickness, it will not significantly affect the overall shape of the ball core 1. In addition, the thickness of the outer sphere 12 is greater than 1.5mm, which can ensure sufficient durability and avoid excessive wear. Moreover, the thickness of the outer sphere 12 determines the width of the gap between the inner sphere 11 and the second mold cavity wall during secondary injection molding. When the gap is too small, the flow area of the molten glue in the gap is too small, and the flow speed is too slow, which can cause the molten glue to fail to fill the entire second mold cavity, resulting in defects in the formed outer sphere 12. Controlling the thickness of the outer sphere 12 to be greater than 1.5mm can effectively improve the above problems.

[0068] Preferably, the radial thickness of the outer sphere 12 is 1.6~1.7mm.

[0069] Optionally, the outer surface of the inner sphere 11 is provided with positioning portions 111, which are positioning protrusions and / or positioning recesses; that is, in some embodiments, the positioning portions 111 only include positioning protrusions; in other embodiments, the positioning portions 111 only include positioning recesses; and in yet other embodiments, the positioning portions 111 include both positioning protrusions and positioning recesses.

[0070] The positioning portions 111 provided on the outer surface of the inner sphere 11 can form a concave-convex structure that interlocks after the outer sphere 12 is injection molded, thus effectively improving the reliability of the joint between the inner sphere 11 and the outer sphere 12 and solving the problem of separation between the inner sphere 11 and the outer sphere 12.

[0071] For example, when the surface of the inner sphere 11 is provided with positioning protrusions, the outer sphere 12 will form corresponding recesses at the positions corresponding to the positioning protrusions after the outer sphere 12 is injection molded; and when the surface of the inner sphere 11 is provided with positioning recesses, the outer sphere 12 will form corresponding protrusions at the positions corresponding to the positioning recesses after the outer sphere 12 is injection molded. Optionally, the positioning portions 111 provided on the inner sphere 11 are preferably multiple, which can be individually provided as positioning protrusions, individually provided as positioning recesses, or provided in combination of positioning protrusions and positioning recesses. Through the provision of multiple positioning portions 111, the joint reliability between the inner sphere 11 and the outer sphere 12 can be further ensured.

[0072] Optionally, referring to FIG. 4, the multiple positioning portions 111 are dot-matrix distributed on the outer surface of the inner sphere 11.

[0073] Each positioning portion 111 can form a joint with the outer sphere 12, and the dot-matrix distribution makes the joints uniformly distributed on the surface of the inner sphere 11, thus forming a strong joint network. This network structure can significantly improve the joint strength between the inner sphere 11 and the outer sphere 12 and realize the resistance to the interaction force between the inner sphere 11 and the outer sphere 12 on each square.

[0074] In optional embodiments, the positioning portions 111 dot-matrix distributed on the outer surface of the inner sphere 11 can be circular, square, elliptical, olive-shaped, or other shapes.

[0075] Optionally, referring to FIG. 5, the positioning portions 111 are arc-shaped strips, and are arranged perpendicular to the rotation direction of the core 1.

[0076] In other words, the ball core 1 rotates around the rotation axis a, that is, the inner sphere 11 rotates around the rotation axis a; the inner sphere 11 has a first end and a second end distributed along the direction of the rotation axis a; the ball handle 14 is distributed at the first end of the inner sphere 11, that is, the inner handle 141 is distributed at the first end of the inner sphere 11; the two ends of the length extension direction of the positioning part 111 extend to the first end and the second end of the inner sphere 11 respectively.

[0077] Wherein, the rotation direction of the ball core 1 refers to the direction in which the ball core 1 rotates around the rotation center axis a during the rotation of the ball core 1 driven by the controller 4 through the ball handle 14; during the rotation of the ball core 1, a strong friction force will be generated between the ball core 1 and the valve shell 2, which will hinder the rotation of the ball core 1 in this direction; similarly, during rotation, the inner sphere 11 and the outer sphere 12 will also generate a mutual force around the rotation direction of the ball core 1, and the positioning part 111 is arranged in an arc-shaped strip shape and perpendicular to the rotation direction of the ball core 1, which can exactly provide the maximum area to resist the mutual force, achieving the best effect of strengthening the combination of the inner sphere 11 and the outer sphere 12, so as to ensure that the inner sphere 11 and the outer sphere 12 rotate reliably and synchronously without being easily separated from each other.

[0078] Optionally, the outer sphere 12 can completely cover the positioning part 111.

[0079] The outer sphere 12 completely covers the positioning part 111, which is beneficial to ensure that the outer surface of the outer sphere 12 can be completely used as the outer surface of the entire ball core 1, so as to ensure the smoothness and integrity of the outer surface of the entire ball core 1 and the sealing performance of the combination of the ball core 1 and the valve shell 2.

[0080] Optionally, when the outer sphere 12 is formed by two-step injection molding, the mold is preheated to 60-70℃, for example, 60℃, 62℃, 65℃, 67℃, 70℃, etc., which is not limited here.

[0081] Preheating the mold to 60-70℃ is based on the comprehensive consideration of the characteristics of the injection molding material and the process requirements. On the one hand, this temperature range can ensure that the material has good fluidity and permeability during injection molding, reduce the temperature difference between the material and the mold during injection, thereby reducing the viscosity of the material and promoting its better flow and filling of the mold cavity, which is crucial to ensure that the outer sphere 12 can completely cover the positioning part 111 and form a uniform and dense structure. On the other hand, it can avoid the degradation of the material or the damage of the mold caused by too high temperature, and at the same time, this temperature range is also helpful to achieve the required solidification degree in a shorter time, thereby ensuring the quality and performance of the product.

[0082] In another aspect, the application provides a ball core 1 of a ball valve, which is made by the injection molding method described above, and comprises an inner layer ball 11 and an outer layer ball cover 12 covering the outer surface of the inner layer ball 11, wherein the outer layer ball cover 12 is formed by secondary injection molding on the outer surface of the inner layer ball 11 and is integrated with the inner layer ball 11.

[0083] Similarly, according to the injection molding method of the present embodiment, the ball core 1 has the advantage of higher surface roundness.

[0084] Optionally, the surface where the inner layer ball 11 and the outer layer ball cover 12 contact is provided with a positioning structure.

[0085] The positioning structure is arranged on the surface where the inner layer ball 11 and the outer layer ball cover 12 contact, i.e., a concave-convex structure that engages with each other is formed between the two, which can effectively improve the reliability of the combination of the two and further ensure the durability of the entire ball core 1.

[0086] The inventor has found that, in the injection molding process of the valve body, the ball core is first injection molded, and then the ball core is placed in the molding mold of the valve shell, and the valve shell is directly secondary injection molded on the basis of the ball core. After the valve shell is formed, the ball core 1 is located in the valve shell. In the process of secondary injection molding of the valve shell, the surface of the ball core where the glue inlet is aligned will be scalded under the impact of the high-temperature and high-pressure molten glue, which will cause deformation of the surface of the ball core 1, and further cause the problem of non-circular surface of the ball core. Similarly, after the roundness of the surface of the ball core is damaged, the roundness of the inner surface of the valve shell is also affected.

[0087] In order to overcome the above technical problems, the present embodiment further provides a ball valve injection molding method, which comprises:

[0088] B1. injection molding a ball core 1;

[0089] B2. arranging heat insulation paper 3 on the surface of the ball core 1 corresponding to the glue inlet of the valve shell mold;

[0090] B3. placing the ball core 1 provided with the heat insulation paper 3 into the valve shell mold, and making the heat insulation paper 3 oppositely distributed to the glue inlet of the valve shell mold, and then starting injection molding to form a valve shell 2.

[0091] In the valve shell mold, there is a valve shell cavity, and a mold core corresponding to the communication hole of the ball core 1 is arranged in the valve shell cavity. The ball core 1 is clamped and fixed on the mold core through the communication hole, and the heat insulation paper 3 attached to the ball core 1 after clamping is opposite to the glue inlet of the valve shell mold.

[0092] In the injection molding process, the position of the ball core 1 covered by the heat insulation paper 3, if not covered by the heat insulation paper 3, will be directly impacted by the high-temperature and high-pressure glue liquid, causing deformation; after the heat insulation paper 3 is set, although the part will still be impacted by high temperature and high pressure, the impact is blocked by the heat insulation paper 3, and under the heat insulation effect of the heat insulation paper 3, the part will not quickly increase and soften, so under the impact of the high-temperature and high-pressure glue liquid, it is not easy to deform. The remaining areas not attached to the heat insulation paper 3, although they will directly contact the high-temperature glue liquid, causing the temperature to rise quickly, but the glue liquid will quickly depressurize after entering the valve shell cavity, so it will not cause the high-temperature part of the ball core 1 to be impacted and deformed by high pressure.

[0093] Therefore, by the ball valve injection molding method of the present embodiment, the heat insulation paper 3 is set on the surface of the ball core 1 at a position opposite to the glue injection port before the ball core 1 is placed in the valve shell mold; during glue injection, the problem of the high-temperature and high-pressure molten glue liquid directly impacting the surface of the ball core 1 can be improved, and the heat insulation effect of the heat insulation paper 3 can effectively improve the problem of the surface of the ball core 1 being scalded by the high-temperature glue liquid. In this way, the present application can effectively protect the surface of the ball core 1 during the injection molding of the valve shell 2, improve the problem of the deformation of the outer surface of the ball core 1 and the destruction of the roundness, and further improve the problem of the destruction of the roundness of the inner surface of the valve shell 2, so as to reduce the resistance of the ball core 1 when rotating in the valve shell 2 and reduce the requirement for the output torque of the controller 4 by improving the roundness of the ball core 1 and the inner surface of the valve shell 2; in addition, due to the improvement of the roundness of the ball core 1 and the inner surface of the valve shell 2, the fit between the ball core 1 and the inner surface of the valve shell 2 is improved; in particular, the ball core 1 can still maintain a high fit after rotating relative to the valve shell 2, so the sealing performance of the valve body is improved, and the problem of leakage in the valve body is improved.

[0094] It should be noted that when the ball core 1 provided with the heat insulation paper 3 is placed in the valve shell mold, the glue injection port is opposite to the peripheral wall of the ball core 1 which is not provided with the communication hole 15, i.e. the heat insulation paper 3 covers the peripheral wall of the ball core 1 which is not provided with the communication hole 15 to be distributed opposite to the glue injection port. In step B1, the process of injection molding the ball core 1 adopts the injection molding method of the ball core 1 of the ball valve as described above.

[0095] Optionally, the area of the heat insulation paper 3 is greater than or equal to the area of the glue injection port, and the center of the heat insulation paper 3 is aligned with the center of the glue injection port.

[0096] Based on this arrangement, it is ensured that the heat insulation paper 3 can reliably withstand the impact of the glue liquid flowing into the mold from the glue injection port, and the problem of the high-temperature and high-pressure glue liquid accidentally breaking through the heat insulation paper 3 is improved, so as to ensure that the heat insulation paper 3 can provide effective protection.

[0097] Optionally, the distance from the edge of the heat insulation paper 3 to the edge of the glue injection port is greater than or equal to 3 mm, for example, 3 mm, 3.2 mm, 4 mm, etc., which is not limited here.

[0098] In this way, in addition to ensuring that the heat insulation paper 3 can cover the glue liquid extruded by the straight glue injection port on the spherical core 1, the coverage area of the heat insulation paper 3 on the spherical core 1 is further expanded to provide a larger protection area for the spherical core 1, further ensuring the stability of the surface quality of the spherical core 1. That is, by covering the spherical core 1 with a larger heat insulation paper 3, it is beneficial to ensure that the position of the spherical core 1 opposite to the glue injection port is effectively covered and protected by the heat insulation paper 3. In addition, due to the possibility of certain errors in the arrangement of the heat insulation paper 3 on the surface of the spherical core 1, a larger heat insulation paper 3 can compensate for the errors and ensure that the heat insulation paper 3 can provide effective protection.

[0099] Optionally, the heat insulation paper 3 is a Teflon film or a polyimide film.

[0100] The Teflon film has extremely high high-temperature resistance and can maintain its physical and chemical properties stable in extremely high-temperature environments. This characteristic makes it very suitable as a heat insulation material to prevent high-temperature molten glue from causing burns during the injection molding process. In addition, the Teflon film has strong corrosion resistance to most chemical substances, which means that even if the molten glue contains some corrosive components, the Teflon film will not be damaged during the injection molding process.

[0101] The polyimide film also has excellent high-temperature resistance and can maintain its structural stability in high-temperature environments, which makes it also effective in preventing high-temperature molten glue from causing burns to the spherical core 1 during the injection molding process. In addition, the polyimide film has high mechanical strength and can withstand certain pressure and impact force, and it can maintain its integrity during the injection molding process to ensure the heat insulation effect. The polyimide film has good resistance to a variety of chemical substances and radiation, which further increases its applicability in the injection molding process.

[0102] Optionally, the heat insulation paper 3 is arranged at the position corresponding to the glue injection port of the spherical core 1 by means of attachment.

[0103] Optionally, the heat insulation paper 3 is provided with adhesive and is adhered to the spherical core 1 by the adhesive, or the heat insulation paper 3 is additionally adhered to the spherical core 1 by double-sided adhesive tape or glue.

[0104] Optionally, the heat insulation paper 3 is adhered to the spherical core 1 by a glue with a temperature resistance greater than or equal to 250℃.

[0105] In the injection molding process, the temperature of the molten glue is high, sometimes even more than 200℃; therefore, the glue with temperature resistance greater than or equal to 250℃ is selected to paste the heat insulation paper 3, which is conducive to ensuring that the glue does not fail or melt in a high-temperature environment, thereby maintaining the firm pasting between the heat insulation paper 3 and the ball core 1.

[0106] Optionally, the heat insulation paper 3 is pasted on the ball core 1 by using temperature-resistant epoxy glue or phenolic resin glue.

[0107] The epoxy glue can maintain its bonding strength and stability in a high-temperature environment and is not prone to softening or melting, which enables it to withstand the impact of the high-temperature molten glue in the injection molding process without failing. At the same time, the epoxy glue has excellent adhesion and can firmly paste the heat insulation paper 3 on the ball core 1, and this bonding force can remain stable at high temperatures, ensuring that the heat insulation paper 3 is not prone to falling off.

[0108] It should be understood that in other embodiments, the heat insulation paper 3 can be wrapped on the entire outside of the ball core 1, that is, the heat insulation paper 3 covers not only the position of the ball core 1 corresponding to the glue inlet but also other places except the position corresponding to the glue inlet. In this full-wrapping embodiment, the heat insulation paper 3 can not need to be pasted on the outside of the ball core 1 but can be stably attached to the outside of the ball core 1 by its own elasticity or plasticity.

[0109] The phenolic resin glue has extremely high high-temperature resistance and can maintain the stability of its physical and chemical properties at high temperatures. After curing, the phenolic resin glue has high hardness and strength and can withstand certain pressure and impact force, which helps to ensure that the heat insulation paper 3 does not fall off due to external force during the injection molding process.

[0110] Optionally, in the injection molding method of the present embodiment, after the valve shell 2 is formed, the valve shell 2 with the ball core 1 is ejected, and the ball core 1 is rotated to a position where the heat insulation paper 3 is opposite to the water inlet or the water outlet of the valve shell 2, so as to tear off the heat insulation paper 3 from the water inlet or the water outlet.

[0111] After the shaped valve shell 2 is ejected, the ball core 1 is rotated to a position where the heat insulation paper 3 is opposite to the water inlet or the water outlet of the valve shell 2, so that the tool can extend into the valve shell 2 from the water inlet or the water outlet to tear off the exposed heat insulation paper 3. The heat insulation paper 3 is rotated to be opposite to the water inlet or the water outlet of the valve shell 2 and then torn off, which ensures the operability of tearing off the heat insulation paper 3.

[0112] Tearing off the heat insulation paper 3 can avoid its remaining on the ball core 1 and causing the problem of blocking the water inlet or the water outlet 21 of the valve shell 2 or the pipeline provided with the valve body 5 due to its falling off from the ball core 1 in later use.

[0113] It should be noted that the valve housing 2 is provided with two mutually communicating water inlets and outlets 21, one of which is used as the water inlet and the other as the water outlet.

[0114] Optionally, the valve core is rotated and the heat insulation paper 3 is torn off immediately after the valve housing 2 is ejected.

[0115] After the valve housing 2 is ejected, the temperature is still in a high range, the ball core 1 is relatively easy to rotate, and the heat insulation paper 3 is relatively easy to tear off. Therefore, the tearing operation of the heat insulation paper 3 is performed immediately after the valve housing 2 is ejected, which can reduce the difficulty of tearing. In operation, in order to avoid scalding the hands, the valve housing 2 can be clamped and fixed by using a clamp to facilitate operation.

[0116] In the description herein, it should be understood that the terms "upper", "lower", "left", "right", and the like orientation or position relationship are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only used to distinguish in the description, and have no special meaning.

[0117] In the description of the present specification, the description referring to the terms "an embodiment", "an example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0118] In addition, it should be understood that although the present specification is described in terms of embodiments, each embodiment does not necessarily contain only one independent technical solution, and the description of the specification is only for the sake of clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

[0119] The technical principles of the present application are described above in conjunction with specific embodiments. These descriptions are only for the purpose of explaining the principles of the present application, and cannot be interpreted in any way as a limitation on the scope of protection of the present application. Based on the explanation here, those skilled in the art do not need to make creative efforts to think of other specific embodiments of the present application, which will fall within the scope of protection of the present application. Industrial applicability

[0120] In the present disclosure, the twice injection molding process can significantly improve the yield and reduce waste generation. In addition, since the thickness of the outer layer of the sleeve is smaller relative to the overall thickness of the core, even if the outer layer of the sleeve shrinks after cooling, the degree of shrinkage is smaller and the impact on the roundness of the core is smaller, which can effectively improve the roundness of the outer surface of the core, prolong the service life of the valve body, reduce the replacement frequency due to leakage or wear, thereby reducing resource consumption and environmental pollution caused by discarded valve bodies.

Claims

1. A method of injection molding a ball core of a ball valve, characterized by, The application relates to a ball valve core injection molding method. The outer diameter of the inner layer ball is smaller than that of a standard ball core. The outer layer ball is secondarily injection molded on the basis of the inner layer ball to obtain a standard ball core.

2. The injection molding method of a ball core of a ball valve according to claim 1, characterized by, The radial thickness of the outer layer ball is 1.5-2 mm.

3. The injection molding method of the ball core of a ball valve according to claim 1 or 2, characterized in that, The outer surface of the inner layer ball is provided with positioning parts.

4. The ball valve core injection molding method according to claim 3, wherein The positioning parts are positioning protrusions and / or positioning grooves.

5. The injection molding method of the ball core of a ball valve according to claim 3 or 4, characterized in that, The positioning parts are circular, square, oval, olive-shaped or arc-shaped strips.

6. The injection molding method of the ball core of a ball valve according to any one of claims 3 to 5, characterized in that, The outer surface of the inner layer ball is provided with a plurality of positioning parts which are dot-matrix distributed on the outer surface of the inner layer ball.

7. The injection molding method of the ball core of a ball valve according to any one of claims 3 to 6, characterized in that, The positioning parts are arc-shaped strips, and are arranged perpendicularly to the rotation direction of the ball core.

8. The injection molding method of the ball core of a ball valve according to any one of claims 3 to 7, characterized in that, The outer layer ball can completely cover the positioning parts.

9. The injection molding method of the ball core of a ball valve according to any one of claims 1 to 8, characterized in that, The inner layer ball has a central hole corresponding to the communication hole of the ball core, and the central hole has the same size as the communication hole of the standard ball core.

10. The injection molding method of the ball core of a ball valve according to any one of claims 1 to 9, characterized in that, When the outer layer ball is secondarily injection molded, the mold is preheated to 60-70 DEG C.

11. A method of injection molding a ball valve, the method comprising: The application further relates to a ball valve core injection molding method. The ball core is formed by the ball valve core injection molding method according to any one of claims 1-10. Thermal insulation paper is attached to the surface of the ball core corresponding to the glue injection port of the valve shell mold. The ball core with the attached thermal insulation paper is arranged in the valve shell mold, and the thermal insulation paper is aligned with the glue injection port of the valve shell mold, and then injection molding of the valve shell is started.

12. The ball valve injection molding method of claim 11, wherein, The area of the thermal insulation paper is greater than or equal to that of the glue injection port, and the center of the thermal insulation paper is aligned with that of the glue injection port.

13. The ball valve injection molding method of claim 10, wherein, The edge of the thermal insulation paper is greater than or equal to 3 mm away from the edge of the glue injection port.

14. The ball valve injection molding method according to any one of claims 9-11, wherein, The thermal insulation paper is a Teflon film or a polyimide film.

15. The ball valve injection molding method according to any one of claims 9-12, wherein, The thermal insulation paper is attached to the ball core by using temperature-resistant epoxy glue or phenolic resin glue.

16. A ball core for a ball valve, characterized by The ball core is formed by the ball valve core injection molding method according to any one of claims 1-15, and comprises an inner layer ball and an outer layer ball which is secondarily injection molded on the outer surface of the inner layer ball and is integrated with the inner layer ball.

17. The ball core of the ball valve according to claim 16, characterized in that The surface of the inner layer ball and the outer layer ball is provided with a positioning structure.

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