A ram and design method

Abstract

This invention discloses a pressure head and its design method. The pressure head includes a pressure head body, a connecting part, and a pressing part. The connecting part is located at one end of the pressure head body for connecting to a press. The pressing part is located at the other end of the pressure head body for pressing a cup-shaped plug. The pressing part includes a central hole and an annular arc surface. The central hole is located at the center of the pressing part along the pressing direction of the cup-shaped plug, and the inner side of the annular arc surface surrounds the central hole. This invention increases the contact area between the pressure head and the cup-shaped plug by using the annular arc surface, thereby improving the stability of the contact between the pressure head and the cup-shaped plug and preventing the cup-shaped plug from shifting before the pressure head is pressed in. The central hole prevents the deformation of the cup-shaped plug during the pressing process from interfering with the pressure head, thus improving the success rate of pressing the cup-shaped plug.

Description

Technical Field

[0001] This invention relates to the field of machining technology, and in particular to a pressure head and its design method. Background Technology

[0002] In the field of shell machining, cup-shaped plug press fitting is a common method for hole sealing. The specific procedure is as follows: First, an anaerobic adhesive is applied to the inside of the machined hole of the shell using a mechanism, covering the area around the hole. Then, the cup-shaped plug is press-fitted into the shell using a pressure head. Force and displacement sensors are used to monitor the press fitting process to ensure the sealing between the cup-shaped plug and the shell hole, ultimately achieving the purpose of preventing liquid leakage.

[0003] In the prior art, the fit between the cup-shaped plug and the shell is generally an interference fit. During the pressing process, the cup-shaped plug and the shell generate extrusion force. The cup-shaped plug is subjected to frictional resistance from the shell during the pressing process. The press drives the press head to overcome the frictional resistance between the cup-shaped plug and the shell and press the cup-shaped plug into the shell.

[0004] However, since the cup-shaped plug is a one-piece molded part, its bottom flatness and flatness are not as good as machined parts. Currently, the press head on the press is usually cylindrical. During the pressing process of the cup-shaped plug, only the circumference of the press head's pressing surface contacts the cup-shaped plug. Moreover, it is impossible to ensure a relatively stable contact before pressing. In many cases, the cup-shaped plug is already slightly deflected before the press head is pressed in, resulting in a low pressing success rate. Summary of the Invention

[0005] The purpose of this invention is to provide a pressure head and its design method, which aims to solve the problem that existing pressure heads cannot guarantee a relatively stable contact before pressing a cup-shaped plug.

[0006] To address the aforementioned technical problems, one embodiment of the present invention provides a pressure head for connecting to a press and pressing a cup-shaped plug, comprising: a pressure head body, a connecting part, and a pressing part. The connecting part is disposed at one end of the pressure head body for connecting to the press; the pressing part is disposed at the other end of the pressure head body for pressing the cup-shaped plug; wherein, the pressing part includes a central hole and an annular arc surface, the central hole being disposed at the center of the pressing part along the pressing direction of the cup-shaped plug, and the inner side of the annular arc surface surrounding the central hole.

[0007] Furthermore, the pressing part also includes an annular fillet, the inner side of which is connected to the outer side of the annular arc surface, and the outer side of which is connected to the outer wall of the pressing part.

[0008] Furthermore, the radius of the arc projection of the annular arc surface in the transverse direction of the central hole is greater than the radius of the arc projection of the bowl-shaped plug in the transverse direction of the central hole; the radius of the arc projection of the annular fillet in the transverse direction of the central hole is smaller than the radius of the arc projection of the bowl-shaped plug in the transverse direction of the central hole.

[0009] Furthermore, the pressing part is cylindrical, and the radius of the central hole is half the radius of the pressing part.

[0010] Furthermore, the connecting part includes a connecting hole that penetrates the pressure head body along the pressing direction of the cup-shaped plug and communicates with the central hole.

[0011] This invention increases the contact area between the pressure head and the cup-shaped plug by using an annular arc surface, thereby improving the stability of the contact between the pressure head and the cup-shaped plug and preventing the cup-shaped plug from shifting before the pressure head is pressed in. The central hole can prevent the cup-shaped plug from deforming and interfering with the pressure head during the pressing process, thus improving the success rate of pressing the cup-shaped plug.

[0012] On the other hand, the present invention also provides a method for designing an indenter, comprising:

[0013] The required pressing force for pressing the cup-shaped plug can be obtained from the formula for the pressing force of the interference fit.

[0014] The required pressing force is input into the formula for the actual pressing force of the press head, and the area relationship between the center hole and the annular arc surface is obtained;

[0015] Based on the area calculation formula of the central hole, the area calculation formula of the annular arc surface, and the area relationship between the central hole and the annular arc surface, the relationship between the radius of the central hole and the angle of the annular arc surface is obtained.

[0016] The values ​​of the radius of the central hole and the angle of the annular arc surface are selected based on the relationship between the radius of the central hole and the angle of the annular arc surface, as well as the size of the bowl-shaped plug.

[0017] Furthermore, obtaining the required pressing force for pressing the cup-shaped plug according to the interference fit pressing force formula includes:

[0018] The required pressing force ΔP for pressing the cup-shaped plug in x =P1*2π*R1*L1*f+Δε;

[0019] Wherein, P1 is the contact stress experienced by the cup-shaped plug when it is pressed into the press-fit hole, R1 is the radius of the central hole, L1 is the length of the cup-shaped plug pressed into the press-fit hole, f is the frictional force between the cup-shaped plug and the press-fit hole, and Δε is the error value, which depends on the cylindricity, radius and roughness of the press-fit hole.

[0020] Furthermore, the step of incorporating the required pressing force into the actual pressing force formula of the press head and obtaining the area relationship between the central hole and the annular arc surface includes:

[0021] According to the actual pressing force ΔP of the pressure head 实 =(ΔS1-ΔS2)*P1*f=ΔP x Obtain the area relationship between the central hole and the annular arc surface;

[0022] Wherein, ΔS1 is the area of ​​the annular arc surface, and ΔS2 is the area of ​​the central hole.

[0023] Furthermore, the step of obtaining the relationship between the radius of the central hole and the angle of the annular arc surface based on the area calculation formula of the central hole, the area calculation formula of the annular arc surface, and the area relationship between the central hole and the annular arc surface includes:

[0024] The area of ​​the central hole is ΔS2=π*R1 2 ;

[0025] The area of ​​the annular arc surface is ΔS1 = (ɑ / 360°) * π * R2;

[0026] Where α is the angle of the annular arc surface, and R2 is the radius of the arc projection of the annular arc surface in the transverse direction of the central hole.

[0027] Furthermore, the step of selecting the values ​​of the radius of the central hole and the angle of the annular arc surface based on the size of the bowl-shaped plug includes:

[0028] The radius of the annular arc surface is selected based on the radius of the bowl-shaped plug;

[0029] The relationship between the press-fitting part, the central hole, and the annular arc surface is obtained based on the radius of the annular arc surface;

[0030] The radius of the center hole is selected based on the radius of the press-fitting part;

[0031] The angle of the annular arc surface is obtained based on the relationship between the press-fitting part, the central hole, and the annular arc surface.

[0032] This invention uses the required pressing force of the cup-shaped plug to deduce the values ​​of the radius of the center hole of the press head and the angle of the annular arc surface. The annular arc surface increases the contact area between the press head and the cup-shaped plug, thereby improving the stability of the contact between the press head and the cup-shaped plug and preventing the cup-shaped plug from shifting before the press head is pressed in. The center hole can prevent the cup-shaped plug from deforming during the pressing process and interfering with the press head, thus improving the success rate of pressing the cup-shaped plug. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the indenter from a first-view perspective, provided as an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the indenter from a second perspective, provided in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the indenter from a third-view perspective, provided in an embodiment of the present invention;

[0037] Figure 4 Cross-sectional view AA provided for an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of the bowl-shaped plug provided in an embodiment of the present invention;

[0039] Figure 6 BB is a cross-sectional view provided for an embodiment of the present invention;

[0040] Figure 7 A flowchart illustrating a pressure head design method provided in an embodiment of the present invention;

[0041] Figure 8 This is a schematic diagram of a sub-process of a pressure head design method provided in an embodiment of the present invention.

[0042] Explanation of the markings in the image:

[0043] 1. Indenter body;

[0044] 2. Connecting part; 21. Connecting hole;

[0045] 3. Press-fitting part; 31. Center hole; 32. Annular arc surface; 33. Annular fillet;

[0046] 4. Bowl-shaped stopper. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0049] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0050] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0051] Compared to the bushings currently on the market, which are combinations of multiple components, the pressure head can not only be used as a bushing, but also enhance the function of the bushing, thus achieving better results for automotive parts.

[0052] Combination Figure 1-6 As shown, the present invention provides a pressure head for connecting to a press to press a cup-shaped plug 4, comprising: a pressure head body 1, a connecting part 2, and a pressing part 3. The connecting part 2 is disposed at one end of the pressure head body 1 for connecting to the press; the pressing part 3 is disposed at the other end of the pressure head body 1 for pressing the cup-shaped plug 4; wherein, the pressing part 3 includes a central hole 31 and an annular arc surface 32. The central hole 31 is disposed at the center of the pressing part 3 along the pressing direction of the cup-shaped plug 4, and the inner side of the annular arc surface 32 surrounds the central hole 31.

[0053] In this embodiment, the connecting part 2 of the pressure head is connected to the press, and the pressing part 3 presses the cup-shaped plug 4. The annular arc surface 32 on the pressing part 3 increases the contact area between the pressure head and the cup-shaped plug 4, thereby improving the stability of the contact between the pressure head and the cup-shaped plug 4 and preventing the cup-shaped plug 4 from shifting before the pressure head is pressed in. The setting of the center hole 31 can prevent the deformation of the cup-shaped plug 4 during the pressing process from interfering with the pressure head, thereby improving the success rate of pressing the cup-shaped plug 4.

[0054] In some specific embodiments, the pressing part 3 is detachably connected to the other end of the pressing head body 1. The pressing head can be replaced with different pressing parts 3 according to the different sizes of the cup-shaped plug 4, so that the pressing head can be used to press cup-shaped plugs 4 of different sizes.

[0055] In some embodiments, the pressing part 3 further includes an annular fillet 33, the inner side of the annular fillet 33 is connected to the outer side of the annular arc surface 32, and the outer side of the annular fillet 33 is connected to the outer wall of the pressing part 3.

[0056] In this embodiment, the annular fillet 33 provides a gap for the pressing of the bowl-shaped plug 4. While the annular arc surface 32 presses against the bowl-shaped plug 4, the annular fillet 33 can help press the bowl-shaped plug 4 in.

[0057] In some embodiments, the radius of the arc projection of the annular arc surface 32 in the transverse direction of the central hole 31 is greater than the radius of the arc projection of the bowl-shaped plug 4 in the transverse direction of the central hole 31; the radius of the arc projection of the annular fillet 33 in the transverse direction of the central hole 31 is less than the radius of the arc projection of the bowl-shaped plug 4 in the transverse direction of the central hole 31. Specifically, the radius of the arc projection of the annular arc surface 32 in the transverse direction of the central hole 31 is R2, the radius of the arc projection of the annular fillet 33 in the transverse direction of the central hole 31 is R3, and the radius of the arc projection of the bowl-shaped plug 4 in the transverse direction of the central hole 31 is R4.

[0058] In this embodiment, the radius R2 of the arc projection of the annular arc surface 32 in the transverse direction of the central hole 31 is greater than the radius R4 of the arc projection of the bowl-shaped plug 4 in the transverse direction of the central hole 31. This ensures the contact area between the annular arc surface 32 and the bowl-shaped plug 4, avoiding the situation where the pressure head only forms a circumferential contact with the bowl-shaped plug 4 as in the existing system, thus improving the stability of the contact between the pressure head and the bowl-shaped plug 4. The radius R3 of the arc projection of the annular fillet 33 in the transverse direction of the central hole 31 is less than the radius R4 of the arc projection of the bowl-shaped plug 4 in the transverse direction of the central hole 31. This ensures that when the annular arc surface 32 abuts against the bowl-shaped plug 4, there is a certain gap at the annular fillet 33, which helps to press the bowl-shaped plug 4 in.

[0059] In some specific embodiments, the radius of the arc projection of the annular arc surface 32 in the transverse direction of the central hole 31 is one-tenth larger than the radius of the arc projection of the bowl-shaped plug 4 in the transverse direction of the central hole 31.

[0060] In this embodiment, R2 = 1.1R4, which allows for a larger contact area between the annular arc surface 32 and the bowl-shaped plug 4.

[0061] In some embodiments, the pressing part 3 is cylindrical, and the diameter of the central hole 31 is half the diameter of the pressing part 3.

[0062] In this embodiment, the central hole 31 can prevent the deformation of the cup-shaped plug 4 during the pressing process from interfering with the press head. If the central hole 31 is too small, the middle part of the cup-shaped plug 4 will interfere with the annular arc surface 32 during the pressing process, affecting the pressing effect of the cup-shaped plug 4. If the central hole 31 is too large, the contact area between the annular arc surface 32 and the cup-shaped plug 4 will be reduced. The diameter of the central hole 31 is half the diameter of the pressing part 3, which can better ensure that the contact area between the annular arc surface 32 and the cup-shaped plug 4 is large and that the deformation of the cup-shaped plug 4 during the pressing process will not interfere with the annular arc surface 32.

[0063] In some embodiments, the connecting part 2 includes a connecting hole 21, which penetrates the press head body 1 along the pressing direction of the cup-shaped plug 4 and communicates with the central hole 31.

[0064] In this embodiment, the connecting hole 21 is used to connect the press. The connecting hole 21 passes through the press head body 1 along the pressing direction of the cup-shaped plug 4 and connects to the central hole 31, which can save materials and reduce the production cost of the press head.

[0065] In some specific embodiments, the central hole 31 is inclined toward the connecting hole 21, which prevents the deformation of the cup-shaped plug 4 during the pressing process from interfering with the annular arc surface 32, while ensuring the overall strength of the press head as much as possible.

[0066] Combination Figure 7 As shown, the present invention also provides a method for designing a pressure head, including steps S10 to S40:

[0067] S10. Obtain the required pressing force for pressing the cup-shaped plug 4 according to the formula for the pressing force of the interference fit.

[0068] S20. Input the required pressing force into the formula of the actual pressing force of the press head, and obtain the area relationship between the center hole 31 and the annular arc surface 32;

[0069] S30. Based on the area calculation formula of the central hole 31, the area calculation formula of the annular arc surface 32, and the area relationship between the central hole 31 and the annular arc surface 32, obtain the relationship between the radius of the central hole 31 and the angle of the annular arc surface 32.

[0070] S40. Select the values ​​of the radius of the center hole 31 and the angle of the annular arc surface 32 according to the size of the bowl-shaped plug 4.

[0071] The angle of the annular arc surface 32 is the arc angle of the circular projection of the annular arc surface 32 in the transverse direction of the central hole 31.

[0072] In this embodiment of the invention, the radius of the center hole 31 of the required press head and the angle of the annular arc surface 32 are derived from the pressing force required for the cup-shaped plug 4. The annular arc surface 32 increases the contact area between the press head and the cup-shaped plug 4, thereby improving the stability of the contact between the press head and the cup-shaped plug 4 and preventing the cup-shaped plug 4 from shifting before the press head is pressed in. The setting of the center hole 31 can prevent the deformation of the cup-shaped plug 4 during the pressing process from interfering with the press head, thereby improving the success rate of pressing the cup-shaped plug 4.

[0073] In some embodiments, the pressing force required for pressing the cup-shaped plug 4 is obtained according to the interference fit pressing force formula, including:

[0074] The required pressing force ΔP for pressing the cup-shaped plug 4 into place x =P1*2π*R1*L1*f+Δε;

[0075] Wherein, P1 is the contact stress of the cup-shaped plug 4 when it is pressed into the press-fit hole, R1 is the radius of the central hole 31, L1 is the length of the cup-shaped plug 4 pressed into the press-fit hole, f is the frictional force between the cup-shaped plug 4 and the press-fit hole, and Δε is the error value, which depends on the cylindricity, diameter and roughness of the press-fit hole.

[0076] In this embodiment, the cup-shaped plug 4 is press-fitted into the press-fit hole on the housing, and the cup-shaped plug 4 is interference-fitted with the press-fit hole. The minimum pressing force required to press the cup-shaped plug 4 into the housing is equal to the interference-fit pressing force. The dimensions of the center hole 31 and the annular arc surface 32 of the reverse push head are determined based on the relationship between the two.

[0077] In some specific embodiments, the contact stress P1 experienced by the cup-shaped plug 4 when it is pressed into the press-fit hole is P1 = E / (4R1)*δ max Where E is the elastic modulus of the material, δ max This represents the maximum tolerance for the press-fit hole.

[0078] In some embodiments, the required pressing force is introduced into the formula for the actual pressing force of the press head, and the area relationship between the central hole 31 and the annular arc surface 32 is obtained, including:

[0079] Based on the actual pressing force ΔP of the pressure head 实 =(ΔS1-ΔS2)*P1*f=ΔP x Obtain the area relationship between the central hole 31 and the annular arc surface 32;

[0080] Where ΔS1 is the area of ​​the annular arc surface 32, and ΔS2 is the area of ​​the central hole 31.

[0081] In this embodiment, the area relationship between the center hole 31 and the annular arc surface 32 is obtained based on the actual pressing force of the pressure head being equal to the interference fit pressing force of the cup-shaped plug 4 being pressed into the pressing hole on the housing. This facilitates obtaining the relationship between the radius of the center hole 31 and the angle of the annular arc surface 32.

[0082] In some embodiments, the relationship between the radius of the central hole 31 and the angle of the annular arc surface 32 is obtained based on the area calculation formula of the central hole 31, the area calculation formula of the annular arc surface 32, and the area relationship between the central hole 31 and the annular arc surface 32, including:

[0083] The area of ​​the central hole 31 is ΔS2=π*R1 2 ;

[0084] The area of ​​the annular arc surface 32 is ΔS1=(ɑ / 360°)*π*R2;

[0085] Where α is the angle of the annular arc surface 32, and R2 is the radius of the arc projection of the annular arc surface 32 onto the central hole 31 in the transverse direction.

[0086] In this embodiment, an equation can be established based on the above relationship, the area ΔS2 of the central hole 31 and the area ΔS1 of the annular arc surface 32, thereby obtaining the relationship between the radius of the central hole 31 and the angle of the annular arc surface 32. In actual application scenarios, the larger the radius of the central hole 31, the larger the angle of the annular arc surface 32 will be in order to ensure the actual pressing force of the pressure head, that is, to ensure the contact area between the annular arc surface 32 and the bowl-shaped plug 4.

[0087] R2 is the radius of the arc projection of the annular surface 32 onto the central hole 31 in the transverse direction, hereinafter referred to as the radius of the annular surface 32; R4 is the radius of the arc projection of the bowl-shaped plug 4 onto the central hole 31 in the transverse direction, hereinafter referred to as the radius of the bowl-shaped plug 4.

[0088] Combination Figure 8 As shown, in some embodiments, the value of the radius of the central hole 31 and the angle of the annular arc surface 32 are selected according to the size of the bowl-shaped plug 4, including steps S41 to S44:

[0089] S41. Select the radius of the annular arc surface 32 based on the radius of the bowl-shaped plug 4;

[0090] S42. Obtain the relationship between the press-fitting part 3, the center hole 31, and the annular arc surface 32 based on the radius of the annular arc surface 32;

[0091] S43. Select the radius of the center hole 31 according to the radius of the pressing part 3;

[0092] S44. Obtain the value of the angle of the annular arc surface 32 based on the relationship between the press-fit part 3, the center hole 31 and the annular arc surface 32.

[0093] In this embodiment, firstly, step S41 selects the radius of the annular arc surface 32 according to the radius of the bowl-shaped plug 4. In a specific embodiment, the radius of the annular arc surface 32 is 1.1 times the radius of the bowl-shaped plug 4.

[0094] Secondly, in step S42, the relationship between the pressing part 3, the center hole 31, and the annular arc surface 32 is obtained based on the radius of the annular arc surface 32. That is, the pressing part 3 includes the center hole 31 and the annular arc surface 32, and the diameter of the pressing part 3 is the diameter of the center hole 31 plus the length of the projection of the annular arc surface 32 in the direction of the center hole 31. Based on the radius of the annular arc surface 32, the relationship between the radius of the pressing part 3, the radius of the center hole 31, and the angle of the annular arc surface 32 can be obtained.

[0095] Furthermore, in step S43, the radius of the center hole 31 is selected based on the radius of the pressing part 3. In a specific embodiment, the radius of the center hole 31 is half the radius of the pressing part 3.

[0096] Finally, in step S44, the angle of the annular arc surface 32 can be obtained based on the relationship between the radius of the press-fit part 3, the center hole 31 and the angle of the annular arc surface 32.

[0097] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A pressure head for connecting to a press to press cup-shaped plugs, characterized in that, include: Indenter body; A connecting part is provided at one end of the pressure head body for connecting to a press; A pressing section is provided at the other end of the pressing head body for pressing a cup-shaped plug; The pressing part includes a central hole and an annular arc surface. The central hole is located at the center of the pressing part along the pressing direction of the cup-shaped plug, and the inner side of the annular arc surface surrounds the central hole. The pressing part also includes an annular fillet, the inner side of which is connected to the outer side of the annular arc surface, and the outer side of which is connected to the outer wall of the pressing part; The radius of the arc projection of the annular arc surface in the transverse direction of the central hole is greater than the radius of the arc projection of the bowl-shaped plug in the transverse direction of the central hole; the radius of the arc projection of the annular fillet in the transverse direction of the central hole is smaller than the radius of the arc projection of the bowl-shaped plug in the transverse direction of the central hole. The pressing part is cylindrical, and the radius of the central hole is half the radius of the pressing part.

2. The pressure head according to claim 1, characterized in that, The connecting part includes a connecting hole that penetrates the pressure head body along the pressing direction of the cup-shaped plug and communicates with the central hole.

3. A method for designing a pressure head as described in any one of claims 1-2, characterized in that, include: The required pressing force for pressing the cup-shaped plug can be obtained from the formula for the pressing force of the interference fit. The required pressing force is input into the formula for the actual pressing force of the press head, and the area relationship between the center hole and the annular arc surface is obtained; Based on the area calculation formula of the central hole, the area calculation formula of the annular arc surface, and the area relationship between the central hole and the annular arc surface, the relationship between the radius of the central hole and the angle of the annular arc surface is obtained. The values ​​of the radius of the central hole and the angle of the annular arc surface are selected based on the relationship between the radius of the central hole and the angle of the annular arc surface, as well as the size of the bowl-shaped plug.

4. The method for designing the pressure head according to claim 3, characterized in that, The step of obtaining the required pressing force for pressing the cup-shaped plug according to the interference fit pressing force formula includes: The required pressing force ∆P for pressing the cup-shaped plug in x =P1*2π*R1*L1*f + ∆ε; Wherein, P1 is the contact stress experienced by the cup-shaped plug when it is pressed into the press-fit hole, R1 is the radius of the central hole, L1 is the length of the cup-shaped plug pressed into the press-fit hole, f is the frictional force between the cup-shaped plug and the press-fit hole, and ∆ε is the error value, which depends on the cylindricity, radius and roughness of the press-fit hole.

5. The method for designing the pressure head according to claim 4, characterized in that, The step of incorporating the required pressing force into the formula for the actual pressing force of the press head, and obtaining the area relationship between the center hole and the annular arc surface, includes: According to the actual pressing force ∆P of the pressure head 实 =(∆S1-∆S2)* P1*f=∆P x Obtain the area relationship between the central hole and the annular arc surface; Wherein, ∆S1 is the area of ​​the annular arc surface, and ∆S2 is the area of ​​the central hole.

6. The method for designing the pressure head according to claim 5, characterized in that, The step of obtaining the relationship between the radius of the central hole and the angle of the annular arc surface based on the area calculation formula of the central hole, the area calculation formula of the annular arc surface, and the area relationship between the central hole and the annular arc surface includes: The area of ​​the central hole is ∆S2=π*R1 2 ; The area of ​​the annular arc surface ∆S1=(ɑ / 360°)*π*R2; Where α is the angle of the annular arc surface, and R2 is the radius of the arc projection of the annular arc surface in the transverse direction of the central hole.

7. The method for designing the pressure head according to claim 6, characterized in that, The step of selecting the values ​​of the radius of the central hole and the angle of the annular arc surface based on the relationship between the radius of the central hole and the angle of the annular arc surface and the size of the bowl-shaped plug includes: The radius of the annular arc surface is selected based on the radius of the bowl-shaped plug; The relationship between the press-fitting part, the central hole, and the annular arc surface is obtained based on the radius of the annular arc surface; The radius of the center hole is selected based on the radius of the press-fitting part; The angle of the annular arc surface is obtained based on the relationship between the press-fitting part, the central hole, and the annular arc surface.

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