Auxiliary device and method for installing valve rod assembly of indicator valve of diesel engine

Abstract

According to the auxiliary installation device and method for the valve rod assembly of the indicator valve of the diesel engine, the installation structure of the valve rod assembly is optimized, and under the positioning and guiding effects of the auxiliary device, the upper end of a valve rod is deformed and turned inwards through a press till the maximum diameter positions of a belleville spring and the lower end of a valve head are completely wrapped in a stepped hole in the large-diameter section of the valve rod; the technical problem that the valve rod assembly of the indicator valve cannot be directly assembled is solved, the problem that the valve head is installed in an inner hole of the valve rod and the stroke of the valve is guaranteed by accurately controlling the length of an inner cavity when the valve head, the valve rod and the belleville spring of the indicator valve are assembled can be effectively solved, the valve rod assembly is guaranteed to be smoothly assembled, the structure is simple, operation is easy, use is convenient, and the cost is low. And the assembling quality and the machining efficiency can be effectively guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of diesel engines, and particularly relates to an installation auxiliary device and method for a diesel engine indicator valve stem assembly. Background Art

[0002] The diesel engine indicator valve assembly is a component that measures the in-cylinder explosion pressure of the diesel engine and draws the explosion pressure curve by connecting an indicator. Currently, the common diesel engine indicator valve stem assemblies are mostly split-type, and the valve stem, valve head, and spring are assembled by threaded connection. This type of indicator valve is simple to assemble. However, when adjusting the stroke of the indicator valve, it is necessary to rotate the thread to achieve it. When the nut rotates, it will drive the valve head to rotate. Therefore, there is a risk of damaging the valve surface. And if an indicator valve stem assembly structure as shown in Figure 3 is adopted, the structure is designed as an integral type, making the indicator valve flexible and capable of accurately controlling the length of the inner cavity of the valve stem to ensure the stroke of the valve without further adjustment. However, when assembling the indicator valve, it is necessary to first assemble the valve stem assembly, that is, to sequentially install the disc spring and the indicator valve head into the inner hole of the valve stem head, and make the valve head completely wrapped inside the valve stem. This type of indicator valve structure is flexible and simple in structure. The diameter of the inner hole opening of the valve stem head is Φ13mm, the maximum diameter of the part of the valve head inserted into the valve stem is Φ14.5mm, and the outer diameter of the disc spring is Φ14mm, so it cannot be directly assembled. Therefore, in order to solve the key problem of inserting the valve head into the inner hole of the valve stem and accurately controlling the length of the inner cavity to ensure the stroke of the valve, it is necessary to make improvements. Summary of the Invention

[0003] The technical problem solved by the present invention is to provide an installation auxiliary device and method for a diesel engine indicator valve stem assembly. By optimizing the installation structure of the valve stem assembly and under the positioning and guiding action of the auxiliary device, with the help of a press, the upper end of the valve stem is deformed and turned inward to completely wrap the disc spring and the maximum diameter position of the lower end of the valve head in the stepped hole of the large diameter section of the valve stem, solving the technical problem that the indicator valve stem assembly cannot be directly assembled, and effectively solving the problems of inserting the valve head into the inner hole of the valve stem and accurately controlling the length of the inner cavity to ensure the stroke of the valve during the assembly of the indicator valve head, valve stem, and disc spring, ensuring the smooth assembly of the valve stem assembly, with a simple structure, easy to operate, convenient to use, and capable of effectively ensuring the assembly quality and processing efficiency.

[0004] Technical solution adopted by the present invention: An auxiliary device for installing the valve stem assembly of a diesel engine indicator valve, comprising an upper die, a guide sleeve, a lower die and a base. A central hole is formed in the base for the lower half of the valve stem with the small head section facing downwards to vertically extend into it. The lower end of the guide sleeve is coaxially fixed to the upper end of the base. The lower die is adaptively installed in the guide sleeve, and the lower end face of the lower die contacts the upper end face of the base. The tapered section at the upper end of the valve stem and the lower half of the large-diameter section are adapted to the lower die hole at the upper end of the central hole of the lower die. The upper die is adapted to the guide sleeve, and the upper die hole at the lower end of the central hole of the upper die is adapted to the large-diameter section of the valve stem. The upper end of the upper die extends out of the guide sleeve. When the punch of the press presses the upper die downwards until the lower end face of the upper die contacts the upper end face of the lower die, the upper end of the valve stem is deformed and turned inwards to completely wrap the disc spring and the maximum diameter position of the lower end of the valve head in the stepped hole of the large-diameter section of the valve stem.

[0005] Wherein, the base is a stepped column structure with a smaller upper end diameter than the lower end diameter. The inner hole at the lower end of the guide sleeve is in interference fit with the small-diameter section at the upper end of the base, and the lower end face of the guide sleeve contacts the stepped face of the base.

[0006] Further, the inner hole of the guide sleeve is in clearance fit with the upper die and the lower die, and the lower end face of the lower die contacts the upper end face of the small-diameter section of the base.

[0007] Further, the clearance between the inner hole wall of the guide sleeve and the outer circumferential walls of the upper die and the lower die is 0.025 mm to 0.075 mm.

[0008] Further, the aperture of the upper die hole is larger than the aperture of the central hole of the upper die. The upper die hole and the central hole of the upper die are connected by a fillet transition, and the arc surface formed by the fillet presses the upper end of the valve stem.

[0009] Installation method for the valve stem assembly of a diesel engine indicator valve, comprising the following steps:

[0010] 1) Optimization and installation of the valve stem assembly: Optimize the stepped hole of the large-diameter section of the valve stem to make the aperture at the orifice position of the stepped hole larger than the maximum diameter of the part where the valve head is inserted into the valve stem, and extend the hole depth corresponding to this diameter; Install the disc spring into the stepped hole, and make the valve head pass through the disc spring and install it into the stepped hole, and the maximum diameter position of the valve head is located at the orifice position of the stepped hole;

[0011] 2) Installation of the valve stem assembly and the auxiliary device: Fix the guide sleeve on the base and ensure that the fixing structure of the guide sleeve and the base is stable. Then install the lower die into the guide sleeve, then install the valve stem assembly, and finally install the upper die into the guide sleeve. Among them, it is necessary to ensure that the lower die and the upper die can move up and down flexibly in the guide sleeve;

[0012] 3) Pressing: Place the installed structure on the workbench under the punch of the press. Start the press and stop when the punch of the press presses against the upper die and moves downward until the lower end face of the upper die touches the upper end face of the lower die. At this time, the upper end of the large end of the valve stem in the valve stem assembly turns inward to wrap the maximum diameter position of the valve head inside it;

[0013] 4) After pressing is completed, the punch of the press moves upward, and the upper die and the valve stem assembly can be taken out.

[0014] Further, a lower die hole is concentrically made at the upper end of the central hole of the lower die. The lower die hole consists of a tapered hole in the section communicating with its central hole and an equal-diameter hole at the hole opening position, and the diameter of this equal-diameter hole is larger than the maximum diameter of the large end of the valve stem.

[0015] Further, an upper die hole is concentrically made at the lower end of the central hole of the upper die. The diameter of the upper die hole is smaller than the diameter of the equal-diameter section of the lower die hole and larger than the maximum diameter of the large end of the valve stem. During the process of the punch of the press pressing the upper die downward, the arc surface connecting the upper die hole and the central hole of the upper die presses the upper end of the valve stem.

[0016] Further, the base is integrally adjusted from 45 steel material, and the hardness of the base is 28 - 32 HRC; the upper die, the guide sleeve and the lower die are all made of GCr15 steel, and the hardness of the upper die, the guide sleeve and the lower die is 58 - 62 HRC.

[0017] Further, the diameter of the central hole of the upper die is smaller than the maximum diameter of the valve head and larger than the diameter of the upper end head of the valve head.

[0018] Advantages of the present invention compared with the prior art:

[0019] 1. Through optimizing the installation structure of the valve stem assembly and with the positioning and guiding function of the auxiliary device, this technical solution realizes the inward turning deformation of the upper end of the valve stem by means of a press to completely wrap the disc spring and the maximum diameter position at the lower end of the valve head in the stepped hole of the large diameter section of the valve stem, solves the technical problem that the valve stem assembly of the indicator valve cannot be directly assembled, and can effectively solve the problems that when assembling the valve head, the valve stem and the disc spring of the indicator valve, the valve head is inserted into the inner hole of the valve stem and the length of the inner cavity is accurately controlled to ensure the stroke of the valve, ensuring the smooth assembly of the valve stem assembly;

[0020] 2. This technical solution has a simple structure, simple on-site operation and convenient use, reduces the processing and assembly difficulty of the valve stem assembly, can effectively ensure the assembly quality and processing efficiency, provides a reference solution for the assembly technology of similar valve stem assemblies of indicator valves, and has high application and popularization value. Brief Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of the valve stem assembly and the auxiliary device after installation of the present invention;

[0022] Figure 2 Schematic diagram of the valve stem structure of the present invention;

[0023] Figure 3 Schematic diagram of the structure of the indicator valve stem assembly;

[0024] Figure 4 Cross-sectional view of the lower die of the present invention;

[0025] Figure 5 Cross-sectional view of the upper die of the present invention. Detailed implementation manners

[0026] Next, in combination with the Figures 1-5 in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] It should be noted that in this article, without contrary explanations, it should be understood that: the orientation or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 to the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] In this article, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitations. The element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0029] Installation auxiliary device for the indicator valve stem assembly of a diesel engine, such as Figure 3As shown in the figure, it includes an upper die 1, a guide bushing 2, a lower die 3 and a base 4. A central hole is formed in the base 4 for the lower half of a valve stem 5 with its small head section vertically downward to extend into it. The lower end of the guide bushing 2 is coaxially fixed to the upper end of the base 4. The lower die 3 is adaptively installed in the guide bushing 2, and the lower end face of the lower die 3 contacts the upper end face of the base 4. The tapered section at the upper end of the valve stem 5 and the lower half of the large-diameter section are adapted to the lower die hole 3-1 at the upper end of the central hole of the lower die 3. The upper die 1 is adapted in the guide bushing 2, and the upper die hole 1-1 at the lower end of the central hole of the upper die 1 is adapted to the large-diameter section of the valve stem 5. The upper end of the upper die 1 extends out of the guide bushing 2. When the punch of the press presses the upper die 1 downward until the upper die 1 moves downward until its lower end face contacts the upper end face of the lower die 3, the upper end of the valve stem 5 is deformed and turned inward to completely wrap the disc spring 7 and the maximum diameter position of the lower end of the valve head 6 in the stepped hole 5-1 of the large-diameter section of the valve stem 5.

[0030] The connection structure between the base 4 and the guide bushing 2 is as follows: The base 4 is a stepped column structure with a smaller upper end diameter than the lower end diameter. The inner hole at the lower end of the guide bushing 2 is in interference fit with the small-diameter section at the upper end of the base 4, and the lower end face of the guide bushing 2 contacts the stepped face of the base 4.

[0031] The adaptation structure between the guide bushing 2 and the upper die 1 and the lower die 3 is as follows: The inner hole of the guide bushing 2 is in clearance fit with the upper die 1 and the lower die 3, and the lower end face of the lower die 3 contacts the upper end face of the small-diameter section of the base 4. Specifically, the clearance between the inner hole wall of the guide bushing 2 and the outer circumferential walls of the upper die 1 and the lower die 3 is 0.025 mm to 0.075 mm.

[0032] Among them, the aperture of the upper die hole 1-1 is larger than the aperture of the central hole of the upper die 1, and the upper die hole 1-1 and the central hole of the upper die 1 are connected by a fillet transition, and the arc surface formed by the fillet presses the upper end of the valve stem 5.

[0033] When assembling the indicating valve, it is necessary to first assemble the valve stem assembly, that is, to sequentially install the disc spring 7 and the indicating valve head 6 into the stepped hole 5-1 at the head of the valve stem 5, and then install the valve stem assembly and other components into the valve body. As Figure 3 shown, when the valve stem assembly is assembled, the original inner hole diameter at the head of the valve stem 5 is Φ13, and the maximum diameter of the part of the valve head 6 installed in the valve stem 5 is Φ14.5, and the outer diameter of the disc spring is Φ14.

[0034] If the disc spring 7 and the indicating valve head 6 are to be installed into the inner hole of the stepped hole 5-1 of the valve stem 5, it is necessary to first determine the inner hole diameter at the orifice of the valve stem 5 before assembly. Through analysis, the orifice diameter of the stepped hole 5-1 of the valve stem 5 is designed as Φ16.2 +0.2 0, and the length is 2; in order to control the stroke of the valve, the distance from the orifice end face to the bottom face of the hole is controlled, and the dimension is designed as 10.5 +0.1 0, 6±0.1, as Figure 2As shown in the figure; at the same time, the designer needs to design a device that can press and deform the orifice part of the valve stem 5 to Φ13, enabling the valve head 6 to be reliably inserted into the valve stem 5 and accurately ensuring that the stroke of the valve meets the requirements of the assembly drawing; thus, an auxiliary device is designed.

[0035] The installation method of the diesel engine indicator valve stem assembly includes the following steps:

[0036] 1) Optimization and installation of the valve stem assembly: As Figures 1-2 shown in the figure, optimize the stepped hole 5-1 of the large diameter section of the valve stem 5, making the aperture (φ16.2mm) at the orifice position of the stepped hole 5-1 larger than the maximum diameter (φ14.5mm) of the part where the valve head 6 is inserted into the valve stem 5, and extend the hole depth corresponding to this diameter (from the original 1mm to 2mm); install the disc spring 7 into the stepped hole 5-1, and make the valve head 6 pass through the disc spring 7 and be inserted into the stepped hole 5-1, and the position of the maximum diameter of the valve head 6 is located at the orifice position of the stepped hole 5-1;

[0037] 2) Installation of the valve stem assembly and the auxiliary device: Fix the guide sleeve 2 on the base 4 and ensure that the fixing structure of the guide sleeve 2 and the base 4 is stable. Then install the lower die 3 into the guide sleeve 2, with a clearance fit between them, and the clearance is 0.025mm - 0.075mm. Then install the valve stem assembly, and finally install the upper die 1 into the guide sleeve 2, with a clearance fit between them, and the clearance is 0.025mm - 0.075mm, which can ensure that the lower die 3 and the upper die 1 can move up and down flexibly in the guide sleeve 2, so as to guide during the pressing of the valve stem assembly;

[0038] In this step, for example, as Figures 1-5 shown in the figure, a lower die hole 3-1 is concentrically made at the upper end of the central hole of the lower die 3. The lower die hole 3-1 consists of a tapered hole in the section communicating with its central hole and an equal-diameter hole at the orifice position, and the aperture of this equal-diameter hole (φ20mm) is larger than the maximum diameter of the largest part of the big end of the valve stem 5 (φ18mm); specifically, an upper die hole 1-1 is concentrically made at the lower end of the central hole of the upper die 1, and the aperture of the upper die hole 1-1 (φ18.2mm) is smaller than the aperture of the equal-diameter section of the lower die hole 3-1 (φ20mm) and larger than the maximum diameter of the largest part of the big end of the valve stem 5 (φ18mm). During the process of the press punch pressing the upper die 1 downward, the arc surface connecting the upper die hole 1-1 and the central hole of the upper die 1 presses the upper end of the valve stem 5; specifically, the base 4 is integrally quenched and tempered with 45 steel material, and the hardness of the base 4 is 28 - 32HRC; the upper die 1, the guide sleeve 2, and the lower die 3 are all made of GCr15 steel, and the hardness of the upper die 1, the guide sleeve 2, and the lower die 3 is 58 - 62HRC; specifically, the aperture of the central hole of the upper die 1 (φ13mm) is smaller than the maximum diameter of the valve head 6 (φ14.5mm) and larger than the diameter of the upper end head of the valve head 6;

[0039] 3) Pressing: Place the installed structure on the workbench under the punch of the press, adjust the pressure of the press, start the press, and stop when the punch of the press presses against the upper die 1 and moves down until the lower end face of the upper die 1 touches the upper end face of the lower die 3. At this time, the upper end of the large end of the valve stem 5 in the valve stem assembly turns inward to wrap the maximum diameter position of the valve head 6 inside it, as Figure 3 shown;

[0040] Among them, ① The tapered hole surface of the lower die hole 3-1 in the lower die 3 is the main working part and has a positioning function. Therefore, this tapered hole surface must have high precision, geometric tolerance, and surface roughness. At the same time, to ensure the stroke of the valve, the inner hole diameter and length of the large end of this tapered hole surface also need to have high precision requirements, as Figure 4 shown; ② The pressing part of the upper die hole 1-1 in the upper die 1 must be designed as an arc shape, that is, the arc surface formed by the rounded transition connection between the upper die hole 1-1 and the central hole of the upper die 1. This arc surface needs to have high roughness to ensure that the valve stem 5 has no jamming during the pressing process, as Figure 5 shown; ③ During pressing, when the punch of the press cannot move downward, the pressing is completed. At this time, the bottom plane of the upper die 1 coincides completely with the upper plane of the lower die 3, thus ensuring the stroke of the valve;

[0041] 4) After pressing is completed, the punch of the press moves upward, and the upper die 1 and the valve stem assembly can be taken out.

[0042] Safety and Stability Analysis

[0043] (1) Safety analysis: The device has a simple structure, has no special environmental requirements, has no electricity, gas, etc. as auxiliary, has a light self-weight, and has no safety hazards;

[0044] (2) Stability analysis: According to the functions of each component of the device and the use environment, the material of the base 4 is selected as 45 steel, and the whole is quenched and tempered, with a hardness of 28 - 32HRC; the materials of the upper die 1, the guide sleeve 2, and the lower die 3 are all selected as GCr15, and the whole is quenched + tempered, with a hardness of 58 - 62HRC, which can ensure the assembly stability of the device during long-term operation.

[0045] The present invention has been used in the assembly of the valve stem assembly of the diesel engine indicator valve, solving the problem that the valve stem assembly of the indicator valve cannot be directly assembled. Through on-site debugging, tracking, and verification, the valve stem assembly assembled by using this device can accurately control the length of the inner cavity of the valve stem 5, ensure the stroke of the valve, meet the design requirements, and moreover, the assembly is reliable, the on-site operation is simple, and it is easy to use, ensuring the assembly quality and assembly efficiency of the valve stem assembly of the indicator valve, and at the same time reducing the processing difficulty.

[0046] In this technical solution, by optimizing the installation structure of the valve stem assembly and with the positioning and guiding function of the auxiliary device, the upper end of the valve stem 5 is deformed and turned inward by means of a press to completely wrap the disc spring 7 and the maximum diameter position of the lower end of the valve head 6 in the stepped hole of the large diameter section of the valve stem, solving the technical problem that the valve stem assembly of the indicator valve cannot be directly assembled. It can effectively solve the problems that when assembling the valve head 6, the valve stem 5 and the disc spring 7, the valve head 6 is inserted into the inner hole of the valve stem 5 and the length of the inner cavity is accurately controlled to ensure the stroke of the valve, ensuring the smooth assembly of the valve stem assembly; the structure is simple, the on-site operation is simple, and it is convenient to use, reducing the processing and assembly difficulty of the valve stem assembly, being able to effectively ensure the assembly quality and processing efficiency, providing a reference solution for the assembly technology of similar indicator valve stem assemblies, and having high application and popularization value.

[0047] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0048] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A diesel engine indicator valve stem assembly installation auxiliary device, characterized by: The invention comprises an upper die (1), a guide sleeve (2), a lower die (3) and a base (4); the base (4) is provided with a central hole for the lower half of a valve stem (5) with a small head section arranged vertically downward to extend into the central hole, and the upper end of the central hole is provided with an outward-expanding chamfer; the lower end of the guide sleeve (2) is coaxially fixed to the upper end of the base (4); the lower die (3) is adapted to be installed in the guide sleeve (2), and the lower end surface of the lower die (3) contacts the upper end surface of the base (4); the conical section at the upper end of the valve stem (5) and the lower half of the large diameter section are adapted to the lower die hole (3-1) at the upper end of the central hole of the lower die (3); the upper die (1) is adapted to be installed in the guide sleeve (2) The upper die hole (1-1) at the lower end of the center hole of the upper die (1) is adapted to the upper half of the large diameter section of the valve stem (5); the diameter of the center hole of the upper die (1) is smaller than the maximum diameter of the valve head (6) and larger than the diameter adjacent to the upper end of the maximum diameter position of the valve head (6); the upper end of the upper die (1) extends out of the guide sleeve (2), and when the punch of the press presses the upper die (1) downward until the upper die (1) moves downward and its lower end face contacts the upper end face of the lower die (3), the upper end of the valve stem (5) is deformed and turned inward until the butterfly spring (7) and the maximum diameter position of the lower end of the valve head (6) are completely wrapped in the stepped hole (5-1) of the large diameter section of the valve stem (5).

2. The auxiliary device for installing the valve stem assembly of a diesel engine indicator valve according to claim 1, characterized in that: The base (4) is a stepped column structure with an upper diameter smaller than a lower diameter, the inner hole at the lower end of the guide sleeve (2) is interference fit with the small diameter section at the upper end of the base (4), and the lower end surface of the guide sleeve (2) is in contact with the stepped surface of the base (4).

3. The auxiliary device for installing the valve stem assembly of a diesel engine indicator valve according to claim 2, characterized in that: The inner hole of the guide sleeve (2) is clearance-matched with the upper die (1) and the lower die (3), and the lower end surface of the lower die (3) is in contact with the upper end surface of the small-diameter section of the base (4).

4. The auxiliary device for installing the valve stem assembly of a diesel engine indicator valve according to claim 3, characterized in that: The gap between the inner hole wall of the guide sleeve (2) and the outer circumferential walls of the upper die (1) and the lower die (3) is 0.025 mm to 0.075 mm.

5. The auxiliary device for installing a diesel engine indicator valve stem assembly according to any one of claims 1 to 4, characterized in that: The diameter of the upper die hole (1-1) is larger than the diameter of the center hole of the upper die (1), and the upper die hole (1-1) is connected to the center hole of the upper die (1) through a rounded transition, and the arc surface formed by the rounded corner is pressed against the upper end of the valve stem (5).

6. Installation method of diesel engine indicator valve stem assembly, characterized in that The following steps are involved: 1) Optimization and installation of the valve stem assembly: optimize the stepped hole (5-1) of the large diameter section of the valve stem (5) so that the diameter of the stepped hole (5-1) at the orifice position is larger than the maximum diameter of the valve head (6) inserted into the valve stem (5), and extend the hole depth corresponding to the diameter; install the butterfly spring (7) into the stepped hole (5-1), and allow the valve head (6) to pass through the butterfly spring (7) and be installed into the stepped hole (5-1), and the maximum diameter position of the valve head (6) is located at the orifice position of the stepped hole (5-1); 2) Installation of the valve stem assembly and auxiliary devices: Fix the guide sleeve (2) on the base (4) and ensure that the fixing structure of the guide sleeve (2) and the base (4) is stable, then install the lower mold (3) into the guide sleeve (2), then install the valve stem assembly, and finally install the upper mold (1) into the guide sleeve (2). It is necessary to ensure that the lower mold (3) and the upper mold (1) can move flexibly up and down in the guide sleeve (2); 3) Pressing: Place the assembled structure on a workbench below the punch of the press, start the press, and stop when the punch of the press presses against the upper die (1) and moves downward until the lower end surface of the upper die (1) abuts against the upper end surface of the lower die (3). At this time, the upper end of the large end of the valve stem (5) in the valve stem assembly turns inward to wrap the maximum diameter position of the valve head (6) inside it; 4) After the pressing is completed, the punch of the press moves up and the upper die (1) and the valve stem assembly are taken out.

7. The method for installing a diesel engine indicator valve stem assembly according to claim 6, characterized in that: A lower die hole (3-1) is coaxially formed at the upper end of the center hole of the lower die (3), and the lower die hole (3-1) is composed of a tapered hole in communication with the center hole and an equal-diameter hole located at the hole mouth, and the diameter of the equal-diameter hole is larger than the diameter of the largest part of the large end of the valve stem (5).

8. The method for installing a diesel engine indicator valve stem assembly according to claim 7, characterized in that: An upper die hole (1-1) is concentrically formed at the lower end of the center hole of the upper die (1), and the diameter of the upper die hole (1-1) is smaller than the diameter of the equal diameter section of the lower die hole (3-1) but larger than the diameter of the largest part of the large end of the valve stem (5). When the punch of the press presses the upper die (1) downward, the arc surface of the transition connection between the upper die hole (1-1) and the center hole of the upper die (1) presses the upper end of the valve stem (5).

9. The method for installing a diesel engine indicator valve stem assembly according to claim 8, characterized in that: The base (4) is integrally formed by modulating 45 steel material, and the hardness of the base (4) is 28-32HRC; the upper die (1), the guide sleeve (2) and the lower die (3) are all made of GCr15 steel, and the hardness of the upper die (1), the guide sleeve (2) and the lower die (3) is 58-62HRC.

10. The method for installing a diesel engine indicator valve stem assembly according to any one of claims 6 to 9, characterized in that: The diameter of the central hole of the upper die (1) is smaller than the maximum diameter of the valve head (6) and larger than the diameter of the upper end of the valve head (6).

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