Tappet hole repair tool and method for repairing tappet holes of a diesel engine block in a confined space

Abstract

The present invention provides a tappet hole repair tool and a method for repairing the tappet holes of a diesel engine body in a confined space, which relates to the technical field of diesel engine repair. The problem that it is difficult to repair the tappet holes of a diesel engine body in a confined space and it is difficult to ensure the machining accuracy in the prior art is solved. The through holes of the fixing plate of the present invention are arranged according to the tappet holes and stud holes of the diesel engine body. The center of the tappet hole is determined by the cooperation of the conical positioning part of the positioning sleeve and the mating hole of the body. The position of the fixing plate relative to the tappet hole is ensured by the clearance fit between the cylindrical positioning part of the positioning sleeve and the first through hole of the fixing plate. The position of the tool center relative to the tappet hole is ensured by the clearance fit between the tool shank of the special tool and the third through hole of the fixing plate of the positioning sleeve, ensuring the machining accuracy of the tappet hole and the bushing, and obtaining a tappet hole that meets the requirements. Compared with the prior art, the present invention can be conveniently brought into the confined space to assist in the repair of the tappet hole to reduce the difficulty and can ensure the machining accuracy of the tappet hole.

Description

Technical Field

[0001] The present invention relates to the technical field of diesel engine repair. Specifically, it is a tappet hole repair tool and a method for repairing the tappet holes of a diesel engine body in a confined space. Background Art

[0002] The diesel engine body is the framework of the diesel engine. The structure of the diesel engine body and the tappet hole structure are as Figures 5-7 shown. There are 4 stud holes and two tappet holes around each cylinder hole. There is a coaxial light hole corresponding to the upper part of each tappet hole. Since the tappet hole and the light hole on it are machined simultaneously, they have very good coaxiality. Among them, the tappet hole is one of the holes with relatively high precision requirements on the engine body. The tappet hole has relatively high requirements for position tolerance, cylindricity, and perpendicularity. Usually, it is relatively easy to meet the technical requirements of the tappet hole by using machining equipment such as numerically controlled machine tools.

[0003] After the diesel engine has been used for a long time, some tappet holes will be worn. After the tappet holes are worn, it will affect the normal operation of the diesel engine and even cause failures. Therefore, it is necessary to repair the worn tappet holes. However, after some ship-type diesel engines are installed in the cabin, they usually cannot be lifted and rotated out of the cabin again. If the deck is cut to remove the diesel engine from the cabin and the tappet holes are repaired by using a numerically controlled machine tool, it will waste a lot of manpower and financial resources. Therefore, this method is usually not adopted, but the tappet holes are repaired in the cabin. When repairing the tappet holes in a confined space such as a cabin, a magnetic drill is usually adsorbed on the diesel engine body to drive a fine boring tool extending into the tappet hole to be repaired and a fine reaming tool extending into the bushing installed in the tappet hole after reaming. This method has a relatively large operation difficulty, cannot ensure the position of the fine boring tool and the fine reaming tool relative to the tappet hole, and it is difficult to ensure the machining accuracy of the tappet hole. Summary of the Invention

[0004] The purpose of the present invention is to design a tappet hole repair tool and a method for repairing the tappet holes of a diesel engine body in a confined space, so as to solve the problem that it is difficult to repair the tappet holes of a diesel engine body in a confined space and it is difficult to ensure the machining accuracy.

[0005] The present invention is realized by the following technical solutions:

[0006] The present invention provides a tappet hole repair tool, which includes a plurality of bolts, a number of positioning sleeves, a plurality of special tools and a fixing plate; the positioning sleeve includes a conical positioning portion, a cylindrical positioning portion and a shoulder coaxially arranged in sequence along its axis, the large end of the conical positioning portion is connected to the cylindrical positioning portion, a third through hole extending along its axis is arranged at the center of the positioning sleeve, and a plurality of fourth through holes arranged around its axis are arranged on the shoulder, wherein the bolts are inserted through the fourth through holes; the special tool includes a cylindrical tool shank and a tool head coaxially arranged in sequence along its axis, at least one of the tool heads of all the special tools is a precision reaming tool head or a precision boring tool head, wherein the tool shank is coaxially inserted through the third through hole to achieve a clearance fit; the fixing plate is a flat structural member, on which are provided: two first through holes, four second through holes and a plurality of screw holes vertically penetrating the plate body; the two first through holes are used for coaxial alignment with two tappet holes arranged around a single cylinder hole on the diesel engine body one by one; the four second through holes are used for coaxial alignment with four stud holes arranged around a single cylinder hole on the diesel engine body one by one; a plurality of the screw holes are arranged around each of the first through holes along the axis of the first through hole; wherein at least one of the first through holes is inserted with the positioning sleeve, the cylindrical positioning portion is coaxially inserted through the first through hole to achieve a clearance fit, the end of the conical positioning portion protrudes from the lower surface of the fixing plate, and the shoulder is detachably screwed to the screw hole by the bolt so as to be pressed against the upper surface of the fixing plate.

[0007] When the above-mentioned setting structure is adopted, the first through holes and the second through holes arranged on the fixing plate are in one-to-one alignment with four screw holes and two tappet holes arranged around a single cylinder hole on the diesel engine body, and the screw holes on the fixing plate are arranged around the first through holes for fixing the positioning sleeve. Therefore, the fixing plate can be processed small enough to be easily carried into a confined space such as a cabin and used as an auxiliary tool to reduce the difficulty of repairing the tappet hole in the confined space. The positioning sleeve is detachably coaxially installed in the first through hole on the fixing plate by bolts. The end of the conical positioning portion protrudes from the lower surface of the fixing plate, so that the center of the tappet hole can be determined by matching the conical surface of the conical positioning portion with the corresponding body fitting hole of the tappet hole, and the cylindrical positioning portion has a clearance fit with the first through hole, which can ensure the position of the fixing plate relative to the tappet hole. Since the tool shank of the special tool is coaxially and has a clearance fit with the third through hole of the positioning sleeve, the position of the tool center relative to the tappet hole can be ensured. Therefore, this kind of tappet hole repair tool can ensure the position of the precision boring tool and the precision reaming tool relative to the tappet hole, and further ensure the machining accuracy of the tappet hole.

[0008] Further, to better implement the present invention, the following structural arrangement is particularly adopted: It further includes an elastic gasket, which is disposed between the shoulder and the upper surface of the fixed plate and is pressed by the shoulder against the upper surface of the fixed plate. The gasket is preferably a rubber pad.

[0009] Further, to better implement the present invention: The flatness of the upper surface and the lower surface of the fixed plate is not greater than 0.006 mm; The perpendicularity of the first through hole with respect to the reference plane where the lower surface of the fixed plate is located is not greater than 0.005 mm; The outer diameter of the cylindrical positioning portion is 0.01 - 0.015 mm smaller than the diameter of the first through hole; The diameter of the third through hole is 0.01 - 0.015 mm larger than the diameter of the tool shank.

[0010] The present invention also provides a method for repairing the tappet hole of a diesel engine body in a confined space. This method uses the above-mentioned tappet hole repair tool to repair the tappet hole to be repaired on the diesel engine body, and specifically includes the following steps:

[0011] Step S1, determining the position of the fixed plate relative to the tappet hole: Align the four second through holes on the fixed plate connected with the positioning sleeve with the studs installed in the four stud holes around the cylinder hole where the tappet hole to be repaired is located one by one. Place the fixed plate on the top surface of the engine body with its lower surface facing the top surface of the engine body, so that the first through hole on the fixed plate is aligned with the two tappet holes around the cylinder hole one by one. Insert the conical positioning portion into the corresponding engine body mating hole of the tappet hole to be repaired, and use the conical surface of the conical positioning portion to cooperate and position with the engine body mating hole to determine the position of the fixed plate relative to the tappet hole to be repaired. Then tighten the nuts on the studs to fix the fixed plate on the engine body to ensure that the position of the fixed plate relative to the tappet hole to be repaired no longer changes;

[0012] Step S2, reaming and machining the bushing installation hole: After removing the positioning sleeve from the fixed plate, sleeve it onto the tool shank part of a special tool with a fine boring cutter head. Then insert the special tool and the positioning sleeve simultaneously into the first through hole on the fixed plate. Adjust the conical positioning portion to contact and position with the engine body mating hole and tighten the bolts to determine the center of the positioning sleeve and the special tool. Then use the magnetic drill magnetically attached to the fixed plate to provide power to drive the special tool to machine the tappet hole to be repaired to ream and machine a bushing installation hole at the tappet hole to be repaired. After machining is completed, remove the positioning sleeve and the special tool from the fixed plate;

[0013] Step S3, installing the bushing: Install a bushing with an inner diameter smaller than the diameter of the tappet hole into the corresponding bushing installation hole to achieve an interference fit;

[0014] Step S4, machine the tappet hole as required: Fit the positioning sleeve onto the shank of a special tool with a finishing reamer head as the cutting head, then insert the special tool and the positioning sleeve simultaneously through the first through-hole in the fixing plate. Adjust the conical positioning portion to contact and position with the mating hole of the engine block, and tighten the bolt to determine the center of the positioning sleeve and the special tool. Then, use the magnetic drill attached to the fixing plate to provide power to drive the special tool to machine the inner hole wall of the bushing to form a repaired tappet hole that meets the requirements.

[0015] When adopting the above method, it can be assisted by the tappet hole repair tool. The center of the tappet hole to be repaired can be determined by the cooperation between the conical surface of the conical positioning portion and the corresponding mating hole of the engine block for the tappet hole to be repaired. The cylindrical positioning portion is in clearance fit with the first through-hole to ensure the position of the fixing plate relative to the tappet hole. The relationship of the clearance fit between the shank of the special tool and the third through-hole of the positioning sleeve can ensure the position of the tool center relative to the tappet hole to be repaired, thereby ensuring the machining accuracy of the repaired tappet hole and the bushing, and obtaining a repaired tappet hole with a repair accuracy meeting the requirements.

[0016] Furthermore: The aperture of the tappet hole of the diesel engine block is φ40H7, and the aperture of the mating hole of the engine block is φ44H7; the aperture of the first through-hole is φ50H7, and the diameter of the shank is φ25h6.

[0017] The present invention has the following advantages and beneficial effects:

[0018] In the present invention, the first through-hole and the second through-hole provided on the fixing plate are in one-to-one correspondence with the four screw holes and the two tappet holes provided around a single cylinder hole of the diesel engine block. The screw holes on the fixing plate are provided around the first through-hole for fixing the positioning sleeve. Therefore, the fixing plate can be machined small enough to be easily carried into a restricted space such as a cabin and used as an auxiliary tool to reduce the difficulty of repairing the tappet hole in the restricted space. The positioning sleeve is detachably coaxially installed in the first through-hole on the fixing plate through a bolt. The end of the conical positioning portion protrudes from the lower surface of the fixing plate, so the center of the tappet hole can be determined by the cooperation between the conical surface of the conical positioning portion and the corresponding mating hole of the engine block for the tappet hole. The cylindrical positioning portion is in clearance fit with the first through-hole, which can ensure the position of the fixing plate relative to the tappet hole. Since the shank of the special tool is coaxial and in clearance fit with the third through-hole of the positioning sleeve, the position of the tool center relative to the tappet hole can be ensured. Therefore, this kind of tappet hole repair tool can ensure the position of the finish boring tool and the finishing reamer relative to the tappet hole, thereby ensuring the machining accuracy of the tappet hole and obtaining a tappet hole that meets the requirements. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 Shows the fixed plate structure with a positioning sleeve, gasket and bolt in the embodiment of the present invention;

[0021] Figure 2 Is Figure 1 The B-B cross-sectional view in;

[0022] Figure 3 Is Figure 2 The partial enlarged view of area Ⅰ in;

[0023] Figure 4 Shows the structure of installing a cutting tool on the fixed plate with a positioning sleeve, gasket and bolt in the embodiment of the present invention;

[0024] Figure 5 Is the schematic diagram of the overall external shape of the diesel engine block;

[0025] Figure 6 Is the schematic diagram of the structure of a single cylinder of the diesel engine block in the embodiment of the present invention;

[0026] Figure 7 Is Figure 6 The partial cross-sectional view of A-A in;

[0027] Figure 8 Shows the usage of the tappet hole repair tool when repairing the tappet hole;

[0028] Figure 9 Is Figure 8 The partial enlarged view of area Ⅱ in;

[0029] Figure 10 Shows the structure of the bushing installation hole machined on the tappet hole to be repaired;

[0030] Figure 11 Shows the structure of the bushing.

[0031] The marks in the figure are:

[0032] 1. Bolt;

[0033] 2. Positioning sleeve; 2a. Conical positioning part; 2b. Cylindrical positioning part; 2c. Shoulder; 2d. Third through hole; 2e. Fourth through hole;

[0034] 3. Gasket;

[0035] 4. Fixed plate; 4a. First through hole; 4b. Second through hole; 4c. Screw hole;

[0036] 5. Bushing; A1. Outer diameter of bushing shoulder; B1. Outer diameter of bushing body; C. Inner diameter of bushing; L1. Bushing length; L2. Bushing shoulder length;

[0037] 6. Special tool; 6a. Tool shank; 6b. Tool bit;

[0038] 7. Machine body; 7a. Machine body mating hole; 7b. Tappet hole; 7c. Stud hole; 7d. Bushing mounting hole; A2. Large hole diameter; B2. Small hole diameter; L2'. Large hole depth. Detailed implementation mode

[0039] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. 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 implementation manners obtained by those of ordinary skill in the art without creative efforts shall fall within the scope protected by the present invention.

[0040] In the description of the present invention, it should be noted that unless otherwise specified, the meaning of "a plurality of" is two or more; the orientation or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", 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 thus cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0041] In the description of the present invention, it should also be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] Embodiment 1:

[0043] A tappet hole repair tool can be used to assist in the repair of tappet holes in a restricted space, achieving the purpose of reducing the difficulty of repairing tappet holes, and enabling the tappet holes repaired in the restricted space to meet the accuracy requirements, such as Figure 1 , Figure 2 ,Figure 3 , Figure 4 is specifically configured into the following structure:

[0044] This tappet hole repair tool can be used for the tappet holes at the position of one cylinder hole of the diesel engine block in sequence. The position relationship between the tool center and the tappet hole can be ensured through the fitting relationship between the shaft hole, and the tappet hole meeting the accuracy requirements can be machined.

[0045] As Figure 1 and 4 shown, this tappet hole repair tool includes a plurality of bolts 1, several positioning sleeves 2, a plurality of special tools 6 and a fixing plate 4, which are assembled and used together.

[0046] The fixing plate 4 is a plate-like part, and its structure is designed with reference to the structure of the diesel engine block to be targeted. As Figure 1 and Figure 2 shown, the fixing plate 4 is a rectangular flat plate structural member, which is processed from ferromagnetic material to enable the magnetic drill to be magnetically attracted to it to provide power for the tool. Two first through holes 4a, four second through holes 4b and a plurality of screw holes 4c that penetrate the plate body vertically are provided on the fixing plate 4, and they are arranged according to the layout of the tappet holes and stud holes around a single cylinder hole of the diesel engine block to be targeted. The first through holes 4a are used to be coaxially aligned with the two tappet holes provided around a single cylinder hole of the diesel engine block one by one. Therefore, the two first through holes 4a are symmetrically distributed left and right. The four second through holes 4b are used to be coaxially aligned with the four stud holes provided around a single cylinder hole of the diesel engine block one by one. Therefore, the four second through holes 4b are arranged in a two-dimensional array in the left-right direction and the front-back direction. Four screw holes 4c arranged at equal distances around the axis of each first through hole 4a are provided around each first through hole 4a.

[0047] As Figures 1-4 shown, the positioning sleeve 2 is a shaft-like part, which includes a conical positioning part 2a, a cylindrical positioning part 2b and a shoulder 2c that are coaxially arranged in sequence along its axis. The large end of the conical positioning part 2a is connected to the cylindrical positioning part 2b. At the same time, a third through hole 2d extending along its axis is provided at the central position of the positioning sleeve 2. Four fourth through holes 2e arranged at equal distances around its axis are provided on the shoulder 2c, and the fourth through holes 2e correspond to the screw holes 4c matched with each first through hole 4a on the fixing plate 4 one by one. Among them, bolts 1 are inserted into the fourth through holes 2e, the rod parts of the bolts 1 extend downward into the corresponding screw holes 4c and are screwed with them, and the heads of the bolts 1 press against the upper end of the shoulder 2c to press and fix the positioning sleeve 2 on the fixing plate 4.

[0048] In this embodiment, the positioning sleeve 2 can be provided with one or two. One positioning sleeve 2 corresponds to the repair of one tappet hole. Therefore, at least one positioning sleeve 2 should be inserted into the first through hole 4a. As Figure 1 and Figure 2 shown, a positioning sleeve 2 is installed on the fixing plate 4. The positioning sleeve 2 is specifically installed in the rightmost first through hole 4a. The cylindrical positioning portion 2b of the positioning sleeve 2 coaxially passes through the first through hole 4a. At the same time, the lower end of the conical positioning portion 2a of the positioning sleeve 2 protrudes downward from the lower surface of the fixing plate 4. The shoulder 2c is detachably screwed to the screw hole 4c through the bolt 1 so that the positioning sleeve 2 is pressed against the upper surface of the fixing plate 4 and fixed. There is a clearance fit between the cylindrical positioning portion 2b of the positioning sleeve 2 and the first through hole 4a.

[0049] As Figure 4 shown, the special tool 6 includes a tool shank 6a and a tool bit 6b. The tool shank 6a extends along its axis, and one tool bit 6d coaxially arranged with it is fixedly connected to one end of the tool shank 6a. The tool shank 6a of the special tool 6 coaxially passes through the third through hole 2d, and there is a clearance fit between the tool shank 6a and the third through hole 2d, so that the special tool 6 can rotate in the third through hole 2d or move axially along the third through hole 2d. Since the tappet hole needs to be reamed first and then the inner hole of the bushing is machined for adsorbing the tappet hole, at least two special tools 6 are required. Among them, the tool bit 6b of one special tool 6 is a precision reaming bit, and the tool bit 6b of the other special tool 6 is a precision boring bit.

[0050] As Figure 3 shown, the tappet hole repair tool can also be provided with an elastic gasket 3. The gasket 3 is generally made of rubber material and is disposed at the position between the shoulder 2c and the upper surface of the fixing plate 4 and is pressed against the upper surface of the fixing plate 4 by the shoulder 2c.

[0051] The gasket 3 is used in cooperation with the positioning sleeve 2 and is placed between the positioning sleeve 2 and the fixing plate 4. Since the gasket 3 has a certain elasticity, it can ensure that the conical positioning portion 2a of the positioning sleeve 2 is stably fixed on the fixing plate 4 when it contacts the mating hole 7a of the machine body.

[0052] According to different process requirements, the requirements for geometric tolerances and the like between the structures of the tappet hole repair tool are generally different. For example, the flatness of the upper surface and the lower surface of the fixing plate 4 is not greater than 0.006 mm; the perpendicularity of the first through hole 4a relative to the reference plane where the lower surface of the fixing plate 4 is located is not greater than 0.005 mm; the outer diameter of the cylindrical positioning portion 2b is 0.01 - 0.015 mm smaller than the diameter of the first through hole 4a; the diameter of the third through hole 2d is 0.01 - 0.015 mm larger than the diameter of the tool shank 6a.

[0053] In this embodiment, the first through hole 4a and the second through hole 4b provided on the fixing plate 4 are in one-to-one correspondence with the four screw holes and two tappet holes provided around a single cylinder hole of the diesel engine body. The screw hole 4c on the fixing plate 4 is provided around the first through hole 4a for fixing the positioning sleeve 2. Therefore, the fixing plate 4 can be processed small enough to be easily carried into a restricted space such as a cabin and used as an auxiliary tool to reduce the difficulty of repairing the tappet hole in the restricted space. The positioning sleeve 2 is detachably coaxially mounted in the first through hole 4a on the fixing plate 4 by bolts. The end of the conical positioning portion 2a protrudes from the lower surface of the fixing plate 4. Then, the center of the tappet hole can be determined by matching the conical surface of the conical positioning portion 2a with the corresponding body fitting hole 7a of the tappet hole. The cylindrical positioning portion 2b has a clearance fit with the first through hole 4a, which can ensure the position of the fixing plate 4 relative to the tappet hole. Since the tool shank 6a of the special tool 6 is coaxially and clearance-fitted with the third through hole 2d of the positioning sleeve 2, the position of the tool center relative to the tappet hole can be ensured. Therefore, this type of tappet hole repair tool can ensure the position of the finish boring tool and the finish reaming tool relative to the tappet hole, and thus ensure the machining accuracy of the tappet hole.

[0054] Embodiment 2:

[0055] This embodiment discloses a method for repairing a tappet hole of a diesel engine body in a restricted space:

[0056] This method for repairing a tappet hole of a diesel engine body in a restricted space particularly uses the tappet hole repair tool in the above embodiment to repair the tappet hole 7b to be repaired on the diesel engine body, especially to repair the tappet hole 7b to be repaired in a restricted space.

[0057] In this embodiment, a certain type of diesel engine is taken as an example. As Figure 5 shown, the body structure of this type of diesel engine includes 20 cylinder holes. The layout of the tappet holes for a single cylinder hole is as Figure 6 shown. There are 4 stud holes 7c and two tappet holes around each cylinder hole. The diameter of the tappet hole is φ40H7. There is a φ44H7 optical hole coaxially arranged above each tappet hole. Since the φ44H7 optical hole and the φ40H7 tappet hole are machined simultaneously, they have very good coaxiality. Therefore, the center of the tappet hole φ40H7 can be determined through the center of the φ44H7 optical hole. The stud installed in the stud hole 7c of the body 7 can be used to fix the tappet hole repair tool.

[0058] In this embodiment, one of the tappet holes is used as the tappet hole to be repaired 7b, and the light hole machined simultaneously with the tappet hole to be repaired 7b is used as the engine block mating hole 7a to repair the tappet hole to be repaired 7b. The flatness of the upper and lower surfaces of the fixing plate 4 should be ensured to be no greater than 0.006 mm, the perpendicularity of the two first through holes 4a with respect to the plane should be no greater than 0.005 mm, and the diameter of the two first through holes 4a is φ50H7. The flatness of the fixing plate 4 and the perpendicularity of the first through holes 4a are used to ensure that the perpendicularity of the tappet hole is no greater than 0.03 mm. The conical positioning portion 2a of the positioning sleeve 2 determines the center of the tappet hole to be repaired 7b with a diameter of φ40H7 through the center of the engine block mating hole 7a with a diameter of φ44H7 by taking advantage of the high positioning accuracy of the conical circle. The size of the cylindrical positioning portion 2b of the positioning sleeve 2 is configured according to the measured value of the diameter of the first through hole 4a of the fixing plate 4. The outer diameter of the cylindrical positioning portion 2b of the positioning sleeve 2 is 0.01 mm - 0.015 mm smaller than the diameter of the φ50H7 first through hole 4a on the fixing plate 4, and is used to determine the position of the fixing plate 4 relative to the tappet hole to be repaired 7b. In addition, the third through hole 2d in the middle of the positioning sleeve 2 is 0.01 mm - 0.015 mm larger than the measured value of the diameter of the tool shank 6a with a diameter of φ25h6 of the special tool 6, and is used to determine the position of the tool center relative to the tappet hole to be repaired 7b. The positioning sleeve 2 can ensure that the position tolerance of the tappet hole to be repaired 7b is no greater than 0.05 mm through its conical positioning portion 2a and cylindrical positioning portion 2b.

[0059] The specific steps for repairing the tappet hole to be repaired 7b include the following:

[0060] First, install the positioning sleeve 2 on the fixing plate 4 in the Figure 2 shown form, and firmly fix the positioning sleeve 2 on the fixing plate 4 by tightening the bolts 1 in the four fourth through holes 2e on the shoulder 2c.

[0061] After that, determine the position of the fixing plate 4 relative to the tappet hole to be repaired 7b. Align the four second through holes 4b on the fixing plate 4 connected with the positioning sleeve 2 one by one with the studs installed in the four stud holes around the cylinder hole where the tappet hole to be repaired 7b is located, so that the studs penetrate into the second through holes 4b for positioning. Then, place the fixing plate 4 on the top surface of the engine block 7 with its lower surface facing the top surface of the engine block 7, and roughly adjust the position of the fixing plate 4 so that the first through holes 4a on the fixing plate 4 are aligned with the two tappet holes around the cylinder hole one by one. Then, insert the conical positioning portion 2a of the positioning sleeve 2 into the corresponding engine block mating hole 7a of the tappet hole to be repaired 7b, and use the conical surface of the conical positioning portion 2a to cooperate with the engine block mating hole 7a for positioning to determine the position of the fixing plate 4 relative to the tappet hole to be repaired 7b. Then, tighten the nuts on the studs to fix the fixing plate 4 on the engine block 7 to ensure that the position of the fixing plate 4 relative to the tappet hole to be repaired 7b no longer changes, and finally form the Figure 8 connection form shown in

[0062] After that, ream the bushing installation hole. After removing the positioning sleeve 2 from the fixed plate 4, fit it onto the shank 6a of the special tool 6 with the cutter head 6b being a finish boring cutter head. Then, insert the special tool 6 and the positioning sleeve 2 simultaneously into the first through hole 4a in the fixed plate 4. Adjust the conical positioning portion 2a to contact and position with the mating hole 7a of the body, tighten the bolt 1, and determine the centers of the positioning sleeve 2 and the special tool 6. Then, install the magnetic drill onto the upper surface of the fixed plate 4 using magnetic suction, and install the shank 6a of the special tool 6 onto the magnetic drill, finally forming Figure 8 the connection form shown in. After that, use the magnetic drill to provide power to drive the special tool 6 to machine the to-be-repaired tappet hole 7b, and ream a bushing installation hole 7d at the to-be-repaired tappet hole 7b. The bushing installation hole 7d is a stepped hole for mating with the bushing 5. After the machining of the bushing installation hole 7d is completed, remove the positioning sleeve 2 and the special tool 6 from the fixed plate 4, and then clean and deburr.

[0063] After that, install the bushing. The material of the bushing 5 is the same as that of the body. As Figure 11 shown, the bushing 5 is a stepped bushing with a shoulder at the end, and its shoulder can prevent the bushing 5 from falling off. During installation, use liquid nitrogen or relevant auxiliary tools to install the bushing 5 with the same material as the body into the corresponding bushing installation hole 7d to achieve interference fit. The inner diameter of the bushing 5 is smaller than the diameter of the tappet hole for use in machining the tappet hole later.

[0064] After that, machine the tappet hole as required: Fit the positioning sleeve 2 onto the shank 6a of the special tool 6 with the cutter head 6b being a finish reaming cutter head. Then, insert the special tool 6 and the positioning sleeve 2 simultaneously into the first through hole 4a in the fixed plate 4. Adjust the conical positioning portion 2a to contact and position with the mating hole 7a of the body, tighten the bolt 1, and determine the centers of the positioning sleeve 2 and the special tool 6. Then, use the magnetic drill magnetically attached to the fixed plate 4 to provide power to drive the special tool 6 to machine the inner hole wall of the bushing 5 to form a repaired tappet hole that meets the requirements. After the machining is completed, remove the special finish reamer and the positioning sleeve, clean and deburr, and inspect.

[0065] Among them, the structure of the bushing 5 is as Figure 11 shown. The outer diameter A1 of the bushing shoulder of the bushing 5 is φ43.7 (-0.05 / -0.15) mm, the outer diameter B1 of the bushing body is φ43.5 (+0.059 / +0.043) mm, the inner diameter C of the bushing is φ39 (+0.1 / 0) mm, the length L1 of the bushing is 94 mm, and the length L2 of the bushing shoulder is 10 mm. The structure of the bushing installation hole 7d is as Figure 10As shown, the large hole of the bushing mounting hole 7d is used to mount the shoulder of the bushing 5. The aperture A2 of the large hole is Φ43.7(+0.1 / 0)mm, the aperture B2 of the small hole is φ43.5H6(+0.016 / 0)mm, and the depth L2' of the large hole is 10mm. That is, there is a certain interference when installing the bushing 5. The inner diameter of the bushing 5 is smaller than the diameter of the tappet hole. After installing the bushing 5, it is necessary to supplement the machining of the bushing 5 according to the relevant requirements of the tappet hole.

[0066] When adopting the above method, it can be assisted by the tappet hole repair tool. The center of the tappet hole 7b to be repaired can be determined by the cooperation of the conical surface of the conical positioning part 2a and the corresponding body mating hole 7a of the tappet hole 7b to be repaired. The cylindrical positioning part 2b can be used for clearance fit with the first through hole 4a to ensure the position of the fixing plate 4 relative to the tappet hole. The relationship of clearance fit between the tool shank 6a of the special tool 6 and the third through hole 2d of the positioning sleeve 2 can be used to ensure the position of the tool center relative to the tappet hole 7b to be repaired, thereby ensuring the machining accuracy of the tappet hole 7b to be repaired and the bushing 5, and obtaining a repaired tappet hole with the repair accuracy meeting the requirements.

[0067] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should be covered by the protection scope of the present invention.

Claims

1. A tappet hole repair tool, characterized in that, it includes: a plurality of bolts (1); a number of positioning sleeves (2), the positioning sleeve (2) includes a conical positioning portion (2a), a cylindrical positioning portion (2b) and a shoulder (2c) arranged coaxially along its axis in sequence, the large end of the conical positioning portion (2a) is connected to the cylindrical positioning portion (2b), a third through hole (2d) extending along its axis is provided in the center of the positioning sleeve (2), and a plurality of fourth through holes (2e) arranged around its axis are provided on the shoulder (2c), wherein, the bolt (1) is inserted through the fourth through hole (2e); a plurality of special tools (6), the special tool (6) includes a cylindrical tool shank (6a) and a tool head (6b) arranged coaxially along its axis in sequence, at least one of the tool heads (6b) of all the special tools (6) has a finish reaming tool head or a finish boring tool head, wherein, the tool shank (6a) is coaxially inserted into the third through hole (2d) to achieve a clearance fit; a fixing plate (4), which is a flat structural member, and is provided with: two first through holes (4a) vertically penetrating the plate body, which are used for one-to-one coaxial alignment with two tappet holes provided around a single cylinder hole on the diesel engine block; four second through holes (4b), which are used for one-to-one coaxial alignment with four stud holes provided around a single cylinder hole on the diesel engine block; a plurality of screw holes (4c), and a plurality of the screw holes (4c) arranged around the axis of each first through hole (4a) are provided around each first through hole (4a); wherein, at least one of the first through holes (4a) is inserted with the positioning sleeve (2), the cylindrical positioning portion (2b) is coaxially inserted into the first through hole (4a) to achieve a clearance fit, the end of the conical positioning portion (2a) protrudes from the lower surface of the fixing plate (4), and the shoulder (2c) is detachably screwed to the screw hole (4c) by the bolt (1) to press it against the upper surface of the fixing plate (4).

2. A tappet hole repair tool according to claim 1, characterized in that: it further includes an elastic gasket (3), which is disposed at the position between the shoulder (2c) and the upper surface of the fixing plate (4) and is pressed against the upper surface of the fixing plate (4) by the shoulder (2c).

3. A tappet hole repair tool according to claim 2, characterized in that: the gasket (3) is set as a rubber gasket.

4. A tappet hole repair tool according to claim 2, characterized in that: the flatness of the upper surface and the lower surface of the fixing plate (4) is not greater than 0.006 mm; the perpendicularity of the first through hole (4a) with respect to the reference plane where the lower surface of the fixing plate (4) is located is not greater than 0.005 mm.

5. A tappet hole repair tool according to claim 4, characterized in that: the outer diameter of the cylindrical positioning portion (2b) is 0.01 - 0.015 mm smaller than the diameter of the first through hole (4a).

6. A tappet hole repair tool according to claim 5, characterized in that: The diameter of the third through hole (2d) is 0.01 - 0.015 mm larger than the diameter of the tool shank (6a).

7. A method for repairing the tappet holes of a diesel engine block in a confined space, characterized in that: The tappet hole repair tool described in any one of claims 1 - 6 is used to repair the to - be - repaired tappet holes (7b) on the diesel engine block that need to be repaired, and specifically includes the following steps: Step S1, determining the position of the fixing plate relative to the tappet hole: Align the four second through holes (4b) on the fixing plate (4) connected with the positioning sleeve (2) one - to - one with the studs installed in the four stud holes around the cylinder hole where the to - be - repaired tappet hole (7b) is located. Place the fixing plate (4) on the top surface of the engine block (7) with its lower surface facing the top surface of the engine block (7), so that the first through holes (4a) on the fixing plate (4) are aligned one - to - one with the two tappet holes around the cylinder hole. Insert the conical positioning part (2a) into the corresponding engine block mating hole (7a) of the to - be - repaired tappet hole (7b), and use the conical surface of the conical positioning part (2a) to cooperate with the engine block mating hole (7a) for positioning to determine the position of the fixing plate (4) relative to the to - be - repaired tappet hole (7b). Then tighten the nuts on the studs to fix the fixing plate (4) on the engine block (7) to ensure that the position of the fixing plate (4) relative to the to - be - repaired tappet hole (7b) no longer changes; Step S2, reaming and machining the bushing installation hole: After removing the positioning sleeve (2) from the fixing plate (4), sleeve it onto the tool shank (6a) of the special tool (6) with the cutter head (6b) being a fine boring cutter head. Then pass the special tool (6) and the positioning sleeve (2) through the first through hole (4a) on the fixing plate (4) at the same time. Adjust the conical positioning part (2a) to contact and position with the engine block mating hole (7a) and tighten the bolt (1) to determine the center of the positioning sleeve (2) and the special tool (6). Then use the magnetic drill magnetically attached to the fixing plate (4) to provide power to drive the special tool (6) to machine the to - be - repaired tappet hole (7b) to ream and machine a bushing installation hole (7d) at the to - be - repaired tappet hole (7b). After machining is completed, remove the positioning sleeve (2) and the special tool (6) from the fixing plate (4); Step S3, installing the bushing: Install the bushing (5) with an inner diameter smaller than the diameter of the tappet hole into the corresponding bushing installation hole (7d) to achieve an interference fit; Step S4, machining the tappet hole as required: Sleeve the positioning sleeve (2) onto the tool shank (6a) of the special tool (6) with the cutter head (6b) being a fine reaming cutter head. Then pass the special tool (6) and the positioning sleeve (2) through the first through hole (4a) on the fixing plate (4) at the same time. Adjust the conical positioning part (2a) to contact and position with the engine block mating hole (7a) and tighten the bolt (1) to determine the center of the positioning sleeve (2) and the special tool (6). Then use the magnetic drill magnetically attached to the fixing plate (4) to provide power to drive the special tool (6) to machine the inner hole wall of the bushing (5) to form a repaired tappet hole that meets the requirements.

8. A method for repairing the tappet holes of a diesel engine block in a confined space according to claim 7, characterized in that: The diameter of the tappet hole of the diesel engine block is φ40H7, and the diameter of the mating hole (7a) of the block is φ44H7; the diameter of the first through hole (4a) is φ50H7, and the diameter of the tool shank (6a) is φ25h6.

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