Crankshaft crank throw journal external cylindrical grinding fixture

Abstract

To solve the problems of manual operation in the existing external cylindrical grinding method for the crankpin journal of a crankshaft, which not only has low efficiency but also is prone to errors, the present invention proposes an external cylindrical grinding fixture for the crankpin journal of a crankshaft, comprising a rotating chuck, a vertical plate bracket, and a positioning insertion plate; there are two rotating chucks, which are symmetrically fixed on the workpiece rotating disks on both sides of the grinding wheel of the external cylindrical grinding machine in a mirror image; the vertical plate bracket is fixed on the base on the left side of the grinding wheel at the middle and rear of the external cylindrical grinding machine; the positioning insertion plate is arranged on the front end face of the front extension plate of the vertical plate bracket. The beneficial technical effect of the external cylindrical grinding fixture for the crankpin journal of the crankshaft of the present invention is to ensure the accurate positioning of the crankpin journal, and it has a simple structure and is convenient to use.

Description

Technical Field

[0001] The present invention relates to a technology for grinding the outer circle of the crankpin journal of a crankshaft, and particularly to a fixture for grinding the outer circle of the crankpin journal of a crankshaft. Background Art

[0002] The crankshaft is a main component for transmitting torque in an engine. Among them, one of the most important dimensions is the eccentricity and precision of the crankpin journal, and the level of its manufacturing precision directly affects the performance of the engine (see the attached Figure 1 , in the figure, a is the rod part of the crankshaft, b is the crankpin, and c is the crankpin journal). Since there are no structures available for positioning or / and clamping at both ends of the crankpin journal of the crankshaft, therefore, the crankpin journal can only be ground by clamping the rod part of the crankshaft. Also, since the axis of the crankpin journal of the crankshaft is parallel to but not on the same straight line as the axis of the rod part of the crankshaft, therefore, when clamping and fixing the rod part of the crank, it is necessary to accurately position the crankpin journal to ensure that the axis of the crankpin journal is at the rotation center of the workpiece rotating disk of the cylindrical grinder.

[0003] For the method of grinding the outer circle of the crankpin journal using a cylindrical grinder, the crankshaft needs to be fixedly clamped on the workpiece rotating disk of the cylindrical grinder. The workpiece rotating disk drives the workpiece to rotate and radially moves close to the rotating grinding wheel, so as to grind the outer circle of the workpiece. For the grinding of the outer circle of an eccentric shaft such as a crankshaft, an eccentric fixture is often used to clamp both ends of the eccentric shaft, and while clamping and fixing, the position of the eccentric shaft on the clamping circumference is positioned to make it coaxial with the center of the workpiece rotating disk. The existing technology for grinding the outer circle of the crankpin journal of the crankshaft uses measuring tools such as equal-height blocks to position the crankpin journal on the clamping circumference to ensure that the crankpin journal is coaxial with the center of the workpiece rotating disk. That is, before finally clamping the crankshaft, the equal-height blocks are placed on the measuring platform, and then the crankpin journal is placed on the equal-height blocks, and the fixture is tightened so that the crankshaft is clamped and fixed while keeping the crankpin journal placed on the equal-height blocks. Since manual operation is used and the crankshaft cannot be avoided from moving when tightening the fixture,

[0004] Obviously, the existing technology for grinding the outer circle of the crankpin journal of the crankshaft has problems such as manual operation, which not only has low efficiency but also is prone to errors. Summary of the Invention

[0005] To solve the problems of the existing technology for grinding the outer circle of the crankpin journal of the crankshaft, such as manual operation, which not only has low efficiency but also is prone to errors, the present invention proposes a fixture for grinding the outer circle of the crankpin journal of the crankshaft.

[0006] The present invention relates to a fixture for external cylindrical grinding of the crankpin journal of a crankshaft, which includes a rotating chuck, a vertical plate support, and a positioning plug plate. There are two rotating chucks, which are symmetrically fixed on the workpiece rotating disks on both sides of the grinding wheel of an external cylindrical grinding machine in a mirror image. The rotating chuck includes a fixed disk, a support disk, a support plate, a connecting bottom plate, a triangular base, a cushion plate, a clamping cylinder, a support arm, and a pressing rod. The fixed disk is coaxial with the workpiece rotating disk of the external cylindrical grinding machine and is fixed on the workpiece rotating disk of the external cylindrical grinding machine. The diameter of the support disk is smaller than that of the fixed disk, and the center of the support disk is vertically offset from the center of the fixed disk by a set distance and then installed on the fixed disk. Moreover, the set distance by which the center of the support disk is offset from the center of the fixed disk is the same as the eccentricity between the axis of the crankshaft rod part and the axis of the crankpin journal. When the support disk is installed and fixed on the fixed disk, there are two rectangular support plates on the support disk. They are symmetrically fixed on both sides of the center of the outer end face of the support disk through the end face of one of the short sides of the rectangle, and the length of the long side of the rectangle is greater than the length of the crankshaft rod part. The connecting bottom plate is fixedly connected to the bottom of the outer ends of the two support plates, and together with the ends of the two support plates, it forms a U-shaped structure. There are two triangular bases, which are symmetrically fixed on the two inner side faces of the U-shaped structure, thus forming a V-shaped notch. There are two cushion plates, which are respectively fixed on the inclined surfaces of the triangular bases. The height of the V-shaped inclined surface formed by the two cushion plates is such that the axis of the crankshaft rod part is coaxial with the center of the support disk after the crankshaft rod part is placed axially parallel in the V-shaped inclined surface. The piston of the clamping cylinder is vertically upward and fixed at the rear side of the U-shaped structure. There are two support arms, which are oppositely arranged at the connection between the rear side of the U-shaped structure and the clamping cylinder. An articulated hole for articulating the pressing rod is provided at the upper end of the support arm. The pressing rod is a lever structure. Among them, the middle part of the pressing rod is articulated on the support arm, the bottom side of the rear end head is articulated on the piston end head of the clamping cylinder, and the bottom side of the front end head is fixedly connected with a pressing column. The vertical plate support is fixed on the base on the left side of the grinding wheel at the middle and rear of the external cylindrical grinding machine, and includes an L-shaped vertical plate, a front extension plate, and a reinforcing rib plate. The bottom end of the long side of the L-shaped vertical plate is fixed on the base on the left side of the grinding wheel at the middle and rear of the external cylindrical grinding machine. The short side of the L-shaped vertical plate points to the grinding wheel, and the end of the short side is located above the grinding wheel. The front extension plate is a rectangular plate and is fixed at the end of the front side of the short side of the L-shaped vertical plate. The positioning plug plate is arranged on the front end face of the front extension plate of the vertical plate support and includes a trapezoidal sliding seat, a trapezoidal sliding plate, a positioning cylinder, a buffer spring, a connecting plate, and an adjusting nut. The trapezoidal sliding seat is long and is fixedly connected to the front end face of the front extension plate of the vertical plate support through the outer side face. The trapezoidal sliding plate is long and is slidably inserted into the trapezoidal sliding seat. A trapezoidal positioning notch is provided at the bottom end of the trapezoidal sliding plate. The vertical geometric center line of the trapezoidal positioning notch is perpendicular to and intersects with the central axis of the support disk. A connecting stud is provided at the upper end of the trapezoidal sliding plate. Moreover, the upper bottom width of the trapezoidal positioning notch is smaller than the diameter of the crankpin journal, the lower bottom width is greater than the diameter of the crankpin journal, and the height is greater than the diameter of the crankpin journal.The piston of the positioning cylinder is vertically and upwardly fixedly installed on the back side of the trapezoidal slide, and a connecting plate is fixedly connected to the end of the piston; one end of the connecting plate is fixedly connected to the end of the piston of the positioning cylinder, and the other end is movably sleeved on the connecting stud at the upper end of the trapezoidal slide plate; the buffer spring is sleeved on the connecting stud at the upper end of the trapezoidal slide plate and is located below the connecting plate; the adjusting nut is screwed on the connecting stud at the upper end of the trapezoidal slide plate.

[0007] Further, a reinforcing rib plate is provided between the front extension plate of the vertical plate bracket and the L-shaped vertical plate, thus forming a stable triangular structure.

[0008] Further, the rotating chuck backing plates are a sequence combination with different thicknesses, and the thicknesses of each group of backing plates are different; each group of backing plates consists of two pieces with the same thickness and corresponds to the crankshaft with a corresponding rod diameter.

[0009] Further, the pressing column on the bottom side of the front end of the rotating chuck pressing rod is an adjustable bolt structure.

[0010] The beneficial technical effect of the crankshaft crank journal external cylindrical grinding fixture of the present invention is to ensure the accurate positioning of the crank journal, and the structure is simple and the use is convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG Figure 1 is a three-dimensional schematic diagram of the crankshaft;

[0012] FIG Figure 2 is a three-dimensional schematic diagram of the crankshaft crank journal external cylindrical grinding fixture of the present invention;

[0013] FIG Figure 3 is a schematic diagram of another angle of the crankshaft crank journal external cylindrical grinding fixture of the present invention;

[0014] FIG Figure 4 is a three-dimensional schematic diagram of the crankshaft crank journal external cylindrical grinding fixture of the present invention holding the crankshaft;

[0015] FIG Figure 5 is a three-dimensional schematic diagram of the rotating chuck of the present invention;

[0016] FIG Figure 6 is a three-dimensional schematic diagram of the vertical plate bracket and the positioning plug plate of the present invention;

[0017] FIG Figure 7 is a three-dimensional schematic diagram of another angle of the vertical plate bracket and the positioning plug plate of the present invention.

[0018] The following further describes the crankshaft crank journal external cylindrical grinding fixture of the present invention in conjunction with the drawings and specific embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0019] FIG Figure 2It is a three-dimensional schematic diagram of the fixture for external cylindrical grinding of the crank journal of the crankshaft of the present invention, attached Figure 3 It is a schematic diagram of another angle of the fixture for external cylindrical grinding of the crank journal of the crankshaft of the present invention, attached Figure 4 It is a three-dimensional schematic diagram of the fixture for external cylindrical grinding of the crank journal of the crankshaft of the present invention holding a crankshaft, attached Figure 5 It is a three-dimensional schematic diagram of the rotating chuck of the present invention, attached Figure 6 It is a three-dimensional schematic diagram of the vertical plate bracket and the positioning insertion plate of the present invention, attached Figure 7It is another three-dimensional schematic diagram of the upright plate bracket and the positioning insertion plate of the present invention; in the figure, 1 is a rotary chuck, 1-1 is a fixed disk, 1-2 is a support disk, 1-3 is a support plate, 1-4 is a connecting bottom plate, 1-5 is a triangular base, 1-6 is a cushion plate, 1-7 is a clamping cylinder, 1-8 is a support arm, 1-9 is a pressure rod, 2 is an upright plate bracket, 2-1 is an L-shaped upright plate, 2-2 is a front extension plate, 2-3 is a reinforcing rib plate, 3 is a positioning insertion plate, 3-1 is a trapezoidal slide, 3-2 is a trapezoidal slide plate, 3-3 is a positioning cylinder, 3-4 is a connecting plate, 3-5 is an adjusting nut, 3-6 is a buffer spring. It can be seen from the figure that the crankshaft crankpin journal external grinding fixture of the present invention includes a rotary chuck 1, an upright plate bracket 2 and a positioning insertion plate 3; there are two rotary chucks 1, which are symmetrically fixed on the workpiece rotating disks on both sides of the grinding wheel of the external grinding machine in a mirror image, and include a fixed disk 1-1, a support disk 1-2, a support plate 1-3, a connecting bottom plate 1-4, a triangular base 1-5, a cushion plate 1-6, a clamping cylinder 1-7, a support arm 1-8 and a pressure rod 1-9; the fixed disk 1-1 is coaxial with the workpiece rotating disk of the external grinding machine and is fixed on the workpiece rotating disk of the external grinding machine; the diameter of the support disk 1-2 is smaller than that of the fixed disk, and the center of the support disk is vertically offset from the center of the fixed disk by a set distance and then installed on the fixed disk; and, the set distance by which the center of the support disk deviates from the center of the fixed disk is the same as the eccentricity between the axis of the crankshaft rod part and the axis of the crankpin journal; there are two support plates 1-3, which are rectangular, and are symmetrically fixed on both sides of the center of the outer end face of the support disk through the end face of one of the short sides of the rectangle, and the length of the long side of the rectangle is greater than the length of the crankshaft rod part; the connecting bottom plate is fixedly connected to the bottom of the outer ends of the two support plates, and together with the ends of the two support plates, forms a U-shaped structure; there are two triangular bases 1-5, which are symmetrically fixed on the two inner side surfaces of the U-shaped structure, thus forming a V-shaped notch; there are two cushion plates 1-6, which are respectively fixed on the inclined surfaces of the triangular bases, and the height of the V-shaped inclined surface formed by the two cushion plates is such that the axis of the crankshaft rod part is coaxial with the center of the support disk after the crankshaft rod part is axially placed parallel in the V-shaped inclined surface; the piston of the clamping cylinder 1-7 is vertically upward and fixed at the rear side of the U-shaped structure; there are two support arms 1-8, which are oppositely arranged at the connection between the rear side of the U-shaped structure and the clamping cylinder, and there is a hinge hole for hinging the pressure rod at the upper end of the support arm; the pressure rod 1-9 is a lever structure, wherein, the middle of the pressure rod is hinged on the support arm, the bottom side of the rear end head is hinged on the piston end head of the clamping cylinder, and the bottom side of the front end head is fixedly connected with a pressure column; the upright plate bracket 2 is fixed on the base on the left side of the grinding wheel at the middle and rear of the external grinding machine, and includes an L-shaped upright plate 2-1 and a front extension plate 2-2; the bottom end of the long side of the L-shaped upright plate 2-1 is fixed on the base on the left side of the grinding wheel at the middle and rear of the external grinding machine, the short side of the L-shaped upright plate points to the grinding wheel, and the end of the short side is located above the grinding wheel;The front extension plate 2-2 is a rectangular plate and is fixed at the end of the front side of the short side of the L-shaped structure vertical plate; the positioning plug plate 3 is arranged on the front end face of the front extension plate of the vertical plate bracket, and includes a trapezoidal sliding seat 3-1, a trapezoidal sliding plate 3-2, a positioning cylinder 3-3, a connecting plate 3-4, an adjusting nut 3-5 and a buffer spring 3-6; the trapezoidal sliding seat 3-1 is strip-shaped and is fixedly connected to the front end face of the front extension plate of the vertical plate bracket through the outer side; the trapezoidal sliding plate 3-2 is strip-shaped and is slidably inserted into the trapezoidal sliding seat. A trapezoidal positioning notch is arranged at the bottom end of the trapezoidal sliding plate, and the vertical geometric center line of the trapezoidal positioning notch is perpendicular to and intersects with the central axis of the support disc. A connecting stud is arranged at the upper end of the trapezoidal sliding plate; moreover, the upper bottom width of the trapezoidal positioning notch is smaller than the diameter of the crank journal, the lower bottom width is larger than the diameter of the crank journal, and the height is larger than the diameter of the crank journal; the piston of the positioning cylinder 3-3 is vertically and upward fixedly installed on the back side of the trapezoidal sliding seat, and a connecting plate is fixedly connected to the end of the piston; one end of the connecting plate 3-4 is fixedly connected to the end of the piston of the positioning cylinder, and the other end is movably sleeved on the connecting stud at the upper end of the trapezoidal sliding plate; the buffer spring 3-6 is sleeved on the connecting stud at the upper end of the trapezoidal sliding plate and is located below the connecting plate; the adjusting nut 3-5 is screwed on the connecting stud at the upper end of the trapezoidal sliding plate. During specific processing, the rotary chucks are respectively coaxially fixedly connected to the workpiece rotary discs on both sides of the grinding wheel of the cylindrical grinder, so that the rotation axes of the two rotary chucks are coaxial and perpendicular to the feed path of the grinding wheel of the cylindrical grinder, forming mirror symmetry. At the same time, the high-pressure air source is connected to the air source connection part of the rotary chuck of the present invention through a universal seal joint (the technology of connecting the universal seal joint to the high-pressure air source is a mature existing technology). The left and right rod parts of the crankshaft to be ground are respectively placed in the V-shaped inclined planes of the left and right rotary chucks, and note that the crank is placed downward; since the height of the V-shaped inclined plane of the present invention is based on the fact that the axis of the crankshaft rod part is coaxial with the center of the support disc after the crankshaft rod part is axially and parallelly placed in the V-shaped inclined plane, therefore, it can be ensured that the center of the support disc of the left rotary chuck, the axis of the left crankshaft rod part, the axis of the right crankshaft rod part and the center of the support disc of the right rotary chuck are on the same straight line; the positioning cylinder is opened, and the piston of the positioning cylinder pushes the trapezoidal sliding plate to move downward; since the vertical geometric center line of the trapezoidal positioning notch at the bottom end of the trapezoidal sliding plate is perpendicular to and intersects with the central axis of the support disc, the trapezoidal positioning notch of the trapezoidal sliding plate will surely contact the crank journal;Also, since the upper base width of the trapezoidal positioning notch is smaller than the diameter of the crank throw journal, the lower base width is larger than the diameter of the crank throw journal, and the height is larger than the diameter of the crank throw journal. Therefore, when the trapezoidal positioning notch is inserted on the outer circle of the crank throw journal, the vertical geometric center line of the trapezoidal positioning notch must be perpendicular to and intersect with the axis of the crank throw journal. At this time, the axis of the center of the support disk and the axis of the crank throw journal are in the same vertical plane. Also, since the vertical deviation distance between the center of the support disk and the center of the fixed disk is the same as the eccentricity between the axis of the crankshaft rod part and the axis of the crank throw journal, the axis of the crank throw journal is coaxial with the axis of the center of the fixed disk, that is, the axis of the crank throw journal is coaxial with the rotation axes of the workpiece rotation disks on both sides of the grinding wheel of the external cylindrical grinding machine. Open the clamping cylinder, the piston of the clamping cylinder moves upward, pushing the rear end of the pressure rod upward. Through the lever action of the pressure rod, the pressure column at the front end of the pressure rod presses against the upper surface of the crankshaft rod part, so that the crankshaft is pressed and clamped on the left and right rotating chucks. Open the positioning cylinder again, the piston of the positioning cylinder returns to the initial position, driving the trapezoidal slide plate to return to the initial position. At this time, the crankshaft to be machined has been clamped on the left and right rotating chucks, and the axis of the crank throw journal is coaxial with the rotation axes of the workpiece rotation disks on both sides of the grinding wheel of the external cylindrical grinding machine. Open the external cylindrical grinding machine, and the outer circle of the crank throw journal of the crankshaft can be ground. In order to ensure that when the trapezoidal positioning notch is inserted on the outer circle of the crank throw journal, there is a buffer as the position of the crank throw journal is adjusted. A buffer spring is sleeved on the connecting stud at the upper end of the trapezoidal slide plate of the present invention, so that the trapezoidal slide plate can move up and down moderately to avoid hard contact with the crank throw journal. The buffer force of the trapezoidal slide plate can also be adjusted by adjusting the nut. Obviously, the external cylindrical grinding fixture for the crank throw journal of the present invention can effectively ensure the accurate positioning of the crank throw journal, thus ensuring the grinding quality of the outer circle of the crank throw journal; and using cylinders for positioning and clamping operations not only saves time and effort, but also ensures the positioning accuracy and clamping reliability. At the same time, the structure is simple and easy to use.

[0020] In order to improve the stability and reliability of the vertical plate support, a reinforcing rib plate is provided between the front extension plate of the vertical plate support of the present invention and the L-shaped vertical plate, thereby forming a stable triangular structure.

[0021] In order to meet the grinding requirements of the outer circles of crank throw journals of different specifications of crankshafts, the backing plates of the rotating chucks of the present invention are a sequence combination with different thicknesses, and the thicknesses of each group of backing plates are different; each group of backing plates consists of two pieces with the same thickness and corresponds to the crankshaft with a corresponding rod part diameter. It can be seen that after selecting backing plates with different thicknesses and fixing them on the inclined surface of the triangular base of the V-shaped notch, it can meet the requirement that the axis of the crankshaft rod part is coaxial with the center of the support disk after different rod part diameter crankshafts are placed parallel in the V-shaped inclined surface.

[0022] To facilitate the adjustment of the pressing force of the pressure rod on the crankshaft rod, the pressure column at the bottom side of the front end of the rotating chuck pressure rod of the present invention is an adjustable bolt structure. By adjusting the length of the pressure column, the pressing force of the pressure column on the crankshaft rod can be adjusted.

[0023] The beneficial technical effects of the grinding fixture for the outer circle of the crankshaft crankpin of the present invention are that it ensures the accurate positioning of the crankpin and has a simple structure and is convenient to use.

Claims

1. A fixture for external cylindrical grinding of the crankpin journal of a crankshaft, characterized in that, This grinding fixture includes a rotating chuck, a vertical plate bracket, and a positioning plug plate. There are two rotating chucks, which are symmetrically fixed on the workpiece rotating disks on both sides of the grinding wheel of the cylindrical grinder in a mirror image. The rotating chuck includes a fixed disk, a support disk, a support plate, a connecting bottom plate, a triangular base, a cushion plate, a clamping cylinder, a support arm, and a pressure rod. The fixed disk is coaxial with the workpiece rotating disk of the cylindrical grinder and is fixed on the workpiece rotating disk of the cylindrical grinder. The diameter of the support disk is smaller than that of the fixed disk, and the center of the support disk is vertically offset from the center of the fixed disk by a set distance and then installed on the fixed disk. Moreover, the set distance by which the center of the support disk deviates from the center of the fixed disk is the same as the eccentricity between the axis of the crankshaft rod part and the axis of the crankpin journal. When the support disk is installed and fixed on the fixed disk, there are two rectangular support plates on the support disk. They are symmetrically fixed on both sides of the center of the outer end face of the support disk through the end face of one of the short sides of the rectangle, and the length of the long side of the rectangle is greater than the length of the crankshaft rod part. The connecting bottom plate is fixedly connected to the bottom of the outer ends of the two support plates and forms a U-shaped structure together with the ends of the two support plates. There are two triangular bases, which are symmetrically fixed on the two inner side faces of the U-shaped structure, thus forming a V-shaped notch. There are two cushion plates, which are respectively fixed on the inclined surfaces of the triangular bases. The height of the V-shaped inclined surface formed by the two cushion plates is such that the axis of the crankshaft rod part is coaxial with the center of the support disk after the crankshaft rod part is placed axially parallel in the V-shaped inclined surface. The piston of the clamping cylinder is vertically upward and fixed at the rear side of the U-shaped structure. There are two support arms, which are oppositely arranged at the connection between the rear side of the U-shaped structure and the clamping cylinder. An articulated hole for articulating the pressure rod is provided at the upper end of the support arm. The pressure rod is a lever structure. Among them, the middle part of the pressure rod is articulated on the support arm, the bottom side of the rear end head is articulated on the piston end head of the clamping cylinder, and the bottom side of the front end head is fixedly connected with a pressure column. The vertical plate bracket is fixed on the base on the left side of the grinding wheel in the middle and rear of the cylindrical grinder. It includes an L-shaped vertical plate, a front extension plate, and a reinforcing rib plate. The bottom end of the long side of the L-shaped vertical plate is fixed on the base on the left side of the grinding wheel in the middle and rear of the cylindrical grinder. The short side of the L-shaped vertical plate points to the grinding wheel, and the end of the short side is located above the grinding wheel. The front extension plate is a rectangular plate and is fixed at the end of the front side of the short side of the L-shaped vertical plate. The positioning plug plate is arranged on the front end face of the front extension plate of the vertical plate bracket and includes a trapezoidal sliding seat, a trapezoidal sliding plate, a positioning cylinder, a buffer spring, a connecting plate, and an adjusting nut. The trapezoidal sliding seat is long and is fixedly connected to the front end face of the front extension plate of the vertical plate bracket through the outer side face. The trapezoidal sliding plate is long and is slidably inserted into the trapezoidal sliding seat. A trapezoidal positioning notch is provided at the bottom end of the trapezoidal sliding plate. The vertical geometric center line of the trapezoidal positioning notch is perpendicular to and intersects with the central axis of the support disk. A connecting stud is provided at the upper end of the trapezoidal sliding plate. Moreover, the upper bottom width of the trapezoidal positioning notch is smaller than the diameter of the crankpin journal, the lower bottom width is greater than the diameter of the crankpin journal, and the height is greater than the diameter of the crankpin journal.The piston of the positioning cylinder is vertically and upwardly fixedly installed on the back side of the trapezoidal slide seat, and a connecting plate is fixedly connected to the end of the piston; one end of the connecting plate is fixedly connected to the end of the piston of the positioning cylinder, and the other end is movably sleeved on the connecting stud at the upper end of the trapezoidal slide plate; the buffer spring is sleeved on the connecting stud at the upper end of the trapezoidal slide plate and is located below the connecting plate; the adjusting nut is screwed on the connecting stud at the upper end of the trapezoidal slide plate.; 2. The crankshaft crankpin journal outer circle grinding fixture according to claim 1, wherein A reinforcing rib plate is arranged between the front extension plate of the vertical plate bracket and the L-shaped vertical plate, thereby forming a stable triangular structure.

3. The external cylindrical grinding fixture for the crankpin journal of the crankshaft according to claim 1, characterized in that, The rotating chuck backing plate is a sequence combination with different thicknesses, and the thicknesses of each group of backing plates are different; each group of backing plates consists of two pieces with the same thickness and corresponds to the crankshaft with the corresponding rod diameter.

4. The external cylindrical grinding fixture for the crankshaft crankpin journal according to claim 1, wherein The pressing column on the bottom side of the front end of the rotating chuck pressing rod is an adjustable bolt structure.

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