CN113916518A - Cylindrical helical compression spring fatigue test clamp and using method - Google Patents
Cylindrical helical compression spring fatigue test clamp and using method Download PDFInfo
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- CN113916518A CN113916518A CN202111134673.2A CN202111134673A CN113916518A CN 113916518 A CN113916518 A CN 113916518A CN 202111134673 A CN202111134673 A CN 202111134673A CN 113916518 A CN113916518 A CN 113916518A
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- 238000009661 fatigue test Methods 0.000 title claims abstract description 54
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- 238000012360 testing method Methods 0.000 claims abstract description 48
- 238000003801 milling Methods 0.000 claims abstract description 46
- 238000003825 pressing Methods 0.000 claims description 86
- 230000007704 transition Effects 0.000 claims description 20
- 238000000227 grinding Methods 0.000 claims description 10
- 238000012545 processing Methods 0.000 claims description 8
- 230000005484 gravity Effects 0.000 claims description 6
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- 238000012669 compression test Methods 0.000 claims description 5
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- 238000004519 manufacturing process Methods 0.000 description 6
- 238000011056 performance test Methods 0.000 description 3
- 238000005452 bending Methods 0.000 description 1
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Abstract
The invention relates to a cylindrical helical compression spring fatigue test fixture and a use method thereof, the fixture is used for simulating the actual working state of a spring on a common horizontal milling machine, the compression fatigue test of a small-sized cylindrical helical compression spring under the preset amplitude and frequency for lasting preset time can be completed, the test of 8 groups of springs can be simultaneously carried out, and the test efficiency is high; the clamp product has high applicability, and spring fatigue tests with different specifications, different amplitudes and different frequencies can be met by simply replacing the spring positioning element and the eccentric wheel; the clamp is simple and quick to operate, and saves time and labor; the spring fatigue test device is suitable for spring fatigue tests of single-piece and batch production, is low in test cost, and does not need to purchase special spring test equipment.
Description
Technical Field
The invention belongs to the field of machining, and particularly relates to a clamp for a fatigue test of a cylindrical helical compression spring and a using method of the clamp.
Background
The spring is an important element of an industrial system, plays roles of storing energy, automatically controlling, buffering and balancing, returning and positioning and the like in work, and is widely applied to the fields of aviation, automobiles, railways, machinery, electronics and the like. The springs are in various shapes and types, and are mainly divided into compression springs, extension springs, torsion springs, bending springs and the like according to the load bearing property of the springs; the spring can be divided into a simple cylindrical spring and a non-cylindrical spring according to the manufacturing mode and the structural shape. After the spring is manufactured, a plurality of performance tests are required to check whether the spring can achieve the expected design effect. The fatigue test of the spring is an important content of the performance test of the spring. The spring which is not subjected to the fatigue screening test often has failure phenomena such as rigidity reduction, size change and even spring breakage in use.
The existing fatigue test method of the cylindrical helical compression spring comprises the following steps: the spring fatigue test is carried out by using a special spring fatigue testing machine, and the common mechanical spring fatigue test is that a motor and a reducing mechanism are connected with a cam to drive a connecting rod to reciprocate so as to realize the compression motion of the spring. The device is mainly applied to the low-frequency fatigue performance test of various spiral springs, and the amplitude and the frequency of the test can be adjusted according to the technical requirements of the springs. The testing method has the disadvantages of high dependence on equipment, high equipment cost and low testing efficiency, and special testing equipment needs to be purchased.
Disclosure of Invention
The technical problem solved by the invention is as follows: the invention aims to solve the problem that the cylindrical helical compression spring in the prior art is subjected to compression test for a certain duration under certain amplitude and frequency, and simultaneously solves the problems of low test efficiency and high cost of special equipment. The invention provides a cylindrical helical compression spring fatigue test clamp and a using method thereof.
The technical scheme of the invention is as follows: a clamp for a fatigue test of a cylindrical helical compression spring comprises an eccentric wheel, a roller, a pressing plate, a positioning plate, a bottom plate, a bushing and a spring assembly;
the bottom plate is fixedly connected with the positioning plate;
the center of the positioning plate is provided with a through hole, and the bushing is positioned in the through hole and is in interference fit with the inner wall of the through hole;
the pressing plate and the bushing are in clearance fit, and after the pressing plate and the positioning plate are matched, a distance is formed between the pressing plate and the positioning plate and the pressing plate is not contacted;
the spring assemblies are arranged in an area formed between the pressing plate and the positioning plate;
the roller is positioned on the pressing plate through the roller seat and can freely rotate in the roller seat; the middle of the roller is provided with a through hole 1 for fixing the roller 2 in the middle groove of the roller seat through a cylindrical pin, and the thickness of the roller 2 is smaller than the width of the middle groove of the roller seat.
The eccentric wheel is in contact extrusion with the roller wheel, and the roller wheel rotates and drives the roller wheel seat to move axially, so that the pressing plate moves axially simultaneously to compress the spring assembly, and an experiment is carried out.
The further technical scheme of the invention is as follows: the positioning plate is characterized by further comprising a first positioning pin, wherein one end of the first positioning pin is located in the positioning plate mounting hole, the other end of the first positioning pin is located in the pressing plate mounting hole, and the positioning plate and the pressing plate are prevented from rotating relatively.
The further technical scheme of the invention is as follows: the spring assembly comprises a positioning column, a pressing sleeve and a spring; the outer wall of the positioning column is in a multi-step shape, and two ends of the positioning column are respectively positioned in the mounting holes of the pressing plate and the positioning plate; the spring is sleeved on the positioning column, the end face of one end of the spring is limited through the disc surface in the middle of the positioning column, and the spring is original in length; one end of the pressing sleeve is in contact with the end face of the other end of the spring through self weight, and the other end of the pressing sleeve is in contact with the pressing plate.
The further technical scheme of the invention is as follows: the positioning plate is characterized by further comprising a second positioning pin, wherein two ends of the second positioning pin are respectively located in the mounting holes of the positioning plate and the bottom plate, and the positioning plate and the bottom plate are prevented from rotating mutually.
The further technical scheme of the invention is as follows: the two ends of the positioning plate are cylindrical, and the middle part of the positioning plate is disc-shaped; a plurality of step holes are uniformly distributed on the end surface of the disc in the middle of the positioning plate in the circumferential direction and are close to the root part of the cylinder, and the bottom surface of the counter bore is attached to the disc surface in the middle of the positioning column; the diameter of a counter bore in the step hole is larger than the outer diameter of the positioning column disc, so that the positioning column can be easily assembled in the counter bore of the positioning plate; the depth of the counter bore is smaller than the thickness of the positioning column disc, so that the end face of the positioning column disc protrudes out of the positioning plate, the end face of one end of the spring is ensured to be higher than the positioning plate, and the condition of the spring is conveniently observed in the compression test process; the stepped hole on the positioning plate is in interference fit with the small shaft end of the positioning column, and the interference magnitude ensures that the positioning column cannot fall off from the positioning plate; a plurality of step through holes are uniformly distributed on the middle disc of the positioning plate along the circumferential direction and used for fixedly connecting the positioning plate and the bottom plate through inner hexagonal cylindrical head screws.
The further technical scheme of the invention is as follows: one end of the pressure plate is disc-shaped, and the other end of the pressure plate is cylindrical; the cylindrical end of the pressure plate is in clearance fit with the hole in the center of the bushing, and the clearance ensures that the pressure plate can freely move up and down in the hole of the bushing; a plurality of through holes are uniformly distributed on the end face of the pressing plate disc end along the circumference, the through holes are abdicating holes of the positioning columns, the diameter of each through hole is larger than the outer diameter of the long shaft end of each positioning column, and the positioning columns can freely pass through the through holes and cannot interfere with each other when the pressing plate reciprocates up and down; after the positioning plate is installed, the axes of the through holes are superposed with the axes of the through holes which are uniformly distributed on the positioning plate and the bottom plate in the circumferential direction; a blind hole is formed in the center of the disc end of the pressing plate, the blind hole is connected with the small shaft end of the roller seat in an interference fit mode, and the interference magnitude ensures that the roller seat cannot fall off from the pressing plate; the end face of the pressing plate disc is positioned between the through hole and the blind hole, and is provided with a through hole which is used as a yielding hole of the first positioning pin, the hole is in clearance fit with the first positioning pin, and the clearance ensures that the pressing plate can freely reciprocate up and down along the first positioning pin; the root of the small end cylinder of the pressure plate is provided with a grinding wheel overrun groove, so that the processing of the excircle and the end face is facilitated.
The further technical scheme of the invention is as follows: the whole eccentric wheel is a disc part; 2 sections of 180-degree circular arcs are symmetrically designed in the circumferential direction of the eccentric wheel, the center of the circular arc has an eccentric amount relative to the symmetric center of the eccentric wheel along one direction, and the eccentric amount is equal to the compression amount of a spring fatigue test; a through hole is formed in the center of the eccentric wheel, a key groove is formed in the inner wall of the through hole and used for fixing the eccentric wheel on a cutter bar of a common horizontal milling machine through a flat key to realize torque transmission, and the cutter bar drives the eccentric wheel to rotate; the eccentric wheel 1 can compress the spring twice when rotating for one circle.
The further technical scheme of the invention is as follows: the guide column is integrally in a stepped shaft shape and consists of 2 sections of cylinders; the small end of the guide column 9 is inserted into the through hole at the position close to the U-shaped groove on the bottom plate from the bottom surface of the bottom plate 8, and the guide column 9 is ensured not to fall off from the bottom plate 8 by adopting transition fit; the root of the small end of the guide column 9 is provided with a grinding wheel overtravel groove, and the step surface of the guide column 9 is ensured to be attached to the bottom surface of the bottom plate 8 in the vertical direction; the big end of the guide column 9 is exposed out of the bottom surface of the bottom plate 8 and is inserted into a T-shaped groove of a workbench of a common horizontal milling machine, and chamfers are arranged on the end surface of the shaft end of the guide column 9 along the circumferential direction.
The further technical scheme of the invention is as follows: the application method of the clamp for the fatigue test of the cylindrical helical compression spring is characterized by comprising the following steps of:
step 1: completing the preparation work for mounting the components before the test;
step 2: adjusting the height of a workbench of a common horizontal milling machine, and compressing a pressure head assembly through an eccentric wheel 1 according to the requirement of a spring fatigue test to enable a spring to be in a pre-compression state; adjusting the initial position of the eccentric wheel 1 to enable the straight surface part on the circumference of the eccentric wheel 1 to be in contact with the roller 2;
and step 3: setting the revolution of a main shaft of a common horizontal milling machine; starting a main shaft switch of the common horizontal milling machine, wherein the eccentric wheel 1 periodically compresses the roller 2 at the moment, the roller 2 drives the pressure head assembly to periodically compress the spring, and a spring fatigue test is started; starting test timing at the same time;
and 4, step 4: after the preset test time is reached, the height position of a workbench of the common horizontal milling machine is adjusted to separate the eccentric wheel 1 from the roller 2, and a main shaft switch of the common horizontal milling machine is closed; at this point, the spring fatigue test was stopped;
and 5: after the pressure head assembly is taken down, sequentially taking down 8 pressure sleeves 5, and finally sequentially taking down 8 springs; at this time, the spring fatigue test was ended.
The further technical scheme of the invention is as follows: the step 1 comprises the following steps:
step 1.1: the method comprises the following steps of installing a fixture body consisting of a bottom plate 8, a positioning plate 7, a positioning column 6, a lining 11 and a guide column 9 on a workbench of a common horizontal milling machine, inserting the large end of the guide column 9 into a T-shaped groove of the workbench of the milling machine, adjusting a test fixture, fixing the test fixture on the workbench of the common horizontal milling machine through a U-shaped groove on the bottom plate 8 by using a special screw for the T-shaped groove, and ensuring that the test fixture cannot move or rotate;
step 1.2: sequentially sleeving the springs on the long shaft ends of the positioning columns 6, and enabling the lower end faces of the springs to be tightly attached to the circular truncated cone in the middle of the positioning columns 6;
step 1.3: sequentially sleeving the pressing sleeve 5 at the long shaft end of the positioning column 6, wherein the lower end surface of the pressing sleeve 5 is contacted with the upper end surface of the spring by virtue of self weight;
step 1.4: inserting the small shaft end of a pressure plate 4 in a pressure head assembly consisting of a roller 2, a roller seat 3 and a pressure plate 4 into the central hole of a bush 11; rotating the pressure head assembly to enable 8 through holes uniformly distributed along the circumference on the pressure plate 4 to be respectively aligned with 8 positioning columns 6, and simultaneously sleeving the first positioning pin 10 abdicating holes on the pressure plate 4 on the first positioning pin 10 to ensure that the small shaft end of the pressure plate 4 freely reciprocates up and down along the first positioning pin 10; at the moment, the pressure head assembly presses the pressure sleeve 5 under the action of gravity;
step 1.5: a key groove on the inner wall of a central hole of the eccentric wheel (1) fixedly connects the eccentric wheel with a cutter bar of a common horizontal milling machine through a flat key, and the cutter bar drives the eccentric wheel 1 to rotate; the spring can be compressed twice when the eccentric wheel 1 rotates for one circle;
step 1.6: the position of a workbench of a common horizontal milling machine is adjusted, so that the eccentric wheel 1 is in contact with the roller 2 and can rotate relatively, the end surfaces on two sides of the eccentric wheel 1 are positioned in the middle of the end surfaces on two sides of the roller 2, the roller 2 can be periodically compressed when the eccentric wheel 1 rotates, and the pressure head assembly is driven to reciprocate up and down.
Effects of the invention
The invention has the technical effects that: the invention provides a cylindrical helical compression spring fatigue test fixture, which is used for simulating the actual working state of a spring on a common horizontal milling machine, can finish the compression fatigue test of a small cylindrical helical compression spring under the preset amplitude and frequency for a preset time, can simultaneously perform the test of 8 groups of springs, and has high test efficiency; the clamp product has high applicability, and spring fatigue tests with different specifications, different amplitudes and different frequencies can be met by simply replacing the spring positioning element and the eccentric wheel; the clamp is simple and quick to operate, and saves time and labor; the clamp is suitable for spring fatigue tests of single-piece and batch production, the test cost is low, special spring test equipment does not need to be purchased, and the manufacturing cost of the clamp is about 1000 yuan.
The invention realizes the compression fatigue test of the small cylindrical helical compression spring with preset amplitude and frequency by simulating the actual working condition of the spring on a common horizontal milling machine, overcomes the defect that the original test method is greatly limited by test equipment, and has simple operation and convenient spring assembly and disassembly; the clamp has simple structure, easy manufacture and low cost, and is suitable for single-piece and batch production; the set of clamps comprises 8 stations, 8 springs can be tested at the same time, and the test efficiency is high; the applicable spring range of the clamp is wide, the replacement of spring positioning elements with different sizes can be applicable to springs with different specifications, and the replacement of eccentric wheels with different sizes can be applicable to fatigue tests with different amplitudes; the test cost is low, and special equipment does not need to be purchased, and the specific effects are as follows:
1. the spring compression fatigue test device can be fixed on a workbench of a common horizontal milling machine to perform a spring compression fatigue test, can realize the adjustment of test frequency by adjusting the revolution of a main shaft of the milling machine, and has low requirements on equipment and environment;
2. the spring is arranged on the positioning column, so that the applicable spring range is wide; the eccentric wheel is in direct contact with the roller, so that the friction resistance in the motion process can be reduced; the pressing sleeve directly contacts with the spring to compress the spring, so that the end face of the spring is uniformly stressed;
3. 2 working areas are symmetrically designed on the eccentric wheel, the revolution of the motor can be reduced to 50% of the test revolution, the motor can run at a low revolution, and the test safety is improved;
4. this anchor clamps sets up 8 stations, can supply 8 springs to test simultaneously, and product strong adaptability is compatible high, and the test efficiency is high, experimental low cost.
Drawings
FIG. 1 is a three-dimensional schematic view of a spring pre-compression condition test fixture of the present invention.
FIG. 2 is a front view of the spring pre-compression condition test fixture of the present invention.
Fig. 3 is a front view of the spring compression test fixture of the present invention.
Fig. 4 is a schematic view of a spring structure.
Fig. 5 is a schematic view of the eccentric wheel structure.
Fig. 6 is a schematic view of the roller structure.
Fig. 7 is a schematic view of the roller seat structure.
Fig. 8 is a schematic view of a platen structure.
Fig. 9 is a schematic view of a press sleeve structure.
Fig. 10 is a schematic view of a positioning post structure.
FIG. 11a is a front view of the positioning plate.
FIG. 11b is a top view of the positioning plate.
Fig. 12 is a schematic view of the bottom plate structure.
Fig. 13 is a schematic view of a guide post structure.
FIG. 14 is a schematic view of a first alignment pin
Fig. 15 is a schematic view of a bushing structure.
FIG. 16 is a schematic view of a second alignment pin
In the figure, 1-eccentric wheel, 2-roller, 3-roller seat, 4-pressing plate, 5-pressing sleeve, 6-positioning column, 7-positioning plate, 8-bottom plate, 9-guiding column, 10-first positioning pin, 11-bush, 12-second positioning pin and 13-spring
Detailed Description
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.
Referring to fig. 1-16, the fatigue test fixture for the cylindrical helical compression spring of the invention comprises an eccentric wheel 1, a roller 2, a roller seat 3, a pressing plate 4, a pressing sleeve 5, a positioning column 6, a positioning plate 7, a bottom plate 8, a guide column 9, a first positioning pin 10, a bush 11 and a second positioning pin 12. The bottom plate 8 is placed on the work of a common horizontal milling machine; 4 step through holes are uniformly distributed on the circular disc surface of the positioning plate 7 along the circumference, and the positioning plate 7 is fixedly connected with the bottom plate 8 through inner hexagonal cylindrical head screws; a through hole is formed in the positioning plate 7 close to the step hole, and the second positioning pin 12 is connected with the through hole in the corresponding position of the bottom plate 8 through transition fit H7/m6, so that the positioning plate 7 and the bottom plate 8 are prevented from rotating relatively; a through hole is formed in the end face of the long shaft of the positioning plate 7, a first positioning pin 10 is installed in the through hole, the through hole is connected with one end of the first positioning pin 10 through transition fit H7/m6, it is guaranteed that the first positioning pin 10 cannot fall off from the positioning plate 7, one end of the first positioning pin 10 is higher than the end face of the long shaft of the positioning plate 7, the other end of the first positioning pin 10 is always connected with the corresponding through hole in the pressing plate 4, the first positioning pin 10 can serve as an auxiliary guide pillar of the pressing plate 4, the positioning plate 7 and the pressing plate 4 are prevented from rotating relatively, and meanwhile it is guaranteed that the pressing plate 4 cannot be disengaged from the first positioning pin 10 when the spring 13 to be measured is in a free state; 8 step through holes are uniformly distributed in the circular disc surface of the positioning plate 7 along the center of the circular disc surface, the positioning columns 6 are installed in the step through holes, the short shaft ends of the positioning columns 6 are connected with the through holes in an interference fit H7/r6, interference magnitude ensures that the positioning columns 6 cannot fall off from the positioning plate 7, and the step surfaces of the positioning columns 6 are attached to the end surfaces of the step holes of the positioning plate 7 in the vertical direction;
the spring 13 to be tested and the pressing sleeve 5 are sequentially sleeved on the excircle of the long shaft end of the positioning column 6, one end face of the spring 13 is tightly attached to the step face of the positioning column 6 by virtue of gravity, and the pressing sleeve 5 is tightly attached to the other end face of the spring 13 by virtue of gravity; the bushing 11 is connected with a step hole in the center of the positioning plate 7 in an interference fit manner, namely H7/r6, interference magnitude ensures that the bushing 11 cannot fall off from the positioning plate 7, and a step surface of the bushing 11 is attached to an end surface of the step hole in the center of the positioning plate 7 in the vertical direction; the cylindrical end of the pressure plate 4 is connected with the central blind hole of the bush 11 by clearance fit H7/g6, and the clearance amount ensures that the pressure plate 4 can freely move up and down in the central hole of the bush 11; the pressure plate 4 is connected with the first positioning pin 10 by adopting clearance fit D10/m6, the clearance ensures that the pressure plate 4 can freely move up and down along the first positioning pin 10, and the end face of the pressure plate 4 is attached to the end face of the pressure sleeve 5 by means of gravity;
the cylinder at one end of the roller seat 3 is connected with the central hole of the pressure plate 4 by interference fit H7/s6, the interference magnitude ensures that the roller seat 3 cannot fall off from the pressure plate 4, and the step surface of the roller seat 3 is ensured to be attached to the end surface of the pressure plate 4 in the vertical direction; the roller 2 is arranged in a groove-shaped structure at the other end of the roller seat 3 through a cylindrical pin, the roller 2 can freely rotate around the cylindrical pin, two ends of the cylindrical pin are connected with the roller seat 3 by adopting transition fit H7/m6, and the clearance amount ensures that the cylindrical pin cannot fall off from the roller seat 3; a key groove on the inner wall of a central hole of the eccentric wheel 1 fixedly connects the eccentric wheel 1 with a cutter bar of a common horizontal milling machine through a flat key, and the cutter bar drives the eccentric wheel 1 to rotate;
guide posts 9 are installed at two ends of the bottom plate 8, the small ends of the guide posts 9 are connected with mounting holes in the bottom plate 8 through transition fit H7/m6, the guide posts 9 are guaranteed not to fall off from the bottom plate 8, the step faces of the guide posts 9 are guaranteed to be attached to the lower end face of the bottom plate 8 in the vertical direction, the large ends of the guide posts 9 are exposed out of the lower end face of the bottom plate 8 and are inserted into key grooves of a workbench of a common horizontal milling machine, and rotation of the test fixture relative to the workbench is prevented.
Referring to fig. 5; the eccentric wheel 1 is integrally a disc-shaped part and is made of steel materials; 2 sections of 180-degree circular arcs are symmetrically designed in the circumferential direction of the eccentric wheel 1, the center of each circular arc is eccentric relative to the symmetric center of the eccentric wheel 1 along one direction, and the eccentric amount is equal to the compression amount of a fatigue test of the spring 13; a through hole is formed in the center of the eccentric wheel 1, 1 key groove is formed in the inner wall of the through hole and used for fixing the eccentric wheel 1 on a cutter bar of a common horizontal milling machine through a flat key to realize torque transmission, and the cutter bar drives the eccentric wheel 1 to rotate; the spring 13 can be compressed twice when the eccentric wheel 1 rotates for one circle.
Referring to fig. 6; the roller 2 is cylindrical and is made of steel materials; a central hole is formed along the axis of the roller, a cylindrical pin passes through the through hole, the roller 2 is fixed on the roller seat 3, and the roller 2 can rotate around the cylindrical pin;
referring to fig. 7; the roller seat 3 is integrally in a stepped shaft shape, consists of 2 sections of cylinders with different diameters and is made of steel materials; 2 symmetrical planes are arranged on the excircle of the cylinder at the large end of the roller seat 3, so that the roller seat 3 can be clamped conveniently when being installed, and through holes are symmetrically processed on the planes and used for installing the roller 2 through a cylindrical pin; a rectangular groove is formed in the large-end cylinder of the roller seat 3 along the axis direction, and two side faces of the rectangular groove are parallel to a plane on the excircle of the large-end cylinder; the idler wheel 2 is hung in the middle of the rectangular groove, the width of the rectangular groove is 0.3mm larger than that of the idler wheel 2, and the two side faces of the idler wheel 2 cannot interfere with the two side faces of the rectangular groove when rotating;
the through hole on the excircle plane of the cylinder at the large end of the roller seat 3 is connected with the two ends of the cylindrical pin by adopting transition fit H7/m6, so that the cylindrical pin cannot fall off from the roller seat 3, the distance from the through hole to the bottom of the rectangular groove is larger than the radius value of the roller 2 by 1mm, and the excircle of the roller 2 cannot interfere with the bottom surface of the rectangular groove when rotating; the small end shaft of the roller seat 3 is connected with the central hole of the pressure plate 4 by adopting interference fit H7/s6, and the interference magnitude ensures that the roller seat 3 cannot fall off from the pressure plate 4, so that the roller seat 3 and the pressure plate 4 form a combined body and synchronously move up and down; the root of the small end shaft of the roller seat 3 is provided with a grinding wheel overrun groove, so that the processing of the excircle and the end face is convenient, and the root end face of the small end shaft of the roller seat 3 is ensured to be tightly attached to the pressing plate 4;
referring to fig. 8; the pressing plate 4 is made of a steel material; one end is disc-shaped and the other end is cylindrical; the cylindrical end of the pressure plate 4 is connected with a hole in the center of the bush 11 by clearance fit H7/g6, and the clearance amount ensures that the pressure plate 4 can freely move up and down in the hole of the bush 11; 8 through holes are uniformly distributed on the end face of the disc end of the pressure plate 4 along the circumference, the through holes are abdicating holes of the positioning columns 6, the diameter of each hole is larger than the outer diameter of the long shaft end of each positioning column 6, and the positioning columns 6 can freely pass through the holes and cannot interfere with each other when the pressure plate 4 moves up and down in a reciprocating mode; after installation, the axes of the 8 through holes are superposed with the axes of the 8 through holes which are uniformly distributed on the positioning plate 7 and the bottom plate 8 in the circumferential direction; the center of the disc end of the pressing plate 4 is provided with a blind hole, the blind hole is connected with the small shaft end of the roller seat 3 by adopting interference fit H7/s6, and the interference magnitude ensures that the roller seat 3 cannot fall off from the pressing plate 4, so that the roller seat 3 and the pressing plate 4 form a whole and can synchronously carry out up-and-down reciprocating motion; a through hole is formed in the disc end face of the pressing plate 4 and located between the through hole and the blind hole, and serves as a yielding hole of the first positioning pin 10, the hole is connected with the first positioning pin 10 in a clearance fit mode D10/m6, and the clearance amount ensures that the pressing plate 4 can freely reciprocate up and down along the first positioning pin 10; the root of the small end cylinder of the pressure plate 4 is provided with a grinding wheel overrun groove, so that the processing of the excircle and the end face is convenient;
referring to fig. 9; the pressing sleeve 5 is a revolving body part and is made of steel materials; the end face of the pressing sleeve 5 is provided with a central through hole along the axis, the pressing sleeve 5 is sleeved on the long shaft end of the positioning column 6, one end face of the pressing sleeve 5 is contacted with the spring 13, and the other end face of the pressing sleeve is contacted with the pressing plate 4; the diameter of a central through hole of the pressing sleeve 5 is 0.3-0.5 mm smaller than the inner diameter of the spring 13 and 0.3-0.5 mm larger than the outer diameter of the long shaft of the positioning column 6, so that the end face of one end of the pressing sleeve 5 can be completely contacted with the end face of the spring 13, the spring 13 is uniformly stressed when compressed, and meanwhile, the pressing sleeve 5 is ensured to freely reciprocate up and down along the long shaft of the positioning column 6; the height of the pressing sleeve 5 is equal to the free height of the spring 13, so that a certain guiding effect is ensured; chamfers are arranged on two end faces of the pressing sleeve 5 along the circumferential direction, so that smooth edges are guaranteed.
Referring to fig. 10; the positioning column 6 is integrally in a stepped shaft shape, two ends of the positioning column are cylindrical, and the middle of the positioning column is in a disc shape; is made of steel material; the short shaft end of the positioning column 6 is connected with 8 step holes uniformly distributed on the positioning plate 7 in the circumferential direction in an interference fit manner H7/r6, and the interference magnitude ensures that the positioning column 6 cannot fall off from the positioning plate 7; the root of the short shaft end of the positioning column 6 is provided with a grinding wheel overrun groove, so that the processing of an excircle and an end face is facilitated, and meanwhile, the end face of the root of the short shaft end of the positioning column 6 is ensured to be attached to the end face of the step hole of the positioning plate 7; the spring 13 and the pressing sleeve 5 are sequentially sleeved on the excircle of the long shaft of the positioning column 6, the outer diameter of the long shaft of the positioning column 6 is smaller than the inner diameter of the spring 13 by 0.3-0.5 mm, the spring 13 is ensured not to interfere with the long shaft end of the positioning column 6 in a compressed state, and the spring 13 is prevented from being clamped; the length of the long shaft end of the positioning column 6 is not less than the sum of the free height of the spring 13 and the height of the pressing sleeve 5, so that the spring 13 and the pressing sleeve 5 can always reciprocate up and down along the long shaft end of the positioning column 6; the diameter of a disk in the middle of the positioning column 6 is 3-5 mm larger than the outer diameter of the spring 13, so that the end face of the spring 13 can be completely placed on the end face; the root of the long shaft end of the positioning column 6 is provided with a grinding wheel overtravel groove, so that the processing of an excircle and an end face is facilitated; the two end faces of the positioning column 6 are provided with chamfers along the circumferential direction, so that smooth edges are guaranteed, and the spring 13 and the positioning column 6 are convenient to install.
Refer to fig. 11; the two ends of the positioning plate 7 are cylindrical, the middle part of the positioning plate is disc-shaped and made of steel materials; 8 stepped holes are uniformly distributed on the end surface of the disc in the middle of the positioning plate 7 in the circumferential direction, the position of each stepped hole is close to the root of the cylinder, and the bottom surface of each counter bore is attached to the disc surface in the middle of the positioning column 6; the diameter of a counter bore in the step hole is 1-3 mm larger than the outer diameter of a disc of the positioning column 6, so that the positioning column 6 can be easily assembled in the counter bore of the positioning plate 7; the depth of the counter bore is 0.5-1 mm smaller than the thickness of the positioning column 6 disc, so that the end face of the positioning column 6 disc protrudes out of the positioning plate 7, the end face of one end of the spring 13 is higher than the positioning plate 7, and the condition of the spring 13 is conveniently observed in the compression test process; a step hole on a positioning plate 7 is connected with a small shaft end of a positioning column 6 by adopting interference fit H7/r6, and interference magnitude ensures that the positioning column 6 cannot fall off from the positioning plate 7; 4 step through holes are uniformly distributed in the circumferential direction on a disc in the middle of the positioning plate 7 and used for fixedly connecting the positioning plate 7 with the bottom plate 8 through internal hexagonal cylindrical screws, a through hole is further formed in the position, forming an included angle of 20 degrees with one step through hole, on the end face of the disc, and a second positioning pin 12 is installed and penetrates through the through hole and the corresponding through hole in the bottom plate 8 respectively and is connected through transition fit H7/m6, so that the positioning plate 7 and the bottom plate 8 are prevented from rotating relatively;
the length of the long shaft end of the positioning plate 7 is 3-5 mm greater than the free length of the spring 13, so that the positioning plate 7 has a good guiding effect; a through hole is formed in the end face of the long shaft end of the positioning plate 7 along the axis, the axis of the through hole is overlapped with the axis of the through hole at the corresponding position on the pressure plate 4, the through hole is connected with the first positioning pin 10, and the first positioning pin 10 is connected with the first positioning pin 10 in a transition fit H7/m6, so that the first positioning pin 10 cannot fall off from the positioning plate 7; the end face of one end of the first positioning pin 10 is higher than the end face of the long shaft of the positioning plate 7, and the raised distance is equal to the free length of the spring 13, so that one end of the first positioning pin 10 is always in a connection state with a corresponding pin hole on the pressure plate 4 and is used as an auxiliary guide post for the up-and-down reciprocating motion of the pressure plate 4, the positioning plate 7 and the pressure plate 4 are prevented from rotating relatively, and the pressure plate 4 is prevented from being separated from the first positioning pin 10 when the spring 13 is in a free state;
a step through hole is formed in the center of the end face of the long shaft end of the positioning plate 7, the bottom surface of the counter bore is attached to the step face of the bushing 11, the step through hole is connected with the column end of the bushing 11 in an interference fit manner, H7/r6 is adopted, and the interference magnitude ensures that the bushing 11 cannot fall off from the positioning plate 7;
the short shaft end of the positioning plate 7 is connected with the bottom plate 8 by transition fit H7/n6 and is used as initial positioning for mounting the positioning plate 7 on the bottom plate 8; the root of the short shaft end of the positioning plate 7 is provided with a grinding wheel overtravel groove, so that the processing of the excircle and the end face is convenient, and the end face of the disk in the middle of the positioning plate 7 is ensured to be attached to the end face of the bottom plate 8; the end face of the short shaft end of the positioning plate 7 is provided with a chamfer along the circumferential direction, so that smooth edges are guaranteed, and the installation is convenient.
Referring to fig. 12; the bottom plate 8 is a rectangular plate part and is made of steel materials; a through hole is formed in the center of the bottom plate 8, is an initial positioning hole for mounting the positioning plate 7 and is connected with the short shaft end of the positioning plate 7 by adopting transition fit H7/n 6; the position close to the central through hole is circumferentially provided with 8 uniformly distributed through holes which are superposed with the circumference of 8 step through holes uniformly distributed on the positioning plate 7 and the pressing plate 4, wherein the positioning column 6 is detached from the positioning plate 7 through the holes by using a detaching tool;
4 threaded holes are uniformly distributed in the bottom plate 8, the threaded holes coincide with the axes of the threaded holes in the positioning plate 7, a through hole is formed in the position, which forms an included angle of 20 degrees with one of the threaded holes, of the positioning plate 7 fixed on the bottom plate 8 through the connection of inner hexagonal cylindrical head screws, the second positioning pins 12 respectively penetrate through the through holes and the corresponding through holes in the positioning plate 7 and are connected through transition fit H7/m6, and the bottom plate 8 and the positioning plate 7 are prevented from rotating relatively;
two ends of the bottom plate 8 are symmetrically provided with U-shaped grooves along the axis, and the U-shaped grooves are used for fixing the bottom plate 8 on a workbench of a common horizontal milling machine through special screws for T-shaped keyways; two through holes are respectively formed at positions close to the U-shaped grooves and used for installing the guide posts 9, and the through holes are connected with the small ends of the guide posts 9 by adopting transition fit H7/m6, so that the guide posts 9 cannot fall off from the bottom plate 8; the bottom plate 8 is provided with a large chamfer at 4 corners, the bottom is a plane and is directly placed on a workbench of a common horizontal milling machine for use;
referring to fig. 13; the guide column 9 is integrally in a stepped shaft shape, consists of 2 sections of cylinders and is made of steel materials; the small end of the guide post 9 is inserted into the through hole at the position close to the U-shaped groove on the bottom plate from the bottom surface of the bottom plate 8 and is connected by adopting transition fit H7/m6, and the gap amount ensures that the guide post 9 cannot fall off from the bottom plate 8; the root of the small end of the guide column 9 is provided with a grinding wheel overrun groove, so that the processing of an excircle and an end face is facilitated, and the step surface of the guide column 9 is ensured to be attached to the bottom surface of the bottom plate 8 in the vertical direction; the large end of the guide column 9 is exposed out of the bottom surface of the bottom plate 8, and is inserted into a T-shaped groove of a workbench of a common horizontal milling machine to be used as the positioning of the installation of a test fixture, and meanwhile, the test fixture is prevented from rotating relative to the workbench; the shaft end face of the guide column 9 is provided with chamfers along the circumferential direction, so that smooth edges are guaranteed, and the installation is convenient.
Referring to fig. 14; the first locating pin 10 is a cylindrical part and is made of steel materials; one end of the first positioning pin 10 is inserted into a through hole formed in the end face of the long shaft end of the positioning plate 7 along the axis, and is connected with the positioning plate 7 by adopting transition fit H7/m6, so that the first positioning pin 10 cannot fall off from the positioning plate 7; the other end terminal surface of first locating pin 10 is higher than 7 long axle head terminal surfaces of locating plate, and the distance that exceeds equals the free length of spring 13 for correspond the pinhole on first locating pin 10 and the clamp plate 4 and remain connected state throughout, as clamp plate 4 up-and-down reciprocating's supplementary guide pillar usefulness, prevent locating plate 7 and clamp plate 4 simultaneously and take place relative rotation, guarantee that spring 13 can not throw off with first locating pin 10 when free state.
Referring to fig. 15; the bushing 11 is a sleeve part integrally, consists of 2 sections of cylinders and is made of steel materials; the end face of the bush 11 is provided with a central through hole along the axis, the hole is used as a guide sleeve for the pressing plate 4 to reciprocate up and down, the central through hole is connected with the small shaft end of the pressing plate 4 by clearance fit H7/g6, and the clearance ensures that the pressing plate 4 can freely move up and down along the central through hole of the bush 11; the small shaft end of the bushing 11 is inserted into a central step hole of the positioning plate 7 and connected by adopting interference fit H7/r6, and the interference magnitude ensures that the bushing 11 cannot fall off from the positioning plate 7; the step surface of the large end of the bush 11 is attached to the end surface of a step hole in the center of the positioning plate 7; the end face of the small end of the bush 11 is provided with a chamfer angle along the circumferential direction, so that smooth edges are guaranteed, and the installation is convenient.
Referring to fig. 16; the second positioning pin 12 is a cylindrical part and is made of a steel material; the second positioning pins 12 respectively penetrate through holes which are formed in the positioning plate 7 and the bottom plate 8 and form an included angle of 20 degrees with one of the 4 uniformly distributed holes, the through holes are connected by adopting transition fit H7/m6, the gap amount ensures that the second positioning pins 12 cannot fall off from the holes of the positioning plate 7 and the bottom plate 8, and the positioning plate 7 and the bottom plate 8 are prevented from rotating relatively; the end face of one end of the second positioning pin 12 is flush with the upper surface of the middle disc of the positioning plate 7, and the end face of the other end is in the through hole of the bottom plate 8.
During assembly:
1. placing the bottom plate 8 on a common clamp platform;
2. inserting the small shaft end of the positioning plate 7 into the central through hole of the bottom plate 8 by adopting transition fit H7/n6 to serve as initial positioning for mounting the positioning plate 7 on the bottom plate 8;
rotating the positioning plate 7 to enable 4 uniformly distributed step holes and 1 through hole close to the step holes on the end face of the disc in the middle of the positioning plate 7 to be respectively superposed with the axes of the corresponding threaded hole and the corresponding through hole on the bottom plate 8, then respectively inserting 4 internal hexagonal socket head screws into the four step holes on the positioning plate 7, fixing the positioning plate 7 on the bottom plate 8 and ensuring that the disc surface of the positioning plate 7 is tightly attached to the plane of the bottom plate 8;
respectively inserting a second positioning pin 12 into a through hole close to the mounting hole of the inner hexagonal socket head cap screw on the positioning plate 7 and a through hole close to the mounting hole of the inner hexagonal socket head cap screw on the bottom plate 8, and connecting by adopting transition fit H7/m6 to prevent the positioning plate 7 and the bottom plate 8 from rotating relatively;
3. respectively inserting the short shaft ends of 8 positioning columns 6 into 8 step through holes uniformly distributed on the positioning plate 7, and ensuring that the end surface of the circular truncated cone in the middle of each positioning column 6 is attached to the end surface of the step hole of the positioning plate 7;
4. the bushing 11 is inserted into a through hole of a central step of the positioning plate 7 and connected by adopting interference fit H7/r6, interference magnitude ensures that the bushing 11 cannot fall off from the positioning plate 7, and simultaneously ensures that the end surface of the step surface of the bushing 11 is attached to the end surface of the step hole of the positioning plate 7.
5. One end of a first positioning pin 10 is inserted into a through hole formed in the end face of the long shaft of the positioning plate 7 and is connected by transition fit H7/m6, so that the cylindrical pin cannot fall off from the positioning plate 7, the other end of the first positioning pin 10 needs to be higher than the end face of the long shaft of the positioning plate 7, the higher distance is approximately equal to the free length of a spring 13, the positioning plate 7 and a pressure plate 4 are prevented from rotating relatively, and meanwhile, the pressure plate 4 cannot be separated from the first positioning pin 10 when the spring 13 is in a free state;
6. the small end of the guide column 9 is inserted into the through hole close to the U-shaped groove of the bottom plate 8 from the bottom surface of the bottom plate 8 and is connected by adopting transition fit H7/m6, the gap amount ensures that the guide column 9 cannot fall off from the bottom plate 8, and the step surface of the guide column 9 is attached to the bottom surface of the bottom plate 8 in the vertical direction; the large end of the guide column 9 is exposed out of the bottom surface of the bottom plate 8;
and placing a fixture body consisting of the bottom plate 8, the positioning plate 7, the positioning column 6, the bush 11 and the guide column 9 on a clamp stand for later use.
7. The roller 2 is placed in a rectangular groove in the middle of the roller seat 3, a cylindrical pin sequentially penetrates through the roller seat 3 and the roller 2, the roller 2 is suspended and fixed on the roller seat 3, the roller 2 and the roller seat 3 form a combined body, and the roller 2 is ensured to freely rotate in the rectangular groove of the roller seat 3 and cannot interfere with two side surfaces and the bottom surface of the rectangular groove.
8. The small shaft end of the roller seat 3 with the roller 2 is inserted into a blind hole in the middle of a disc of the pressing plate 4 and is connected by adopting interference fit H7/s6, and the interference magnitude ensures that the roller seat 3 cannot fall off from the pressing plate 4, so that the roller 2, the roller seat 3 and the pressing plate 4 form a combined body which can synchronously reciprocate up and down; placing a pressure head assembly consisting of the roller 2, the roller seat 3 and the pressure plate 4 on a clamp platform for standby;
9. and placing the eccentric wheel 1 and the pressing sleeve 5 on a vice bench for standby.
When in work:
1. the fixture body consisting of the bottom plate 8, the positioning plate 7, the positioning column 6, the lining 11 and the guide column 9 is installed on a workbench of a common horizontal milling machine, the large end of the guide column 9 is inserted into a T-shaped groove of the workbench of the milling machine, after the test fixture is adjusted, the test fixture is fixed on the workbench of the common horizontal milling machine through a U-shaped groove on the bottom plate 8 by using a special screw for the T-shaped groove, and the test fixture is guaranteed not to move or rotate.
2. Sequentially sleeving 8 springs 13 on the long shaft end of the positioning column 6, wherein the lower end face of each spring 13 is tightly attached to a circular table in the middle of the positioning column 6;
3. sequentially sleeving 8 pressing sleeves 5 at the long shaft ends of the positioning columns 6, wherein the lower end surfaces of the pressing sleeves 5 are contacted with the upper end surfaces of the springs 13 by means of self weight;
4. inserting the small shaft end of a pressure plate 4 in a pressure head assembly consisting of a roller 2, a roller seat 3 and a pressure plate 4 into the central hole of a bush 11; rotating the pressure head assembly to enable 8 through holes uniformly distributed along the circumference on the pressure plate 4 to be respectively aligned with 8 positioning columns 6, and simultaneously sleeving the first positioning pin 10 abdicating holes on the pressure plate 4 on the first positioning pin 10 to ensure that the small shaft end of the pressure plate 4 freely reciprocates up and down along the first positioning pin 10; at the moment, the pressure head assembly presses the pressure sleeve 5 under the action of gravity;
5. a key groove on the inner wall of a central hole of the eccentric wheel 1 fixes the eccentric wheel 1 on a cutter bar of a common horizontal milling machine through a flat key, and the cutter bar drives the eccentric wheel 1 to rotate; the spring 13 can be compressed twice when the eccentric wheel 1 rotates for one circle;
6. adjusting the position of a workbench of a common horizontal milling machine to enable the eccentric wheel 1 to be in contact with the roller 2 and to rotate relatively, and enabling the end surfaces on two sides of the eccentric wheel 1 to be positioned between the end surfaces on two sides of the roller 2, so as to ensure that the roller 2 can be periodically compressed when the eccentric wheel 1 rotates, and further drive the pressure head assembly to reciprocate up and down;
at this time, the preparation work before the test is finished;
7. adjusting the height of a workbench of a common horizontal milling machine, and compressing a pressure head assembly through an eccentric wheel 1 according to the fatigue test requirement of a spring 13 to enable the spring 13 to be in a pre-compression state; adjusting the initial position of the eccentric wheel 1 to enable the straight surface part on the circumference of the eccentric wheel 1 to be in contact with the roller 2;
at this time, the pre-compression work before the test of the spring 13 is completed;
8. setting the revolution of a main shaft of a common horizontal milling machine, wherein the revolution is 50% of the revolution required by the fatigue test of the spring 13;
starting a main shaft switch of the common horizontal milling machine, wherein the eccentric wheel 1 periodically compresses the roller 2 at the moment, the roller 2 drives the pressure head assembly to periodically compress the spring 13, and a fatigue test of the spring 13 is started; starting test timing at the same time;
9. after the preset test time is reached, the height position of a workbench of the common horizontal milling machine is adjusted to separate the eccentric wheel 1 from the roller 2, and a main shaft switch of the common horizontal milling machine is closed; at this time, the fatigue test of the spring 13 is stopped;
10. after the pressure head assembly is taken down, sequentially taking down 8 pressure sleeves 5, and finally sequentially taking down 8 springs 13; at this time, the fatigue test of the spring 13 is ended.
Through verification of a large number of compression fatigue tests of the springs 13, the clamp for the fatigue test of the cylindrical helical compression spring 13 can meet the test requirements of the production process of the cylindrical helical compression spring 13, is not limited by equipment and production conditions, and is simple in structure, convenient and quick to use, low in production cost and suitable for single-piece and batch production. The invention uses the matching of the eccentric wheel, the roller seat, the pressing plate, the pressing sleeve, the positioning column, the positioning plate, the bottom plate, the guide column and the bush, can quickly complete the compression fatigue test of the spring 13 and can realize the simultaneous test of a plurality of springs 13; the invention has certain universality and wide application range, and can realize the fatigue test of the spring 13 with different specifications, different amplitudes and different frequencies by replacing the positioning element and the eccentric wheel of the spring 13.
Claims (10)
1. The clamp for the fatigue test of the cylindrical helical compression spring is characterized by comprising an eccentric wheel (1), a roller (2), a pressing plate (4), a positioning plate (7), a bottom plate (8), a bushing (11) and a spring assembly;
the bottom plate (8) is fixedly connected with the positioning plate (7);
a through hole is formed in the center of the positioning plate (7), and the bushing (11) is positioned in the through hole and is in interference fit with the inner wall of the through hole;
the pressing plate (4) is in clearance fit with the bushing (11), and after the pressing plate (4) is matched with the positioning plate (7), a distance is formed between the pressing plate and the positioning plate without contact;
the spring assemblies are arranged in an area formed between the pressing plate (4) and the positioning plate (7);
the roller (2) is positioned on the pressing plate (4) through a roller seat and can freely rotate in the roller seat; the middle of the roller (2) is provided with a through hole (1) for fixing the roller (2) in the middle groove of the roller seat through a cylindrical pin, and the thickness of the roller (2) is smaller than the width of the middle groove of the roller seat.
The eccentric wheel (1) is in contact extrusion with the roller (2), the roller (2) rotates and drives the roller seat to move axially, and the pressing plate (4) moves axially simultaneously to compress the spring assembly for experiments.
2. The clamp for the fatigue test of the cylindrical helical compression spring as claimed in claim 1, further comprising a first positioning pin (10), wherein one end of the first positioning pin is positioned in the mounting hole of the positioning plate (7), and the other end of the first positioning pin is positioned in the mounting hole of the pressure plate (4), so that the positioning plate (7) and the pressure plate (4) are prevented from rotating relatively.
3. The clamp for the fatigue test of the cylindrical helical compression spring as claimed in claim 1, wherein the spring assembly comprises a positioning column (6), a pressing sleeve (5) and a spring (13); the outer wall of the positioning column (6) is multi-step, and two ends of the positioning column are respectively positioned in the mounting holes of the pressing plate (4) and the positioning plate (7); the spring (13) is sleeved on the positioning column (6), the end face of one end of the spring is limited through the middle disc surface of the positioning column (6), and the spring (13) is original in length in the initial state; the pressing sleeve (5) is sleeved on the positioning column (6), one end of the pressing sleeve is contacted with the end face of the other end of the spring through self weight, and the other end of the pressing sleeve (5) is contacted with the pressing plate (4).
4. The clamp for the fatigue test of the cylindrical helical compression spring as claimed in claim 1, further comprising a second positioning pin (12), wherein two ends of the second positioning pin (12) are respectively positioned in the mounting holes of the positioning plate (7) and the bottom plate (8) to prevent the positioning plate (7) and the bottom plate (8) from rotating with each other.
5. The clamp for the fatigue test of the cylindrical helical compression spring as claimed in claim 1, wherein the positioning plate (7) has two cylindrical ends and a disk-shaped middle part; a plurality of step holes are uniformly distributed on the end surface of the disc in the middle of the positioning plate (7) in the circumferential direction, the position of the step holes is close to the root part of the cylinder, and the bottom surface of the counter bore is attached to the disc surface in the middle of the positioning column (6); the diameter of a counter bore in the step hole is larger than the outer diameter of a disc of the positioning column (6), so that the positioning column (6) can be easily assembled in the counter bore of the positioning plate (7); the depth of the counter bore is smaller than the thickness of the positioning column (6) disc, so that the end face of the positioning column (6) disc protrudes out of the positioning plate (7), the end face of one end of the spring is guaranteed to be higher than the positioning plate (7), and the condition of the spring is conveniently observed in the compression test process; a step hole on a positioning plate (7) is in interference fit with a small shaft end of a positioning column (6), and interference is guaranteed to prevent the positioning column (6) from falling off from the positioning plate (7); a plurality of step through holes are uniformly distributed on the disc in the middle of the positioning plate (7) along the circumferential direction and used for fixedly connecting the positioning plate (7) and the bottom plate (8) through inner hexagonal cylindrical head screws.
6. The clamp for fatigue test of a cylindrical helical compression spring according to claim 1, wherein the pressure plate (4) has a disk shape at one end and a cylindrical shape at the other end; the cylindrical end of the pressure plate (4) is in clearance fit with a hole in the center of the bushing (11), and the clearance ensures that the pressure plate (4) can freely move up and down in the hole of the bushing (11); a plurality of through holes are uniformly distributed on the end face of the disc end of the pressure plate (4) along the circumference, the through holes are abdicating holes of the positioning columns (6), the diameter of each through hole is larger than the outer diameter of the long shaft end of each positioning column (6), so that the positioning columns (6) can freely pass through the through holes when the pressure plate (4) moves up and down in a reciprocating mode, and interference cannot occur; after installation, the axes of the through holes are superposed with the axes of the through holes which are uniformly distributed on the positioning plate (7) and the bottom plate (8) in the circumferential direction; a blind hole is formed in the center of the disc end of the pressing plate (4), the blind hole is connected with the small shaft end of the roller seat (3) in an interference fit mode, and interference is guaranteed so that the roller seat (3) cannot fall off from the pressing plate (4); the end face of the disc of the pressing plate (4) is positioned between the through hole and the blind hole and is provided with a through hole which is used as a yielding hole of the first positioning pin (10), the hole is in clearance fit with the first positioning pin (10), and the clearance ensures that the pressing plate (4) can freely reciprocate up and down along the first positioning pin (10); the root of the small end cylinder of the pressure plate (4) is provided with a grinding wheel overrun groove, so that the processing of the excircle and the end face is facilitated.
7. The clamp for the fatigue test of the cylindrical helical compression spring according to claim 1, wherein the eccentric wheel (1) is integrally a disk-like member; 2 sections of 180-degree circular arcs are symmetrically designed in the circumferential direction of the eccentric wheel (1), the circle center of each circular arc has an eccentric amount relative to the symmetric center of the eccentric wheel (1) along one direction, and the eccentric amount is equal to the compression amount of a spring fatigue test; a through hole is formed in the center of the eccentric wheel (1), a key groove is formed in the inner wall of the through hole and used for fixing the eccentric wheel (1) on a cutter bar of a common horizontal milling machine through a flat key to realize torque transmission, and the cutter bar drives the eccentric wheel (1) to rotate; the eccentric wheel 1 can compress the spring twice when rotating for one circle.
8. The clamp for the fatigue test of the cylindrical helical compression spring as claimed in claim 1, further comprising a guide post (9), wherein the guide post (9) is in a stepped shaft shape as a whole and is composed of 2 sections of cylinders; the small end of the guide column 9 is inserted into the through hole at the position close to the U-shaped groove on the bottom plate from the bottom surface of the bottom plate 8, and the guide column 9 is ensured not to fall off from the bottom plate 8 by adopting transition fit; the root of the small end of the guide column 9 is provided with a grinding wheel overtravel groove, and the step surface of the guide column 9 is ensured to be attached to the bottom surface of the bottom plate 8 in the vertical direction; the big end of the guide column 9 is exposed out of the bottom surface of the bottom plate 8 and is inserted into a T-shaped groove of a workbench of a common horizontal milling machine, and chamfers are arranged on the end surface of the shaft end of the guide column 9 along the circumferential direction.
9. The method for using the jig for a fatigue test of a cylindrical helical compression spring according to claim 1, comprising the steps of:
step 1: completing the preparation work for mounting the components before the test;
step 2: adjusting the height of a workbench of a common horizontal milling machine, and compressing a pressure head assembly through an eccentric wheel 1 according to the requirement of a spring fatigue test to enable a spring to be in a pre-compression state; adjusting the initial position of the eccentric wheel 1 to enable the straight surface part on the circumference of the eccentric wheel 1 to be in contact with the roller 2;
and step 3: setting the revolution of a main shaft of a common horizontal milling machine; starting a main shaft switch of the common horizontal milling machine, wherein the eccentric wheel 1 periodically compresses the roller 2 at the moment, the roller 2 drives the pressure head assembly to periodically compress the spring, and a spring fatigue test is started; starting test timing at the same time;
and 4, step 4: after the preset test time is reached, the height position of a workbench of the common horizontal milling machine is adjusted to separate the eccentric wheel 1 from the roller 2, and a main shaft switch of the common horizontal milling machine is closed; at this point, the spring fatigue test was stopped;
and 5: after the pressure head assembly is taken down, sequentially taking down 8 pressure sleeves 5, and finally sequentially taking down 8 springs; at this time, the spring fatigue test was ended.
10. The use method according to claim 9, wherein the step 1 comprises the following steps:
step 1.1: the method comprises the following steps of installing a fixture body consisting of a bottom plate 8, a positioning plate 7, a positioning column 6, a lining 11 and a guide column 9 on a workbench of a common horizontal milling machine, inserting the large end of the guide column 9 into a T-shaped groove of the workbench of the milling machine, adjusting a test fixture, fixing the test fixture on the workbench of the common horizontal milling machine through a U-shaped groove on the bottom plate 8 by using a special screw for the T-shaped groove, and ensuring that the test fixture cannot move or rotate;
step 1.2: sequentially sleeving the springs on the long shaft ends of the positioning columns 6, and enabling the lower end faces of the springs to be tightly attached to the circular truncated cone in the middle of the positioning columns 6;
step 1.3: sequentially sleeving the pressing sleeve 5 at the long shaft end of the positioning column 6, wherein the lower end surface of the pressing sleeve 5 is contacted with the upper end surface of the spring by virtue of self weight;
step 1.4: inserting the small shaft end of a pressure plate 4 in a pressure head assembly consisting of a roller 2, a roller seat 3 and a pressure plate 4 into the central hole of a bush 11; rotating the pressure head assembly to enable 8 through holes uniformly distributed along the circumference on the pressure plate 4 to be respectively aligned with 8 positioning columns 6, and simultaneously sleeving the first positioning pin 10 abdicating holes on the pressure plate 4 on the first positioning pin 10 to ensure that the small shaft end of the pressure plate 4 freely reciprocates up and down along the first positioning pin 10; at the moment, the pressure head assembly presses the pressure sleeve 5 under the action of gravity;
step 1.5: a key groove on the inner wall of a central hole of the eccentric wheel (1) fixedly connects the eccentric wheel (1) with a cutter bar of a common horizontal milling machine through a flat key, and the cutter bar drives the eccentric wheel 1 to rotate; the spring can be compressed twice when the eccentric wheel 1 rotates for one circle;
step 1.6: the position of a workbench of a common horizontal milling machine is adjusted, so that the eccentric wheel 1 is in contact with the roller 2 and can rotate relatively, the end surfaces on two sides of the eccentric wheel 1 are positioned in the middle of the end surfaces on two sides of the roller 2, the roller 2 can be periodically compressed when the eccentric wheel 1 rotates, and the pressure head assembly is driven to reciprocate up and down.
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