A coordinate measuring machine and a method for measuring the dimensional tolerance of mechanical parts

Abstract

The present invention belongs to the technical field of three-axis measuring instruments, and discloses a three-coordinate measuring instrument and a method for measuring the dimensional tolerance of mechanical parts thereof, comprising a workbench, wherein first transverse guide rails are fixedly installed on both sides of the top of the workbench, and a gantry is provided above the workbench, and the left and right sides of the bottom of the gantry are movably connected with the two first transverse guide rails. The present invention utilizes the up and down bouncing of the probe during measurement, converts it into left and right displacement through the conversion of the linkage component, and cooperates with the correspondence between the laser ranging transmitter and the laser ranging receiver, so that the up and down bouncing can be converted into left and right displacement, so that it only needs to detect the left and right displacement to achieve the measurement of accurate data, and at the same time, the limit spring is installed horizontally, and the free end is not stressed, which can effectively reduce the elastic fatigue, so that the displacement accuracy of the probe is guaranteed, the measurement deviation is reduced, and the measurement accuracy is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of three-axis measuring instruments, and specifically relates to a three-coordinate measuring instrument and a method for measuring the dimensional tolerance of mechanical parts thereof. Background Art

[0002] A three-coordinate measuring instrument is a high-precision measuring instrument, which plays an important role in fields such as product design, mold equipment, gear measurement, blade measurement, machinery manufacturing, tooling fixtures, automotive mold accessories, electronic appliances, etc. Among them, the three-axis measuring instrument mainly realizes the precise measurement of workpieces through the displacement of the X, Y, and Z axes. Among them, the three-dimensional measurement of workpieces is mainly realized by relying on a probe, and it is mainly divided into contact type and non-contact type. The non-contact type is applicable to some special parts, and the contact type probe is generally used for conventional parts to measure the size of workpieces.

[0003] When measuring the size of a workpiece, generally, the displacement of the probe is realized through the displacement of the three axes, and the probe is kept in contact with the surface of the workpiece all the time. By cooperating with software, the three-dimensional data of the workpiece can be obtained. Among them, in order to ensure that the probe can always be in contact with the surface of the workpiece, the probe is generally installed elastically, and the spring is generally installed longitudinally. The free end of the spring is stressed for a long time. After long-term use, this installation method will have an elastic fatigue phenomenon. At this time, the displacement accuracy of the probe will decrease, resulting in measurement deviation, and improvement is urgently needed.

[0004] At the same time, since the three-axis measuring instrument generally relies extremely on the up and down displacement of the probe to realize the precise measurement of the workpiece size, and the overall measurement accuracy is relatively high. When not in use, the probe of the device is generally exposed. When it is affected by an external force, the probe will be affected by vibration and force, resulting in the probe being tilted or deviated to varying degrees, seriously affecting the measurement accuracy. Summary of the Invention

[0005] The purpose of the present invention is to provide a three-coordinate measuring instrument and a method for measuring the dimensional tolerance of mechanical parts thereof, so as to solve the problems raised in the above background art.

[0006] To achieve the above object, the present invention provides the following technical solution: A three-coordinate measuring instrument, including a workbench, on both left and right sides of the top of the workbench are fixedly installed first horizontal rails, above the workbench is provided a gantry, between the left and right sides of the bottom of the gantry and the two first horizontal rails are movably clamped, the gantry moves back and forth relative to the first horizontal rails, the top of the gantry is fixedly connected with a second horizontal rail, on the outer side of the second horizontal rail is movably clamped a longitudinal electric wall, the longitudinal electric wall moves left and right relative to the second horizontal rail, at the bottom of the longitudinal electric wall is movably installed an adjustment block, the adjustment block moves up and down relative to the longitudinal electric wall, in the middle of the bottom of the adjustment block is movably installed a longitudinal rail, at the bottom of the longitudinal rail is provided a probe, on both left and right sides near the bottom of the adjustment block are fixedly installed horizontal rails, inside the longitudinal rail is movably clamped a linkage assembly, the linkage assembly is movably clamped with the horizontal rails, on the outer side of the adjustment block is movably sleeved a sealing assembly, the sealing assembly moves up and down relative to the adjustment block, on both front and back sides of the bottom of the first horizontal rail are fixedly installed sucker bases.

[0007] When measuring the dimensions of mechanical parts, the device can be fixed by connecting the sucker bases at the bottom of the first horizontal rails with the workbench. After fixing, by controlling the back-and-forth movement of the gantry, the left-and-right movement of the longitudinal electric wall, and simultaneously controlling the up-and-down movement of the adjustment block, the probe can be driven to perform X, Y, and Z axis displacements, so that the probe contacts the surface of the workpiece to complete the three-dimensional dimension measurement of the workpiece.

[0008] As a further technical solution of the present invention, the linkage assembly includes a longitudinal guide block, the longitudinal guide block is movably clamped with the longitudinal rail, the longitudinal guide block moves up and down relative to the longitudinal rail, the top of the probe penetrates the bottom of the longitudinal rail and is connected with the bottom of the longitudinal guide block.

[0009] As a further technical solution of the present invention, on both left and right sides of the longitudinal guide block are fixedly installed first fixing seats, at the end of each first fixing seat away from the longitudinal guide block is movably connected with a connecting rod through a rotating shaft, and at the end of each connecting rod away from the first fixing seat is movably connected with a second fixing seat through a rotating shaft.

[0010] As a further technical solution of the present invention, on the top of each second fixing seat are fixedly installed transverse guide blocks, the transverse guide blocks are movably clamped with the transverse rails, the transverse guide blocks move left and right relative to the transverse rails, at the relatively far ends of the two transverse guide blocks are fixedly installed limiting springs located inside the transverse rails, and the other end of the limiting spring is connected with one side of the inner cavity of the transverse rail.

[0011] As a further technical solution of the present invention, a laser distance measuring transmitter is fixedly installed at the top end of the limit spring. Grooves are formed on the left and right sides near the bottom end of the adjustment block, and laser distance measuring receivers are fixedly installed inside the grooves. The laser distance measuring transmitter and the laser distance measuring receiver correspond to each other, and the middle parts of the laser distance measuring transmitter and the laser distance measuring receiver are on the same central axis.

[0012] When measuring the size of a workpiece, the bottom end of the probe can be always in contact with the surface of the workpiece by the up and down displacement of the adjustment block. At this time, the probe bounces up and down. When the probe moves upward, the longitudinal guide block moves upward accordingly. At this time, the two connecting rods deflect, that is, the angle between the connecting rod and the longitudinal guide block increases. At this time, the two transverse guide blocks move relatively away from each other, and the limit spring is compressed accordingly.

[0013] When the longitudinal guide block moves downward, the two transverse guide blocks move relatively closer to each other. When the two transverse guide blocks move relative to the transverse guide rail, the laser distance measuring transmitter can move with the transverse guide block, and the distance between the laser distance measuring transmitter and the laser distance measuring receiver changes accordingly. The up and down displacement amount of the probe can be obtained through the measured distance change between the laser distance measuring transmitter and the laser distance measuring receiver. By measuring a single measurement point multiple times, the value-taking process of a single measurement point can be completed.

[0014] By utilizing the up and down bouncing of the probe during measurement, through the conversion of the linkage component, it is transformed into left and right displacement, and in cooperation with the correspondence between the laser distance measuring transmitter and the laser distance measuring receiver, the up and down bouncing can be transformed into left and right displacement, enabling it to measure accurate data only by detecting the left and right displacement amount. At the same time, the limit spring is installed horizontally and the free end is not stressed, which can effectively slow down the elastic fatigue, ensuring the displacement accuracy of the probe, reducing the measurement deviation, and improving the measurement accuracy.

[0015] As a further technical solution of the present invention, electromagnetic blocks are installed on the left and right sides near the middle of the adjustment block. The closing component includes an end face cover plate, and side cover plates are fixedly installed at the left and right ends of the end face cover plate.

[0016] As a further technical solution of the present invention, the end face cover plate is movably sleeved with the adjustment block, and the end face cover plate moves up and down relative to the adjustment block. When the top end of the side cover plate adsorbs with the adjustment block, the side cover plate is directly above the laser distance measuring transmitter, and the bottom end of the end face cover plate is above the probe. When the bottom end of the side cover plate contacts the top end of the transverse guide rail, one side of the side cover plate completely blocks the laser distance measuring receiver, and the bottom end of the end face cover plate protrudes from the bottom end of the probe.

[0017] When it is necessary to measure the size of a workpiece, the power supply of the electromagnetic block can be turned on. At this time, the electromagnetic block generates a magnetic force and exerts an attractive force on the side cover plate. At this time, the side cover plate is adsorbed to the electromagnetic block, and the side cover plate and the end cover plate move upward, so that the probe can be exposed to measure the surface of the workpiece, and the laser distance measuring receiver is exposed to cooperate with the laser distance measuring transmitter to assist in completing the measurement;

[0018] When the size of the workpiece is not being measured, the power supply of the electromagnetic block is turned off at this time, and the side cover plate no longer receives the attractive force. The side cover plate and the end cover plate then descend until the inner side of the side cover plate contacts the top of the laser distance measuring transmitter. At this time, the side cover plate can block the laser distance measuring transmitter and the laser distance measuring receiver, and the bottom end of the end cover plate can block the bottom end of the probe to complete the automatic protection process.

[0019] By using a closed component that can move up and down, combined with the position design of the laser distance measuring transmitter, the laser distance measuring receiver, and the probe, when the device is not in use, it can automatically protect the probe, the laser distance measuring transmitter, and the laser distance measuring receiver, effectively avoiding the phenomenon of vibration or deviation of the probe caused by external forces, reducing the possibility of its inclination or deviation, and further improving its measurement accuracy.

[0020] A method for measuring the dimensional tolerance of mechanical parts of a coordinate measuring machine includes the following steps:

[0021] S1: When in use, the mechanical part to be measured needs to be placed on the workbench and fixed according to needs. After fixing, by moving the gantry back and forth, moving the longitudinal electric wall left and right, and controlling the up and down displacement of the adjustment block, the probe can be displaced in the three-axis directions and brought into contact with the surface of the workpiece to complete the size measurement process;

[0022] S2: When starting the measurement, the electromagnetic block can be turned on. At this time, the electromagnetic block generates a magnetic force and exerts an attractive force on the side cover plate. At this time, the side cover plate and the end cover plate rise, and the probe and the laser distance measuring receiver are exposed waiting to be measured;

[0023] S3: As the probe contacts the surface of the workpiece, the probe then bounces up and down. When the probe bounces up and down, it can drive the longitudinal guide block to bounce up and down and drive the connecting rod to deflect, thus driving the lateral guide block to move left and right and driving the laser distance measuring transmitter to displace relative to the laser distance measuring receiver. At this time, the distance between the laser distance measuring transmitter and the laser distance measuring receiver changes;

[0024] S4: The vertical displacement of the probe can be obtained by the change in the distance between the laser ranging transmitter and the laser ranging receiver. When performing single-point measurement, the tolerance of a single measurement point of a mechanical component can be obtained by measuring the single measurement point no less than three times and comparing the difference in the distance between the laser ranging transmitter and the laser ranging receiver during the three measurements.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. The present invention utilizes the up and down bouncing of the probe during measurement, converts it into left and right displacement through the conversion of the linkage component, and cooperates with the correspondence between the laser ranging transmitter and the laser ranging receiver to convert the up and down bouncing into left and right displacement, so that it only needs to detect the left and right displacement to achieve accurate data measurement. At the same time, the limit spring is installed horizontally, and the free end is not stressed, which can effectively slow down the elastic fatigue, so that the displacement accuracy of the probe is guaranteed, the measurement deviation is reduced, and the measurement accuracy is improved.

[0027] 2. The present invention utilizes a closed component that can be moved up and down, and cooperates with the position design of the laser ranging transmitter, the laser ranging receiver and the probe, so that when the device is not in use, it can automatically protect the probe, the laser ranging transmitter and the laser ranging receiver, which can effectively prevent the probe from vibrating or deviating due to external forces, reduce the possibility of tilt or deviation, and further improve its measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 is a schematic diagram of the bottom structure of the present invention;

[0030] Figure 3 It is an exploded schematic diagram of the second transverse guide rail and the longitudinal electric wall structure of the present invention;

[0031] Figure 4 It is a schematic diagram of the closed component in the present invention in an open state;

[0032] Figure 5 It is a schematic diagram of the closing component in the present invention in a closed state;

[0033] Figure 6 It is a schematic diagram of the coordination of the adjustment block and the linkage assembly structure of the present invention;

[0034] Figure 7 A side cross-sectional schematic diagram of the adjustment block structure of the present invention;

[0035] Figure 8 It is an exploded schematic diagram of the longitudinal guide rail, the transverse guide rail and the linkage assembly structure of the present invention.

[0036] In the figure: 1, workbench; 2, first transverse guide rail; 3, gantry; 4, second transverse guide rail; 5, longitudinal electric wall; 6, adjustment block; 7, electromagnetic block; 8, sealing assembly; 801, end face cover plate; 802, side cover plate; 9, longitudinal guide rail; 10, transverse guide rail; 11, probe; 12, linkage assembly; 121, longitudinal guide block; 122, first fixing seat; 123, second fixing seat; 124, connecting rod; 125, transverse guide block; 126, limiting spring; 13, laser distance measuring transmitter; 14, laser distance measuring receiver; 15, suction cup base. Specific embodiments

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0038] As Figures 1 to 8 shown, in the embodiment of the present invention, a three-coordinate measuring instrument includes a workbench 1. First transverse guide rails 2 are fixedly installed on both the left and right sides of the top end of the workbench 1. A gantry 3 is provided above the workbench 1. The left and right sides of the bottom end of the gantry 3 are movably clamped with the two first transverse guide rails 2. The gantry 3 moves back and forth relative to the first transverse guide rails 2. The top end of the gantry 3 is fixedly connected with a second transverse guide rail 4. A longitudinal electric wall 5 is movably clamped on the outer side surface of the second transverse guide rail 4. The longitudinal electric wall 5 moves left and right relative to the second transverse guide rail 4. An adjustment block 6 is movably installed at the bottom end of the longitudinal electric wall 5. The adjustment block 6 moves up and down relative to the longitudinal electric wall 5. A longitudinal guide rail 9 is movably installed in the middle of the bottom end of the adjustment block 6. A probe 11 is provided at the bottom end of the longitudinal guide rail 9. Transverse guide rails 10 are fixedly installed on both the left and right sides near the bottom end of the adjustment block 6. A linkage assembly 12 is movably clamped inside the longitudinal guide rail 9. The linkage assembly 12 is movably clamped with the transverse guide rails 10. A sealing assembly 8 is movably sleeved on the outer side surface of the adjustment block 6. The sealing assembly 8 moves up and down relative to the adjustment block 6. Suction cup bases 15 are fixedly installed on both the front and back sides of the bottom end of the first transverse guide rail 2.

[0039] When measuring the dimensions of mechanical parts, the suction cup base 15 at the bottom end of the first transverse guide rail 2 can be connected to the workbench to complete the fixation of the device. After the fixation is completed, the gantry 3 can be controlled to move back and forth, and the longitudinal electric wall 5 can be controlled to move left and right. At the same time, the adjustment block 6 is controlled to move up and down, so as to drive the probe 11 to perform X, Y, and Z axis displacements, making the probe 11 contact the surface of the workpiece to complete the three-dimensional dimension measurement of the workpiece.

[0040] As Figure 4 and Figure 6 as well as Figure 7 and Figure 8 shown, the linkage assembly 12 includes a longitudinal guide block 121, which is movably clamped with the longitudinal guide rail 9. The longitudinal guide block 121 is displaced up and down relative to the longitudinal guide rail 9. The top end of the probe 11 penetrates through the bottom end of the longitudinal guide rail 9 and is connected to the bottom end of the longitudinal guide block 121. First fixing seats 122 are fixedly installed on both the left and right sides of the longitudinal guide block 121. One end of each first fixing seat 122 away from the longitudinal guide block 121 is movably connected to a connecting rod 124 through a rotating shaft. One end of each connecting rod 124 away from the first fixing seat 122 is movably connected to a second fixing seat 123 through a rotating shaft. Transverse guide blocks 125 are fixedly installed at the top ends of the second fixing seats 123. The transverse guide blocks 125 are movably clamped with the transverse guide rail 10. The transverse guide blocks 125 are displaced left and right relative to the transverse guide rail 10. Limiting springs 126 located inside the transverse guide rail 10 are fixedly installed at the relatively far ends of the two transverse guide blocks 125. The other end of each limiting spring 126 is connected to one side of the inner cavity of the transverse guide rail 10. A laser distance measuring transmitter 13 is fixedly installed at the top end of the limiting spring 126. Grooves are formed on both the left and right sides near the bottom end of the adjusting block 6, and laser distance measuring receivers 14 are fixedly installed inside the grooves. The laser distance measuring transmitter 13 and the laser distance measuring receiver 14 correspond to each other, and the middles of the laser distance measuring transmitter 13 and the laser distance measuring receiver 14 are on the same central axis.

[0041] Embodiment: When measuring the size of a workpiece, the bottom end of the probe 11 can be made to always contact the surface of the workpiece by displacing the adjusting block 6 up and down. At this time, the probe 11 bounces up and down accordingly. When the probe 11 is displaced upward, the longitudinal guide block 121 is displaced upward accordingly. At this time, the two connecting rods 124 deflect accordingly, that is, the angle between the connecting rod 124 and the longitudinal guide block 121 increases. At this time, the two transverse guide blocks 125 move relatively away from each other, and the limiting spring 126 is compressed accordingly;

[0042] When the longitudinal guide block 121 is displaced downward, the two transverse guide blocks 125 move relatively closer to each other. When the two transverse guide blocks 125 are displaced relative to the transverse guide rail 10, the laser distance measuring transmitter 13 can move with the transverse guide block 125. The distance between the laser distance measuring transmitter 13 and the laser distance measuring receiver 14 changes accordingly. The up and down displacement amount of the probe 11 can be obtained through the change in the distance measured by the laser distance measuring transmitter 13 and the laser distance measuring receiver 14. By measuring a single measurement point multiple times, the value-taking process of a single measurement point can be completed.

[0043] When measuring by using the up-and-down movement of the probe 11, through the conversion of the linkage component 12, it is transformed into left-and-right displacement. By coordinating the correspondence between the laser distance measurement transmitter 13 and the laser distance measurement receiver 14, the up-and-down movement can be transformed into left-and-right displacement, enabling the measurement of accurate data by only detecting the left-and-right displacement amount. At the same time, the limiting spring 126 is installed horizontally and its free end is not stressed, which can effectively slow down the elastic fatigue, ensuring the displacement accuracy of the probe 11, reducing the measurement deviation, and improving the measurement accuracy.

[0044] As Figure 1 and Figure 3 and Figure 4 and Figure 5 As shown, electromagnetic blocks 7 are installed on both the left and right sides near the middle of the adjustment block 6. The closing component 8 includes an end face cover plate 801. Side cover plates 802 are fixedly installed at both the left and right ends of the end face cover plate 801. The end face cover plate 801 is movably sleeved between the adjustment block 6, and the end face cover plate 801 moves up and down relative to the adjustment block 6. When the side cover plates 802 are adsorbed to the adjustment block 6 at the top, the side cover plates 802 are directly above the laser distance measurement transmitter 13, and the bottom end of the end face cover plate 801 is above the probe 11. When the bottom end of the side cover plate 802 contacts the top end of the horizontal guide rail 10, one side of the side cover plate 802 completely blocks the laser distance measurement receiver 14, and the bottom end of the end face cover plate 801 protrudes from the bottom end of the probe 11.

[0045] Embodiment: When it is necessary to measure the size of a workpiece, the power supply of the electromagnetic block 7 can be turned on. At this time, the electromagnetic block 7 generates a magnetic force and applies an attractive force to the side cover plate 802. At this time, the side cover plate 802 is adsorbed to the electromagnetic block 7, and the side cover plate 802 and the end face cover plate 801 move up, exposing the probe 11 to measure the surface of the workpiece, and the laser distance measurement receiver 14 is exposed to cooperate with the laser distance measurement transmitter 13 to assist in completing the measurement.

[0046] When the size of the workpiece is not being measured, the power supply of the electromagnetic block 7 is turned off at this time, and the side cover plate 802 no longer receives the attractive force. The side cover plate 802 and the end face cover plate 801 descend until the inner side of the side cover plate 802 contacts the top end of the laser distance measurement transmitter 13. At this time, the side cover plate 802 can block the laser distance measurement transmitter 13 and the laser distance measurement receiver 14, and the bottom end of the end face cover plate 801 can block the bottom end of the probe 11 to complete the automatic protection process.

[0047] By utilizing the closable component 8 that can be displaced up and down, in conjunction with the position design of the laser distance measuring transmitter 13, the laser distance measuring receiver 14, and the probe 11, when the device is not in use, it can automatically protect the probe 11, the laser distance measuring transmitter 13, and the laser distance measuring receiver 14. It can effectively prevent the probe 11 from vibrating or shifting due to external forces, reduce the possibility of its tilting or deviation, and further improve its measurement accuracy.

[0048] A method for measuring the dimensional tolerance of mechanical parts of a three - coordinate measuring instrument includes the following steps:

[0049] S1: During use, the mechanical part to be measured needs to be placed on the workbench 1 and fixed as required. After fixation, by moving the gantry 3 back and forth, moving the longitudinal electric wall 5 left and right, and controlling the up - and - down displacement of the adjustment block 6, the probe 11 is displaced in three - axis directions and brought into contact with the workpiece surface to complete the dimensional measurement process;

[0050] S2: At the start of measurement, the electromagnetic block 7 can be turned on. At this time, the electromagnetic block 7 generates magnetic force and attracts the side cover plate 802. Then, the side cover plate 802 and the end cover plate 801 rise, exposing the probe 11 and the laser distance measuring receiver 14 for measurement;

[0051] S3: As the probe 11 comes into contact with the workpiece surface, the probe 11 bounces up and down. When the probe 11 bounces up and down, it drives the longitudinal guide block 121 to bounce up and down, drives the connecting rod 124 to deflect, and then drives the lateral guide block 125 to move left and right, driving the laser distance measuring transmitter 13 to displace relative to the laser distance measuring receiver 14. At this time, the distance between the laser distance measuring transmitter 13 and the laser distance measuring receiver 14 changes;

[0052] S4: The up - and - down displacement of the probe 11 can be obtained from the change in the distance between the laser distance measuring transmitter 13 and the laser distance measuring receiver 14. When performing single - point measurement, by measuring a single measurement point no less than three times and comparing the differences in the distances between the laser distance measuring transmitter 13 and the laser distance measuring receiver 14 during the three measurements, the tolerance of a single measurement point of the mechanical part can be obtained.

[0053] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A three - coordinate measuring instrument, comprising a workbench (1), characterized in that: On both the left and right sides of the top end of the workbench (1), first horizontal guide rails (2) are fixedly installed. Above the workbench (1), there is a gantry (3). The left and right sides of the bottom end of the gantry (3) are movably clamped with the two first horizontal guide rails (2). The gantry (3) moves back and forth relative to the first horizontal guide rails (2). The top end of the gantry (3) is fixedly connected with a second horizontal guide rail (4). A longitudinal electric wall (5) is movably clamped on the outer side of the second horizontal guide rail (4). The longitudinal electric wall (5) moves left and right relative to the second horizontal guide rail (4). An adjustment block (6) is movably installed at the bottom end of the longitudinal electric wall (5). The adjustment block (6) moves up and down relative to the longitudinal electric wall (5). In the middle of the bottom end of the adjustment block (6), a longitudinal guide rail (9) is movably installed. A probe (11) is provided at the bottom end of the longitudinal guide rail (9). On both the left and right sides near the bottom end of the adjustment block (6), horizontal guide rails (10) are fixedly installed. A linkage component (12) is movably clamped inside the longitudinal guide rail (9). The linkage component (12) is movably clamped with the horizontal guide rails (10). A sealing component (8) is movably sleeved on the outer side of the adjustment block (6). The sealing component (8) moves up and down relative to the adjustment block (6). On both the front and back sides of the bottom end of the first horizontal guide rail (2), sucker bases (15) are fixedly installed; The linkage component (12) includes a longitudinal guide block (121). The longitudinal guide block (121) is movably clamped with the longitudinal guide rail (9). The longitudinal guide block (121) moves up and down relative to the longitudinal guide rail (9). The top end of the probe (11) penetrates through the bottom end of the longitudinal guide rail (9) and is connected to the bottom end of the longitudinal guide block (121); On both the left and right sides of the longitudinal guide block (121), first fixing seats (122) are fixedly installed. One end of each first fixing seat (122) far from the longitudinal guide block (121) is movably connected with a connecting rod (124) through a rotating shaft. One end of each connecting rod (124) far from the first fixing seat (122) is movably connected with a second fixing seat (123) through a rotating shaft; On the top ends of the second fixing seats (123), horizontal guide blocks (125) are fixedly installed. The horizontal guide blocks (125) are movably clamped with the horizontal guide rails (10). The horizontal guide blocks (125) move left and right relative to the horizontal guide rails (10). On the relatively far ends of the two horizontal guide blocks (125), limiting springs (126) located inside the horizontal guide rails (10) are fixedly installed. The other end of each limiting spring (126) is connected to one side of the inner cavity of the horizontal guide rail (10); The top end of the limiting spring (126) is fixedly installed with a laser distance measuring transmitter (13). Grooves are formed on the left and right sides near the bottom end of the adjusting block (6), and laser distance measuring receivers (14) are fixedly installed inside the grooves. The laser distance measuring transmitter (13) corresponds to the laser distance measuring receiver (14), and the middles of the laser distance measuring transmitter (13) and the laser distance measuring receiver (14) are on the same central axis.

2. A three - coordinate measuring instrument according to claim 1, characterized in that: Electromagnetic blocks (7) are installed on the left and right sides near the middle of the adjusting block (6). The sealing assembly (8) includes an end face cover plate (801), and side cover plates (802) are fixedly installed at the left and right ends of the end face cover plate (801).

3. A three-coordinate measuring instrument according to claim 2, characterized in that: The end face cover plate (801) is movably sleeved with the adjusting block (6), and the end face cover plate (801) moves up and down relative to the adjusting block (6). When the top end of the side cover plate (802) is adsorbed to the adjusting block (6), the side cover plate (802) is directly above the laser distance measuring transmitter (13), and the bottom end of the end face cover plate (801) is above the probe (11). When the bottom end of the side cover plate (802) contacts the top end of the transverse guide rail (10), one side of the side cover plate (802) completely blocks the laser distance measuring receiver (14), and the bottom end of the end face cover plate (801) protrudes from the bottom end of the probe (11).

4. A method for measuring the dimensional tolerance of mechanical parts of a three - coordinate measuring instrument according to claim 3, characterized in that: It includes the following steps: S1: During use, the mechanical component to be measured needs to be placed on the workbench (1) and fixed as required. After fixation, by moving the gantry (3) back and forth and moving the longitudinal electric wall (5) left and right, and controlling the up and down displacement of the adjusting block (6) to make the probe (11) displace in three axial directions and contact the surface of the workpiece, the dimension measurement process is completed. S2: When starting the measurement, the electromagnetic block (7) can be turned on. At this time, the electromagnetic block (7) generates magnetic force and generates an attractive force on the side cover plate (802). At this time, the side cover plate (802) and the end face cover plate (801) rise accordingly, and the probe (11) and the laser distance measuring receiver (14) are exposed for measurement. S3: As the probe (11) contacts the surface of the workpiece, the probe (11) jumps up and down at this time. When the probe (11) jumps up and down, it can drive the longitudinal guide block (121) to jump up and down, drive the connecting rod (124) to deflect, drive the transverse guide block (125) to displace left and right, and drive the laser distance measuring transmitter (13) to displace relative to the laser distance measuring receiver (14). At this time, the distance between the laser distance measuring transmitter (13) and the laser distance measuring receiver (14) changes accordingly. S4: The up and down displacement of the probe (11) can be obtained through the change in the distance between the laser ranging transmitter (13) and the laser ranging receiver (14). When performing single-point measurement, by measuring a single measurement point no less than three times and comparing the differences in the distances between the laser ranging transmitter (13) and the laser ranging receiver (14) during the three measurements, the tolerance of a single measurement point of the mechanical component can be obtained.

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