A modular crossbeam structure for a gantry coordinate measuring machine

Abstract

This invention discloses a modular crossbeam structure for a gantry coordinate measuring machine, relating to the technical field of coordinate measuring equipment. It includes a modular triangular crossbeam, with a triangular socket at one end and a triangular plug at the other. The triangular plug and socket are fitted together. An inner shaft groove is formed at the center of the triangular plug, and an inner insertion shaft is rotatably mounted at the center of the triangular socket, fitting into the inner shaft groove. This invention employs a three-layer coaxial and concentric connection of the outer triangular profile, a middle locking pin layer, and a central inner insertion shaft, resulting in high joint stiffness, far exceeding that of traditional flange connections. The central inner insertion shaft penetrates the center of both crossbeam sections, forming a composite force transmission system of external triangular bending resistance and internal circular shaft torsion resistance, significantly improving bending, shear, and torsional stiffness. This completely eliminates bending deformation and step errors caused by the self-weight and moving loads of large-span crossbeams, ensuring long-term stability of the guide rail installation reference.

Description

Technical Field

[0001] This invention relates to the field of coordinate measuring equipment technology, specifically to a modular crossbeam structure for a gantry coordinate measuring machine. Background Technology

[0002] As a large-scale precision geometric measurement equipment, the gantry coordinate measuring machine (CMM) is widely used in high-precision measurement scenarios for large-sized workpieces in aerospace, automobile manufacturing, and wind turbine blades. With the continuous increase in the size of the workpieces being measured, the span of the CMM's crossbeam has also increased (often exceeding 5m), placing stringent requirements on the structural rigidity, splicing accuracy, torsional stability, and ease of disassembly and maintenance of the crossbeam.

[0003] A Chinese patent (publication number: CN207582681U) discloses an assembled crossbeam of a modular steel structure system. Existing modular crossbeams generally use end-face flanges and circumferential high-strength bolts for connection. This type of structure exposes the following core defects in the application of large-span gantry coordinate measuring machines: 1. Severely insufficient node stiffness, becoming the "weakest link" in the overall machine accuracy. Traditional flange connections rely solely on end-face contact and bolt pre-tightening for force transmission, resulting in a joint node stiffness of only 40%–60% of the overall crossbeam. The self-weight of the large-span crossbeam and the load on the Z-axis moving parts easily lead to warping of the joint surface, step errors, and local depressions, directly damaging the straightness of the crossbeam and the guide rail installation datum, causing orthogonality errors in the measurement space and length measurement errors. 2. Extremely poor torsional performance, unable to adapt to alternating loads on a 15° inclined axis system. To optimize force distribution and reduce the influence of gravity, if the gantry coordinate measuring machine adopts a 15° inclined mounting surface layout, making the crossbeam working surface 45°, the vertical force component will be balanced. However, traditional flange connections rely on friction to transmit torque. Under the long-term alternating torsional torque generated by gravity on the Y / Z axes, bolts are prone to loosening and the splicing surfaces may experience slight slippage, leading to torsional deformation of the crossbeam and drift in accuracy. After long-term operation, the measurement accuracy deteriorates sharply.

[0004] 2. Large spans result in significant cumulative errors, making it difficult to guarantee neutrality and straightness. Large-span beams (Y-axis) require multi-segment splicing. Traditional round or square flanges lack circumferential positioning capabilities, relying entirely on manual alignment. After splicing, straightness and coaxiality errors accumulate, failing to meet the high-precision benchmark requirements for long-stroke guide rail installation. Furthermore, uneven flange bolt preload can lead to asynchronous operation at both ends of the beam and excessive parallelism of the guide rail, further exacerbating motion errors and measurement uncertainties.

[0005] 3. Low disassembly and maintenance efficiency and high replacement costs: Traditional flange connections require tightening and disassembling multiple bolts one by one. A single section of a large-span beam can weigh hundreds of kilograms, making disassembly and assembly time-consuming and labor-intensive, and easily damaging the precision of the splicing surface. If a section of the beam is partially damaged, multiple modules need to be disassembled for replacement, resulting in high maintenance costs, long downtime, and seriously affecting equipment uptime. Summary of the Invention

[0006] The purpose of this invention is to provide a modular crossbeam structure for a gantry coordinate measuring machine in order to solve the above problems.

[0007] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0008] A modular crossbeam structure for a gantry coordinate measuring machine includes a modular triangular crossbeam. One end of the modular triangular crossbeam is provided with a triangular socket, and the other end is provided with a triangular plug. The triangular plug is adapted to be inserted into the triangular socket. The center of the triangular plug is provided with an inner shaft groove. The center of the triangular socket is rotatably installed with an inner insertion shaft, which is adapted to the inner shaft groove.

[0009] The inner wall of the triangular socket has an outer pin hole, and the inner wall of the triangular plug has a through-hole with a stepped sliding hole. A double-ended pin is slidably connected inside the sliding hole, and a magnetic block that can attract the double-ended pin is provided inside the sliding hole. The double-ended pin is stepped, and a telescopic head is slidably connected to one end of the double-ended pin near the inner shaft groove. A retaining spring is provided between the telescopic head and the inner wall of the double-ended pin. The outer side of the inner plug shaft has three sets of arc-shaped grooves and inner pin holes arranged in an alternating pattern.

[0010] Furthermore, the cross-section of the modular triangular beam is an equilateral triangle.

[0011] Furthermore, the cross-section of the triangular socket is an equilateral triangle.

[0012] Furthermore, the center line of the outer pin hole passes through the center of the triangle of the triangular socket.

[0013] Furthermore, the modular triangular beam is installed on a mounting surface with a horizontal inclination angle of 15°. After installation, the top of the mounting surface is close to the working surface of the modular triangular beam.

[0014] Furthermore, a drive guide groove is provided on the outer side of the inner insertion shaft. The drive guide groove consists of a straight part and a spiral part. The straight part is located in an arc-shaped groove. A drive guide rod is provided on the inner wall of the inner shaft groove. The drive guide rod can slide along the drive guide groove.

[0015] Furthermore, the center of the triangular socket is provided with a rotating groove, the inner plug shaft is inserted into the rotating groove, and a flange is installed on the outside of the rotating groove, the flange limiting the inner plug shaft in the rotating groove.

[0016] Furthermore, the outer pin hole and the inner pin hole are provided with a sealing inner liner, and the inner pin hole is provided with a filling hole, the inlet of which is located on the bottom surface of the modular triangular beam.

[0017] The beneficial effects of this invention are as follows:

[0018] 1. This invention employs a three-layer coaxial and concentric connection consisting of an outer triangular profile, a middle locking pin layer, and a central inner insert shaft. This results in high joint stiffness, far exceeding that of traditional flange connections. The central inner insert shaft penetrates the center of both crossbeams, forming a composite force transmission system that combines the bending resistance of the outer triangular profile with the torsional resistance of the inner circular shaft. This significantly improves bending, shear, and torsional stiffness, completely eliminating bending deformation and step errors caused by the self-weight and moving loads of large-span crossbeams, ensuring the long-term stability of the guide rail installation reference.

[0019] 2. This invention's triangular socket adopts an equilateral triangular frame structure, automatically achieving circumferential anti-rotation positioning and angle limiting when plugged in with a triangular plug. No manual alignment or additional tooling is required; circumferential angle accuracy is guaranteed upon insertion. The centerline of the outer pin hole precisely passes through the geometric center of the triangle, and the locking force acts on the mechanically neutral surface, eliminating eccentric bending moments and preventing warping and localized deformation of the spliced ​​surface caused by locking. After multi-segment splicing, the overall straightness and coaxiality errors are almost zero, perfectly meeting the micron-level reference requirements for the installation of large-span, long-stroke guide rails.

[0020] 3. During the insertion process of this invention, the drive guide rod slides along the straight line of the inner insertion shaft, and the spiral drive guide groove slides, automatically driving the inner insertion shaft to rotate. This simultaneously completes the entire process of pressing in the telescopic head, aligning the double-headed pins, and locking with the spring return, without requiring manual intervention. The magnetic block attracts the pins, causing them to automatically retract during insertion without affecting the connection. After reaching the correct position, the spring return achieves a double lock between the double-headed pins and the socket, and between the telescopic head and the inner insertion shaft. Combined with the central shaft, this forms a triple mechanical anti-loosening mechanism, eliminating the risk of loosening under long-term vibration and alternating loads.

[0021] 4. During disassembly, this invention only requires injecting pressurized medium through the filling hole on the bottom of the crossbeam. The expansion of the sealed inner liner simultaneously ejects the double-headed pin and the telescopic head, achieving rapid separation of the two crossbeam sections. This eliminates the need to remove multiple bolts, allowing for single-person operation and reducing disassembly time from several hours to just a few minutes. Damaged single crossbeam sections can be disassembled and replaced independently without disassembling the entire crossbeam, significantly reducing maintenance costs and downtime, and improving equipment uptime. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the three-dimensional structure of the gantry coordinate measuring machine of the present invention;

[0023] Figure 2 This is a schematic diagram of the modular triangular beam structure of the present invention;

[0024] Figure 3 This is a schematic diagram of the modular triangular beam crossbeam structure of the present invention;

[0025] Figure 4 This is a schematic diagram of the internal insertion shaft structure of the present invention.

[0026] Reference numerals: 1. Gantry coordinate measuring machine; 2. Mounting surface; 3. Modular triangular crossbeam; 31. Triangular socket; 32. Triangular plug; 33. Internal insertion shaft; 331. Arc-shaped groove; 332. Internal pin hole; 333. Drive guide groove; 34. Inner shaft groove; 35. External pin hole; 36. Sliding hole; 37. Double-headed pin; 371. Telescopic head; 372. Snap ring; 38. Drive guide rod. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0028] Example 1, as Figures 1-4 As shown, a modular crossbeam structure for a gantry coordinate measuring machine is disclosed. One end of the modular triangular crossbeam 3 has a triangular socket 31, and the other end has a triangular plug 32. The triangular plug 32 is fitted into the triangular socket 31. An inner shaft groove 34 is formed in the center of the triangular plug 32. An inner insertion shaft 33 is rotatably mounted in the center of the triangular socket 31, and the inner insertion shaft 33 is fitted into the inner shaft groove 34. An outer pin hole 35 is formed on the inner wall of the triangular socket 31, and the center line of the outer pin hole 35 passes through the triangular center of the triangular socket 31. The inner wall of the triangular plug 32... A sliding hole 36 is provided through the wall. The sliding hole 36 is stepped. A double-headed pin 37 is slidably connected inside the sliding hole 36. A magnetic block that can attract the double-headed pin 37 is provided inside the sliding hole 36. The double-headed pin 37 is stepped. A telescopic head 371 is slidably connected to one end of the double-headed pin 37 near the inner shaft groove 34. A retaining spring 372 is provided between the telescopic head 371 and the inner wall of the double-headed pin 37. Three sets of arc-shaped grooves 331 and inner pin holes 332 are circumferentially opened on the outer side of the inner insertion shaft 33. The inner pin holes 332 and the arc-shaped grooves 331 are staggered.

[0029] The outer side of the inner shaft 33 is provided with a drive guide groove 333, which is composed of a straight part and a spiral part. The straight part is located in the arc-shaped groove 331. The inner wall of the inner shaft groove 34 is provided with a drive guide rod 38, which can slide along the drive guide groove 333.

[0030] The three-prong socket 31 has a central slot, into which the inner connector shaft 33 is inserted. A flange is installed on the outside of the slot, which limits the inner connector shaft 33 within the slot. This design facilitates easy assembly and disassembly.

[0031] The specific operation is as follows: Insert the triangular plug 32 of one set of modular triangular beams 3 into the triangular socket 31 of another set of modular triangular beams 3, and insert the inner shaft 33 into the inner shaft groove 34. Under the action of the magnetic block, the double-ended pin 37 is completely attracted into the sliding hole 36, without affecting the insertion. Initially, the drive guide rod 38 slides along the straight part of the drive guide groove 333, the inner shaft 33 does not rotate, and the telescopic head 371 rests against the inner wall of the arc-shaped groove 331. The outer diameter of the telescopic head 371 is larger than the outer diameter of the drive guide rod 38, so the telescopic head 371 will not enter the drive guide groove 333. As insertion continues, when the drive guide rod 38 enters the spiral part of the drive guide groove 333, the drive guide rod 38 drives the inner shaft through the spiral part. When the inner plug shaft 33 rotates, it presses the telescopic head 371 into the double-ended pin 37 through the arc-shaped groove 331. The telescopic head 371 compresses the retaining spring 372, and the other end of the double-ended pin 37 presses against the inner wall of the triangular socket 31, ensuring that the telescopic head 371 retracts stably. When the outer pin hole 35 and the inner pin hole 332 move to the position of the double-ended pin 37, under the action of the retaining spring 372, the double-ended pin 37 and the telescopic head 371 are respectively inserted into the outer pin hole 35 and the inner pin hole 332, achieving complete self-locking. The double-ended pin 37 restricts the separation of the triangular plug 32 from the triangular socket 31, and the telescopic head 371 restricts the separation of the triangular plug 32 from the inner plug shaft 33, achieving double locking. It is a three-layer connection structure with high connection strength.

[0032] Traditional modular crossbeams often use end flanges and bolts for connection, with node stiffness only 40%-60% of the overall crossbeam. Uneven bolt preload can easily lead to warping and step errors at the splicing surface, becoming the "weakest link" in the overall machine's precision. This quick-connect structure, through three layers of coaxial and concentric connections and triple mechanical locking, makes the splicing node stiffness approach the level of the overall crossbeam. Simultaneously, the inner insert shaft 33 passes through the center of two modules, forming a composite anti-torsional structure of an outer triangular shaft and an inner circular shaft, resulting in higher torsional stiffness than pure flange connections. This design specifically addresses the unique stress problems caused by the 15° inclined axis layout: the inclined layout causes the gravity of the Y / Z axes to generate a torsional moment. Traditional bolted connections are prone to bolt loosening and splicing surface slippage under long-term alternating torsional loads, while the central shaft of this structure can withstand most of the torsional moment, completely eliminating precision drift caused by torsional slippage.

[0033] Example 2, based on the above examples, further includes a modular triangular beam 3 with an equilateral triangle cross section. The modular triangular beam 3 is installed on a mounting surface 2 with a horizontal inclination angle of 15°. After installation, the top of the mounting surface 2 is close to the working surface of the modular triangular beam 3 (the working surface is the surface on which the slide rail is installed on the modular triangular beam 3), making the working surface of the modular triangular beam 3 45°, so that the vertical force component is the same and the force is more evenly distributed.

[0034] The gantry coordinate measuring machine 1 is pre-installed on the ground, and the mounting surface 2 of its X-axis slide rail module is adjusted to 15°. The modular triangular crossbeam 3 adopts an equilateral triangular cross section, with extremely strong structural symmetry. Its bending, shear, and compressive strength in the three directions are completely consistent, and it is not subject to eccentric load.

[0035] In embodiment three, based on the above embodiments, the cross-section of the triangular socket 31 is an equilateral triangular frame. The center line of the outer pin hole 35 passes through the triangular center of the triangular socket 31.

[0036] The triangular socket 31 is designed with an equilateral triangular frame structure. When it is plugged into the triangular plug 32 of the same shape, it has a fully automatic circumferential positioning and angle limiting function. The circumferential anti-rotation positioning can be completed by plugging in, without the need for additional alignment tooling. This prevents circumferential deflection and misalignment between modules after splicing, and ensures the overall straightness and coaxiality of the multi-section crossbeam after splicing. It is suitable for high-precision long-stroke module assembly.

[0037] The center line of the outer pin hole 35 passes through the geometric center of the triangle, ensuring balanced locking force across the entire joint. The center line of the outer pin hole 35 precisely passes through the geometric center of the equilateral triangular socket 31, placing the locking point of the double-ended pin 37 at the mechanically neutral plane of the entire splice joint. Locking force, shear force, and pull-out force all converge on the structural central axis. The locking force has no eccentric bending moment, preventing warping or localized compression deformation of the splice surface due to locking. This further ensures a tight fit between the splice surfaces even at a 15° tilt, eliminating any micro-movement gaps.

[0038] Example 4, based on the above examples, further includes a sealed inner liner inside the outer pin hole 35 and the inner pin hole 332, and a filling hole is opened inside the inner pin hole 332, with the inlet of the filling hole located on the bottom surface of the modular triangular beam 3.

[0039] When disassembly is required, water is injected through the filling hole on the bottom of the modular triangular crossbeam 3. Under hydraulic pressure, the sealing liner expands, pushing the double-headed pin 37 and the telescopic head 371 away from the outer pin hole 35 and the inner pin hole 332. The two modular triangular crossbeams 3 can then be directly separated, achieving quick disassembly. The operation is simple, and individual crossbeams can be replaced later, resulting in high disassembly and assembly efficiency.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A modular crossbeam structure for a gantry coordinate measuring machine, comprising a modular triangular crossbeam (3), characterized in that, One end of the modular triangular beam (3) is provided with a triangular socket (31), and the other end is provided with a triangular plug (32). The triangular plug (32) is adapted to be plugged into the triangular socket (31). The center of the triangular plug (32) is provided with an inner shaft groove (34). The center of the triangular socket (31) is rotatably installed with an inner insertion shaft (33). The inner insertion shaft (33) is adapted to the inner shaft groove (34). The inner wall of the triangular socket (31) is provided with an outer pin hole (35), and the inner wall of the triangular plug (32) is provided with a sliding hole (36). The sliding hole (36) is stepped, and a double-ended pin (37) is slidably connected inside the sliding hole (36). A magnetic block that can attract the double-ended pin (37) is provided inside the sliding hole (36). The double-ended pin (37) is stepped, and a telescopic head (371) is slidably connected to one end of the double-ended pin (37) near the inner shaft groove (34). A retaining ring (372) is provided between the telescopic head (371) and the inner wall of the double-ended pin (37). The outer side of the inner plug shaft (33) is provided with three sets of arc-shaped grooves (331) and inner pin holes (332). The inner pin holes (332) and arc-shaped grooves (331) are staggered.

2. The modular crossbeam structure for a gantry coordinate measuring machine according to claim 1, characterized in that, The cross-section of the modular triangular beam (3) is an equilateral triangle.

3. The modular crossbeam structure for a gantry coordinate measuring machine according to claim 2, characterized in that, The cross-section of the triangular socket (31) is an equilateral triangle.

4. A modular crossbeam structure for a gantry coordinate measuring machine according to claim 3, characterized in that, The center line of the outer pin hole (35) passes through the center of the triangle of the triangular socket (31).

5. A modular crossbeam structure for a gantry coordinate measuring machine according to claim 4, characterized in that, The modular triangular beam (3) is installed on the mounting surface (2) with a horizontal inclination angle of 15°. After installation, the top of the mounting surface (2) is close to the working surface of the modular triangular beam (3).

6. A modular crossbeam structure for a gantry coordinate measuring machine according to claim 1, characterized in that, The outer side of the inner insertion shaft (33) is provided with a drive guide groove (333), which is composed of a straight part and a spiral part. The straight part is located in the arc-shaped groove (331). The inner wall of the inner shaft groove (34) is provided with a drive guide rod (38), which can slide along the drive guide groove (333).

7. A modular crossbeam structure for a gantry coordinate measuring machine according to claim 6, characterized in that, The center of the triangular socket (31) has a rotating groove, and the inner plug shaft (33) is inserted into the rotating groove. A flange is installed on the outside of the rotating groove, and the flange limits the inner plug shaft (33) to be installed in the rotating groove.

8. A modular crossbeam structure for a gantry coordinate measuring machine according to claim 1, characterized in that, The outer pin hole (35) and the inner pin hole (332) are provided with sealed inner liner. The inner pin hole (332) is provided with a filling hole. The inlet of the filling hole is located on the bottom surface of the modular triangular beam (3).

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