A method for manufacturing a small hole measuring needle

Abstract

The application discloses a manufacturing method of a small-hole measuring needle. The method comprises the following steps: step one, processing and forming a measuring head semi-product; step two, clamping a tightening process step in the inner threaded hole of a measuring rod by a torque wrench; step three, placing two equal-height V-shaped supporting blocks under the measuring rod, and placing the V-shaped supporting blocks on a marble platform; a flange end of the measuring rod is fixed with a calibration step, and a reference line of the calibration step is leveled; step four, drawing two parallel lines by a marking tool; step five, removing the upper region and the lower region of the two lines; step six, precisely grinding a reference process step; step seven, forming a reference hole on the measuring head, which is perpendicular to the surface of the reference process step; step eight, cutting off the length of the reference process step; step nine, cutting off the tightening process step; and step ten, fixedly installing the measuring needle in the reference hole of the measuring head through interference fit.

Description

Technical Field

[0001] This invention relates to the field of detection technology, specifically to a method for manufacturing a pinhole probe. Background Technology

[0002] Gear molds are required in the production of powder metallurgy gears. In the manufacturing process of small-diameter gear molds with an inner hole of less than 10mm, a measuring rod is needed to precisely measure the gear tooth profile of the mold.

[0003] Traditional measuring rods currently have the following problems:

[0004] 1. The measuring head and measuring rod need to adopt a detachable and replaceable structure, while ensuring repeatability accuracy each time they are disassembled and replaced. Currently, there is a lack of a method to quickly determine the installation accuracy.

[0005] 2. The conversion mechanism at the head of the measuring rod is relatively large, causing interference when it enters the toothed hole of the female mold, making measurement impossible. Due to the large size of the conversion mechanism, there is an urgent need for a structure that directly fixes the probe on the measuring head. This structure requires a probe hole to be made on the measuring head. When the probe hole of the measuring head is machined using slow wire EDM, the measuring rod flange end reference is needed to position the machining position, thereby ensuring the perpendicularity of the measuring rod flange end reference to the probe hole. However, during slow wire EDM, the measuring rod needs to be completely immersed in the electrolyte. Immersion in the liquid will cause uncontrollable corrosion of the measuring rod flange reference, and the surface is prone to rust, which will affect the positioning accuracy.

[0006] There is an urgent need for a machining method that can ensure the machining accuracy of the probe hole on the measuring head without immersing the entire measuring rod in the electrolyte. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for manufacturing a pinhole probe, which solves at least one of the above-mentioned technical problems.

[0008] The technical solution of the present invention is: a method for manufacturing a pinhole probe, characterized by comprising the following steps:

[0009] Step 1: Processing and shaping the semi-finished measuring head;

[0010] The semi-finished measuring head includes an axially arranged tightening process step, a disc portion, a probe mounting portion, and a threaded connection portion, wherein the threaded connection portion is provided with an external thread for threaded connection of the measuring rod.

[0011] Step 2: Clamp the measuring head semi-finished product onto the tightening process step using a torque wrench, and tighten the thread of the measuring head semi-finished product into the internal thread hole of the measuring rod according to the set standard torque value;

[0012] Step 3: Place two V-shaped support blocks of equal height under the measuring rod, and place the V-shaped support blocks on the marble platform;

[0013] A movable measuring tool is installed on the marble platform, the movable measuring tool including two tabular length measuring tools arranged one above the other;

[0014] A calibration step is fixed to the flange end of the measuring rod. The upper and lower surfaces of the calibration step are calibrated by moving the measuring tool. The position of the calibration step is adjusted by rotating the measuring rod to level the baseline of the calibration step.

[0015] Step 4: Install a scribing fixture on the marble platform. Use the scribing fixture to scribing two parallel lines on the side of the disc away from the measuring rod. The two scribing lines are parallel to the baseline of the calibration step and are located above and below the tightening process step.

[0016] Step 5: Remove the semi-finished measuring head from the measuring rod and process away the upper and lower areas of the two scribing lines;

[0017] Step 6: Clamp the measuring head semi-finished product onto the tightening process step using a torque wrench, and tighten the thread of the measuring head semi-finished product into the internal thread hole of the measuring rod according to the set standard torque value;

[0018] On a surface grinder, the assembly of the measuring rod and the semi-finished measuring head is leveled and precision ground to form a reference process step. The upper and lower surfaces of the reference process step are parallel to the reference line of the measuring rod.

[0019] Step 7: Remove the semi-finished measuring head from the measuring rod, level the semi-finished measuring head according to the reference process step, and open a reference hole on the measuring head that is perpendicular to the surface of the reference process step.

[0020] Step 8: Remove the semi-finished measuring head from the measuring rod and cut off both sides of the reference process step length;

[0021] Step 9: Cut off the tightening process step, and the reference process step will be used as the tightening part in the future;

[0022] Step 10: Fix the probe to the reference hole of the measuring head by interference fit to make the finished small-hole probe.

[0023] In a further preferred embodiment, in step one, the tightening process step is centrally located on the disc portion;

[0024] The radius of the disc portion is greater than the length of the probe in step ten.

[0025] The width of the tightening process step is less than the width of the reference process step in step six, and the difference is 1.5-2.5mm.

[0026] The purpose is to ensure that when grinding the reference process table, the grinding wheel will not come into contact with the tightening process step, and that the tightening process step is not completely parallel to the reference process step.

[0027] More preferably, in step two, when the internal thread hole of the measuring rod is M3, the set standard torque value is 0.8 to 1.2 N·m;

[0028] When the internal thread hole of the measuring rod is M2, the standard torque value is set to 0.4–0.7 N·m;

[0029] In step six, when the internal thread hole of the measuring rod is M3, the standard torque value is set to 0.8 to 1.2 N·m;

[0030] When the internal thread hole of the measuring rod is M2, the standard torque value is set to 0.4–0.7 N·m.

[0031] The optimal torque range is 0.8–1.2 N·m. For example, a torque value ≤0.8 N·m may result in insufficient tightening and wobbling. A torque value >1.2 N·m, with its high torque, can easily cause stripping and deformation.

[0032] In a further preferred embodiment, in step three, the measuring tool for measuring the length is a dial indicator or a micrometer.

[0033] In a further preferred embodiment, the method for leveling the baseline of the calibration step in step three is as follows:

[0034] First, the upper and lower dial length measuring tool slides radially along the measuring rod on the calibration step. The difference between the upper dial length measuring unit sliding to the two extreme positions is taken as the measurement change value A1 on the upper surface of the calibration step.

[0035] The difference between the length measurement units on the lower side and the two extreme positions is used as the measurement change value A2 of the lower surface of the calibration step;

[0036] Rotate the measuring rod to adjust A2 to 0. If A1 is 0, the axial section of the calibration step is rectangular, and the baseline of the calibration step is leveled. If A1 is not equal to 0, the axial section of the calibration step is trapezoidal. Divide the value of A1 by 2 to obtain the calibration value. Rotate the measuring rod to adjust A1 and A2 to the calibration value, and the baseline of the calibration step is leveled.

[0037] A further preferred method is step six, which involves leveling the assembly of the measuring rod and the semi-finished measuring head, using the same method as step three, which involves calibrating the baseline of the step.

[0038] In a further preferred embodiment, in step six, after the assembly of the measuring rod and the semi-finished measuring head is leveled, the upper surface of the reference process step is precision ground, and the upper surface of the reference process step is parallel to the reference line of the measuring rod.

[0039] After rotating the assembly of the measuring rod and the semi-finished measuring head by 180° to level it, the lower surface of the reference process step is precision ground, and the lower surface of the reference process step is parallel to the reference line of the measuring rod.

[0040] In a further preferred embodiment, in step seven, a pre-machined hole is created using electrical discharge machining; the cutting line of the slow wire EDM passes through the pre-machined hole, and the reference hole is formed by slow wire EDM on the measuring head.

[0041] More preferably, the pinhole probe includes a threaded measuring head and a measuring rod, wherein the measuring head includes a tightening part, a probe mounting part and a threaded connecting part connected in sequence;

[0042] The probe mounting section is equipped with a probe;

[0043] The upper and lower surfaces of the tightening part are parallel to the reference line of the calibration step on the measuring rod;

[0044] The upper and lower surfaces of the tightening part are perpendicular to the axial direction of the probe.

[0045] More preferably, the pinhole probe is suitable for measuring holes with an inner diameter greater than 6 mm.

[0046] When measuring holes of 6mm-8mm, the internal thread of the measuring rod is M2. The outer diameter of the probe mounting part is 3mm-3.5mm.

[0047] When measuring holes of 8mm-10mm, the internal thread of the measuring rod is M3. The outer diameter of the probe mounting part is 5mm-5.5mm.

[0048] When measuring an 8mm hole, preferably, the internal thread of the measuring rod is M3. The outer diameter of the probe mounting part is 5mm-5.5mm.

[0049] More preferably, the measuring head and measuring rod are made of stainless steel or titanium alloy.

[0050] Compared with the prior art, the present invention has the following advantages:

[0051] 1. The reference conversion was achieved through the reference process step, which transferred the reference on the measuring rod to the position of the measuring head, thus solving the problem that the original reference at the flange end of the measuring rod could not be used in slow wire EDM.

[0052] 2. By extending the reference process platform before cutting, the problem of high-precision alignment in slow wire EDM machining is solved. Without extending the reference step surface, a longer measuring stylus leads to amplified errors for the same angular error.

[0053] 3. Ensure the repeatability of measuring head assembly and disassembly by tightening the process steps and fixing the standard torque.

[0054] 4. By removing the tightening process step at the end, the volume of the measuring head is reduced, improving the adaptability of blind hole measurement.

[0055] 5. By simultaneously measuring the upper and lower planes of the measuring rod flange using two dial gauge length measuring tools, the calibration error caused by the width of the two planes was eliminated.

[0056] 6. This invention reconstructs a 'reference process step' parallel to the original reference on the measuring head body, completely eliminating the dependence on the measuring rod flange reference for subsequent wire EDM alignment, thus avoiding the interference of liquid immersion on accuracy. This invention, through a combined process of 'reference transfer and de-reference,' transforms machining dependent on the measuring rod flange reference into independent machining with its own reference on the measuring head body. This achieves the complete absence of the measuring rod during wire EDM, fundamentally eliminating the interference of electrolyte immersion on accuracy and overcoming the bottleneck of traditional processes that cannot simultaneously achieve small dimensions and high precision. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of one structure of the pinhole probe of the present invention;

[0058] Figure 2 This is a schematic diagram of the orifice probe of the present invention from another perspective;

[0059] Figure 3 This is a schematic diagram of the product structure after step one of the specific embodiments of the present invention;

[0060] Figure 4 This is a schematic diagram of the moving measuring tool calibrating the upper and lower surfaces of the calibration step in step three of a specific embodiment 1 of the present invention;

[0061] Figure 5 This is a schematic diagram of step three in a specific embodiment 1 of the present invention;

[0062] Figure 6 This is a schematic diagram of the product structure after step four in a specific embodiment of the present invention;

[0063] Figure 7 This is a schematic diagram of the product structure after step five in a specific embodiment of the present invention;

[0064] Figure 8This is a schematic diagram of the product structure after step six in a specific embodiment of the present invention;

[0065] Figure 9 This is a schematic diagram of the structure of the measuring head semi-finished product after step seven in a specific embodiment of the present invention;

[0066] Figure 10 This is a schematic diagram of the structure of the measuring head semi-finished product after step eight in a specific embodiment of the present invention.

[0067] 1 is the measuring rod, 2 is the measuring head, 3 is the measuring stylus, 4 is the V-shaped support block, and 5 is the dial indicator length measuring tool;

[0068] 11 is the calibration step, 111 is the upper surface, 112 is the lower surface, 12 is the scribing line, 13 is the tightening process step, 14 is the disc part, and 15 is the threaded connection part.

[0069] 21 is the reference process step, and 22 is the reference hole. Detailed Implementation

[0070] See Figures 1 to 10 Specific embodiment 1, a method for manufacturing a small-hole probe 3, includes the following steps:

[0071] Step 1: Processing and shaping the semi-finished measuring head;

[0072] The semi-finished measuring head includes an axially arranged tightening process step 13, a disc portion 14, a probe 3 mounting portion, and a threaded connection portion 15. The threaded connection portion 15 is provided with an external thread for threaded connection of the measuring rod 1; see also Figure 3 The tightening process step 13 includes two parallel tightening surfaces positioned vertically. The two tightening surfaces are connected by an outwardly convex arc-shaped surface.

[0073] The tightening process step 13 is centrally located on the disc portion 14; the radius of the disc portion 14 is greater than the length of the probe 3 in step ten; the width of the tightening process step 13 is less than the width of the reference process step 21 in step six, with a difference of 1.5-2.5 mm. That is, the distance between the two tightening surfaces of the tightening process step 13 is less than the longitudinal width of the reference process step 21 in step six. The longitudinal width of the reference process step 21 is 2 / 3-3 / 4 of the outer diameter of the measuring rod 1. The outer diameter of the probe 3 mounting portion matches the outer diameter of the measuring rod 1. The purpose is to ensure that the grinding wheel does not touch the tightening process step 13 during the grinding of the reference process table, and that the tightening process step 13 and the reference process step 21 are not completely parallel.

[0074] Step 2: Using a torque wrench clamped on the tightening process step 13, tighten the threads of the measuring head semi-finished product into the internal thread hole of the measuring rod 1 according to the set standard torque value.

[0075] When the internal thread of the measuring rod is M3, the standard torque value is set to 0.8–1.2 N·m. Controlling the torque value within the 0.8–1.2 N·m range is most suitable. For example, a torque value ≤0.8 N·m may result in incomplete tightening and wobbling. A torque value >1.2 N·m, with its high torque, is prone to stripping and deformation.

[0076] When the internal thread of the measuring rod is M2, the standard torque value is set to 0.4–0.7 N·m. This range is optimal to avoid wobbling and stripping.

[0077] Step 3: Place two V-shaped support blocks 4 of equal height under the measuring rod 1, and place the V-shaped support blocks 4 on the marble platform;

[0078] A movable measuring tool is installed on the marble platform. The movable measuring tool includes two tabular length measuring tools 5 set up one above the other.

[0079] A calibration step 11 is fixed to the flange end of the measuring rod 1. The upper surface 111 and lower surface 112 of the calibration step 11 are calibrated by moving the measuring tool. The position of the calibration step 11 is adjusted by rotating the measuring rod 1, leveling the baseline of the calibration step 11. (See also...) Figure 4 as well as Figure 5 .

[0080] The length measuring tool 5 is a dial indicator or a micrometer.

[0081] The method for leveling the baseline of calibration step 11 is as follows: First, the upper and lower dial length measuring tool 5 slides radially along the measuring rod 1 on calibration step 11. The difference between the two extreme positions of the upper length measuring unit is taken as the measurement change value A1 of the upper surface of calibration step 11; the difference between the two extreme positions of the lower length measuring unit is taken as the measurement change value A2 of the lower surface of calibration step 11. Rotate the measuring rod 1 to adjust A2 to 0. If A1 is 0, the axial section of calibration step 11 is rectangular, and the baseline leveling of calibration step 11 is completed. If A1 is not equal to 0, the axial section of calibration step 11 is trapezoidal. Divide the value of A1 by 2 to obtain the calibration value. Rotate the measuring rod 1 to adjust A1 and A2 to the calibration value, and the baseline leveling of calibration step 11 is completed.

[0082] Step four: A scribing fixture is installed on the marble platform. Two parallel scribing lines 12 are drawn on the side of the disc 14 away from the measuring rod 1 using the scribing fixture. The two scribing lines 12 are parallel to the baseline of the calibration step 11 and are located above and below the tightening process step 13; see [link / reference] Figure 6The distance between the two scribing lines 12 is greater than the longitudinal width of the reference process step 21 in step six. The difference between the distance between the two scribing lines 12 and the longitudinal width of the reference process step 21 is 1mm-1.2mm. A grinding finishing allowance of 0.5-0.6mm is left on each side.

[0083] Step 5: Remove the semi-finished measuring head from measuring rod 1, and process and remove the upper and lower areas of the two scribing lines 12; see [link / reference] Figure 7 This step involves roughing out the upper and lower areas of the two scribing lines 12.

[0084] Step Six: Using a torque wrench clamped on the tightening process step 13, tighten the threads of the measuring head semi-finished product into the internal threaded hole of the measuring rod 1 according to the set standard torque value. When the internal threaded hole of the measuring rod is M3, the set standard torque value is 0.8~1.2 N·m. Controlling the torque value within the range of 0.8~1.2 N·m is most suitable. For example, a torque value ≤0.8 N·m may not be tightened properly, resulting in wobbling. A torque value >1.2 N·m, due to high torque, is prone to stripping and deformation. When the internal threaded hole of the measuring rod is M2, the set standard torque value is 0.4–0.7 N·m. This range is most suitable to avoid wobbling and stripping.

[0085] On a surface grinder, the assembly of measuring rod 1 and the semi-finished measuring head is leveled, and a reference process step 21 is precision ground. The upper and lower surfaces of the reference process step 21 are parallel to the reference line of measuring rod 1; see [link to related document]. Figure 8 .

[0086] The method for leveling the assembly of measuring rod 1 and the semi-finished measuring head is the same as the method for leveling the baseline of calibration step 11 in step three. In step six, after leveling the assembly of measuring rod 1 and the semi-finished measuring head, the upper surface of the reference process step 21 is precision ground, and the upper surface of the reference process step 21 is parallel to the baseline of measuring rod 1; after rotating the assembly of measuring rod 1 and the semi-finished measuring head 180° to level it, the lower surface of the reference process step 21 is precision ground (at this time, the lower surface is flipped and located on the upper side), and the lower surface of the reference process step 21 is parallel to the baseline of measuring rod 1.

[0087] Step 7: Remove the semi-finished measuring head from the measuring rod 1. Level the semi-finished measuring head according to the reference process step 21. Create a reference hole 22 perpendicular to the surface of the reference process step on the measuring head 2. (See also...) Figure 9 .

[0088] Specifically, it can be done by using electrical discharge machining to create a pre-machined hole; the cutting line of the slow wire EDM process passes through the pre-machined hole and forms the reference hole 22 on the measuring head 2 through slow wire EDM.

[0089] Step 8: Remove the semi-finished measuring head from measuring rod 1, and cut off both sides of the length of the reference process step 21; see [link / reference]. Figure 10 .

[0090] Step 9: Cut off the tightening process step 13, and the reference process step 21 will be used as the tightening part in the future.

[0091] Step 10: Fix the probe 3 to the reference hole 22 of the measuring head 2 by interference fit to make the finished small hole probe 3.

[0092] See Figure 1 as well as Figure 2 The small hole probe 3 includes a threaded measuring head 2 and a measuring rod 1. The measuring head 2 includes a tightening part, a probe 3 mounting part, and a threaded connection part 15 connected in sequence. The probe 3 is mounted on the probe 3 mounting part. The upper and lower surfaces of the tightening part are parallel to the reference line of the calibration step 11 on the measuring rod 1, and the upper and lower surfaces of the tightening part are perpendicular to the axial direction of the probe 3. The small hole probe 3 is suitable for measuring holes with an inner diameter greater than 6 mm. The measuring head 2 and the measuring rod 1 are made of stainless steel or titanium alloy.

[0093] Compared with existing technologies, the core advantage of this invention lies in creating an 'offline absolute reference'. Through the coordinated operation of steps two through six, a new reference (reference process step) is constructed on the measuring head body, with its parallelism error strictly controlled compared to the original reference (calibration step). This makes the measuring head an independent unit with its own high-precision reference. This brings about a revolutionary effect not disclosed in existing technologies: in subsequent wire EDM machining processes, the measuring rod can be completely absent, thoroughly avoiding all potential impacts on accuracy caused by the measuring rod being immersed in the electrolyte. This combined process concept of 'reference transfer and separation' is something that no single existing technology document can provide inspiration for.

[0094] In specific embodiment 2, based on specific embodiment 1, a horizontal line laser generator is further provided. The horizontal line laser generator is mounted on a lifting bracket, which is installed on the marble platform. The lifting bracket can be an electrically controlled lifting mechanism. In step three, the method for leveling the baseline of calibration step 11 is as follows: the horizontal line emitted by the horizontal line laser generator is aligned with the lower side of the calibration step to achieve initial positioning. The upper and lower dial length measuring tool 5 slides radially along the measuring rod 1 on the calibration step 11. The difference between the two extreme positions of the upper length measuring unit is taken as the measurement change value A1 of the upper surface of the calibration step 11; the difference between the two extreme positions of the lower length measuring unit is taken as the measurement change value A2 of the lower surface of the calibration step 11. Rotate the measuring rod 1 to adjust A2 to 0. If A1 is 0, the axial section of the calibration step 11 is rectangular, and the baseline of the calibration step 11 is leveled. If A1 is not equal to 0, the axial section of the calibration step 11 is trapezoidal. Divide the value of A1 by 2 to obtain the calibration value. Rotate the measuring rod 1 to adjust A1 and A2 to the calibration value, and the baseline of the calibration step 11 is leveled.

[0095] In specific embodiment 2, based on specific embodiment 1, in step four, the scribing fixture includes a base, on which a horizontally sliding guide rail is mounted. A sliding frame is slidably connected to the guide rail, and a lifting rod is mounted on the sliding frame. A scribing tool is mounted on the lifting rod. This facilitates the formation of a groove by the scribing tool through the horizontal sliding of the sliding frame. The height of the scribing tool is adjusted by the lifting rod. The lifting rod can be an electric lifting mechanism.

[0096] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a pinhole probe, characterized in that, Includes the following steps: Step 1: Processing and shaping the semi-finished measuring head; The semi-finished measuring head includes an axially arranged tightening process step, a disc portion, a probe mounting portion, and a threaded connection portion, wherein the threaded connection portion is provided with an external thread for threaded connection of the measuring rod. Step 2: Clamp the measuring head semi-finished product onto the tightening process step using a torque wrench, and tighten the thread of the measuring head semi-finished product into the internal thread hole of the measuring rod according to the set standard torque value; Step 3: Place two V-shaped support blocks of equal height under the measuring rod, and place the V-shaped support blocks on the marble platform; A movable measuring tool is installed on the marble platform, the movable measuring tool including two tabular length measuring tools arranged one above the other; A calibration step is fixed to the flange end of the measuring rod. The upper and lower surfaces of the calibration step are calibrated by moving the measuring tool. The position of the calibration step is adjusted by rotating the measuring rod to level the baseline of the calibration step. Step 4: Install a scribing fixture on the marble platform. Use the scribing fixture to scribing two parallel lines on the side of the disc away from the measuring rod. The two scribing lines are parallel to the baseline of the calibration step and are located above and below the tightening process step. Step 5: Remove the semi-finished measuring head from the measuring rod and process away the upper and lower areas of the two scribing lines; Step 6: Clamp the measuring head semi-finished product onto the tightening process step using a torque wrench, and tighten the thread of the measuring head semi-finished product into the internal thread hole of the measuring rod according to the set standard torque value; On a surface grinder, the assembly of the measuring rod and the semi-finished measuring head is leveled and precision ground to form a reference process step. The upper and lower surfaces of the reference process step are parallel to the reference line of the measuring rod. Step 7: Remove the semi-finished measuring head from the measuring rod, level the semi-finished measuring head according to the reference process step, and open a reference hole on the measuring head that is perpendicular to the surface of the reference process step. Step 8: Remove the semi-finished measuring head from the measuring rod and cut off both sides of the reference process step length; Step 9: Cut off the tightening process step, and the reference process step will be used as the tightening part in the future; Step 10: Fix the probe to the reference hole of the measuring head by interference fit to make the finished small-hole probe.

2. The method for manufacturing a pinhole probe according to claim 1, characterized in that: Step 1: The tightening process step is centrally located on the disc portion; The radius of the disc portion is greater than the length of the probe in step ten. The width of the tightening process step is less than the width of the reference process step in step six, and the difference is 1.5-2.5mm.

3. The method for manufacturing a pinhole probe according to claim 1, characterized in that: In step two, when the internal thread hole of the measuring rod is M3, the standard torque value is set to 0.8~1.2 N·m; When the internal thread hole of the measuring rod is M2, the standard torque value is set to 0.4–0.7 N·m; In step six, when the internal thread hole of the measuring rod is M3, the standard torque value is set to 0.8 to 1.2 N·m; When the internal thread hole of the measuring rod is M2, the standard torque value is set to 0.4–0.7 N·m.

4. The method for manufacturing a pinhole probe according to claim 1, characterized in that: In step three, the measuring tool for measuring the length is a dial indicator or a micrometer.

5. The method for manufacturing a pinhole probe according to claim 1, characterized in that: In step three, the method for leveling the baseline of the calibration step is as follows: First, the upper and lower dial length measuring tool slides radially along the measuring rod on the calibration step. The difference between the upper dial length measuring unit sliding to the two extreme positions is taken as the measurement change value A1 on the upper surface of the calibration step. The difference between the length measurement units on the lower side and the two extreme positions is used as the measurement change value A2 of the lower surface of the calibration step; Rotate the measuring rod to adjust A2 to 0. If A1 is 0, the axial section of the calibration step is rectangular, and the baseline of the calibration step is leveled. If A1 is not equal to 0, the axial section of the calibration step is trapezoidal. Divide the value of A1 by 2 to obtain the calibration value. Rotate the measuring rod to adjust A1 and A2 to the calibration value, and the baseline of the calibration step is leveled.

6. The method for manufacturing a pinhole probe according to claim 1, characterized in that: Step six, the method for leveling the assembly of the measuring rod and measuring head semi-finished product is the same as the method for leveling the benchmark line of the calibration step in step three.

7. The method for manufacturing a pinhole probe according to claim 1, characterized in that: In step six, after the assembly of the measuring rod and the semi-finished measuring head is leveled, the upper surface of the reference process step is precision ground, and the upper surface of the reference process step is parallel to the reference line of the measuring rod. After rotating the assembly of the measuring rod and the semi-finished measuring head by 180° to level it, the lower surface of the reference process step is precision ground, and the lower surface of the reference process step is parallel to the reference line of the measuring rod.

8. A method for manufacturing a pinhole probe according to claim 1, characterized in that: In step seven, a pre-machined hole is made using electrical discharge machining (EDM); the cutting line of the wire EDM machine passes through the pre-machined hole, and the reference hole is formed by wire EDM on the measuring head.

9. A method for manufacturing a pinhole probe according to claim 1, characterized in that: The pinhole probe includes a threaded measuring head and a measuring rod. The measuring head includes a tightening part, a probe mounting part, and a threaded connection part connected in sequence. The probe mounting section is equipped with a probe; The upper and lower surfaces of the tightening part are parallel to the reference line of the calibration step on the measuring rod; The upper and lower surfaces of the tightening part are perpendicular to the axial direction of the probe.

10. A method for manufacturing a pinhole probe according to claim 9, characterized in that: The pinhole probe is suitable for measuring holes with an inner diameter greater than 6 mm; When measuring holes of 6mm-8mm, the internal thread of the measuring rod is M2; the outer diameter of the probe mounting part is 3mm-3.5mm. When measuring holes of 8mm-10mm, the internal thread of the measuring rod is M3; the outer diameter of the probe mounting part is 5mm-5.5mm.

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