Cylindrical external thread coating control process

Abstract

According to the plating layer control process of the cylindrical external thread, the pitch diameter of the thread of the part before coating is measured and screened according to the thickness requirement range of the coating layer, so that the thread part is subjected to classified coating according to different thread pitch diameter intervals, and the coated thread part meets the size requirement. According to the plating layer control process for the cylindrical thread, the pitch diameter size of the thread before coating can be controlled more accurately, and the problem that a product which is detected to be qualified through a conventional go gauge before coating is possibly unqualified after coating can be avoided; and meanwhile, the defects that part of the coated products are qualified products, and the parts of the coated products are unqualified and discarded through conventional no-go gauge detection before coating are overcome, so that the detection result is more targeted, the output of waste products is reduced, and the yield is improved. In addition, according to different sizes obtained through detection, the method that the thickness of the preset plating layer is designed in a targeted mode can further effectively improve the consistency of products.

Description

Technical Field

[0001] The invention relates to the technical field of thread coating, and in particular to a process for detecting the effective mean diameter of threads by a comparative measurement method before coating of external threaded parts to control the thickness of the coating. Background Art

[0002] External threaded parts (such as bolts) usually need to be coated to improve the surface mechanical properties and anti-oxidation and anti-corrosion properties of threaded parts. Coating will cause the thread size to change (increase or decrease), so it is necessary to measure the thread before coating to reserve enough margin to avoid unqualified threaded parts after coating. At present, cylindrical thread detection mainly uses cylindrical thread gauges (through gauges, stop gauges), and cylindrical gauges can only inspect the thread quality according to the limit size judgment principle of the thread during detection: pass or fail, qualified or unqualified, that is, it can determine whether the thread is larger or smaller than the limit size range of the cylindrical gauge, that is, after two tests with two gauges of different limit sizes, the measurement result obtained is a numerical range, not an accurate measurement value, and the actual size of the middle diameter of the thread to be tested cannot be obtained. On this basis, the threaded parts that are further coated and plated must have poor dimensional consistency.

[0003] Using conventional thread stop gauges and thread go gauges for testing, there are only qualified or unqualified products (the conventional understanding is: only products that pass the go gauge and do not pass the stop gauge are qualified products). For products that pass the pre-plating inspection, the outer diameter or inner diameter of the thread and the middle diameter of the thread will change after coating and plating, and it is possible that they will become unqualified after coating and plating; and for unqualified products that pass the go gauge and the stop gauge before plating, it is possible that they will become qualified products after coating and plating.

[0004] Therefore, when the effective mean diameter of the threaded part is close to the calibrated size of the through gauge, it is possible that the thread after coating and plating cannot meet the design requirements of the product. That is, even if the through gauge test is used before plating and it is judged to be qualified, coating and plating may still cause a certain number of defective products, that is, the thread through gauge test fails. After these defective products are repaired, they not only need to be further screened through the through gauge and the stop gauge, which wastes manpower and material resources, but also because the coating itself consumes various costs, it brings a lot of waste.

[0005] At the same time, when threaded parts are judged as unqualified products by the go gauge and the no-go gauge before plating, they may become qualified products (pass the go gauge and stop the no-go gauge) after plating. If this part of the products is directly discarded, it will undoubtedly lead to waste. Summary of the invention

[0006] The technical problem to be solved by the embodiments of the present invention is to provide a coating control process for cylindrical external threads, so as to solve the problem that the existing external threaded parts are subjected to traditional thread go gauge and thread stop gauge detection methods before coating, resulting in some products that fail the stop gauge detection before coating but pass the detection after coating being mistakenly treated as defective products, and some products that pass the go gauge detection before coating but fail the detection after coating being mistakenly collected as qualified products.

[0007] In order to solve the above technical problems, the present invention provides a coating control process for cylindrical external threads, comprising:

[0008] Step 1: Obtain the tolerance range D±γ of the mid-diameter dimension of the coated threaded parts to be delivered;

[0009] Step 2: Obtain uncoated threaded parts and determine the minimum value a and maximum value b of the coating thickness that meets the performance requirements of qualified products;

[0010] Step 3: Provide a gauge with an internal tapered thread, and the pitch diameter value of the internal tapered thread covers the range from (D+γ-4a) to (D-γ-4b), and mark the pitch diameter values ​​of the tapered thread corresponding to point A (D+γ-4a), point B (D-γ-4b), first tolerance reference point F, and second tolerance reference point G on the gauge; A>F>G>B;

[0011] Step 4: Provide the threaded parts to be tested before coating, and screw the threaded parts to be tested into the gauge with tapered threads until the threaded parts reach the limit position and cannot be screwed any further, provided that the applied torque does not cause yield deformation on the threaded surface of the parts;

[0012] Step 5: calibrate the limit position corresponding to the end face of the threaded part in the tightened state, and determine whether the point is between the two marking points (F and G). If so, it is determined to be a qualified product; if it is between the marking points (B and G) or (F and A), it is determined to be a qualified product to be controlled; otherwise, it is a failed product;

[0013] Step 6: Determine the effective mean diameter of the cylindrical threaded part according to the different axial distances between the end face of the threaded part and the reference point of the gauge with tapered thread. During the production process of the part, reserve a margin to meet the specified coating thickness and adjust the size to the optimal state for processing;

[0014] Step 7: Coat the qualified products and the qualified products to be controlled according to the coating method with a preset thickness.

[0015] Point F is located at 3 / 4 of the upper tolerance, that is, it is between points A and B, and the distance between point A and point B is 1 / 3 of the distance between point F and point B.

[0016] Point G is located at 1 / 3 of the lower tolerance, that is, between points A and B, and its distance from point A is twice its distance from point B.

[0017] Step five also includes further determining the thread diameter value of the part to be tested according to the limit position, and matching the preset coating thickness during coating according to the thread diameter value.

[0018] The coating method according to the preset thickness in step seven includes:

[0019] (1) When the limit position is between or close to the marked points (B and G), the qualified products to be controlled are coated according to the preset maximum thickness b;

[0020] (2) When the limit position is between or close to the marked points (A and F), the qualified products to be controlled are coated according to the preset minimum thickness a when coating the threaded parts;

[0021] (3) When the limit position is between the two marking points (F and G), it is a qualified product. When coating the threaded parts, the preset thickness is any value between (a and b).

[0022] The coating method according to the preset thickness in step 7 also includes:

[0023] The threaded parts to be tested of categories (1), (2) and (3) are collected separately and coated respectively according to the coating method with a preset thickness.

[0024] The coating thickness is controlled by determining the coating time, current, coating solution concentration, etc. according to the preset coating thickness value.

[0025] The thread is a cylindrical thread, including metric common thread, American unified thread, pipe thread, etc.

[0026] The gauge with tapered threads is a gauge with internal tapered threads, and the limit position of the threaded part in the gauge can be obtained intuitively or with the help of tools.

[0027] By opening a longitudinal notch on the side of the gauge or a step surface at the minor diameter end of the internal tapered thread of the gauge, the position of the threaded part inside the gauge can be directly observed;

[0028] Alternatively, use a ruler, vernier caliper, depth gauge, etc. to detect the limit position of the threaded part in the gauge.

[0029] The coating control process of cylindrical threads provided by the present invention can make the thread diameter size control before coating more accurate, not only avoiding the problem that products that pass the conventional through gauge test before coating may be unqualified after coating, but also making up for the defect that some products are qualified after coating but are unqualified and scrapped after the conventional stop gauge test before coating, so that the test results are more targeted, the output of waste products is reduced, and the yield rate is improved. According to the different sizes obtained by the test, the method of designing the preset coating thickness in a targeted manner can also more effectively improve the consistency of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of a gauge according to an embodiment of the present invention.

[0031] Figure 2 It is a cross-sectional view of the gauge described in the embodiment of the present invention.

[0032] Figure 3 A top view of the gauge according to an embodiment of the present invention.

[0033] Figure 4 Schematic diagram of the change in thread diameter before and after coating;

[0034] Figure 5 It is a comparison diagram of the size range of threaded parts measured by the present invention and the size range of threaded parts measured by conventional methods;

[0035] Figure 6 yes Figure 5 The enlarged partial diagram in the figure shows the range of parts that are mistakenly accepted and the range of parts that are mistakenly rejected by the conventional method (minimum coating thickness);

[0036] Figure 7 is with Figure 6 For comparison, the range of parts that are mistakenly accepted and the range of parts that are mistakenly scrapped using the conventional method are shown below when the maximum coating thickness is used. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0038] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0040] The present invention provides a coating control process for cylindrical external threads, comprising:

[0041] Step 1: Obtain the tolerance range of the median diameter of the coated threaded parts to be delivered, D±γ, where D is the median diameter of the thread and γ is the tolerance;

[0042] Step 2: Obtain uncoated threaded parts, and determine the minimum value a and maximum value b of the coating thickness that meets the performance requirements of qualified products; the minimum value and maximum value are the minimum and maximum values ​​obtained by testing the coated threads on the premise of meeting the performance requirements of the threaded parts; they can be empirical values ​​or values ​​obtained from experimental data;

[0043] Step 3: Provide a gauge with an internal tapered thread, and the pitch diameter value of the internal tapered thread covers the range from (D+γ-4a) to (D-γ-4b), and mark the pitch diameter values ​​of the tapered thread corresponding to point A (D+γ-4a), point B (D-γ-4b), the first tolerance reference point F, and the second tolerance reference point G on the gauge; A>F>D>G>B; reference Figure 1-2As shown, since the three-dimensional shape of the thread is relatively complex, a straight line is used in this embodiment to replace the position of the thread diameter; due to the shape of the internal tapered thread, the thread diameter also forms a virtual boundary of the internal tapered shape; by measuring the thread diameter values ​​at the upper and lower ends of the two-end tapered thread, and combining the height of the gauge, according to the difference in the taper of the middle diameter cone and the axial distance of the gauge with the internal tapered thread, the thread diameter value at any height position can be calculated, and the positions of the four points A, F, G, and B can be calculated; in this embodiment, a vertical notch is opened on the side of the gauge, and the internal thread can be observed through the notch. When the threaded part is screwed into the inside of the gauge, the position of the head end face of the threaded part (that is, the limit position) can be observed through the notch on the side of the gauge, so that it can be judged in which scale range the limit position of the threaded part is;

[0044] Step 4: Provide the threaded parts to be tested before coating, and screw the threaded parts to be tested into the gauge with tapered threads until the threaded parts reach the limit position and cannot be screwed any further, provided that the applied torque does not cause yield deformation on the threaded surface of the parts;

[0045] Step 5. Calibrate the limit position corresponding to the end face of the threaded part in the tightened state, and determine whether the point is between the two marking points (F and G), and judge it as a qualified product; between the marking points (F and A) or (B and G), it is judged as a qualified product to be controlled; otherwise, it is a non-conforming product; among them, the threaded parts between (B and G) and between (F and A) need to be further classified, because the parts in the two intervals need to use different coating thicknesses;

[0046] Step 6: Determine the effective mean diameter of the cylindrical threaded part according to the different axial distances between the end face of the threaded part and the reference point of the gauge with tapered thread. During the production process of the part, reserve a margin to meet the specified coating thickness and adjust the size to the optimal state for processing;

[0047] Step 7: Coat the qualified products and the qualified products to be controlled according to the coating method with a preset thickness.

[0048] Point F is located at 3 / 4 of the upper tolerance, that is, it is between points A and B, and the distance between point A and point B is 1 / 3 of the distance between point F and point B.

[0049] Point G is located at 1 / 3 of the lower tolerance, that is, between points A and B, and its distance from point A is twice its distance from point B.

[0050] The selection of points F and G is based on the criteria of increasing the yield rate and reducing the scrap rate as much as possible, and they may also be other values ​​that meet the requirements.

[0051] Step five also includes further determining the thread diameter value of the part to be tested according to the limit position, and matching the preset coating thickness during coating according to the thread diameter value.

[0052] The coating method according to the preset thickness in step seven includes:

[0053] (1) When the limit position of the qualified product is between or close to the marking points (B and G), the coating of the threaded parts is controlled according to the preset maximum thickness b; since the limit position of the threaded parts is close to (B and G), it means that the thread diameter of the parts is slightly smaller and a larger coating thickness is required to meet the requirements after coating;

[0054] (2) For qualified products to be controlled when the limit position is between or close to the marked points (A and F), the coating of threaded parts is controlled according to the preset minimum thickness a; since the limit position of the threaded parts is close to (A and F), it means that the thread diameter of the parts is slightly larger and only a smaller coating thickness is required. If a larger coating thickness is used, the size after coating is likely to be larger and no longer meet the requirements;

[0055] (3) When the limit position is between the two marking points (F and G), it is a qualified product. When coating the threaded parts, the preset thickness is any value between (a and b).

[0056] The coating method according to the preset thickness in step 7 also includes:

[0057] The threaded parts to be tested of categories (1), (2) and (3) are collected separately and coated respectively according to the coating method with a preset thickness.

[0058] The coating time, current, coating solution concentration, etc. are determined according to the preset coating thickness value, thereby controlling the coating thickness.

[0059] The thread is a cylindrical thread, including metric common thread, American unified thread, pipe thread, etc.

[0060] The gauge with tapered threads is a gauge with internal tapered threads, and the limit position of the threaded part in the gauge can be obtained intuitively or with the help of tools.

[0061] The cone taper of the median diameter of a gauge with a tapered thread is selected based on comprehensive considerations such as the cylindrical thread model specification, the cylindrical thread median diameter tolerance range, the cylindrical thread engagement length, and ease of calculation.

[0062] By opening a longitudinal notch on the side of the gauge or a step surface at the minor diameter end of the internal tapered thread of the gauge, the position of the threaded part inside the gauge can be directly observed;

[0063] Alternatively, use a ruler, vernier caliper, depth gauge, etc. to detect the limit position of the threaded part in the gauge.

[0064] The coating control process of cylindrical threads provided by the present invention can make the thread diameter size control before coating more accurate, not only avoiding the problem that products that pass the conventional through gauge test before coating may be unqualified after coating, but also making up for the defect that some products are qualified after coating but are unqualified and scrapped after the conventional stop gauge test before coating, so that the test results are more targeted, the output of waste products is reduced, and the yield rate is improved. According to the different sizes obtained by the test, the method of designing the preset coating thickness in a targeted manner can also more effectively improve the consistency of the product.

[0065] Those skilled in the art can know that the main design point of the gauge is the tapered thread structure, which is supplemented by other shapes or structural features to achieve the purpose of detection. Obviously, based on this technical concept, it is impossible to exhaust all product types, so as long as the gauge is an internal tapered thread, it is the technical concept of the present invention.

[0066]

[0067] The above table compares the test results of this process method and the traditional cylindrical thread gauge (no-go gauge, through gauge) test method. The most obvious point is that it can prevent both mis-acceptance and mis-rejection, which can save a lot of costs for the enterprise and improve the quality of the product.

[0068] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A coating control process for cylindrical external threads, comprising: Step 1: Obtain the tolerance range D±γ of the mid-diameter dimension of the coated threaded parts to be delivered; Step 2: Obtain uncoated threaded parts and determine the minimum value a and maximum value b of the coating thickness that meets the product performance requirements; Step 3: Provide a gauge with an internal tapered thread, and the pitch diameter value of the internal tapered thread covers the range from (D+γ-4a) to (D-γ-4b), and mark the pitch diameter values ​​of the tapered thread corresponding to point A (D+γ-4a), point B (D-γ-4b), first tolerance reference point F, and second tolerance reference point G on the gauge; A>F>G>B; Step 4: Provide the threaded parts to be tested before coating, screw the threads to be tested into the gauge with internal tapered threads, and screw until the thread surface of the parts reaches the limit position and cannot be screwed any further, provided that the applied torque does not cause yield deformation; Step 5: calibrate the limit position corresponding to the end face of the threaded part in the tightened state, and determine whether the point is between the two marked points (F and G). If so, it is determined to be a qualified product; if it is between the marked points (F and A) or (B and G), it is determined to be a qualified product to be controlled; otherwise, it is a failed product; Step 6: Determine the effective mean diameter of the cylindrical threaded part based on the different axial distances between the end face of the threaded part and the reference point of the gauge with tapered thread; Step 7: Coat the qualified products and the qualified products to be controlled according to the preset coating thickness method.

2. The coating control process according to claim 1, characterized in that: Point F is located at 3 / 4 of the upper tolerance, that is, it is between points A and B, and the distance between point A and point B is 1 / 3 of the distance between point F and point B.

3. The coating control process according to claim 1, characterized in that: Point G is located at 1 / 3 of the lower tolerance, that is, between points A and B, and its distance from point A is twice its distance from point B.

4. The coating control process according to any one of claims 1 to 3, characterized in that: Step five also includes further determining the thread diameter value of the part to be tested according to the limit position, and matching the preset coating thickness during coating according to the thread diameter value.

5. The coating control process according to claim 1, characterized in that: The coating method according to the preset coating thickness in step 7 includes: (1) When the limit position is between or close to the marked points (B and G), the qualified products to be controlled are coated according to the preset maximum thickness b; (2) When the limit position is between or close to the marked points (A and F), the qualified products to be controlled are coated according to the preset minimum thickness a when coating the threaded parts; (3) When the limit position is between the two marking points (F and G), it is a qualified product. When coating the threaded parts, the preset thickness is any value between (a and b).

6. The coating control process according to claim 5, characterized in that: The coating method according to the preset coating thickness in step 7 further includes: The threaded parts to be tested of categories (1), (2) and (3) are collected separately and coated according to the method of preset coating thickness.

7. The coating control process according to claim 6, characterized in that: The coating thickness is controlled by determining the coating time, current, coating solution concentration, etc. according to the preset coating thickness value.

8. The coating control process according to claim 1, characterized in that: The thread is a cylindrical thread, including metric common thread, American unified thread, pipe thread, etc.

9. The coating control process according to claim 1, characterized in that: The gauge with tapered threads is a gauge with internal tapered threads, and the limit position of the threaded part in the gauge can be obtained intuitively or with the help of tools.

10. The coating control process according to claim 9, characterized in that: By opening a longitudinal notch on the side of the gauge or a step surface at the minor diameter end of the internal tapered thread of the gauge, the position of the threaded part inside the gauge can be directly observed; Alternatively, use a ruler, vernier caliper, depth gauge, etc. to detect the limit position of the threaded part in the gauge.

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