阅读说明：本技术 一种坑压式接触件压接质量的可视化检测方法 (Visual detection method for compression joint quality of pit-pressing type contact ) 是由 林殿夫 王震 王飞 毛文陆 刘玺伟 于 2020-06-16 设计创作，主要内容包括：本发明提供了一种坑压式接触件压接质量的可视化检测方法,解决了现有的接触体与导线压接质量检测不能直观、深入地进行检测,压接质量问题常具有隐蔽性的问题。本发明的检测方法综合压痕、金相两种微观组合可视化,可以从根本上掌握接触件的压接情况,提早识别出质量风险,可作为验收、归零和压接研究的重要依据。(The invention provides a visual detection method for the compression joint quality of a pit-pressed contact, which solves the problems that the compression joint quality of the existing contact and a wire cannot be detected intuitively and deeply and the compression joint quality is often hidden. The detection method integrates the micro combination visualization of indentation and metallographic phase, can fundamentally master the crimping condition of the contact element, identifies the quality risk in advance, and can be used as an important basis for acceptance, zero return and crimping research.)

1. The utility model provides a visual detection method of pressure welding quality of pressure welding formula contact member for to the pressure welding quality of pressure welding formula contact member and wire, the pressure welding formula contact member includes the contact member body in pit, the tail section of contact member body is the crimping section of thick bamboo, is equipped with the observation hole on the crimping section of thick bamboo, and its characterized in that, this detection method includes following step:

(1) taking a contact sample, selecting a lead matched with the contact sample and a jaw gear of a crimping clamp, and pressing a catcher booklet to carry out standard crimping;

(2) observing the longitudinal compression condition of the compression-jointed contact piece sample by adopting an electron microscope to obtain and retain a longitudinal indentation micrograph of the sample;

(3) acquiring a transverse section metallographic image of the contact element sample subjected to compression joint by using a metallographic microscope;

(4) taking the indentation micrograph obtained in the step (2) and the section metallographic obtained in the step (3) as standard patterns, and taking the standard patterns as qualified basis for crimping of the contact element;

(5) taking another contact piece to be tested which is the same as the contact piece sample, after the matched lead is pressed and connected by a pressing clamp, observing the longitudinal pressing and connecting condition of the pressed and connected contact piece to be tested by adopting an electron microscope to obtain a longitudinal indentation micrograph of the contact piece to be tested, and simultaneously obtaining a transverse section metallographic picture of the contact piece to be tested;

(6) and (4) comparing the indentation micrograph and the section metallographic of the contact to be tested obtained in the step (5) with the standard pattern of the contact sample obtained in the step (4), wherein the indentation micrograph is used for checking the overvoltage condition, the section metallographic is used for checking the undervoltage condition, and the indentation micrograph and the section metallographic are comprehensively analyzed to obtain the crimping quality of the contact to be tested.

2. The visual detection method for the crimp quality of the under-pit contact piece according to claim 1, wherein the visual detection method for the crimp quality of the under-pit contact piece further comprises crimp quality verification, and the specific verification method comprises the following steps:

and (4) selecting a plurality of spare parts in the same state respectively for the contact pieces to be detected after crimping to perform physical verification, wherein the verification comprises a tension boundary test and a bending boundary test, the verification is performed on the tension bearing and the bending bearing times, and then the comparison is performed with the crimping quality analysis result of the contact pieces to be detected in the step (6) to obtain a final detection conclusion.

3. The visual detection method for the crimp quality of the under-pit contact according to claim 1, wherein the specific method for obtaining the cross-section metallographic image is as follows:

step a, cutting: shearing the wire after the contact element is in compression joint by using wire cutting pliers, and removing the wire outside a compression joint cylinder of the contact element to be tested;

step b, sample inlaying:

selecting embedding powder, sending the embedding powder and the contact piece into an embedding machine, adjusting to a high-temperature and high-pressure state, heating the contact piece and the residual lead to 150 ℃, keeping for 15min, and finally, compactly wrapping the contact piece by the solidified embedding powder and exposing the tail end edge of the contact piece for grinding;

step c, grinding;

step d, etching

Selecting proper corrosive liquid for corrosion according to the contact material;

step e, image analysis

And imaging the corroded contact element by adopting a metallographic microscope, finding a reasonable view field by adjusting the focal length and the position of an objective table, and observing the sizes of gaps between the contact element and the wire core and between the wire core and the wire core in a cross-section metallographic image.

4. The visual detection method for the compression joint quality of the under-pit contact piece according to claim 3, wherein the setting powder in the step b is thermosetting PF2A4-161J phenolic molding compound powder.

5. The method for visually detecting the crimping quality of the under-pit contact according to claim 3, wherein the grinding in the step c is performed in the following steps:

(a) coarse grinding: grinding the tail end of the contact by using a floor type grinder to an actual crimping position on a crimping cylinder of the contact, and cooling by adopting a water cooling mode to prevent the metal structures of the contact and the lead from changing due to heat generated by friction of the contact and a grinding wheel;

(b) fine grinding: after cooling, cleaning and drying the contact element subjected to rough grinding, grinding the contact element on rough abrasive paper and fine abrasive paper, repeating the grinding process in the same direction for a certain number of times, and then rotating for 90 degrees for continuous grinding;

(c) polishing: and polishing the surface roughness left after fine grinding by using a polishing infrared carbon-sulfur analyzer to reduce the roughness of the contact piece to Ra0.04.

Technical Field

The invention belongs to the technical field of contact crimping processes, and relates to a visual detection method for the crimping quality of a pit-pressed contact.

Background

The wire harness product is the main body of the equipment circuit network, wherein the electrical connection between the connector and the wire core is the most critical. In order to meet the demand of the development of the connector towards miniaturization, most of the connectors adopt the pit pressing type crimping, the crimping quality problem is usually hidden and is usually exposed after being used for a long time, and the problems of wire harness products are rare in recent years.

The pit pressing type crimping is completed through crimping pliers, and a contact wire pressing cylinder is tightly connected with a lead by controlling pressure and displacement of a jaw to form pit indentations. During the crimping process, under-voltage and over-voltage should be avoided. The under-voltage can cause the gap between the contact element and the lead to be overlarge, and the stretching resistance, bending resistance and vibration resistance of the wire harness product can be reduced; the excessive pressure can increase the radial shearing of a crimping section of thick bamboo to the sinle silk, harms the sinle silk, crushes a crimping section of thick bamboo even, influences the electric conduction. The wire core is not fed in place, the gear of the crimping pliers is incorrect, the contact is not taken and fed normally, and the hardness of the contact and the wire core is too high, so that undervoltage and overvoltage can be caused.

The current inspection methods specified in the crimping standard are all used for indirectly evaluating the quality of the crimping quality of the contact element by measuring environmental-resistant macroscopic indexes such as tensile force resistance, contact resistance and the like, and the inspection and analysis methods of the microstructure are not deep enough, so that the visual study of the crimped microstructure is carried out.

Disclosure of Invention

In order to solve the technical problems, the invention provides a visual detection method for the compression joint quality of the under-pit contact piece, which integrates two microcosmic combination visualization of indentation and metallographic phase, can fundamentally master the compression joint condition of the contact piece, identifies the quality risk in advance, and can be used as an important basis for acceptance, zero return and compression joint research.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a visual detection method of pressure welding quality of pressure welding formula contact member for to the pressure welding quality of pressure welding formula contact member and wire, the pressure welding formula contact member includes the contact member body in pit, the tail section of contact member body is the crimping section of thick bamboo, is equipped with the observation hole on the crimping section of thick bamboo, and this detection method includes following step:

(1) taking a contact sample, selecting a lead matched with the contact sample and a jaw gear of a crimping clamp, and pressing a catcher booklet to carry out standard crimping;

(2) observing the longitudinal compression condition of the compression-jointed contact piece sample by adopting an electron microscope to obtain and retain a longitudinal indentation micrograph of the sample;

(3) acquiring a transverse section metallographic image of the contact element sample subjected to compression joint by using a metallographic microscope;

(4) taking the indentation micrograph obtained in the step (2) and the section metallographic obtained in the step (3) as standard patterns, and taking the standard patterns as qualified basis for crimping of the contact element;

(5) taking another contact piece to be tested which is the same as the contact piece sample, after the matched lead is pressed and connected by a pressing clamp, observing the longitudinal pressing and connecting condition of the pressed and connected contact piece to be tested by adopting an electron microscope to obtain a longitudinal indentation micrograph of the contact piece to be tested, and simultaneously obtaining a transverse section metallographic picture of the contact piece to be tested;

(6) and (4) comparing the indentation micrograph and the section metallographic of the contact to be tested obtained in the step (5) with the standard pattern of the contact sample obtained in the step (4), wherein the indentation micrograph is used for checking the overvoltage condition, the section metallographic is used for checking the undervoltage condition, and the indentation micrograph and the section metallographic are comprehensively analyzed to obtain the crimping quality of the contact to be tested.

Further, the visual detection method for the compression joint quality of the indentation type contact piece further comprises compression joint quality verification, and the specific verification method comprises the following steps:

and (4) selecting a plurality of spare parts in the same state respectively for the contact pieces to be detected after crimping to perform physical verification, wherein the verification comprises a tension boundary test and a bending boundary test, the verification is performed on the tension bearing and the bending bearing times, and then the comparison is performed with the crimping quality analysis result of the contact pieces to be detected in the step (6) to obtain a final detection conclusion.

Further, the specific method for obtaining the cross-section metallographic image comprises the following steps:

step a, cutting: shearing the wire after the contact element is in compression joint by using wire cutting pliers, and removing the wire outside a compression joint cylinder of the contact element to be tested;

step b, sample inlaying:

selecting embedding powder, sending the embedding powder and the contact piece into an embedding machine, adjusting to a high-temperature and high-pressure state, heating the contact piece and the residual lead to 150 ℃, keeping for 15min, and finally, compactly wrapping the contact piece by the solidified embedding powder and exposing the tail end edge of the contact piece for grinding;

step c, grinding;

step d, etching

Selecting proper corrosive liquid for corrosion according to the contact material;

step e, image analysis

And imaging the corroded contact element by adopting a metallographic microscope, finding a reasonable view field by adjusting the focal length and the position of an objective table, and observing the sizes of gaps between the contact element and the wire core and between the wire core and the wire core in a cross-section metallographic image.

Further, the setting powder in the step b is thermosetting PF2A4-161J phenolic molding compound powder.

Further, the grinding of the step c is carried out in the following steps:

(a) coarse grinding: grinding the tail end of the contact by using a floor type grinder to a position where the actual crimping position on the crimping cylinder of the contact can be observed, namely the middle positions of the inlet of the crimping cylinder and the observation hole, and cooling by adopting a water cooling mode to prevent the metal structures of the contact and the lead from changing due to heat generated by friction of the contact and a grinding wheel;

(b) fine grinding: after cooling, cleaning and drying the contact element subjected to rough grinding, grinding the contact element on rough abrasive paper and fine abrasive paper, repeating the grinding process in the same direction for a certain number of times, and then rotating for 90 degrees for continuous grinding;

(c) polishing: and polishing the surface roughness left after fine grinding by using a polishing infrared carbon-sulfur analyzer to reduce the roughness of the contact piece to Ra0.04.

Compared with the prior art, the invention has the following beneficial effects:

(a) under the ocular lens, the user can observe the ocular lens by naked eyes to draw a conclusion, so that the cost of manpower, equipment, time and the like is saved.

(b) The traditional mechanical test is more destructive, the states of the contact element and the lead are changed after the test, and the secondary recheck cannot be carried out for tracing.

(c) The traditional method is an indirect method by measuring the tension, the bending times and the like; the detection method provided by the invention has a more visual observation mode.

(d) The observation mode is clearer, the actual condition of each wire core can be known, and the problem can be fundamentally searched.

Drawings

FIG. 1 is a schematic view of a dimple contact configuration according to the present invention;

FIG. 2 is an indentation micrograph of a contact sample after crimping;

FIG. 3 is a cross-sectional metallographic view of a contact sample after crimping;

FIG. 4 is an indentation micrograph of sample A, sample B, sample C and sample D of the example;

FIG. 5 is a cross-sectional metallographic view of a sample A, a sample B, a sample C and a sample D in the example;

FIG. 6 is a schematic view of the contact piece after being fixed with the insert powder;

in the figure: 1-a crimping barrel; 2-Observation hole.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.