Forming process of high-strength steel bar connecting bolt sleeve

Abstract

A forming process of a high-strength steel bar connecting bolt sleeve comprises the following steps that S1, a bar is cut into a proper length, then the outer circle of the bar is machined on a lathe, and the outer diameter of the bar reaches the designed outer diameter size; s2, thread machining is conducted in an extrusion tap machining mode, and a bolt sleeve is obtained; wherein the step S2 specifically comprises the following steps: step S2 (a), before machining, optimizing parameters of a thread machining process; s2, before machining, the structure of the extrusion tap is optimized; and S2 (c), the optimized thread machining technological parameters and the extrusion tap are adopted for thread machining. According to the forming process of the high-strength steel bar connecting bolt sleeve, the two key factors, namely the thread machining process parameters and the structure of the extrusion tap, which most affect the thread quality in the machining process are optimized, a high-strength thread extrusion process specification can be formed, and the forming quality of the steel bar connecting bolt sleeve is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sleeve thread forming, and in particular relates to a forming process for a high-strength steel bar connecting bolt sleeve. Background Art

[0002] Rebar connection bolt sleeves, also commonly known as rebar joints or rebar connection sleeves, are a type of equipment used to connect rebars, mainly used in the construction industry. These sleeves connect to the external threads at the end of the rebar through the internal threads to achieve a stable connection between two or more rebars.

[0003] The steel bar connection bolt sleeve is usually a cylindrical structure with a thread inside, and the accuracy of the thread of the steel bar connection bolt sleeve is crucial to the tightness of the connection between the bolt and the steel bar connection bolt sleeve. For example, if the thread profile is inaccurate, such as the tooth profile angle deviation is too large, the contact area between the bolt and the sleeve will be reduced. When subjected to tension, the stress per unit area will increase, which is easy to cause wear or damage to the thread. In the installation of high-precision equipment, even if the tooth profile angle deviation of the M8 bolt sleeve is only 1°, the connection between the bolt and the sleeve may fail quickly under the vibration and stress during the operation of the equipment. For another example, if there is an error in the pitch, the error will affect the smoothness of the bolt's screwing. If the pitch is too small, the bolt will be too tight when screwed in, or may even be unable to be screwed in; if the pitch is too large, the connection will be loose.

[0004] Therefore, the quality of thread forming is an important factor affecting the stability and service life of the steel bar connection bolt sleeve. The forming quality of the thread is closely related to the processing method, process parameters, tool structure and other factors. The present invention studies the influence of various factors on thread forming in the forming process of the steel bar connection bolt sleeve, and proposes a high-quality thread processing process. After forming, the hardness of the thread root, tooth top, tooth side and other parts are all improved to a certain extent. Summary of the invention

[0005] Purpose of the invention: In order to overcome the above shortcomings, the purpose of the present invention is to provide a forming process for a high-strength steel bar connecting bolt sleeve, which has a reasonable design and optimizes the thread processing parameters and the structure of the extrusion tap, the two key factors that most affect the thread quality in the processing process, so as to form a high-strength thread extrusion process specification and improve the forming quality of the steel bar connecting bolt sleeve.

[0006] The objective of the present invention is achieved through the following technical solutions: A forming process for a high-strength steel bar connecting bolt sleeve comprises the following steps: S1: Cut the bar into appropriate lengths, and then process its outer diameter on a lathe to achieve the designed outer diameter; S2: Thread processing is performed by using an extrusion tap to obtain a bolt sleeve; Wherein, the S2 specifically includes the following steps: S2 (a): Before processing, the thread processing parameters are optimized; S2 (b): Before processing, the structure of the extrusion tap is optimized; S2 (c): Thread processing is performed using optimized thread processing parameters and an extrusion tap.

[0007] Among the thread processing methods, cutting tap processing is the most common. Cutting tap processing has simple equipment requirements and is easy to process. It is suitable for various machine tools. Extrusion tap processing is a new type of thread forming process. Extrusion taps themselves have no cutting edges or chip grooves, and chipping usually does not occur during processing.

[0008] Compared with tap cutting, no chips are generated during extrusion tap processing, the material utilization rate is higher, the surface of the thread after forming is smooth and flat, there are no obvious scratches, the processing quality is good, the tooth height is higher than that of the cut thread, the degree of grain refinement and the density of metal fiber structure of the extruded thread are higher than those of the cut thread, and the work hardening of the metal during the extrusion process increases the hardness of the thread and the depth of the hardened layer.

[0009] In order to improve the forming quality of extruded threads, the present invention optimizes the two key factors that most affect the thread quality during the processing process - thread processing process parameters and the structure of the extrusion tap, so as to improve the thread forming quality of the steel bar connecting bolt sleeve.

[0010] Furthermore, the forming process of the above-mentioned high-strength steel bar connecting bolt sleeve, S2 (a), specifically includes the following contents: first, through the numerical simulation method, find out the influence of the thread processing parameters on the extrusion torque and temperature; then, through the orthogonal analysis method, optimize the designed thread processing parameters to obtain the optimized thread processing parameters.

[0011] The present invention combines finite element simulation and experiment, and aims at the extrusion torque and extrusion temperature factors that affect the thread quality during the processing process. The numerical simulation method is first used to obtain the influence of the processing parameters on the extrusion torque and temperature, and some obviously unreasonable parameter ranges are efficiently screened out, thereby reducing the number of debugging times in actual processing, improving production efficiency, and avoiding quality problems in actual processing.

[0012] Then, the orthogonal analysis method is used to comprehensively consider the influence of multiple processing parameters on extrusion torque and temperature, and the optimal combination of these parameters is found, so that during the thread forming process, the extrusion torque and temperature can be controlled within the ideal range, thereby ensuring the forming quality of the thread.

[0013] Since the processing parameters are the best combination obtained through scientific analysis, it can effectively avoid the situation where the bolt sleeve thread is unqualified due to unreasonable processing parameters, reduce material waste and reprocessing costs. At the same time, appropriate processing parameters can also extend the service life of the tap and reduce tool costs.

[0014] Furthermore, in the above-mentioned forming process of the high-strength steel bar connecting bolt sleeve, the processing parameters include bottom hole diameter, machine tool speed, and lubricating medium.

[0015] The bottom hole diameter, machine tool speed, and lubricating medium are all important factors affecting the thread quality in the processing parameters. Among them, the bottom hole diameter is directly related to the forming accuracy of the thread. If the bottom hole diameter is too large, the thread profile height will be reduced, resulting in a decrease in the strength of the threaded connection; if the bottom hole diameter is too small, the extrusion force on the tap will increase during the extrusion tap processing, which is easy to cause the tap to break and increase the surface roughness of the thread. The bottom hole diameter will also affect the force of the tap during the processing. The appropriate bottom hole diameter can make the tap evenly stressed during the extrusion process and ensure the stability of the processing. The appropriate machine tool speed helps to obtain good thread surface quality, and at the same time, more thread length can be processed per unit time, improving production efficiency. In the process of extrusion tap processing, the lubricating medium plays a vital role, which can reduce friction and heat generation and protect the surface of the tap and bar.

[0016] Furthermore, in the above-mentioned forming process of the high-strength steel bar connecting bolt sleeve, the said S2 (b) specifically includes the following contents: first, by means of numerical simulation, find out the influence of the structural parameters of the extrusion tap on the extrusion torque and temperature; then, by means of orthogonal analysis, optimize the structural parameters of the designed extrusion tap to obtain the optimized structure of the extrusion tap.

[0017] First, we use numerical simulation to find out the influence of the structural parameters of the extrusion tap on the extrusion torque and temperature, so that we can fully understand how each structural parameter affects the extrusion torque and temperature during the processing. For example, for the number of rib teeth, numerical simulation can simulate the variation curve of extrusion torque and temperature under different numbers of rib teeth, so as to clearly see the specific influence trend on extrusion torque and temperature when the number of rib teeth increases or decreases, which is difficult to obtain so comprehensively and meticulously through actual experiments.

[0018] Then the orthogonal analysis method can be used to comprehensively optimize multiple structural parameters. In actual processing, these structural parameters affect each other, and orthogonal analysis can take into account this interaction and find the best combination of multiple structural parameters.

[0019] Furthermore, in the molding process of the above-mentioned high-strength steel bar connecting bolt sleeve, the extrusion tap includes a ridged tooth portion and a clamping portion from front to back, and the ridged tooth portion and the clamping portion are integrally molded.

[0020] Furthermore, in the forming process of the above-mentioned high-strength steel bar connecting bolt sleeve, the ridged tooth portion includes, from front to back, an extruded cone angle portion, an extruded cone portion, and a calibration portion, and the outer surface is provided with ridged teeth for thread processing; the outer surface of the ridged tooth portion also includes a plurality of lubricating liquid grooves extending along the axial direction of the ridged tooth portion cone, and the lubricating liquid grooves separate the ridged teeth into a plurality of independent ridged tooth teeth.

[0021] The ridged teeth of the extrusion tap are used for thread processing, and the clamping part is used for clamping and fixing the extrusion tap. The ridged teeth include an extrusion cone angle, an extrusion cone part, and a calibration part from front to back. The existence of the extrusion cone angle helps to reduce the resistance encountered when the extrusion tap is screwed into the bar material, ensuring that the load borne by the ridged teeth of the extrusion cone part is uniform during the process of thread processing. The extrusion cone part causes the metal material to flow by extrusion, gradually filling the grooves between the ridged teeth to form the thread. The calibration part is responsible for correcting and finishing the initially formed thread teeth; the function of the lubricating liquid tank is to allow the lubricating medium to enter the processing area to prevent the lubricating liquid from being blocked at the bottom when processing the blind hole.

[0022] Furthermore, in the above-mentioned molding process of the high-strength steel bar connecting bolt sleeve, the clamping part includes a shaft neck, a knife handle, and a square head from front to back.

[0023] Furthermore, in the above-mentioned forming process of the high-strength steel bar connecting bolt sleeve, the structural parameters of the extrusion tap include the number of ridge teeth, the amount of relief, the angle of the extrusion cone corner, the length of the extrusion cone corner, the length of the extrusion part, the length of the calibration part, the length of the shaft neck, the length of the tool handle, and the length of the square head.

[0024] The number of ridge teeth, the amount of relief, the angle of the extrusion cone, the length of each part of the ridge teeth, and the length of each part of the clamping part are all important factors affecting the quality of the thread. Among them, the number of ridge teeth determines the number of times the extrusion tap squeezes the bar in one rotation, and also affects the extrusion torque. The relief affects the back angle of the ridge teeth of the tap, and also affects the cutting edge shape of the extrusion tap. The angle of the extrusion cone directly affects the difficulty of the tap cutting into the bar, and also affects the quality of the starting section of the thread. The length of each part of the ridge teeth is related to the thread forming process. The length of each part of the clamping part is related to the clamping and torque transmission of the tap.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The forming process of the high-strength steel bar connection bolt sleeve of the present invention adopts an extrusion tap processing method to perform thread processing, and optimizes the two key factors that most affect the thread quality during the processing process - thread processing process parameters and the structure of the extrusion tap, so as to form a high-strength thread extrusion process specification and improve the forming quality of the steel bar connection bolt sleeve; (2) The forming process of the high-strength steel bar connecting bolt sleeve described in the present invention combines finite element simulation and experiment. For the extrusion torque and extrusion temperature factors that affect the thread quality during the processing, the numerical simulation method is first used to obtain the influence of the processing parameters and the structural parameters of the extrusion tap on the extrusion torque and temperature, and some obviously unreasonable parameter ranges are efficiently screened out, thereby reducing the number of debugging times in actual processing and improving production efficiency, thereby avoiding quality problems in actual processing; then, the orthogonal analysis method is used to comprehensively consider the influence of multiple processing parameters and the structural parameters of the extrusion tap on the extrusion torque and temperature, and find the optimal combination of the processing parameters and the optimal combination of the structural parameters of the extrusion tap, so that in the thread forming process, the extrusion torque and temperature can be controlled within the ideal range, thereby ensuring the forming quality of the thread. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a forming process diagram of the high-strength steel bar connecting bolt sleeve of the present invention; Figure 2 It is a front view of an extrusion tap (without ridge teeth) for the forming process of the high-strength steel bar connection bolt sleeve of the present invention; Figure 3 A side view of an extrusion tap for the forming process of the high-strength steel bar connecting bolt sleeve of the present invention; In the figure: a ridged tooth portion 21, an extrusion cone angle portion 211, an extrusion cone portion 212, a calibration portion 213, ridged teeth 214, a lubricating liquid groove 215, and a clamping portion 22, wherein the ridged tooth portion 21, the clamping portion 22, the shaft neck 221, the tool handle 222, the square head 223, the back-shoveling amount a, the angle b of the extrusion cone angle portion, the length c of the extrusion cone angle portion, the length d of the extrusion portion, the length e of the calibration portion, the length f of the shaft neck, the length g of the tool handle, and the length h of the square head. DETAILED DESCRIPTION

[0027] The following will be attached Figure 1 , 2 , 3, and Example 1 and Example 2, combined with specific experimental data, clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. The following embodiment 1 provides a molding process for a high-strength steel bar connecting bolt sleeve.

[0028] Example 1 like Figure 1 As shown, the forming process of the high-strength steel bar connecting bolt sleeve of Example 1 includes the following steps: S1: Cut the bar into appropriate lengths, and then process its outer diameter on a lathe to achieve the designed outer diameter; S2: Thread processing is performed by using an extrusion tap. Before processing, the thread processing process parameters and the structure of the extrusion tap are optimized. Specifically: 1. First, through the method of numerical simulation, find out the influence of thread processing parameters (bottom hole diameter, machine tool speed, lubricating medium) on extrusion torque and temperature; then through the method of orthogonal analysis, optimize the designed thread processing parameters to obtain the optimized thread processing parameters.

[0029] 2. First, find out the structural parameters of the extrusion tap (such as Figure 3 As shown in the figure, the number of ridge teeth, the amount of back relief a, the angle of the extrusion cone b, the length of the extrusion cone c, the length of the extrusion part d, the length of the calibration part e, the length of the shaft neck f, the length of the tool handle g, and the length of the square head h) affect the extrusion torque and temperature; then, the structural parameters of the designed extrusion tap are optimized by the orthogonal analysis method to obtain the optimized structure of the extrusion tap.

[0030] Among them, the extrusion torque is measured by a force measuring tool holder, and the extrusion tap is connected to the force measuring tool holder through a reducing sleeve. The measured torque data is transmitted to the computer through a signal receiver. Since the deformation zone of thread processing is located at the through hole of the bar, it is difficult to directly measure the temperature of this area. The temperature of the deformation zone is measured by drilling a hole on the outer surface of the bar. During measurement, a thermocouple is inserted into the drilled hole, and the temperature change of the deformation zone is sensed by the thermocouple. The thermocouple is connected to a thermometer, and the temperature data is transmitted to the computer through a signal receiver through the thermometer.

[0031] After optimizing the thread processing parameters and the structure of the extrusion tap, the extrusion torque and temperature can be significantly reduced. The gap between the extrusion tap teeth and the deformation zone of the rod is increased, the wear of the extrusion tap and the rod is reduced, and the service life of both is increased. The hardness of the thread and the depth of the hardened layer can also be increased, thereby improving the forming quality of the thread.

[0032] 3. Thread processing with the optimal processing parameters and the structure of the extrusion tap can form high-strength thread extrusion process specifications and improve the forming quality of the steel bar connection bolt sleeve.

[0033] The following embodiment 2 provides an extrusion tap structure for a forming process of a steel bar connection bolt sleeve.

[0034] Example 2 like Figure 2 As shown, the extrusion tap structure of the forming process of the steel bar connection bolt sleeve of Example 2 includes a ridged tooth portion 21 and a clamping portion 22 from front to back. The ridged tooth portion 21 and the clamping portion 22 are integrally formed. The ridged tooth portion 21 is used for thread processing, and the clamping portion 22 is used for clamping and fixing the extrusion tap.

[0035] Among them, the outer surface of the ridged tooth portion 21 is provided with ridged teeth 214, which are used for thread processing, and a plurality of lubricating liquid grooves 215 are provided along the axial direction of the cone of the ridged tooth portion 21, and the lubricating liquid grooves 215 separate the ridged teeth 214 into a plurality of independent ridged teeth. The lubricating liquid grooves 215 allow the lubricating medium to enter the processing area to prevent the lubricating liquid from being blocked at the bottom when processing the blind hole. In addition, the tooth portion 21 is divided into three parts from front to back, namely, an extrusion cone angle portion 211, an extrusion cone portion 212, and a calibration portion 213. The existence of the cone angle of the extrusion cone angle portion 211 helps to reduce the resistance encountered when the extrusion taper is screwed into the bar material, ensuring that the load on the teeth of the extrusion cone portion is uniform during the thread processing process. The extrusion cone portion 212 causes the metal material to flow in an extrusion manner, gradually filling the grooves between the teeth 214 to form the thread. The calibration portion 213 is responsible for correcting and finishing the initially formed thread teeth.

[0036] The clamping portion 22 includes a journal 221 , a tool handle 222 , and a square head 223 from front to back.

[0037] like Figure 2 , 3 As shown, the number of ridge teeth, the amount of relief a, the angle b of the extrusion cone angle, the length c of the extrusion cone angle, the length d of the extrusion portion, the length e of the calibration portion, the length f of the shaft neck, the length g of the shank, and the length h of the square head are all important factors affecting the quality of the thread. Among them, the number of ridge teeth determines the number of times the extrusion tap squeezes the bar in one rotation, and also affects the extrusion torque. The relief a affects the back angle of the ridge teeth of the extrusion tap, and also affects the cutting edge shape of the extrusion tap. The angle b of the extrusion cone angle directly affects the difficulty of the tap cutting into the bar, and also affects the quality of the starting section of the thread. The length of each part of the ridge portion 21 is related to the thread forming process. The length of each part of the clamping portion 22 is related to the clamping and torque transmission of the tap.

[0038] The present invention has many specific application paths, and the above is only a preferred embodiment of the present invention. It should be pointed out that the above embodiments are only used to illustrate the present invention, and are not used to limit the protection scope of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements can also be made, and these improvements should also be regarded as the protection scope of the present invention.

Claims

1. A forming process for a high-strength steel bar connecting bolt sleeve, characterized in that: The steps include: S1: Cut the bar into appropriate lengths, and then process its outer diameter on a lathe to achieve the designed outer diameter; S2: Thread processing is performed by using an extrusion tap to obtain a bolt sleeve; Wherein, the S2 specifically includes the following steps: S2 (a): Before processing, the thread processing parameters are optimized; S2 (b): Before processing, the structure of the extrusion tap is optimized; S2 (c): Thread processing is performed using optimized thread processing parameters and an extrusion tap.

2. The forming process of the high-strength steel bar connecting bolt sleeve according to claim 1 is characterized in that: The S2 (a) specifically includes the following contents: first, by numerical simulation method, find out the influence of thread processing parameters on extrusion torque and temperature; then, by orthogonal analysis method, optimize the designed thread processing parameters to obtain optimized thread processing parameters.

3. The forming process of the high-strength steel bar connecting bolt sleeve according to claim 2 is characterized in that: The processing parameters include bottom hole diameter, machine tool speed, and lubricating medium.

4. The forming process of the high-strength steel bar connecting bolt sleeve according to claim 1 is characterized in that: The S2 (b) specifically includes the following contents: first, by using a numerical simulation method, find out the influence of the structural parameters of the extrusion tap on the extrusion torque and temperature; then, by using an orthogonal analysis method, optimize the structural parameters of the designed extrusion tap to obtain the optimized structure of the extrusion tap.

5. The forming process of the high-strength steel bar connecting bolt sleeve according to claim 4 is characterized in that: The extrusion tap comprises, from front to back, an angular tooth portion (21) and a clamping portion (22), wherein the angular tooth portion (21) and the clamping portion (22) are integrally formed.

6. The forming process of the high-strength steel bar connecting bolt sleeve according to claim 5 is characterized in that: The ridged tooth portion (21) comprises, from front to back, an extrusion cone angle portion (211), an extrusion cone portion (212), and a calibration portion (213), and an outer surface is provided with ridged teeth (214) for thread processing; the outer surface of the ridged tooth portion (21) also comprises a plurality of lubricating liquid grooves (215) extending along the axial direction of the cone of the ridged tooth portion (21), and the lubricating liquid grooves (215) separate the ridged teeth (214) into a plurality of independent ridged teeth.

7. The forming process of the high-strength steel bar connecting bolt sleeve according to claim 6 is characterized in that: The clamping portion (22) comprises, from front to back, a shaft neck (221), a tool handle (222), and a square head (223).

8. The forming process of the high-strength steel bar connecting bolt sleeve according to claim 4, characterized in that: The structural parameters of the extrusion tap include the number of ridge teeth, the amount of relief, the angle of the extrusion cone corner, the length of the extrusion cone corner, the length of the extrusion part, the length of the calibration part, the length of the shaft neck, the length of the tool handle, and the length of the square head.

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