A cold heading process for projection weld bolts

Abstract

This invention provides a cold heading forming process for projection weld bolts, relating to the field of cold heading forming, including: Step 1: Shearing a cylindrical blank; Step 2: Extruding the cylindrical blank through a cold heading die at a first station to create a bottom guide chamfer; Step 3: Clamping the blank obtained in Step 2 into a second station, and using a strong forward extrusion die at the second station to extrude the double flat surfaces of the shank and extrude an anti-rotation positioning groove at the tail end; Step 4: Pre-forming the head: Using a die at a third station, balling is performed on the material used for forming the head in the blank obtained in Step 3, pre-pressing it into an inverted cone shape; Step 5: Head upsetting and forming a step feature at the top of the workpiece head; Step 6: Forming the weld point and installing the small flat part in the middle step. This invention uses cold heading to form projection weld bolts, reducing machining, improving product consistency, and increasing material utilization.

Description

Technical Field

[0001] This invention relates to the field of cold heading technology, specifically to a cold heading process for projection weld bolts. Background Technology

[0002] In the automotive parts manufacturing industry, cold heading has become the mainstream processing method due to its high efficiency, high material utilization, and good mechanical properties. However, traditional cold heading of automotive parts still faces several technical bottlenecks. For example, processing double-flat parts requires first cold-forging a round rod blank, and then cutting it by adding a milling process. This process not only increases production steps and extends the manufacturing cycle, but also wastes material due to milling, thus increasing production costs. Summary of the Invention

[0003] This invention provides a cold heading forming process for projection weld bolts to solve the technical problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, this invention discloses a cold heading forming process for projection weld bolts, comprising:

[0005] Step 1: Cut the cylindrical blank;

[0006] Step 2: Extrude the cylindrical blank through the cold heading die at the first station to create a bottom guide chamfer;

[0007] Step 3: Clamp the blank obtained in Step 2 into the second station, and use the mold in the second station to press out the double flat plane of the rod and press out the anti-rotation positioning groove at the tail end.

[0008] Step 4: Use the punch of the third station mold to perform a balling operation on the blank obtained in step 3 for forming the head, and pre-press it into an inverted cone shape.

[0009] Step 5: Clamp the blank obtained in Step 4 into the cold heading mold of the fourth station to roughen the head and form a stepped feature at the top of the workpiece head.

[0010] Step 6: Clamp the blank obtained in Step 5 into the cold heading mold at the fifth station for final shaping to obtain a complete part.

[0011] Preferably, in step 1, the blank of the required raw material length is cut off by the shearing mechanism of the cold heading machine.

[0012] Preferably, in step 6, the weld point is formed and the small flat part is installed in the middle step.

[0013] Preferably, the cold heading of each batch of projection welded bolts shall be carried out at least once based on the detection to determine the required extrusion speed and required extrusion pressure.

[0014] Preferably, the extrusion parameter determination process in step 3 is performed between step 2 and step 3, including:

[0015] Step 31: Perform ultrasonic testing on the billet completed in Step 2, and determine the density coefficient based on the maximum amplitude of the actual ultrasonic echo signal; perform hardness testing on the billet completed in Step 2 to determine the hardness coefficient; perform thermal conductivity testing on the billet completed in Step 2 to determine the thermal conductivity characteristic coefficient.

[0016] Step 32: Based on the design dimensions and mold dimensions in Step 3, determine the flat feature coefficient, the positioning groove feature coefficient, and the extrusion dimension matching coefficient;

[0017] Step 33: Determine the required extrusion pressure based on the density coefficient, hardness coefficient, and extrusion size matching coefficient; determine the required extrusion speed based on the required extrusion pressure, flatness characteristic coefficient, positioning groove characteristic coefficient, and thermal conductivity characteristic coefficient.

[0018] Preferably, after determining the required extrusion speed and extrusion pressure based on detection, the process further includes:

[0019] Step 34: Before the test in Step 3, control the temperature of the cold heading die cavity at the second station to the first rated temperature and control the temperature of the blank completed in Step 2 to the second rated temperature. Test the blank completed in Step 2 with the required extrusion pressure and the required extrusion temperature in Step 3.

[0020] After the test in step 3 is completed, scan the temperature of the critical area of ​​the cavity of the cold heading die in the second station to determine the first heating coefficient and the first temperature gradient coefficient.

[0021] During the test in step 3, the vibration parameters of the upper mold of the cold heading mold in the second station are detected; after the test in step 3 is completed, the key dimensional parameters and temperature of the blank completed in step 3 are detected; based on the temperature of the blank completed in step 3, the second heating coefficient and the second temperature gradient coefficient are determined.

[0022] Step 35: Determine the vibration coupling parameters based on the vibration parameters of the upper mold and the key dimensional parameters of the blank completed in Step 3;

[0023] Step 36: Determine the extrusion pressure-extrusion speed-temperature change coupling coefficient based on the first heating coefficient, the first temperature gradient coefficient, the second heating coefficient, and the second temperature gradient coefficient; issue an early warning when the extrusion pressure-extrusion speed-temperature change coupling coefficient and the vibration coupling parameter are not within the corresponding preset range;

[0024] Step 37: If no warning is issued in step 36, determine the maximum allowable pressure fluctuation value and the maximum allowable speed fluctuation value based on the extrusion pressure-extrusion speed-temperature change coupling coefficient and vibration coupling parameters;

[0025] Step 38: If no warning is issued in step 36, determine the maximum allowable vibration intensity based on the vibration coupling parameters.

[0026] Preferably, during the actual batch execution of step 3, an alarm is triggered when any of the following occurs: the actual pressure fluctuation value is greater than the maximum allowable pressure fluctuation value, the actual speed fluctuation value is greater than the maximum allowable speed fluctuation value, or the actual vibration intensity is greater than the maximum allowable vibration intensity.

[0027] Preferably, an intelligent detection process is performed during the batch execution of the target steps. The intelligent detection process includes:

[0028] Step 01: Perform a sub-inspection process periodically. The sub-inspection process includes: temperature detection of the corresponding key temperature detection area of ​​the mold cavity before the current blank is formed in the target step; temperature detection of the corresponding key temperature detection area of ​​the mold cavity after the current blank is formed in the target step; and multiple detections of extrusion pressure and extrusion speed during the current blank forming process in the target step.

[0029] Step 02: Determine the target coupling coefficient based on the parameters obtained in Step 01; the target coupling coefficient is the extrusion pressure-extrusion speed-die temperature change coupling coefficient;

[0030] Step 03: Based on the current heat dissipation parameters of the mold corresponding to the target step, construct the blank quantity-target coupling coefficient curve within the latest preset time period using the target coupling coefficient;

[0031] Step 04: Based on the current heat dissipation parameters of the mold corresponding to the target step, construct the equivalent temperature rise of the billet after forming within the latest preset time period, and construct the billet quantity-equivalent temperature rise curve.

[0032] Step 05: When either the slope of the curve of the number of formed blanks - the target coupling coefficient is not within the corresponding allowable slope range and / or the maximum temperature of the mold cavity is greater than the preset temperature after the blanks are formed, an early warning will be issued;

[0033] Step 06: When a warning is issued in step 05, the target heat dissipation power of the heat dissipation device of the mold corresponding to the target step is determined based on steps 03 and 04, and the actual heat dissipation power of the heat dissipation device of the mold corresponding to the target step is adjusted to the target heat dissipation power.

[0034] Preferably, the target step is any one of steps 2 to 6.

[0035] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention integrates multiple technologies such as shaping, upsetting, strong binding, and extrusion to form a complete cold heading forming process. The invention of this forming process enables the production of a projection weld bolt to: 1. achieve large-scale and efficient production with a capacity of up to 50 pieces / minute; 2. achieve cold heading forming with a raw material utilization rate of nearly 100%, reducing machining waste; 3. greatly improve the tensile strength, fatigue strength, and torsional strength of the parts.

[0038] Using cold-forged projection welded bolts reduces machining, improves product consistency, and changes the shape of the blank through plastic deformation, replacing the large amount of metal waste generated by milling double flat sections on a milling machine. This greatly improves material utilization, significantly reduces costs, and generates considerable economic benefits. At the same time, it enables high-speed production, shortens the production cycle, and greatly enhances the market competitiveness of the products.

[0039] The cold heading process ensures the integrity of the metal flow lines. If a milling machine is used to cut the double flat section, the tool will cut off the internal flow lines of the metal, which will create a "flow interruption" and may lead to stress concentration, thereby reducing the strength of the part. However, the cold heading process creates a double flat section, which preserves the continuous and complete metal flow lines inside the part, greatly improving the tensile strength, fatigue strength and torsional strength of the part. Attached Figure Description

[0040] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0041] Figure 1 This is a schematic diagram of the process flow of the present invention;

[0042] Figure 2 This is a schematic diagram of the blank material in each step of the present invention;

[0043] Figure 3 This is a schematic diagram of the main components of the first-station cold heading die of the present invention;

[0044] Figure 4 This is a schematic diagram of the main components of the second-station cold heading die of the present invention;

[0045] Figure 5 This is a schematic diagram of the main components of the third-station cold heading die of the present invention;

[0046] Figure 6 This is a schematic diagram of the main components of the fourth-station cold heading die of the present invention;

[0047] Figure 7 This is a schematic diagram of the main components of the fifth-station cold heading mold of the present invention.

[0048] In the picture:

[0049] 11. First shrinking punch; 21. First die sleeve; 31. First main die sleeve; 41. First main die core; 51. First main die ejector pin;

[0050] 12. Second shrinking punch; 22. Second die sleeve; 32. Second main die sleeve; 421. Second main die core I; 422. Second main die core II; 52. Second main die ejector pin;

[0051] 13. Third punch; 23. Third die; 33. Third main die sleeve; 43. Third main die core; 53. Third main die ejector pin;

[0052] 14. Fourth die punch; 24. Fourth die; 34. Fourth main die sleeve; 441. Fourth main die core I; 442. Fourth main die core II; 54. Fourth main die ejector pin;

[0053] 15. Fifth punch die; 35. Fifth main die sleeve; 451. Fifth main die core I; 452. Fifth main die core II; 55. Fifth main die ejector pin. Detailed Implementation

[0054] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0055] Furthermore, in this invention, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions and features of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0056] The present invention provides the following embodiments:

[0057] Example 1: This embodiment of the invention provides a cold heading process for projection weld bolts, such as... Figures 1-7 As shown, it includes:

[0058] Step 1: Cutting: Cut the cylindrical blank;

[0059] Step 2: Shaping: The cylindrical blank is extruded through the cold heading die at the first station to create a bottom guide chamfer;

[0060] Step 3: Double flat section of the rod part: The blank obtained in step 2 is clamped into the second station, and the double flat section of the rod part is extruded by the positive strong extrusion of the mold in the second station, and the anti-rotation positioning groove is extruded at the tail end.

[0061] Step 4: Pre-forming the head: Using the punch of the third station mold, the material used to form the head in the blank obtained in step 3 is balled up and pre-pressed into an inverted cone shape.

[0062] Step 5: Head upsetting and forming head step: The blank obtained in step 4 is clamped into the cold upsetting mold of the fourth station to upset the head and form a step feature at the top of the workpiece head.

[0063] Step 6: Forming weld points and installing small flat parts in the middle step: Clamp the blank obtained in step 5 into the cold heading mold in the fifth station for final forming to obtain a complete part.

[0064] In step 1, the blank of the required raw material length is cut off by the shearing mechanism of the cold heading machine.

[0065] In step 6, the weld points are formed and the small flat parts are installed in the middle step.

[0066] This invention proposes a multi-station cold heading precision forging process, achieving the following technological breakthroughs: While ensuring product appearance and precision, it achieves one-time forming of double-flat sections, avoiding the potential risks associated with milling the double-flat sections after cold heading, thus enabling the projection weld bolt to be formed in a single operation. The forming process of this invention is entirely a creative invention based on multi-station cold heading technology, completely realizing the non-cutting machining of this double-flat projection weld bolt.

[0067] The forming process of this invention uses only multi-station cold heading technology, and employs the latest forming techniques in cold heading technology to confirm the feasibility of cold heading forming of this irregularly shaped projection weld bolt.

[0068] The beneficial effects of the above technical solution are as follows:

[0069] This invention integrates multiple technologies such as shaping, upsetting, strong binding, and extrusion to form a complete cold heading forming process. The invention of this forming process enables the production of a projection weld bolt to: 1. achieve large-scale and efficient production with a capacity of up to 50 pieces / minute; 2. achieve cold heading forming with a raw material utilization rate of nearly 100%, reducing machining waste; 3. greatly improve the tensile strength, fatigue strength, and torsional strength of the parts.

[0070] Using cold-forged projection welded bolts reduces machining, improves product consistency, and changes the shape of the blank through plastic deformation, replacing the large amount of metal waste generated by milling double flat sections on a milling machine. This greatly improves material utilization, significantly reduces costs, and generates considerable economic benefits. At the same time, it enables high-speed production, shortens the production cycle, and greatly enhances the market competitiveness of the products.

[0071] The cold heading process ensures the integrity of the metal flow lines. If a milling machine is used to cut the double flat section, the tool will cut off the internal flow lines of the metal, which will create a "flow interruption" and may lead to stress concentration, thereby reducing the strength of the part. However, the cold heading process creates a double flat section, which preserves the continuous and complete metal flow lines inside the part, greatly improving the tensile strength, fatigue strength and torsional strength of the part.

[0072] Example 2, based on Example 1, includes a step 3 extrusion parameter determination process between steps 2 and 3 (this process can be performed once per batch of billets), including:

[0073] Step 31: Perform ultrasonic testing on the billet completed in Step 2, and determine the density coefficient based on the maximum amplitude of the actual ultrasonic echo signal; perform hardness testing on the billet completed in Step 2 to determine the hardness coefficient; perform thermal conductivity testing on the billet completed in Step 2 to determine the thermal conductivity characteristic coefficient.

[0074] The density coefficient E = the maximum amplitude of the actual ultrasonic echo signal ÷ the maximum amplitude of the standard ultrasonic echo signal;

[0075] Hardness coefficient G = Actual test hardness of the billet completed in step 2 ÷ Hardness of the standard billet;

[0076] Thermal conductivity characteristic coefficient H = actual thermal conductivity of the billet completed in step 2 ÷ thermal conductivity of the standard billet;

[0077] Step 32: Based on the design dimensions and mold dimensions in Step 3, determine the flat feature coefficient, the positioning groove feature coefficient, and the extrusion dimension matching coefficient;

[0078] Flatness characteristic coefficient R = (flatness width ÷ flatness thickness).

[0079] Extrusion dimensional fit coefficient Y= ;in, This refers to the outer diameter of the blank completed in step 2 (excluding the chamfered area). The target cavity inner diameter of the mold at the second station (corresponding to the minimum diameter of the blank completed in step 3); for The corresponding standard value (determined based on the initial mold used and the ideal outer diameter of the blank completed in step 2);

[0080] The characteristic coefficient U of the positioning groove is calculated as follows: (Design depth of positioning groove × Design width of positioning groove) ÷ 2 ;

[0081] Step 33: Determine the required extrusion force F based on the density coefficient, hardness coefficient, and extrusion size matching coefficient; determine the required extrusion speed based on the required extrusion force, flatness characteristic coefficient, positioning groove characteristic coefficient, and thermal conductivity characteristic coefficient.

[0082] ;

[0083] Standard extrusion pressure (corresponding to standard conditions (maximum amplitude of standard ultrasonic echo signal, standard billet hardness, standard billet thermal conductivity, ...) , , (The best forming effect is achieved in step 3, which is determined based on experimental or historical data). , , These are the standard density coefficient, standard hardness coefficient, and standard extrusion dimensional fit coefficient, respectively. , , These are the extrusion pressure correction coefficients corresponding to the density coefficient, the extrusion pressure correction coefficients corresponding to the hardness coefficient, and the extrusion dimensional fit coefficients, respectively.

[0084] Extrusion speed needs to be set ;

[0085] Standard extrusion speed (corresponding to the maximum amplitude of standard ultrasonic echo signal, standard billet hardness, standard billet thermal conductivity, , , Step 3 will yield the best forming results. These are the standard flat position characteristic coefficients; The characteristic coefficient of the standard positioning groove; The characteristic coefficient of standard thermal conductivity; , , These are, respectively, the extrusion speed correction index corresponding to the required extrusion pressure, the extrusion speed correction index corresponding to the structural characteristic coefficient, and the extrusion speed correction coefficient corresponding to the thermal conductivity characteristic coefficient;

[0086] ; These are structural characteristic coefficients; , These are the weights corresponding to the flat feature coefficient and the positioning groove feature coefficient, respectively. , The sum is 1, and the weights are determined based on the importance of the flat feature coefficient and the positioning groove feature coefficient, with the more important ones having larger values.

[0087] , , , , These are standard condition parameters, corresponding to the standard extrusion pressure, and serve as the basis for subsequent adjustments to extrusion pressure and extrusion speed.

[0088] The amplitude of the ultrasonic echo signal is related to the material density; the higher the density, the greater the maximum amplitude of the ultrasonic echo signal. This coefficient is used to quantify the difference between the density of the billet completed in step 2 and the density of the standard billet. Density affects the deformation resistance and other properties of the material during subsequent extrusion.

[0089] Hardness reflects a material's ability to resist localized deformation. Different billet hardnesses require different extrusion forces during the extrusion process. This coefficient is used to measure the relationship between the actual billet hardness and the standard billet hardness, providing a basis for determining the extrusion force.

[0090] Thermal conductivity affects heat transfer during the extrusion process, which in turn affects the material's plasticity and other properties. This coefficient is used to reflect the difference between the thermal conductivity of the actual billet and the standard billet, and helps determine the extrusion speed (for materials with slow thermal conductivity, excessively fast extrusion can easily lead to problems such as localized overheating due to heat accumulation).

[0091] Standard ultrasonic echo signal maximum amplitude: For the same material, it is the ideal ultrasonic echo intensity for achieving the required density. Divide the actual ultrasonic echo maximum amplitude of the billet from step 2 by this value to obtain the "density coefficient".

[0092] Standard billet hardness: is the ideal value for the hardness of the same material to meet the standard.

[0093] , , This method involves obtaining the corrected factor through single-factor experiments. Two other factors are fixed as standard values, while only one factor (such as the density coefficient) is changed. Multiple extrusion pressure tests are conducted, and the difference between the actual extrusion pressure obtained from the tests and the standard extrusion pressure is compared. The correction factor for the corresponding factor is then determined by reverse derivation using the extrusion pressure formula. For example, by fixing the hardness coefficient and the extrusion dimensional fit coefficient as standard values ​​and changing the density coefficient, extrusion pressure tests are performed to determine the corrected factor. . , , The values ​​range from 0.05 to 0.5.

[0094] , , Method of obtaining the data: Also obtained through single-factor experiments. With other factors fixed as standard values, only one factor is changed (e.g., the required extrusion pressure). Multiple sets of extrusion speed tests are conducted, and the difference between the actual extrusion speed obtained from the tests and the standard extrusion speed is compared. The correction index for the corresponding factor is determined by reverse derivation using the extrusion speed formula. For example, by fixing the structural characteristic coefficient and thermal conductivity characteristic coefficient as standard values, changing the required extrusion pressure, and conducting extrusion speed tests, the correction index for the corresponding factor can be determined. . , The value range is 0.05 to 0.7; The value range is 0.3 to 0.8;

[0095] Standard blank thermal conductivity: is the inherent ideal value of the thermal conductivity of the same material (the thermal conductivity of the same material is theoretically stable).

[0096] The beneficial effects of the above technical solution are as follows:

[0097] By precisely quantifying billet characteristics using parameters such as density coefficient and hardness coefficient, and clarifying part structural parameters such as flatness characteristic coefficient and positioning groove characteristic coefficient, combined with extrusion pressure and extrusion speed formulas, material deformation during cold heading can be more precisely controlled. The introduction of thermal conductivity characteristic coefficients allows for adjustment of the extrusion speed based on the actual thermal conductivity of the billet.

[0098] A proper match between extrusion pressure and extrusion speed can avoid surface scratches and wrinkles caused by excessive extrusion pressure or speed, making the surface of the projection weld bolt smoother and flatter, thus meeting the high requirements for product appearance and use.

[0099] Without relying on workers' experience for repeated trial and error adjustments, the required extrusion pressure and speed can be quickly calculated using clearly defined formulas and coefficients obtained through testing, significantly reducing process adjustment time. When changing product specifications or billet batches, parameter switching can be completed rapidly, reducing equipment downtime and improving production efficiency.

[0100] Standardized parameter determination processes and formulaic calculation methods make the setting of extrusion pressure and extrusion speed in the production process more consistent and stable, keeping the production rhythm stable, avoiding production interruptions or efficiency declines caused by parameter fluctuations, and increasing product output per unit time.

[0101] By rationally adjusting the extrusion speed based on parameters such as thermal conductivity, wear on the die caused by overheating or uneven stress is reduced, extending the die's service life and lowering the frequency and cost of die replacement. Precise parameter control reduces the scrap rate, minimizes material waste caused by dimensional inconsistencies or internal defects, and saves on raw material costs.

[0102] Example 3, based on Example 1 or 2, further includes the following after determining the required extrusion speed and pressure through detection (the process of determining the required extrusion speed and pressure through detection can employ existing technology):

[0103] Step 34: Before the test in Step 3, control the temperature of the cold heading die cavity at the second station to the first rated temperature and control the temperature of the blank completed in Step 2 to the second rated temperature. Test the blank completed in Step 2 with the required extrusion pressure and the required extrusion temperature in Step 3.

[0104] After the test in step 3 is completed, scan the temperature of the critical area of ​​the cavity of the cold heading die in the second station to determine the first heating coefficient and the first temperature gradient coefficient.

[0105] During the test in step 3, the vibration parameters of the upper mold of the cold heading mold in the second station are detected; after the test in step 3 is completed, the key dimensional parameters (i.e., the verticality below) and temperature of the blank completed in step 3 are detected; based on the temperature of the blank completed in step 3, the second heating coefficient and the second temperature gradient coefficient are determined.

[0106] Step 35: Determine the vibration coupling parameters based on the vibration parameters of the upper mold and the key dimensional parameters of the blank completed in Step 3;

[0107] Step 36: Determine the extrusion pressure-extrusion speed-temperature change coupling coefficient based on the first heating coefficient, the first temperature gradient coefficient, the second heating coefficient, and the second temperature gradient coefficient; when the extrusion pressure-extrusion speed-temperature change coupling coefficient and vibration coupling parameter are not within the corresponding preset range (the safe range for normal production), issue an early warning; re-inspect the mold and / or fine-tune the preset temperature (set the fine-tuning gradient / preset temperature as needed) and retest until the early warning condition is not met;

[0108] Step 37: If no warning is issued in step 36, determine the maximum allowable pressure fluctuation value and the maximum allowable speed fluctuation value based on the extrusion pressure-extrusion speed-temperature change coupling coefficient and vibration coupling parameters;

[0109] Step 38: If no warning is issued in step 36, determine the maximum allowable vibration intensity based on the vibration coupling parameters.

[0110] During the actual batch execution of step 3 (based on the final determined required extrusion pressure and extrusion speed mentioned above), an alarm will be triggered if any of the following occurs: the actual pressure fluctuation value exceeds the maximum allowable pressure fluctuation value, the actual speed fluctuation value exceeds the maximum allowable speed fluctuation value, or the actual vibration intensity exceeds the maximum allowable vibration intensity. All fluctuation values ​​mentioned above are absolute values.

[0111] First temperature rise coefficient = (Average temperature of the cavity after step 3 - Average temperature of the cavity before step 3 test) ÷ Average temperature of the cavity before step 3 test;

[0112] Second heating coefficient = (Maximum temperature of billet after step 3 - Average temperature of billet before step 3 test) ÷ Average temperature of billet before step 3 test;

[0113] First temperature gradient coefficient = (Maximum temperature of the cavity after step 3 - Minimum temperature of the cavity after step 3) ÷ Distance between the temperature measuring point where the maximum temperature of the cavity is located after step 3 and the temperature measuring point where the minimum temperature of the cavity is located after step 3;

[0114] Second temperature gradient coefficient = (Maximum temperature of billet after step 3 - Minimum temperature of billet after step 3) ÷ Distance between the temperature measuring point where the maximum temperature of billet is located after step 3 and the temperature measuring point where the minimum temperature of billet is located after step 3;

[0115] Extrusion pressure-extrusion speed-temperature coupling coefficient E = pressure ratio × speed ratio ÷ overall temperature coefficient;

[0116] Pressure ratio = Required extrusion pressure ÷ Standard extrusion pressure;

[0117] Speed ​​ratio = Required extrusion speed ÷ Standard extrusion speed;

[0118] Overall temperature coefficient = min( ); , , , They are respectively , , , The corresponding maximum allowed value;

[0119] The standard value of the coupling coefficient between extrusion pressure, extrusion speed, and temperature change;

[0120] Step 37: Determine the maximum allowable pressure fluctuation value and the maximum allowable speed fluctuation value based on the extrusion pressure-extrusion speed-temperature change coupling coefficient and vibration coupling parameters;

[0121] Maximum permissible pressure fluctuation value = Standard maximum permissible pressure fluctuation value (1 + Correction factor) × ( + Correction factor three × ((vibration coupling parameter - standard vibration coupling parameter) ÷ standard vibration coupling parameter));

[0122] Maximum permissible speed fluctuation value = Standard maximum permissible speed fluctuation value (1 + Correction factor 2 × ( + Correction factor four × ((vibration coupling parameter - standard vibration coupling parameter) ÷ standard vibration coupling parameter));

[0123] The correction coefficients were determined through multiple sets of experiments (the absolute value of the correction coefficients is greater than 0 and less than 1): different "extrusion pressure-extrusion speed-temperature change coupling coefficient E" and different "vibration coupling parameter deviations from standard vibration coupling parameters" were set up, and the maximum allowable pressure and speed fluctuation values ​​that do not produce molding defects were recorded; the relationship between "E" and "vibration coupling parameter deviations" in the experiments and the actual and standard maximum allowable fluctuation values ​​were compared; finally, mathematical methods such as linear or nonlinear fitting were used to determine the specific values ​​of each correction coefficient in order to match the influence of multi-parameter coupling on the maximum allowable fluctuation value.

[0124] Vibration coupling parameter = vibration intensity determined based on the vibration parameters of the upper mold ÷ (absolute value of verticality deviation of the blank completed in step 3 + preset positive number); the preset positive number is a preset value to prevent the denominator from being 0, and the preset positive number can be 0.001;

[0125] The vibration intensity determined based on the vibration parameters of the upper mold can be evaluated using the existing RMS method; RMS vibration intensity refers to the average energy intensity of the vibration signal over a period of time, measured by the root mean square (RMS) value.

[0126] The absolute value of the perpendicularity deviation of the billet completed in step 3 = |actual perpendicularity of the billet completed in step 3 - design perpendicularity of the billet completed in step 3|;

[0127] The perpendicularity of a blank refers to the degree of perpendicularity between its axis (or main reference plane) and a set vertical direction (usually the vertical direction of the mold, the vertical reference of the processing equipment, etc.) during processing such as cold heading.

[0128] First rated temperature: This is the target temperature of the cavity that is preset before the test in step 3 to ensure that the cavity of the cold heading mold in the second station is in a suitable initial working state. By controlling the cavity temperature to this value, a stable initial thermal environment can be provided for the subsequent cold heading process of the blank, reducing the impact of temperature fluctuations on the forming quality.

[0129] The second rated temperature is the target temperature that the billet completed in step 2 needs to reach before the test in step 3. Controlling the billet temperature at this rated value ensures that the temperature of the billet meets the process requirements when it enters the cold heading mold in the second station, ensuring the stability of the material's plasticity and other properties during the cold heading process, which is conducive to obtaining qualified molded products.

[0130] Standard extrusion pressure: In the cold heading process, this is a standard value of extrusion pressure determined through experiments and process verification for specific billet and product requirements. It ensures the normal forming of the billet without defects. It serves as a benchmark for measuring whether the actual required extrusion pressure is reasonable. The ratio of the required extrusion pressure to the standard extrusion pressure (pressure ratio) is used to assess the degree of deviation of the extrusion pressure.

[0131] Standard extrusion speed: This is also a standard value for extrusion speed suitable for cold heading of billets, determined through process optimization. A ratio (speed ratio) between the extrusion speed and the standard extrusion speed needs to be set to judge the rationality of the extrusion speed. The combination of extrusion pressure and extrusion speed is crucial to the quality of cold heading.

[0132] Standard vibration coupling parameters: These are standard values ​​determined based on the upper die vibration parameters and key dimensions of the billet, under normal and stable cold heading die vibration conditions. The deviation of the actual vibration coupling parameters from these standard values ​​is used to assess the impact of die vibration on the cold heading process, and subsequently to correct for maximum allowable pressure and speed fluctuations.

[0133] The standard value of the extrusion pressure-extrusion speed-temperature change coupling coefficient is a standard parameter determined through experiments, process verification, and optimization in the cold heading process, specifically for certain billets and product requirements. It comprehensively considers the coupling effect between extrusion pressure, extrusion speed, and temperature change, serving as a benchmark for assessing the reasonableness of the extrusion pressure-extrusion speed-temperature change coupling degree in actual production. Comparing the actual extrusion pressure-extrusion speed-temperature change coupling coefficient with this standard value provides a basis for process adjustments.

[0134] The beneficial effects of the above technical solution are as follows:

[0135] The solution fully considers the coupling relationship between core process parameters such as temperature, pressure, speed, and vibration during cold heading, and constructs a joint correction mechanism for the "maximum allowable pressure fluctuation value" and "maximum allowable speed fluctuation value" using the "temperature change coupling coefficient E" and "vibration coupling parameter". When temperature change coupling (such as abnormal temperature changes and gradients between the cavity and the blank) intensifies, the maximum allowable fluctuation value is corrected by E, strictly limiting the fluctuation range of pressure and speed, and avoiding problems such as material plasticity instability and incomplete forming caused by temperature factors. When the mold vibration is abnormal (vibration coupling parameter deviates from the standard), the fluctuation value is corrected by the deviation of the vibration coupling parameter to prevent blank positioning displacement and uneven mold stress caused by vibration, thus laying a solid foundation for the stable execution of the cold heading process from multiple dimensions.

[0136] The evaluation of key parameters (such as rated temperature, verticality, vibration intensity) and various coupling coefficients are clearly quantified and calculated using formulas, thus eliminating the ambiguity of "experience-based judgment" in traditional processes.

[0137] When the extrusion pressure-extrusion speed-temperature coupling coefficient and vibration coupling parameters are outside the corresponding preset ranges, the system issues a timely warning, facilitating early detection of potential problems with the mold and billet (such as insufficient mold assembly precision, initial billet state deviation, etc.). The system then re-inspects the mold and / or fine-tunes the preset temperature before retesting until the warning conditions are no longer met. If no warning is issued in step 36, and during the actual batch execution of step 3, if any of the following occurs: actual pressure fluctuation exceeding the maximum allowable pressure fluctuation, actual speed fluctuation exceeding the maximum allowable speed fluctuation, or actual vibration intensity exceeding the maximum allowable vibration intensity, the system will issue a timely alarm. This helps operators quickly troubleshoot mold, billet, or equipment malfunctions (such as mold wear, large billet verticality deviation, abnormal equipment transmission, etc.), reducing downtime and rework time caused by defective products accumulating. Simultaneously, based on the maximum allowable fluctuation and vibration intensity determined by the temperature coupling coefficient and vibration coupling parameters, the system can guide the equipment to automatically adjust process parameters such as pressure and speed (dynamically optimizing within the allowable range) without frequent manual intervention. This reduces labor costs and maximizes equipment production efficiency while ensuring quality.

[0138] Example 4, based on Example 3, includes an intelligent detection process during the batch execution of the target steps. The intelligent detection process includes:

[0139] Step 01: Perform a sub-inspection process periodically. The sub-inspection process includes: temperature detection of the corresponding key temperature detection area of ​​the mold cavity before the current blank is formed in the target step; temperature detection of the corresponding key temperature detection area of ​​the mold cavity after the current blank is formed in the target step; and multiple detections of extrusion pressure and extrusion speed during the current blank forming process in the target step.

[0140] Step 02: Determine the target coupling coefficient based on the parameters obtained in Step 01; the target coupling coefficient is the extrusion pressure-extrusion speed-die temperature change coupling coefficient;

[0141] Step 03: Based on the current heat dissipation parameters of the mold corresponding to the target step, construct the blank quantity-target coupling coefficient curve within the latest preset time period using the target coupling coefficient;

[0142] Step 04: Based on the current heat dissipation parameters of the mold corresponding to the target step, construct the equivalent temperature rise of the billet after forming within the latest preset time period, and construct the billet quantity-equivalent temperature rise curve.

[0143] Step 05: When either the slope of the curve of the number of formed blanks - target coupling coefficient is not within the corresponding allowable slope range (set as needed) or the maximum temperature of the mold cavity is greater than the preset temperature (not reached but close to the abnormal temperature that affects production) occurs after the blanks are formed, an early warning will be issued;

[0144] Step 06: When a warning is issued in step 05, the target heat dissipation power of the heat dissipation device of the mold corresponding to the target step is determined based on steps 03 and 04, and the actual heat dissipation power of the heat dissipation device of the mold corresponding to the target step is adjusted to the target heat dissipation power.

[0145] The coupling coefficient of extrusion pressure-extrusion speed-die temperature change is as described in Example 3, wherein the comprehensive temperature coefficient in Example 4 is = Extrusion pressure - extrusion speed - die temperature coupling coefficient = pressure ratio × speed ratio ÷ overall temperature coefficient;

[0146] Equivalent temperature rise = (actual temperature of the mold after forming a single blank - actual temperature of the mold before forming a single blank) - (standard temperature of the mold after forming a single blank under current heat dissipation parameters - standard temperature of the mold before forming a single blank under current heat dissipation parameters).

[0147] "Standard temperature of the mold after forming a single blank under current heat dissipation parameters": This refers to the temperature that the mold should reach theoretically or statistically based on experimental data after completing one cold heading operation of the mold in the target step, under the action of the current mold heat dissipation device (such as a cooling water system, whose flow rate, temperature, and other parameters are fixed), according to normal and stable process rules.

[0148] "Standard temperature of the mold before forming a single blank under the current heat dissipation parameters": This refers to the temperature that the mold should be at before performing a cold heading operation in the target step, based on normal process conditions, either theoretically or experimentally.

[0149] First, determine the predicted temperature rise as the maximum equivalent temperature rise of the "number of formed blanks - equivalent temperature rise curve";

[0150] The above "Quantity of formed blanks - equivalent temperature rise curve" is the name of the curve, where - is a horizontal bar, not a minus sign;

[0151] Based on the predicted temperature rise, the heat dissipation J required by the corresponding heat dissipation device during the molding process of a single blank in the mold corresponding to the target step is determined (the above is determined by combining the thermodynamic model of the mold with experiments or simulations; this is existing technology and will not be elaborated here). The additional heat dissipation power = J × (standard target coupling coefficient ÷ latest target coupling coefficient) ÷ molding time of a single blank in the mold corresponding to the target step.

[0152] Obtain the latest actual heat dissipation power - effective heat dissipation power efficiency fitting curve of the heat dissipation device, and first determine the target position of the actual heat dissipation power corresponding to the current heat dissipation parameters on the actual heat dissipation power - effective heat dissipation power efficiency fitting curve. Then determine the adjusted position of the effective heat dissipation power after adding the heat dissipation power to be added (adjusting from the target position). The actual heat dissipation power corresponding to this adjusted position is the target heat dissipation power; the actual heat dissipation power is the input heat dissipation power.

[0153] Effective heat dissipation power efficiency = Effective heat dissipation power ÷ Corresponding actual heat dissipation power;

[0154] The target step is any one of steps 2 to 6.

[0155] The beneficial effects of the above technical solution are as follows:

[0156] By periodically monitoring the temperature, extrusion pressure, and extrusion speed of the die before and after billet forming, the dynamic changes in process parameters can be monitored in a timely manner. Based on these parameters, a target coupling coefficient is determined, and relevant curves are constructed to accurately monitor the coupling relationship between die temperature changes and process parameters. An early warning is issued when the curve slope is abnormal or the die cavity temperature exceeds the limit, thereby adjusting the power of the heat dissipation device. This effectively avoids problems such as thermal deformation and thermal fatigue caused by abnormal die temperature, ensuring the stability of the cold heading forming process and ultimately improving the dimensional accuracy and surface quality of the product.

[0157] By utilizing the equivalent temperature rise curve of the number of formed blanks and the efficiency fitting curve of actual heat dissipation power versus effective heat dissipation power, the target heat dissipation power of the heat dissipation device can be accurately determined. This approach considers both the actual temperature change of the mold during blank forming and the efficiency characteristics of the heat dissipation device, making the adjustment of heat dissipation power more targeted. This avoids insufficient or excessive heat dissipation, improves energy utilization efficiency, and reduces production energy consumption.

[0158] Reasonable heat dissipation control can maintain the mold temperature within a suitable range, reducing damage to the mold material caused by excessive temperature or large temperature fluctuations, such as thermal wear and thermal cracking, thereby extending the service life of the mold and reducing the frequency of mold replacement and production costs.

[0159] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A cold heading process for projection bolting, characterized by: Comprise: Step 1: cutting the cylindrical blank; Step 2: extruding the bottom guide chamfer of the cylindrical blank through the first station cold heading die; Step 3: clamping the blank obtained in step 2 into the second station, and extruding the double flat position plane of the rod part and the anti-rotation positioning groove at the tail end through the second station die; Step 4: using the punch of the third station die to perform a balling operation on the material used for forming the head of the blank obtained in step 3, and pre-pressing it into an inverted cone shape; Step 5: clamping the blank obtained in step 4 into the fourth station cold heading die to upset the head, and forming a step feature at the top end of the workpiece head; Step 6: clamping the blank obtained in step 5 into the fifth station cold heading die for final forming to obtain a complete part; The cold heading forming of each batch of projection welded bolts at least once based on detection to determine the required extrusion speed and the required extrusion force process; Between step 2 and step 3, the step 3 extrusion parameter determination process is performed, which comprises: Step 31: ultrasonic detection is performed on the blank completed in step 2, and the density coefficient is determined based on the maximum amplitude of the actual ultrasonic echo signal; hardness detection is performed on the blank completed in step 2 to determine the hardness coefficient; and the thermal conductivity coefficient of the blank completed in step 2 is detected to determine the thermal conductivity coefficient characteristic coefficient; Step 32: based on the design size of step 3 and the die size, the flat position characteristic coefficient, the positioning groove characteristic coefficient and the extrusion size matching coefficient are determined; Step 33: based on the density coefficient, the hardness coefficient and the extrusion size matching coefficient, the required extrusion force is determined, and based on the required extrusion force, the flat position characteristic coefficient, the positioning groove characteristic coefficient and the thermal conductivity coefficient characteristic coefficient, the required extrusion speed is determined.

2. A cold heading process for forming a projection welded bolt as claimed in claim 1, characterized in that: Step 1: cutting the blank of the required raw material length through the shearing mechanism of the cold heading machine.

3. A cold heading process for forming a projection welded bolt as claimed in claim 1, wherein: The step 6 forms a welding point and a small flat position on the middle step.

4. A cold heading process for forming a projection welded bolt as claimed in claim 1, wherein: After the process of determining the required extrusion speed and the required extrusion force based on detection, it further comprises: Step 34: controlling the temperature of the second station cold heading die cavity to be a first rated temperature before step 3 test and controlling the temperature of the blank completed in step 2 to be a second rated temperature, and performing step 3 test on the blank completed in step 2 with the required extrusion force and the required extrusion temperature; After step 3 test is completed, the temperature of the key area of the second station cold heading die cavity is scanned to determine the first temperature rise coefficient and the first temperature gradient coefficient; During step 3 test, the vibration parameters of the upper die of the second station cold heading die are detected; after step 3 test is completed, the key size parameters and the temperature of the blank completed in step 3 are detected; based on the temperature of the blank completed in step 3, the second temperature rise coefficient and the second temperature gradient coefficient are determined; Step 35: based on the vibration parameters of the upper die and the key size parameters of the blank completed in step 3, the vibration coupling parameters are determined; Step 36: based on the first temperature rise coefficient, the first temperature gradient coefficient, the second temperature rise coefficient and the second temperature gradient coefficient, the extrusion force-extrusion speed-temperature change coupling coefficient is determined; when the extrusion force-extrusion speed-temperature change coupling coefficient and the vibration coupling parameters are not within the corresponding preset range, a warning is given. Step 37: When step 36 does not give an early warning, determine the maximum allowable pressure fluctuation value and the maximum allowable speed fluctuation value based on the extrusion pressure-extrusion speed-temperature change coupling coefficient and the vibration coupling parameter; Step 38: When step 36 does not give an early warning, determine the maximum allowable vibration intensity based on the vibration coupling parameter.

5. A cold heading process for forming a projection welded bolt as claimed in claim 4, characterized in that: During the actual batch execution of step 3, an alarm is given when any of the following occurs: the actual pressure fluctuation value is greater than the maximum allowable pressure fluctuation value, the actual speed fluctuation value is greater than the maximum allowable speed fluctuation value, and the actual vibration intensity is greater than the maximum allowable vibration intensity.

6. A cold heading process for forming a projection welded bolt as claimed in claim 1, wherein: Intelligent detection process is carried out during the target step batch execution process, and the intelligent detection process includes: Step 01: Periodically perform a sub-detection process, which includes: detecting the temperature of the corresponding mold cavity key temperature detection area before the current billet of the target step is formed; detecting the temperature of the corresponding mold cavity key temperature detection area after the current billet of the target step is formed; detecting the extrusion force and the extrusion speed during the forming process of the current billet of the target step; Step 02: Determine the target coupling coefficient based on the parameters obtained in step 01; the target coupling coefficient is the extrusion force-extrusion speed-mold temperature change coupling coefficient; Step 03: Based on the target coupling coefficient determined within the latest preset time under the current heat dissipation parameter of the mold corresponding to the target step, a formed billet quantity-target coupling coefficient curve is constructed; Step 04: Based on the equivalent temperature rise of the formed billet within the latest preset time under the current heat dissipation parameter of the mold corresponding to the target step, a formed billet quantity-equivalent temperature rise curve is constructed; Step 05: When the slope of the formed billet quantity-target coupling coefficient curve is not within the corresponding slope allowable range and / or the maximum temperature of the mold cavity after the billet is formed is greater than any of the preset temperatures, an early warning is given; Step 06: When step 05 gives an early warning, determine the target heat dissipation power of the heat dissipation device of the mold corresponding to the target step based on steps 03 and 04, and adjust the actual heat dissipation power of the heat dissipation device of the mold corresponding to the target step to the target heat dissipation power; the target step is any of steps 2-6.

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