A friction block forging process

Abstract

A friction block forging process comprises the following steps: (1) blanking; (2) heating; (3) bending; (4) pre-forging; (5) final forging; (6) trimming; (7) correction. The present invention proposes a new friction block forging process, which has the advantages of simple operation, low production cost, high material utilization rate, good quality of forged friction block forgings, high yield rate, reasonable mold structure corresponding to each process and long service life.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile industry, and in particular relates to a friction block forging process. Background Art

[0002] The friction block, also known as the steel back, is part of the brake pad and is used in automobile disc brakes. The friction block is a flat plate structure, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the main plane is basically rectangular, one long side is an outward convex arc side, and the middle of the other long side is a concave arc. Two symmetrical pits 1 are designed on one side of the friction block, and there are several long strip protrusions 2 evenly distributed in the pits 1. The friction block of this structure has the following problems during the forging process:

[0003] (1) The friction block is a flat structure. The length and width dimensions of the friction block are more than twenty times and more than ten times of its thickness dimension a, respectively. When the bar billet is used for forging, the billet deformation is large, which has a great impact on the selection of billet size, billet making process, and the difficulty of billet placement, and ultimately reduces the quality of forgings and raw material utilization, and increases production costs.

[0004] (2) One long side of the friction block is a convex arc side, and the middle part of the other long side is a concave arc side. The bar blank is a straight bar. There is a mismatch between the distribution of the raw materials and the shape of the friction block forging. When forging directly, it is necessary to increase the bar diameter, thereby increasing the bar weight, and the material utilization rate is low.

[0005] (3) Since the thickness dimension a of the friction block is small and the plane dimension is large, and its dimensional tolerance requirement of ±0.25mm is relatively strict, it has high requirements on forging process, die design, forging equipment, etc.

[0006] (4) There are evenly distributed long strip protrusions 2 in the pit 1. In the pit 1, since the thickness of the forging itself is small, the metal flow between the upper and lower dies of the forging die will be very intense during the final forming, and the wear on the die cavity will be relatively serious. Therefore, it is necessary to reduce the wear by reducing the volume of the blank; on the other hand, the long strip protrusion 2 is higher than the plane of the friction block and the width of the protrusion is small, which is not easy to fill. It is necessary to increase the volume of the blank to ensure the quality of the forging. Therefore, if the blank making during the forging process is not appropriate, it will have a great impact on the quality of the forging and the life of the die. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a friction block forging process which is easy to form, has high material utilization rate, high forging quality and long die service life.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solution: a friction block forging process, comprising the following steps:

[0009] (1) Cutting materials;

[0010] (2) Heating;

[0011] (3) Bending;

[0012] (4) Pre-forging;

[0013] (5) Final forging;

[0014] (6) Trimming;

[0015] (7) Correction.

[0016] The specific process of the blanking process in step (1) is as follows: using Q235 round steel bars with a diameter of φ34 mm and a blanking weight of 1.66±0.02 kg; using a P50B high-speed circular saw to saw the round steel bars into blanks, the speed of the high-speed circular saw equipment is 120-130 r / s, the tooth cutting thickness is 0.065-0.07 mm, the blanking time of a single blank is 11 s, the blanking length tolerance is ±0.05 mm, and the end horseshoe degree is ≤0.1 mm; the high-speed circular saw has a fast blanking speed and a high blanking precision, which is a reliable guarantee for improving the consistency of forging quality.

[0017] The specific process of the heating process in step (2) is as follows: a 630KW medium frequency induction heating furnace is used to heat the billet, and the heating temperature range is 1120-1200°C. The method for controlling the billet temperature is to use an infrared thermometer to sort the heated billet, and the sorting is: normal billet (1120-1200°C), low temperature billet (<1120°C), and high temperature billet (>1200°C). The sorted billet reaches the designated position through different slides; a low temperature material basket and a high temperature material basket are set at the terminals of the low temperature material and high temperature material slides, and a feed port is opened on the top of the material basket and locked to ensure that the materials are not mixed and to prevent workers from taking unqualified billets; the low temperature material can be heated again, and it is scrapped if it is underheated again, so as to avoid multiple heating causing the forging structure to fail to meet the requirements, and also to avoid excessive billet burnout causing the forging to produce insufficiency defects; the high temperature material is directly scrapped, and the quality personnel regularly clean the high temperature material and mark and isolate it.

[0018] The specific process of the bending process in step (3) is as follows: since one long side of the friction block forging is an outward convex arc side and the middle part of the other long side is a concave arc side, in order to ensure that the forging is full and improve the utilization rate of raw materials, it is necessary to bend the round bar material into a blank so that the cross-sectional area distribution of the bar material is more consistent with the cross-sectional area distribution of the friction block forging. A bending die is installed on a 160-ton crank press. During the bending process, the downward movement limit of the bending punch can be adjusted by adjusting the height of the slider of the press, that is, the thickness of the blank after bending is adjusted; at the same time, bending positioning step grooves with a depth of 2 mm are respectively provided at both ends of the arc groove of the bending die, so as to facilitate workers to place the heated blank, reduce operating errors, and improve production efficiency.

[0019] The specific process of the pre-forging process in step (4) is as follows: first, the pre-forging die is preheated in a die preheating furnace. After the pre-forging die preheating temperature reaches about 350° C., the pre-forging die is installed on a 2500-ton hot die forging press. The bottom of the cavity of the pre-forging lower die of the pre-forging die is provided with an arc-shaped positioning groove along the length direction. The bottom profile of the cross-section of the arc-shaped positioning groove is an arc segment with a radius of 18 mm. The bent blank is placed in the cavity of the pre-forging lower die. The bent blank is positioned by the arc-shaped positioning groove. Finally, the 2500-ton hot die forging press is started. The pre-forging upper die pre-forges the blank in the cavity of the pre-forging lower die. The pre-forged blank forms an arc-shaped flat plate-shaped pre-forged part.

[0020] The specific process of the final forging process in step (5) is as follows: the final forging die is installed on a 2500-ton hot die forging press, the bottom of the cavity of the final forging lower die is provided with a friction surface forging structure corresponding to the pit on the surface of one side of the friction block final forging and a plurality of long strip-shaped protrusions, four guide holes are vertically opened in the final forging lower die on the outer side of the friction surface forging structure, each guide hole is provided with a push rod, a jaw is provided between the final forging upper die and the final forging lower die, and the width of the burr bridge portion of the final forging die is 8 mm; the pre-forging is placed in the cavity of the final forging lower die of the final forging die, the hot die forging press is started, the final forging upper die presses the pre-forging in the cavity of the final forging lower die downwardly, after the final forging is completed, the final forging upper die is lifted upward, and the four push rods push the friction block final forging upward under the action of the cylinder, and the friction block final forging is clamped with a clamp and taken out from the cavity of the final forging lower die.

[0021] The specific process of the trimming process in step (6) is as follows: the trimming die is installed on a 400-ton closed single-point press, and the guide rail clearance of the 400-ton closed single-point press is ≤0.5 mm, so as to ensure the consistency of the circumferential burr of the forging after trimming; a conveyor belt is installed next to the trimming die, and the friction block final forging after trimming is placed on the conveyor belt for cooling, which can also effectively avoid bumps and scratches caused by the accumulation of forgings.

[0022] The specific process of the calibration process in step (7) is as follows: the calibration die is installed on a 300-ton friction press, and the forgings are calibrated in the order of trimming. The calibration temperature is 550-600°C, and the thickness tolerance of the forging size after calibration is within ±0.25mm.

[0023] In the pre-forging and final forging processes, workers use a spray gun to spray graphite emulsion on the pre-forging and final forging dies during the forging process to lubricate the dies while lowering the temperature of the die cavity surface. The weight ratio of graphite emulsion to water is 1:7, which can achieve the most effective lubrication effect while reducing the amount of graphite emulsion used.

[0024] By adopting the above technical solution, the present invention has the following technical effects:

[0025] (1) The heating process is very important. Low-temperature materials can easily cause: ① The fluidity of the billet is weakened, and the corners of the cavity are prone to underfilling, resulting in the scrapping of the forging; ② The deformation resistance of the billet is increased, which increases the impact force of the equipment and the force on the mold, causing damage to the equipment and mold; ③ The forming force of the forging eventually exceeds the maximum impact force of the equipment, resulting in the geometric dimensions of the forging being out of tolerance in the height direction or causing the equipment to be stuck. High-temperature materials can easily cause: the grain size of the billet is coarse, the strength and mechanical properties of the forging are reduced, resulting in the scrapping of the forging.

[0026] In order to find out the fault of medium frequency induction heating furnace in time, the infrared temperature measuring port of medium frequency induction heating furnace is equipped with display screen and alarm. The display screen can show the temperature of billet in real time. If there are more than 2 pieces of low temperature material and high temperature material in succession, the alarm will sound, prompting workers to check whether the medium frequency induction heating furnace has any fault, so as to avoid the occurrence of batch accidents. In order to improve the surface quality of friction block forgings and reduce the wear of pre-forging dies and final forging dies, an oxide scale treatment box is added to the discharge port of medium frequency induction heating furnace, and 2MP high pressure water is used to remove the oxide scale of billet to improve the surface quality of forgings.

[0027] (2) The die preheating furnace heats the pre-forging die, which has the following advantages: ① The pre-forging die preheating temperature uniformity is good; ② After the pre-forging die is installed, the pre-forging die does not need to be preheated again, which improves production efficiency; ③ The service life of the pre-forging die is increased.

[0028] (3) To ensure the consistency of the forging quality of the friction block, it is necessary to ensure the consistency of the placement of the blank during pre-forging and final forging. The pre-forging die is equipped with an arc-shaped positioning groove that matches the press-bent blank in the cavity of the pre-forging lower die, which can accurately place the press-bent blank in the cavity of the pre-forging die without affecting the final forging. Adjusting the specific dimensions of the surrounding shape of the pre-forging can make the surrounding contour of the pre-forging basically consistent with the final forging. In addition, adjusting the height of the parting line of the pre-forging die and the final forging die can accurately place the pre-forging into the cavity of the final forging die. The improved pre-forging die makes it easier for workers to place blanks, reduces operating errors, and improves production efficiency.

[0029] (4) When modifying the design of the pre-forging die, the thickness of the pre-forging needs to be adjusted and strictly controlled during the production process to ensure that the final forging fills the cavity and minimizes the relative flow of metal of the pre-forging during final forging, thereby reducing the wear of the final forging die cavity. There are many long protrusions on one side of the friction block final forging. This side is closely fitted with the final forging cavity, so it is easy to get stuck during the forging process. For this reason, the cavity on one side of the protrusion is set to the lower die of the final forging die, and four ejector pins are set in the lower die. After forging, the friction block forging is taken out with the help of the ejection force of the equipment. At the same time, a jaw is set on the die. In view of the thin thickness of the friction block and the relatively large plane size, the width of the burr bridge of the final forging die is reduced from 15mm to 8mm, and different bridge thicknesses are set. While ensuring that the final forging is fully formed, the final forming force can be reduced and the wear of the die can be reduced, the service life of the die can be extended, and the production cost can be reduced.

[0030] In order to further improve the consistency of forgings and the life of the mold, and reduce the mold cost of a single forging, the present invention uses intelligent additive manufacturing welding strengthening to stack a certain thickness of high-strength mold welding materials in the pre-forging and final forging cavity parts, that is, ordinary mold materials are used as the mold base, and high-strength materials are used as the working part of the mold cavity. In this way, while improving the mold life, it also takes into account the mold production cost and use cost. After testing using this technology, the mold life was increased from 500 pieces / set to 3000 pieces / set.

[0031] In summary, the present invention proposes a friction block forging process, which has the advantages of simple operation, low production cost, high material utilization rate, good quality of forged friction block forgings, high yield rate, and reasonable mold structure corresponding to each process and long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a front view schematic diagram of the friction block forging;

[0033] Figure 2 It is a schematic diagram of the back side of the friction block forging;

[0034] Figure 3 yes Figure 1 Bottom view of

[0035] Figure 4 yes Figure 3 A partial enlarged schematic diagram of the M in the middle;

[0036] Figure 5 is a cross-sectional schematic diagram of a press-bending die;

[0037] Figure 6 yes Figure 5EE cross-sectional diagram of the intermediate pressure bend positioning step groove;

[0038] Figure 7 1 is a top view schematic diagram of a pre-forging lower die of a pre-forging die;

[0039] Figure 8 yes Figure 7 Schematic diagram of the cross section of the middle arc positioning groove DD;

[0040] Fig. 9 It is a top view schematic diagram of the final forging lower die of the final forging die;

[0041] Fig.10 yes Fig. 9 Schematic diagram of the cross section at the middle jaw BB;

[0042] Fig.11 yes Fig. 9 Schematic diagram of the cross section at AA of the middle flash edge. DETAILED DESCRIPTION

[0043] like Figure 5-11 As shown, a friction block forging process of the present invention comprises the following steps:

[0044] (1) Cutting materials;

[0045] (2) Heating;

[0046] (3) Bending;

[0047] (4) Pre-forging;

[0048] (5) Final forging;

[0049] (6) Trimming;

[0050] (7) Correction.

[0051] The specific process of the blanking process in step (1) is as follows: using Q235 round steel bars with a diameter of φ34 mm and a blanking weight of 1.66±0.02 kg; using a P50B high-speed circular saw to saw the round steel bars into blanks, the speed of the high-speed circular saw equipment is 120-130 r / s, the tooth cutting thickness is 0.065-0.07 mm, the blanking time of a single blank is 11 s, the blanking length tolerance is ±0.05 mm, and the end horseshoe degree is ≤0.1 mm; the high-speed circular saw has a fast blanking speed and a high blanking precision, which is a reliable guarantee for improving the consistency of forging quality.

[0052] The specific process of the heating process in step (2) is as follows: a 630KW medium frequency induction heating furnace is used to heat the billet, and the heating temperature range is 1120-1200°C. The method for controlling the billet temperature is to use an infrared thermometer to sort the heated billet, and the sorting is: normal billet (1120-1200°C), low temperature billet (<1120°C), and high temperature billet (>1200°C). The sorted billet reaches the designated position through different slides; a low temperature material basket and a high temperature material basket are set at the terminals of the low temperature material and high temperature material slides, and a feed port is opened on the top of the material basket and locked to ensure that the materials are not mixed and to prevent workers from taking unqualified billets; the low temperature material can be heated again, and it is scrapped if it is underheated again, so as to avoid multiple heating causing the forging structure to fail to meet the requirements, and also to avoid excessive billet burnout causing the forging to produce insufficiency defects; the high temperature material is directly scrapped, and the quality personnel regularly clean the high temperature material and mark and isolate it.

[0053] The specific process of the bending process in step (3) is as follows: since one long side of the friction block forging is an outward convex arc side and the middle part of the other long side is a concave arc side, in order to ensure that the forging is full and improve the utilization rate of raw materials, it is necessary to bend the round bar material into a blank so that the cross-sectional area distribution of the bar material is more consistent with the cross-sectional area distribution of the friction block forging. A bending die is installed on a 160-ton crank press. During the bending process, the downward movement limit of the bending punch 3 can be adjusted by adjusting the height of the slider of the press, that is, the thickness of the blank after bending is adjusted; at the same time, bending positioning step grooves 5 with a depth of 2 mm are respectively provided at both ends of the arc groove of the bending die 4, so as to facilitate workers to place the heated blank, reduce operating errors, and improve production efficiency.

[0054] The specific process of the pre-forging process in step (4) is as follows: first, the pre-forging die is preheated in a die preheating furnace. After the pre-forging die preheating temperature reaches about 350° C., the pre-forging die is installed on a 2500-ton hot die forging press. The bottom of the cavity of the pre-forging lower die 6 of the pre-forging die is provided with an arc-shaped positioning groove 7 along the length direction. The bottom profile of the cross section of the arc-shaped positioning groove 7 is an arc segment with a radius of 18 mm. The bent blank is placed in the cavity of the pre-forging lower die 6. The bent blank is positioned by the arc-shaped positioning groove 7. Finally, the 2500-ton hot die forging press is started. The pre-forging upper die pre-forges the blank in the cavity of the pre-forging lower die 6. The pre-forged blank forms an arc-shaped flat plate-shaped pre-forged part.

[0055] The specific process of the final forging process in step (5) is as follows: the final forging die is installed on a 2500-ton hot die forging press, the bottom of the cavity of the final forging lower die 8 is provided with a friction surface forging structure 9 corresponding to the pits and a plurality of long strip-shaped protrusions on the surface of one side of the friction block final forging, four guide holes are vertically opened in the final forging lower die 8 on the outer side of the friction surface forging structure 9, each guide hole is provided with a push rod 10, a jaw 11 is provided between the final forging upper die 12 and the final forging lower die 8, and the width of the burr bridge portion 13 of the final forging die is 8 mm; the pre-forged piece is placed in the cavity of the final forging lower die 8 of the final forging die, the hot die forging press is started, the final forging upper die 12 forges the pre-forged piece in the cavity of the final forging lower die 8 downward, after the final forging is completed, the final forging upper die 12 is lifted upward, and the four push rods 10 push the friction block final forging upward under the action of the cylinder, and the friction block final forging is clamped with a clamp and taken out of the cavity of the final forging lower die 8.

[0056] The specific process of the trimming process in step (6) is as follows: the trimming die is installed on a 400-ton closed single-point press, and the guide rail clearance of the 400-ton closed single-point press is ≤0.5 mm, so as to ensure the consistency of the circumferential burr of the forging after trimming; a conveyor belt is installed next to the trimming die, and the friction block final forging after trimming is placed on the conveyor belt for cooling, which can also effectively avoid bumps and scratches caused by the accumulation of forgings.

[0057] The specific process of the calibration process in step (7) is as follows: the calibration die is installed on a 300-ton friction press, and the forgings are calibrated in the order of trimming. The calibration temperature is 550-600°C, and the thickness tolerance of the forging size after calibration is within ±0.25mm.

[0058] In the pre-forging and final forging processes, workers use a spray gun to spray graphite emulsion on the pre-forging and final forging dies during the forging process to lubricate the dies while lowering the temperature of the die cavity surface. The weight ratio of graphite emulsion to water is 1:7, which can achieve the most effective lubrication effect while reducing the amount of graphite emulsion used.

[0059] This embodiment does not impose any formal limitation on the shape, material, structure, etc. of the present invention. Any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A friction block forging process, characterized in that: The following steps are involved: (1) Cutting materials; (2) Heating; (3) Bending; (4) Pre-forging; (5) Final forging; (6) Trimming; (7) Calibration; The specific process of the bending process in step (3) is as follows: since one long side of the friction block forging is an outward convex arc side and the middle part of the other long side is a concave arc side, in order to ensure that the forging is full and improve the utilization rate of raw materials, it is necessary to bend the round bar material into a blank so that the cross-sectional area distribution of the bar material is more consistent with the cross-sectional area distribution of the friction block forging. A bending die is installed on a 160-ton crank press. During the bending process, the downward movement limit of the bending punch can be adjusted by adjusting the height of the slider of the press, that is, the thickness of the blank after bending is adjusted; at the same time, bending positioning step grooves with a depth of 2 mm are respectively provided at both ends of the arc groove of the bending die, so as to facilitate workers to place the heated blank, reduce operating errors, and improve production efficiency; The specific process of the pre-forging process in step (4) is as follows: first, the pre-forging die is preheated in a die preheating furnace. After the pre-forging die preheating temperature reaches about 350° C., the pre-forging die is installed on a 2500-ton hot die forging press. The bottom of the cavity of the pre-forging lower die of the pre-forging die is provided with an arc-shaped positioning groove along the length direction. The bottom profile of the cross section of the arc-shaped positioning groove is an arc segment with a radius of 18 mm. The bent blank is placed in the cavity of the pre-forging lower die. The bent blank is positioned by the arc-shaped positioning groove. Finally, the 2500-ton hot die forging press is started. The pre-forging upper die pre-forges the blank in the cavity of the pre-forging lower die. The pre-forged blank forms an arc-shaped flat plate-shaped pre-forged part. The specific process of the final forging process in step (5) is as follows: the final forging die is installed on a 2500-ton hot die forging press, the bottom of the cavity of the final forging lower die is provided with a friction surface forging structure corresponding to the pit on the surface of one side of the friction block final forging and a plurality of long strip-shaped protrusions, four guide holes are vertically opened in the final forging lower die on the outer side of the friction surface forging structure, each guide hole is provided with a push rod, a jaw is provided between the final forging upper die and the final forging lower die, and the width of the burr bridge portion of the final forging die is 8 mm; the pre-forging is placed in the cavity of the final forging lower die of the final forging die, the hot die forging press is started, the final forging upper die presses the pre-forging in the cavity of the final forging lower die downwardly, after the final forging is completed, the final forging upper die is lifted upward, and the four push rods push the friction block final forging upward under the action of the cylinder, and the friction block final forging is clamped with a clamp and taken out from the cavity of the final forging lower die.

2. A friction block forging process according to claim 1, characterized in that: The specific process of the blanking process in step (1) is as follows: using Q235 round steel bars with a diameter of φ34 mm and a blanking weight of 1.66±0.02 kg; using a P50B high-speed circular saw to saw the round steel bars into blanks, the speed of the high-speed circular saw equipment is 120-130 r / s, the tooth cutting thickness is 0.065-0.07 mm, the blanking time of a single blank is 11 s, the blanking length tolerance is ±0.05 mm, and the end horseshoe degree is ≤0.1 mm; the high-speed circular saw has a fast blanking speed and a high blanking precision, which is a reliable guarantee for improving the consistency of forging quality.

3. A friction block forging process according to claim 1, characterized in that: The specific process of the heating process in step (2) is as follows: a 630KW medium frequency induction heating furnace is used to heat the billet, and the heating temperature range is 1120-1200°C. The method for controlling the billet temperature is to use an infrared thermometer to sort the heated billet, and the billet is sorted into: normal billet with a temperature of 1120-1200°C, low-temperature billet with a temperature of less than 1120°C, and high-temperature billet with a temperature of more than 1200°C. The sorted billet reaches the designated position through different slides; a low-temperature material basket and a high-temperature material basket are arranged at the terminals of the low-temperature material and high-temperature material slides, and a feed port is opened on the top of the material basket and locked to ensure that the materials are not mixed and to prevent workers from taking unqualified billets; the low-temperature material can be heated again, and if it is underheated again, it is scrapped to avoid multiple heating causing the forging structure to fail to meet the requirements, and also to avoid excessive billet burnout causing the forging to produce insufficiency defects; the high-temperature material is directly scrapped, and the quality personnel regularly clean the high-temperature material and mark and isolate it.

4. A friction block forging process according to claim 1, characterized in that: The specific process of the trimming process in step (6) is as follows: the trimming die is installed on a 400-ton closed single-point press, and the guide rail clearance of the 400-ton closed single-point press is ≤0.5 mm, so as to ensure the consistency of the circumferential burr of the forging after trimming; a conveyor belt is installed next to the trimming die, and the friction block final forging after trimming is placed on the conveyor belt for cooling, which can also effectively avoid bumps and scratches caused by the accumulation of forgings.

5. A friction block forging process according to claim 4, characterized in that: The specific process of the calibration process in step (7) is as follows: the calibration die is installed on a 300-ton friction press, and the forgings are calibrated in the order of trimming. The calibration temperature is 550-600°C, and the thickness tolerance of the forging size after calibration is within ±0.25mm.

6. A friction block forging process according to claim 4, characterized in that: In the pre-forging and final forging processes, workers use a spray gun to spray graphite emulsion on the pre-forging and final forging dies during the forging process to lubricate the dies while lowering the temperature of the die cavity surface. The weight ratio of graphite emulsion to water is 1:7, which can achieve the most effective lubrication effect while reducing the amount of graphite emulsion used.

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