Manufacturing process of a mining round-link chain

Abstract

The present invention relates to the field of round-link chains, and in particular discloses a manufacturing process for mining round-link chains, which comprises the following steps: prefabricating a bar stock and forming lapping parts at both ends, opening locking grooves on the lapping parts, prefabricating locking pins, bending the bar stock into a special-shaped ring body composed of two U-shaped parts, connecting the special-shaped ring body with a chain link and driving the two U-shaped parts to relatively twist around the central axis of the middle section of the bar stock, deforming the special-shaped ring body into a chain link, butting the locking grooves to form a locking hole, installing and fixing the locking pin in the locking hole, and finally successively performing surface treatment, heat treatment and post-treatment for the forming of the round-link chain. In this process, the chain link joint is fixedly connected by means of a locking member, with a stable and reliable structure, overcoming the defect that the welded joint of the previous joint is prone to fracture. During the processing of the chain link, longitudinal upsetting is not required, ensuring the standard size and shape of the chain links incorporated into the same round-link chain. During the working process, the chain links are evenly stressed, reducing the wear rate and improving the transmission efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of round-link chains, and particularly to a manufacturing process of mining round-link chains. Technical Background

[0002] Round-link chains are widely used in mining machinery and equipment and are often used as traction components in important mining equipment such as coal plows, scraper conveyors, and transfer conveyors. Once a chain break occurs during their operation, it will lead to the shutdown of the entire working face and even cause safety accidents. Therefore, extremely high requirements are imposed on safety. At present, the manufacturing processes of mining round-link chains are mostly the same. Usually, high-strength alloy steel is cut to obtain bar materials, and a wire knitting machine is used to bend them into long-round-shaped chain links composed of two straight arms and two arc-shaped ends and incorporate them into the chain. Finally, the joints are welded to make the chains. The overall strength is relatively high. However, due to the large and uneven loads borne by mining round-link chains during operation and the extremely harsh working environment, chain breaks are still inevitable. Existing statistical data show that in the case of chain breaks in mining round-link chains, the vast majority of the fracture positions of the chain links are in the welding area. The reason is that although higher strength can be obtained by welding at the joint compared with other connection methods, due to factors such as the material differences between the welding material and the base material, the existence of welding defects, and the retention of residual stresses, surface shallow cracks are likely to initiate at the welding joint. These shallow cracks are often difficult to be detected in time during daily maintenance and become the biggest safety hazard during operation, which is the main inducement for the fracture of the welding joint. Especially when the motor is overloaded and jammed and the working load increases sharply, the welding joint with cracks is more likely to break compared with other parts of the chain link.

[0003] The existing chain links of mining round-link chains are usually bent from a single bar material and have a single-joint structure. The joints are welded by flash butt welding. During the flash butt welding process, the chain link will be longitudinally shortened as a whole under the upsetting force. Since the molten substances on the joint surfaces of the two joints are extruded, there is a certain material loss. The other straight arm without a joint will be correspondingly shortened by plastic deformation without material loss, which results in the unequal dimensions and shapes of the two straight arms of the chain link. At the same time, it is difficult to pre-control the balance of the plastic deformation generated by the straight arm without a joint during the upsetting process, and significant uneven deformations such as local bending and local thickening may even occur. In addition, during the upsetting process, the two arc-shaped ends are often compressed and will also generate certain deformations, and the deformation state is difficult to control. The above factors lead to the non-standard and non-uniform shapes of the chain links of the round-link chains produced by the existing process. During operation, the force distribution of the chain links is unbalanced, and the matching between the chain links and between the chain links and the chain teeth is poor, which easily causes adverse phenomena such as chain skipping, tooth hitting, and difficult tooth disengaging, exacerbating the wear rate of mining round-link chains. This is also one of the important reasons for the easy chain break and short service life of the existing round-link chains. Summary of the Invention

[0004] To overcome the above-mentioned deficiencies of the existing mine-used round-link chains, the present invention provides a brand-new manufacturing process for mine-used round-link chains. The mine-used round-link chains produced by this process have a stable structure, precise dimensions, and balanced stress, and can significantly improve the overall strength and service life of the mine-used round-link chains.

[0005] To achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] A manufacturing process for mine-used round-link chains, comprising the following steps:

[0007] a. Preparing a preformed rod and performing pretreatment

[0008] Cutting the alloy steel raw material to obtain a rod, straightening the rod to make it tend to a standard cylinder, cutting the two ends of the rod to form semi-cylindrical lapping parts respectively, opening locking grooves on the lapping parts and chamfering the two ports of the locking grooves, removing the residual material on the rod and ensuring that there are no burrs on the cutting parts of the lapping parts;

[0009] b. Preparing a locking pin

[0010] Making a locking pin with the same alloy steel as the rod material. The locking pin is columnar and its length is greater than the outer diameter of the rod, and its cross-section is in the shape of an 8.

[0011] c. Linking the chains

[0012] c1. Fixing the middle section of the rod, and performing a 180-degree bending treatment on the parts on both sides of the middle section in the planes where the flat side walls of the corresponding lapping parts are located, forcing the rod to plastically deform to form two integrally connected U-shaped parts, thereby prefabricating the rod into a non-closed special-shaped ring body; In the above-mentioned special-shaped ring body, the two U-shaped parts have the same dimensional parameters and the same relative position relationship with the corresponding lapping parts. Regarding the lapping parts as semi-cylinders, one lapping part and its locking groove are symmetric with the other lapping part and its locking groove in a plane, and the central axis of the middle section of the rod is located on the symmetric plane of the two lapping parts. There is a gap between the two lapping parts for the adjacent chain links to be buckled and connected;

[0013] c2. Taking a special-shaped ring body, buckling and connecting it with the chain link to be connected by means of the gap between the two lapping parts, clamping the arc ends of the two U-shaped parts respectively, and driving the two U-shaped parts to rotate relatively around the central axis of the middle section of the rod, so that the two lapping parts are assembled and butt-jointed to form a cylindrical structure. At this time, the two U-shaped parts are in the same plane to form a closed chain link with two straight arms and two arc ends. The locking grooves on the two lapping parts are butt-jointed and communicated to form a locking hole with a cross-section in the shape of an 8 and capable of accommodating the locking pin. The chamfers at the ports of the locking grooves are butt-jointed with each other to form a bevel at both ends of the locking hole;

[0014] c3. Insert the locking pin into the locking hole, and use a pressure device to extrude both ends of the locking pin, causing plastic deformation at both ends of the locking pin and accumulating in the grooves at both ends of the locking hole. Remove the parts of the locking pin that protrude beyond the outer wall of the overlapping part at both ends to ensure that the outer wall at the chain link joint is smooth and neat.

[0015] d. Surface treatment and heat treatment

[0016] As the chain is being woven, surface treatment is carried out on the newly woven chain links to remove impurities and burrs on the surface of the chain links, and heat treatment is carried out to improve the physical properties.

[0017] e. Post-treatment of the round-link chain after forming

[0018] Weave the round-link chain to the predetermined length in the above manner, carry out stretching and straightening on the formed round-link chain, and after inspection and pairing, it can be dipped in paint and stored in the warehouse.

[0019] The manufacturing process of the mining round-link chain disclosed by the present invention has the following technical effects compared with the prior art:

[0020] Since the joints of the chain links are fixedly connected by means of locking parts, the structure is stable and reliable. Compared with the previous welding method, welding defects, different expansion coefficients of welding materials and base materials, heat-affected zones and other significant adverse factors are eliminated. Cracks are not likely to occur at the joints, overcoming the main cause of easy fracture at the welding joints of the previous round-link chains, and solving the defect of easy fracture at the joints of the previous round-link chains. Based on the specific forming method of the chain links in this process, longitudinal upsetting is not required during the processing of the chain links. The two straight arms of the closed-formed chain links are relatively straight and tend to be the same in shape. The overall chain links hardly produce accidental deformation during the manufacturing process, ensuring that the size and shape of the chain links incorporated into the same round-link chain are standard and unified. The force distribution of the chain links during operation is more balanced, and at the same time, the high-speed wear caused by the mismatch of the size and shape of the ring chains is reduced. To sum up, the mining round-link chain produced by this manufacturing process is not likely to break, has a low wear rate, has more stable performance, and the safety and service life are significantly improved. At the same time, due to the standardization of the shape and size of the chain links, the transmission efficiency of the round-link chain is improved to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the initial structure of the bar stock.

[0022] Figure 2 It is a schematic diagram of the structure of the bar stock after the overlapping parts are made at both ends.

[0023] Figure 3 It is a schematic diagram of the relative positions of the overlapping parts at both ends of the bar stock.

[0024] Figure 4 It is a schematic diagram of the structure after the locking groove is opened on the overlapping part.

[0025] Figure 5 It is a schematic structural diagram of the end of the bar stock.

[0026] Figure 6 It is a schematic structural diagram of the locking pin.

[0027] Figure 7 It is a schematic diagram of the forming process of bending the bar stock into a special-shaped ring body.

[0028] Figure 8 It is a schematic structural diagram of the special-shaped ring body after forming.

[0029] Figure 9 It is a schematic diagram of the relative position state of the two overlapping parts in the special-shaped ring body.

[0030] Figure 10 It is a schematic diagram of the forming process of twisting the special-shaped ring body into a link.

[0031] Figure 11 It is a schematic structural diagram of the link after forming.

[0032] Figure 12 It is a schematic diagram of the cooperation of the two overlapping parts after the link is formed.

[0033] Figure 13 It is a schematic structural diagram after inserting the locking pin into the locking hole.

[0034] Figure 14 It is a schematic structural diagram after the three of the two overlapping parts and the locking pin are firmly connected.

[0035] Figure 15 It is a schematic structural diagram with multiple groups of locking pins and locking holes arranged on the two overlapping parts.

[0036] In the figure, 1 is the bar stock, 101 is the overlapping part, 102 is the locking groove, 103 is the middle section, 2 is the locking pin, 3 is the special-shaped ring body, 301 is the U-shaped part, 4 is the link, 401 is the arc end, 402 is the straight arm, 5 is the locking hole, and 501 is the bevel. Specific Embodiments

[0037] The following will describe in detail the manufacturing process of the mine-used round link chain disclosed in the present invention in conjunction with the embodiments.

[0038] 23MnNiMoCr54 alloy steel is a commonly used mine-used chain steel. The mine-used round link chain made of it has the characteristics of good wear resistance, high fatigue times, high strength, strong impact resistance, and large load-bearing capacity. In this application, the materials of the bar stock 1 and the locking pin 2 are both 23MnNiMoCr54 alloy steel.

[0039] a. Pre-fabricate the bar stock and perform pre-treatment on the bar stock

[0040] Such asFigure 1 As shown, according to the requirements of the model of the mining round link to be produced, select alloy steel round steel or wire rod of corresponding specifications, straighten it, cut it with a precision bar shear to obtain a bar 1 of a predetermined length, and straighten the bar 1 with a straightening machine to make the shape of the bar 1 tend to a standard cylinder. It can be inspected and screened by the test station method, and the bar 1 with unqualified straightness is straightened again; such as Figure 2 、 3 As shown, use a fixture to clamp and fix the straightened bar 1, and use a precision tool to perform cutting on both ends of the bar 1 respectively, so that semi-cylindrical lapping parts 101 are formed at both ends of the bar 1, and the included angle between the planes of the side walls of the two lapping parts 101 that are flat is ∠α; such as Figure 4 、 5 As shown, a locking groove 102 is opened on the lapping part 101 and the two ends of the locking groove 102 are chamfered. The cross-section of the locking groove 102 is C-shaped and the side opening is located on the flat side wall of the lapping part 101. At the same time, the extending direction of the locking groove 102 is parallel to the end plane of the lapping part 101 where it is located; after the above pretreatment, the remaining materials on the bar 1 are removed, and it is ensured that there are no burrs on the parts of the lapping part 101 that are cut and grooved;

[0041] b. Precast locking pin

[0042] As Figure 6 shown, make a locking pin 2 with alloy steel 23MnNi MoCr54 of the same material as the bar. The locking pin 2 is columnar and its length is greater than the outer diameter of the bar, and the cross-section is in the shape of an 8;

[0043] c. Chain making

[0044] c1. As Figures 7-9 shown, take a bar 1 that has been pretreated, use a fixture to fix the middle section 103 of the bar 1, and perform bending on the parts on both sides of the middle section 103 respectively in the plane where the flat side walls of the corresponding lapping parts 101 are located. The bending angle is 180 degrees, forcing the bar 1 to plastically deform to form two U-shaped parts 301. The two U-shaped parts 301 are connected by the middle section 103 of the bar 1 to form an integral structure. Thus, the bar 1 is prefabricated into a non-closed special-shaped ring 3. ∠α makes there be a gap between the two lapping parts 101, and this gap can be used for the special-shaped ring 3 to be buckled and connected with the adjacent link 4; in the special-shaped ring 3 obtained above, the dimensional parameters of the two U-shaped parts 301 are the same and the relative positional relationship with the corresponding lapping parts 101 is the same. If the lapping part 101 is regarded as an independent semi-cylinder, then one lapping part 101 and its locking groove 102 and the other lapping part 101 and its locking groove 102 are plane-symmetric with respect to the plane β, and the central axis of the middle section 103 of the bar is exactly located on the plane β;

[0045] c2. See Figure 10 , 11 , 12, 13, take a special-shaped ring body 3, and connect it with the chain link 4 to be connected by means of the gap between the two overlapping parts 101, that is, connect it into the already woven round link chain, use two rotatable clamps to clamp and fix the arc ends of the two U-shaped parts 301 respectively, drive the two U-shaped parts 301 to rotate relatively around the central axis of the middle section 103 of the bar material 1, so that the flat side wall of one overlapping part 101 gradually approaches the flat side wall of the other overlapping part 101, and finally the two overlapping parts 101 are connected. The planar side walls of the two overlapping parts 101 will overlap each other, that is, the two overlapping parts 101 are assembled and butted to form a cylindrical structure. At this time, the two U-shaped parts 301 are in the same plane to form a closed oblong chain link 4, which has two straight arms 402 and two arc-shaped ends 401. The locking grooves 102 on the two overlapping parts 101 are butted and connected to form a locking hole 5. The cross-section of the locking hole 5 is in an 8-shaped shape and can just allow the locking pin 2 to pass through it. The chamfers of the ends of the locking grooves 102 are butted against each other to form a bell-shaped groove 501 at both ends of the locking hole 5.

[0046] c3. See Figure 13 , 14 , insert the locking pin 2 into the locking hole 5, and use a pressure device to apply pressure from both ends of the locking pin 2 at the same time. The part of the locking pin 2 located in the locking hole 5 cannot be deformed due to space limitations, while the two ends located outside the locking hole 5 are plastically deformed and accumulated in the grooves 501 at both ends of the locking hole 5. At this point, the two overlapping parts 101 and the locking pin 2 are firmly connected; use a tool or a grinder to remove the parts of the outer wall of the overlapping part 101 at both ends of the locking pin 2 to ensure that the outer wall of the joint of the chain link 4 is smooth and neat;

[0047] d. Surface treatment and heat treatment

[0048] As the chain is being braided, the newly braided chain rings 4 are subjected to surface treatment and heat treatment in sequence. The surface treatment is used to remove impurities and burrs on the surface of the chain rings 4, and the heat treatment is used to improve the physical properties of the round link chain.

[0049] e. Post-processing of round link chain

[0050] After the round link chain is braided to the required length in the aforementioned manner, a fully automatic stretching and correction machine is used to stretch and correct the formed round link chain. The stretching load is 85% of the breaking load to optimize the performance of the round link chain. The surface quality, size, breakage and other items of the round link chain are then inspected, and the qualified round link chains are paired and finally can be dipped in paint and put into storage.

[0051] See also Figure 1 , 10, as shown in Fig. 11, in the manufacturing process of this mine-used round link chain, the link 4 is not directly bent into an oblong shape in the same plane from the bar stock 1. Instead, the bar stock 1 is first preformed into a special-shaped ring body 3 composed of two integrally connected U-shaped parts 301, and then the special-shaped ring body 3 is deformed into an oblong-shaped link 4 by twisting. Based on this technological feature, on the one hand, the two overlapping parts 101 can be more tightly butt-jointed. By processing in a high-precision manner in the prior art, the joint can tend to be seamless, thereby improving the stability of the joint. On the other hand, during the twisting process of the two U-shaped parts 301, the middle section 103 of the bar stock 1 will undergo plastic torsional deformation, whereby the physical properties of the middle section 103 of the bar stock 1 can be improved to a certain extent, which has a certain beneficial effect on the overall strength of the link 4.

[0052] See Figure 14 , as shown in the figure, in the mine-used round link chain produced by this process, since the joints of the link 4 are connected by locking parts, the structure is more stable and reliable. Compared with the previous welding method, it avoids the influence of significant adverse factors such as welding defects, different expansion coefficients between the welding material and the base material, and the heat-affected zone, making it not easy for cracks to initiate at the joints, eliminating the main cause of easy fracture at the welded joints of the previous link 4, and overcoming the defect of easy fracture at the joints of the previous round link chain.

[0053] See Figure 14 , as shown in the figure, the stress state during the working process of the mine-used round link chain is relatively complex, but generally mainly longitudinal tension, which acts concentratedly on the inner sides of the two arc ends and then is transmitted to the entire link 4. The joints formed by the two overlapping parts 101 of the link 4 and the straight arms 402 where the joints are located bear the maximum load in the longitudinal direction; in the mine-used round link chain produced by this process, the cross-section of the overlapping part 101 is semi-circular, so that the joints formed by the butt-joint of the overlapping parts 101 have a lower tensile strength compared with the previous welded joints. However, when dealing with the longitudinal load, the straight arm 402 where the joint is located will not be stressed alone, but share the load with the other straight arm 402. Based on the above stress characteristics of the link 4, the overlapping part 101 and the joints formed by its butt-joint have sufficient ability to cope with the maximum load they receive, rather than the weakest part prone to fracture in the link 4; at the same time, because the connection method in this process avoids many adverse factors existing in the welding process, the connection method is more stable and reliable, it is not easy to generate cracks at the joints, and in addition, the shape of the link 4 is standard, and the stress during the working process is relatively balanced, so it is less likely to fracture at the joints compared with the previous welding method; furthermore, during the manufacturing process, the middle section 103 of the bar stock 1 will be screwed and undergo plastic deformation, so that the mechanical properties of the corresponding straight arm 402 are improved to a certain extent, and it can share more load during the working process of the link 4 to reduce the risk of fracture of the overlapping part 101 and the joints formed by its butt-joint, and improve the overall tensile performance of the link 4.

[0054] SeeFigure 3 , 7 As shown, in the manufacturing process of this mine-used round-link chain, after cutting both ends of the bar stock 1 to form the lapping parts 101, the included angle between the planes where the side walls of the two lapping parts 101 are flat is ∠α. In this process, there are two requirements for the value of ∠α. On the one hand, after the bar stock 1 is bent into the special-shaped ring body 3, the gap size between the two lapping parts 101 is directly determined by ∠α. The value of ∠α should ensure that the above gap can allow the special-shaped ring to be buckled into the adjacent link 4 for subsequent chain-making operations. On the other hand, in the chain-making link, the torsion angle when the two U-shaped parts 301 are twisted to form the closed oval-shaped link 4 is directly determined by ∠α. The value of ∠α should ensure that the above torsion angle is within a reasonable range so that the middle section 103 of the bar stock 1 can obtain a significant improvement in physical properties through torsional deformation. Therefore, based on the above two requirements, an optimal numerical range of ∠α can be obtained through debugging, testing, and comparison.

[0055] See Figure 14 As shown, in the manufacturing process of this mine-used round-link chain, based on the specific forming method and joint connection method of the round-link chain, there is no flash butt welding link during the processing of the link 4, and thus there is no need for upsetting in the length direction. That is, during the processing after the link 4 is formed, it will not be deformed due to force in the length direction, making the two straight arms 402 of the link 4 relatively straight and the dimensions tend to be the same, and the shapes of the two arc ends 401 also tend to be the same. This ensures that the dimensions and shapes of all the links 4 incorporated into the same round-link chain are standard and unified. During the working process, the force distribution of each link 4 is more uniform and balanced. At the same time, it reduces the high-speed wear caused by the non-matching and non-standard dimensions and shapes between the links 4 and between the links 4 and the sprocket, making the performance of the round-link chain more stable, and significantly improving its safety and service life. At the same time, because the shapes and dimensions of the links 4 are standard and the same, the matching with the sprocket is good during the working process, which improves the transmission efficiency of the round-link chain to a certain extent.

[0056] See Figure 14 , 15As shown, in the manufacturing process of the above-mentioned mining round-link chain, the two overlapping parts 101 mainly rely on the cooperation between the locking pins 2 and the locking holes 5 to achieve the corresponding locking and fixing effect. In order to prevent the connection part of the two overlapping parts 101 from becoming a weak part affecting the overall strength of the chain link 4, multiple groups of locking pins 2 and locking holes 5 can be set according to the actual situation such as the size specifications and strength requirements of the round-link chain. Specifically, a plurality of locking grooves 102 distributed in parallel are provided on each overlapping part 101, and the number of locking grooves 102 on the two overlapping parts 101 is the same. When the side walls of the two overlapping parts 101 that are in a plane abut and overlap, the multiple locking grooves 102 on the two overlapping parts 101 are correspondingly butted and communicated to form multiple locking holes 5, and a locking pin 2 is installed on each locking hole 5. Thus, the multiple locking holes 5 and the locking pins 2 cooperate together to ensure that the connection part of the two overlapping parts 101 has sufficient strength.

[0057] See Figure 2 As shown, in the manufacturing process of the above-mentioned mining round-link chain, the overlapping part 101 is formed by cutting the end of the rod material 1. If the length of the overlapping part 101 is too long, more materials need to be cut, increasing the material cost and processing cost of the chain link 4. If the length of the overlapping part 101 is too short, a stable connection effect cannot be achieved. Through debugging, comparison and analysis of the above factors, the optimal length of the overlapping part 101 is 1.5 - 2 times the diameter of the rod material 1. At this size, the manufacturing material cost of the chain link 4 is relatively low, it is relatively easy to manufacture, and there is enough space on the overlapping part 101 to open one or more locking grooves 102 to meet the strength requirements of the chain link 4 for the connection part of the two overlapping parts 101.

[0058] See Figure 4 、 11 As shown, in the manufacturing process of the above-mentioned mining round-link chain, before bending the rod material 1 into the special-shaped ring body 3, the cutting surface generated during the manufacturing process of the overlapping part 101 and the end plane of the overlapping part 101 are polished using a grinding tool to improve the dimensional accuracy of the overlapping part 101, make the joint of the two overlapping parts 101 more tightly closed after the chain link 4 is formed, and ensure the connection stability at the joint of the chain link 4.

[0059] In the manufacturing process of the above-mentioned mining round-link chain, the rod material 1 is bent into the special-shaped ring body 3 by hot pressing. Before bending, the rod material 1 is heated using a heating device so that the temperature of the part to be bent is 800 - 850 °C. At this temperature, the part to be bent has good plasticity, which can reduce the processing difficulty and improve the processing accuracy, and at the same time can avoid the generation of cracks.

[0060] In the manufacturing process of the above-mentioned mine-used round link chain, before the two U-shaped parts 301 are twisted relative to each other, the bar stock 1 is heated by a heating device so that the temperature of the middle section 103 is 700 - 750 °C. The special-shaped ring body 3 will be deformed into a closed oval-shaped link 4 by hot forming; at this temperature, the middle section 103 of the bar stock 1 has good plasticity, which can reduce the processing difficulty and improve the closing accuracy at the joint, and at the same time, cracks in the middle section 103 of the bar stock 1 can be avoided.

[0061] In the manufacturing process of the above-mentioned mine-used round link chain, the locking pin 2 and the locking hole 5 adopt an interference fit, thereby ensuring the connection stability between the two.

[0062] Furthermore, in the manufacturing process of the mine-used round link chain disclosed above, the technological processes of bending the bar stock 1 into the special-shaped ring body 3, twisting the two U-shaped parts 301 relative to each other, and assembling the locking pin 2 by interference fit are carried out successively, and the corresponding temperature maintained by the bar stock 1 is decreasing. Considering this characteristic, in the process of chain making, the bar stock 1 is first heated as a whole to 800 - 850 °C, then the parts on both sides of the middle section 103 are bent, and the bar stock 1 is bent into the special-shaped ring body 3. Then, the special-shaped ring body 3 is cooled by air cooling. When the temperature of the middle section 103 is 700 - 750 °C, the two U-shaped parts 301 are twisted relative to each other to deform the special-shaped ring body 3 into the link 4. Finally, after further cooling the link 4 by air cooling, the locking pin 2 can be assembled into the locking hole 5 by interference fit. Thus, after the bar stock 1 is heated once, the above technological processes can be successively completed by using the waste heat of the workpiece, which can significantly improve the processing efficiency and reduce the process cost.

[0063] In the manufacturing process of the above-mentioned mine-used round link chain, in the heat treatment link, first, pre-heat treatment is carried out by normalizing process, the normalizing temperature is 820 - 880 °C, keep warm for 20 minutes, and air cooling; then quenching is carried out, the quenching temperature is 920 - 980 °C, and finally tempering is carried out, the tempering temperature is 400 - 450 °C, keep warm for 30 minutes and then rapidly cool; through comparative analysis, after the round link chain is heat treated with the above process parameters, the structure of the link chain is more uniform and refined, and the tensile strength and comprehensive mechanical properties have been improved to a certain extent.

Claims

1. A manufacturing process for mining round-link chains, characterized in that, it includes the following steps: a. Preparing the blank and pre-treating Cut the alloy steel raw material to obtain a blank, straighten the blank to make it tend to a standard cylinder, cut both ends of the blank to form semi-cylindrical lapping parts respectively, open a locking groove on the lapping parts and chamfer the two ends of the locking groove. The cross-section of the locking groove is C-shaped and the side opening is located on the flat side wall of the lapping part. The extending direction of the locking groove is parallel to the end plane of the lapping part where it is located; remove the residual material on the blank and ensure that there are no burrs at the cutting parts of the lapping parts; b. Preparing the locking pin Make the locking pin with the same alloy steel as the blank. The locking pin is columnar and its length is greater than the outer diameter of the blank, and its cross-section is in the shape of an 8; c. Linking the chains c1. Fix the middle section of the blank, and perform a 180-degree bending treatment on the parts on both sides of the middle section respectively in the plane where the flat side walls of the corresponding lapping parts are located, forcing the blank to plastically deform to form two integrally connected U-shaped parts, thereby prefabricating the blank into a non-closed special-shaped ring body; in the above-mentioned special-shaped ring body, the size parameters of the two U-shaped parts are the same and the relative position relationships with the corresponding lapping parts are the same. Regarding the lapping part as a semi-cylinder, one lapping part and its locking groove are symmetric with the other lapping part and its locking groove in a plane, and the central axis of the middle section of the blank is located on the symmetric plane of the two lapping parts. There is a gap between the two lapping parts for buckling and connecting with adjacent chain links; c2. Take a special-shaped ring body, buckle and connect it with the chain link to be connected by means of the gap between the two lapping parts, clamp the arc ends of the two U-shaped parts respectively, and drive the two U-shaped parts to rotate relatively around the central axis of the middle section of the blank, so that the two lapping parts are assembled and butted to form a cylindrical structure. At this time, the two U-shaped parts are in the same plane to form a closed chain link with two straight arms and two arc ends. The locking grooves on the two lapping parts are butted and connected to form a locking hole with a cross-section in the shape of an 8 and capable of accommodating the locking pin. The chamfers at the ports of the locking grooves are butted with each other to form bevels at both ends of the locking hole; c3. Insert the locking pin into the locking hole, and use a pressure device to extrude both ends of the locking pin, so that both ends of the locking pin are plastically deformed and accumulated in the bevels at both ends of the locking hole, and remove the parts of the locking pin protruding outside the outer side wall of the lapping part to ensure that the outer wall of the chain link joint is smooth and neat; d. Surface treatment and heat treatment As the chain linking progresses, perform surface treatment on the newly incorporated chain links to remove impurities and burrs on the surface of the chain links, and perform heat treatment to improve the physical properties; e. Post-treatment after the round-link chain is formed Link the round-link chain to the predetermined length in the above manner, perform stretching and correction on the formed round-link chain, and after inspection and pairing, it can be dipped in paint and stored in the warehouse.

2. The manufacturing process for mining round-link chains according to claim 1, characterized in that: The materials of the blank and the locking pin are both 23MnNiMoCr54 alloy steel.

3. The manufacturing process for mining round-link chains according to claim 1, characterized in that: A plurality of locking grooves distributed in parallel are provided on each overlapping portion. The number of locking grooves on the two overlapping portions is the same. When the side walls of the two overlapping portions that are in a plane abut and overlap, the plurality of locking grooves on the two overlapping portions are correspondingly butted and communicated to form a plurality of locking holes, and a locking pin is installed on each locking hole.

4. The manufacturing process of the mining round link chain according to claim 1, characterized in that: The length of the overlapping portion is 1.5-2 times the diameter of the bar stock.

5. The manufacturing process of the mining round link chain according to claim 1, characterized in that: Before bending the bar stock into a special-shaped ring body, the cutting surface generated during the manufacturing process of the overlapping portion and the end plane of the overlapping portion are polished by a grinding tool to improve the dimensional accuracy of the overlapping portion.

6. The manufacturing process of the mining round link chain according to claim 1, characterized in that: The bar stock is bent into a special-shaped ring body by hot press bending. Before pressing, the bar stock is heated by a heating device so that the temperature of the portion to be bent is 800-850 °C.

7. The manufacturing process of the mining round link chain according to claim 1, characterized in that: Before the two U-shaped portions are twisted relative to each other, the bar stock is heated by a heating device so that the temperature of the middle section is 700-750 °C, and the special-shaped ring body will be deformed into a closed oval-shaped link by hot forming.

8. The manufacturing process of the mining round link chain according to claim 1, characterized in that: The locking pin and the locking hole are in interference fit.

Images