CN101347850A - Assembling and welding method of ultra-thin thickness and large-diameter saw blade - Google Patents

Abstract

A method for assembling and welding ultra-thin thick and large-diameter saw blades, including process steps such as saw blade forming, preheating, welding, heat preservation and slow cooling, etc. It involves saw blade tailor welding methods and the selection of welding materials, saw blade tailor welding Design content of structure, preheating and slow cooling method and parameters, welding process and process. It is used for welding carbon tool steel, alloy tool steel and spring steel materials, and manufactures ultra-thin large-diameter saw blade products with a diameter between Φ2800mm~Φ5200mm and a thickness of 11mm~18mm. It has the following advantages: the equipment used is simple, the welding method is popular, and the operation process is easy to master; the design of the tailor welding structure and welding process of the saw blade is reasonable, and welding can be carried out without fixing the weld spot welding process, and the welding stress is evenly distributed. The overall saw blade is smooth without deformation, and the weld seam has no cracks; the reasonable selection of welding materials meets the performance requirements of the weld seam, and keeps the color of the weld seam the same as the base material.

Description

Assembling and welding method of ultra-thin thickness and large-diameter saw blade

technical field

The invention relates to a method for assembling and welding ultra-thin and large-diameter saw blades, which belongs to the saw blade production industry.

Background technique

Circular saw blades are mainly used for sawing steel, stone and wood, and large diameter saw blades are mainly used for sawing larger volumes of steel and stone. This kind of saw blade is relatively thin, the thickness is generally below 18mm, and the diameter is between Φ2800mm～Φ5200mm. The product requires high strength, rigidity and hardness, so tool steel (carbon tool steel, alloy tool steel, high-speed tool steel) is generally used. Steel) and spring steel and other materials, in order to improve the service life, it is usually necessary to weld the carbide head on the tooth.

The raw materials used for the saw blades are all made of commercially available plates. There is no such large-scale plates in the market at present, so the saw blades need to be assembled and welded. Due to the high strength, rigidity and hardness required for this kind of giant piece, after welding, it has to bear the assessment of forming cutting, heat treatment, precision calibration, machining and other processes, and the diameter of the saw blade is large and thin, which meets these requirements. It is very difficult. At present, the maximum diameter of the assembled and welded saw blades available in the market is 2.8M. The welding structure is shown in Figure 7. Although the welding seam is relatively small, due to the unreasonable welding structure, the length of the single welding seam is long, and the welding groove is X-shaped. Therefore, the cross-section of the weld seam is relatively large, and the deformation after welding is large, and it is not welded in a furnace, it is difficult to ensure sufficient overall preheating temperature of the saw blade, so it is easy to produce hardened structure in the heat-affected zone, and the result is very difficult during the welding process. Cracks are prone to occur. Even if the welded saw blade is free of defects, it often cracks in the heat-affected zone during subsequent processing, and the scrap rate is extremely high. These problems are not only the material and structural shape of the saw blade itself, which is the biggest difficulty in welding (as we all know), the main reason is that the welding structure, welding groove, preheating conditions, welding process design are unreasonable, and the welding materials used are also unreasonable. .

Contents of the invention

The purpose of the present invention is to provide a method of assembling and welding ultra-thin large-diameter saw blades capable of welding carbon tool steel, alloy tool steel and spring steel materials, with a diameter between Φ2800mm～Φ5200mm and a thickness of 11mm～18mm, so as to solve the current problem. There is a key problem that the welding is easy to crack in the technical existence.

The technical solution of the present invention is: a method for assembling and welding ultra-thin thick large-diameter saw blades, comprising the following process steps:

(1) Forming of the saw blade: a circular saw blade is composed of four equal fan-shaped pieces whose diameter is the symmetry line. There are sawtooth on the outer periphery of the circular saw blade and a mounting hole in the center; The splicing seams between the sector pieces are provided with double U-shaped welding grooves;

(2) Preheating: the circular saw blade formed by splicing four equal sector pieces is installed on the lower base in an electric heating furnace, and a welding fixture is installed on the sawtooth end. Use cutting corners whose shape matches the sawtooth; the preheating temperature is 330-400°C;

(3) Welding: After the above preheating temperature is reached, cover the four pieces of heat insulating material on the four pieces of saw blades to leak out the welding parts, and then start manual arc welding; the assembled saw blades are four symmetrical and ten The four welds are welded at the same time, and the welding speed is kept consistent. First, the bottom end of the U-shaped welding groove above is welded; then the middle weld is welded in a single-pass, intermittent manner ( For saw blades with a thickness > 11mm, the intermediate welds are welded in a multi-pass and intermittent manner); finally, the welding of the single-pass cover welds is performed; After preheating temperature, carry out welding on the other side, and the welding process on both sides is the same;

(4) Heat preservation and slow cooling: Press an upper pressure plate not lower than 200°C on the welded saw blade, heat it up to 400°C for 2 hours, then cool down naturally with the furnace to below 50°C and take out the saw blade.

The welding process of each weld seam described above all adopts single-pass, intermittent bottoming welding, and single-pass, intermittent intermediate weld seam welding (for saw blades with a thickness > 11mm, the intermediate weld seam is welded in a multi-pass, intermittent manner. ), the welding method of single pass and continuous capping seam requires that the capping seam be smooth and flat, the height of the welding meat shall not be greater than 3mm, and the lack of meat is not allowed.

The electric heating furnace is a resistance furnace, the furnace is cylindrical in diameter larger than the diameter of the saw blade, the bottom and the circumference are equipped with a resistance heat source, a furnace cover is provided on the top of the furnace, and a fan is provided on the furnace cover; A temperature control device is installed on the resistance heat source, and the lower base is installed at the bottom of the furnace, and the lower base is used as a platform for assembling and welding of saw blades.

The diameter of the furnace hearth is Φ5000mm～Φ7000mm (decided according to the diameter of the saw blade); the material of the lower base and the upper platen is cast iron, the diameter is Φ4500mm～Φ6500mm (determined according to the diameter of the saw blade), and the thickness is 300mm, there are heat transfer channels on the lower base and the upper platen, which is conducive to the direct rise of the heat of the resistance wire at the bottom and even heating of the saw blade.

The saw blade is made of carbon tool steel, alloy tool steel or spring steel, with a diameter between Φ2800mm-Φ5200mm and a thickness of 11mm-18mm.

The present invention has the following advantages: (1) The equipment used is simple, the welding method is popular, and the operation process is easy to master. Generally, saw blade enterprises have this condition, and the utility model has strong versatility. (2) The design of the tailor-welded structure and welding process of the saw blade is reasonable, and welding can be carried out without spot welding and fixing the welding seam. The welding stress is evenly distributed, and the overall saw blade after welding is flat and free of deformation. (3) The process parameters of preheating before welding and slow cooling after welding are designed reasonably, which can effectively eliminate welding stress, prevent the generation of hardened structure of welded joints, and avoid weld cracking. (4) The reasonable selection of welding materials meets the sufficient strength and other performance requirements of the weld. What is more remarkable is that the color of the weld remains the same as the base material.

Description of drawings

Fig. 1 is a top view structural schematic diagram of a tailor-welded saw blade of the present invention;

Fig. 2 is the cross-sectional structure schematic diagram of welding groove of the present invention;

Fig. 3 is the structure and heating mode schematic diagram of electric heating furnace of the present invention;

Fig. 4 is a schematic diagram of assembling, positioning and locking the tailor-welded saw blade fixture of the present invention;

Fig. 5 is a schematic diagram of the saw blade welding sequence of the present invention;

Fig. 6 is a sectional view along A-A of Fig. 5 (rotated 90 degrees).

Explanation of reference signs:

1. Saw blade, 2. Weld seam, 3. Sawtooth, 4. Sink, 5. Process hole, 6. Welding groove, 61. Bottom weld seam, 62. Middle weld seam, 63. Cover weld seam, 7 , fixture, 8, positioning solder joint, 9, center hole, 11, fan, 12, furnace cover, 13, upper platen, 14, heat transfer channel, 15, lower base, 16, heating wire, 17, heating wire support, 18. Insulation layer.

Detailed ways

Referring to Figures 1 to 6, the present invention will be further described by taking the assembly and welding of Φ3500mm large-diameter diamond matrix saw blade products as an example.

The saw blade 1 is made of 45Mn2V, normalized before welding, with a diameter of 3482 mm and a thickness of 13 ^{± 0.2} mm before welding. Use laser cutting equipment to cut the steel plate into four fan-shaped raw materials of the same size according to the design structure shown in Figure 1, and process the center hole 9, process hole 5, water tank 4, sawtooth 3, welding groove 6, and one side The form of the welding groove 6 is U-shaped, the width b of the mouth is 8mm, and the reserved gap a of the weld is 2mm, as shown in Figure 2. The design of the symmetrical weld seam of the cross stitching structure can effectively distribute the welding stress evenly. The design of double U-shaped welding groove 6 can realize small-section welds, which not only saves welding materials and shortens welding time, but also the less welding meat, the higher the performance of welded joints and the lower the probability of welding defects. Low, and welding deformation is also small. The 2mm wide welding gap a is easy to realize single-sided welding and back forming.

The splicing structure is designed to facilitate the assembly of saw blades. The jig 7 used for assembly is to use the four corners of the cutting saw teeth 3. It is beneficial to adjust the width of the reserved gap a of the weld seam, and welding can be carried out without spot fixing the weld seam, which can reduce the defects such as slag inclusion easily caused by the spot welding spot 8, as shown in Fig. 4 .

The welding method and selection of welding materials in this embodiment: according to the structural shape and technical requirements of the saw blade 1, the manual arc welding method is selected to assemble and weld the saw blade. This method can more effectively control the welding quality and welding quality than automatic welding. It is easy to realize welding construction, flexible and convenient to operate in the welding process, and the manufacturing cost is much lower, and the general saw blade production unit has the conditions to realize it.

According to the chemical composition, mechanical properties and use requirements of the saw blade material (the welding seam is required to be similar in color to the base metal), stainless steel or non-ferrous metals are not allowed to be used as welding materials, so it is limited to the selection of structural steel and alloy steel. Welding materials of the same type, the welding rod is a low-hydrogen type high-toughness electrode with a strength level between 800 and 850MPa, and the electrode selected in this embodiment is an 850MPa low-hydrogen type high-toughness electrode, and the electrode specification for the bottom weld 61 is Φ3.2mm , The welding rod specification used in the middle weld 62 and the cover weld 63 is Φ4.0mm. The performance of the weld seam after welding with this kind of electrode meets all the technical indicators required for the assembled welding saw blade, and what is more prominent is that the color of the weld seam maintains the same color as the base material.

The preheating and slow cooling mode and parameter formulation of this embodiment: use the self-made special electric furnace wire to heat the pit furnace to perform preheating and slow cooling of the saw blade before welding. The structure of the electric furnace is shown in Figure 3. The diameter of the furnace is Φ5000mm, the effective depth is 1500mm, and the maximum temperature is 600°C. The furnace temperature, heating speed and holding time can be manually set and automatically controlled. The bottom and the circumference are evenly covered with heating resistance wires 16, and the furnace cover 12 is provided with a fan 11. The design of this structure can ensure that the temperature in the furnace is evenly distributed.

The purpose of the lower base 15 is to assemble the tailor-welded saw blade 1 and serve as a welding workbench for the saw blade 1 . The purpose of the upper pressing plate 13 is to press on the saw blade 1 after welding, so as to avoid deformation of the saw blade 1 during heating and cooling. The lower base 15 and the upper platen 13 are made of cast iron, with a diameter of Φ4500mm and a thickness of 300mm. There are evenly distributed circular heat transfer channels 14. This design can not only ensure no deformation under cyclic heating and cooling conditions, but also heat transfer channels 14 have It is beneficial for the heat of the bottom resistance wire 16 to rise directly and evenly heat the saw blade.

Before welding, put the lower base 15 and the upper platen 13 into the furnace, cover the furnace cover 12 and heat it up at 250°C, so that the overall temperature of the lower base 15 and the upper platen 13 reaches 250°C evenly, then open the furnace cover 12, take out On the upper platen 13, the four pieces of saw blade 1 are centered and flatly placed on the lower base 15 to form a circular saw blade shape. At the same time, the saw blade 1 is positioned and locked with the clamp 7 as shown in FIG. Solder spot 8 welding). Then check that the saw blade must be placed flat and not dislocated, and the gap a reserved for the weld seam is 1.5-2.5mm. Then cover the furnace cover 12 and continue to heat up to 350° C. and keep warm for 2 hours, so that the saw blade 1 and the lower base 15 all evenly reach 350° C., and then the welding work can be carried out.

The welding process and process formulation of this embodiment: after the saw blade preheating temperature evenly reaches 350°C, open the furnace cover 12 for welding. Because the furnace temperature is very high, it is difficult for welding personnel to go in and operate. Cover the saw with four thick asbestos cloth On the top of the saw blade, but the welding part must be leaked, the asbestos cloth can not only play a role in heat insulation, but also play a role in heat preservation of the saw blade 1.

Assembled saw blade 1 is four symmetrical welds 2, which adopts the process of simultaneous welding of four welds 2, and implements the intermittent welding method, and requires the four welds to maintain a consistent welding speed as much as possible, which can effectively avoid welding Severe deformation problems. The welding joint is designed in the form of double U-shaped grooves 6. For the welding of ultra-thin thickness and large-diameter circular saw blades, if the conventional process of symmetrical welding on both sides of the front and back is adopted, repeated turning of the saw blade will increase multiple reversals and repetitions. Preheating and other processes. This welding process is to weld one side of the saw blade to shape, then flip the saw blade to weld the other side. The design of the welding process effectively solves the complicated procedures (such as repeatedly flipping the ultra-thin thickness and large-diameter circular steel saw blade, etc.), improves production efficiency, and the saw blade after welding does not produce deformation.

The welding process of this implementation is to carry out bottom welding (welding bottom welding seam 61, see Fig. 6) first, require single-sided welding to form on the back, must weld through, carry out the welding of middle welding seam 62 and cover welding seam 63 subsequently, Welding is carried out sequentially as shown in Figure 5. The meaning of each number represented on the graph in Figure 5 represents the sequence of intermittent welding, and the length of each number is the length of one welding rod. With this single-sided welding process, the saw blade after welding can still remain flat and not deformed. Turn the saw blade 1 that has been welded on one side 180° at once, cover the furnace cover 12 and continue to preheat to 350°C, and then weld according to the same sequence and process specifications as above, until all are welded. The welding seam is required to be free from defects such as air holes, slag inclusions, and undercuts. The welding seam on the cover surface is required to be smooth and flat, and the height of the welding meat should not exceed 3mm, but no lack of meat is allowed.

The saw blade 1 after welding needs to continue to keep warm and cool slowly in the furnace. The method of this implementation is to press the upper platen 13 not lower than 200°C on the saw blade 1, cover the furnace cover 12 and raise the temperature to 400°C and keep it warm for 2 hours. , and then take out the saw blade 1 after cooling down to below 50°C with the furnace for subsequent processing.

The present invention fills up a blank in the saw blade industry for manufacturing ultra-thin and large-diameter circular saw blades. The method is also applicable to the welding of similar products made of the above-mentioned materials, so it has high practical value and economic benefits, and also has certain advantages. social significance.

After welding and heat treatment in the present invention, the overall flatness is less than 5mm, the performance of the weld 2 is close to the performance index of the base metal, the welded joint must not have any defects that affect the performance of the product, and can withstand rough calibration, grinding, fine calibration and other processing processes . The saw blade 1 has a thickness of 9.5 ^{± 0.29} mm after processing and a flatness of less than 0.6 mm. The key to welding technology is to avoid hardened structure, minimize welding stress, reduce welding deformation, and prevent welding cracks.

Claims (5)

1. A method of assembling and welding an ultra-thin thickness and large-diameter saw blade, characterized in that: it comprises the following process steps: (1) Forming of the saw blade: a circular saw blade is composed of four equal fan-shaped pieces whose diameter is the symmetry line. There are sawtooth on the outer periphery of the circular saw blade and a mounting hole in the center; The splicing seams between the sector pieces are provided with double U-shaped welding grooves; (2) Preheating: the circular saw blade formed by splicing four equal sector pieces is installed on the lower base in an electric heating furnace, and a welding fixture is installed on the sawtooth end. It is made of cut corners whose shape matches the sawtooth; the preheating temperature is 330-400°C; (3) Welding: After reaching the above preheating temperature, cover the four pieces of heat insulating material on the four pieces of saw blades, leak out the welding parts, and then start manual arc welding; the assembled saw blades are four symmetrical in a cross shape The four welds are welded at the same time, the welding speed is kept consistent, and the welding sequence is: first, the bottom of the U-shaped welding groove above is welded; Seam welding, for saw blades with a thickness > 11mm, the middle weld is welded in a multi-channel, intermittent manner; finally, a single-channel, continuous cover weld is welded; after the above-mentioned welding on one side is completed, immediately turn over the saw blade and After reheating to the preheating temperature, perform welding on the other side, and the welding process on both sides is the same; (4) Heat preservation and slow cooling: Press an upper pressure plate not lower than 200°C on the welded saw blade, heat it up to 400°C for 2 hours, then cool down naturally with the furnace to below 50°C and take out the saw blade. 2. The method for assembling and welding ultra-thin thick and large-diameter saw blades according to claim 1, characterized in that: the welding process of each weld seam adopts single-pass and intermittent bottom welding; single-pass, Intermittent intermediate weld welding, for saw blades with a thickness greater than 11mm, the intermediate weld is welded in a multi-pass, intermittent manner; the single-pass, continuous cover weld welding method requires the cover weld to be smooth and flat, and the weld meat The height shall not be greater than 3mm, and no lack of meat is allowed. 3. The method for assembling and welding ultra-thin thick and large-diameter saw blades according to claim 1, characterized in that: the electric heating furnace is a resistance furnace, and the furnace chamber is cylindrical in diameter larger than the diameter of the saw blade. The bottom and the circumference are equipped with a resistance heat source, a furnace cover is provided on the top of the furnace, and a fan is provided on the furnace cover; a temperature control device is installed on the resistance heat source, and the bottom of the furnace is equipped with the The lower base is used as a platform for the assembly and welding of the saw blade. 4. The method for assembling and welding ultra-thin thick and large-diameter saw blades according to claim 1, characterized in that: the diameter of the furnace is Φ5000 mm to Φ7000 mm, which depends on the diameter of the saw blade; the lower base and The material of the upper platen is cast iron, the diameter is Φ4500mm～Φ6500mm, it depends on the diameter of the saw blade; the thickness is 300mm, there are heat transfer channels on the lower base and the upper platen, which is beneficial to the heat of the bottom resistance wire to rise directly and evenly heat the saw blade . 5. The method of assembling and welding ultra-thin thick and large-diameter saw blades according to claim 1, characterized in that: the saw blades are made of carbon tool steel, alloy tool steel or spring steel, and the diameter is between Φ2800mm～Φ5200mm Between, thickness 11mm ~ 18mm.

Images