阅读说明：本技术 圆锯片裂纹的焊接修复方法 (Welding repair method for circular saw blade cracks ) 是由 郭毅 安永亮 田永波 窦玉莲 安凤占 郭面焕 于 2020-12-17 设计创作，主要内容包括：本发明公开了一种圆锯片裂纹的焊接修复方法,具体来说是提供一种能在较低预热温度下焊接修复圆锯片裂纹缺陷的手工电弧焊工艺方法,该方法特别之处在于：焊接材料为能够实现窄向运条法焊接和宽向运条法焊接的扁平形电焊条；窄小坡口焊接；振动冲击消除焊缝应力；采用窄向运条法焊接打底焊缝和填充焊缝,采用宽向运条法焊接盖面焊缝；圆锯片预热温度100℃,焊接修复温度保持在80℃～100℃。本发明有效解决了焊接预热温度过高的难题,同时也使焊接操作和普通施焊一样简便可行,能实现对圆锯片上面裂纹行之有效的焊接修复,具有很高的实用价值和经济效益。(The invention discloses a welding repair method for circular saw blade cracks, and particularly provides a manual electric arc welding process method capable of welding and repairing the circular saw blade cracks at a lower preheating temperature, which is characterized in that: the welding material is a flat welding rod which can realize the welding of a narrow electrode conveying method and the welding of a wide electrode conveying method; welding a narrow groove; eliminating weld stress by vibration impact; welding backing weld seams and filling weld seams by adopting a narrow-direction strip conveying method, and welding cover weld seams by adopting a wide-direction strip conveying method; the preheating temperature of the circular saw blade is 100 ℃, and the welding repair temperature is kept at 80-100 ℃. The invention effectively solves the problem of overhigh welding preheating temperature, simultaneously ensures that the welding operation is simple, convenient and feasible as common welding, can realize effective welding repair of cracks on the circular saw blade, and has high practical value and economic benefit.)

1. A welding repair method for circular saw blade cracks is characterized in that: the welding material is a flat welding rod which can realize the welding of a narrow electrode conveying method and the welding of a wide electrode conveying method; welding a narrow groove; eliminating weld stress by vibration impact; welding backing weld seams and filling weld seams by adopting a narrow-direction strip conveying method, and welding cover weld seams by adopting a wide-direction strip conveying method; the preheating temperature of the circular saw blade is 100 ℃, and the welding repair temperature is kept at 80-100 ℃.

2. The method for repairing cracks of a circular saw blade by welding as claimed in claim 1, wherein the flat welding rod is a low-hydrogen type welding rod having a similar color and luster between a welding metal and a saw blade metal, and having high toughness and tensile strength higher than that of the saw blade by 10MPa to 50MPa, and the cross section of the welding core is 2mm x 4 mm.

3. The method for welding and repairing the cracks of the circular saw blade as claimed in claim 1, wherein the welding groove is formed by grinding along the direction of the through cracks on the circular saw blade by using an angle grinding wheel, when the thickness of the saw blade is less than or equal to 6mm, the groove is in a single-side U shape, the width of the groove is the same as the thickness of the saw blade, the thickness of the truncated edge is 1-1.5 mm, a forced forming pad is adhered, and the back surface is welded on the single side for forming; when the thickness of the saw blade is larger than 6mm, the groove is a double-sided symmetrical U-shaped groove, the width of the groove is 6mm, the front side and the back side are symmetrically welded and formed, the thickness of the truncated edge of the welding groove is 1.5-2 mm, and the rest height of the welding seam of the cover surface is smaller than 1.5 mm.

4. The method for repairing cracks of a circular saw blade by welding as claimed in claim 1, wherein the tip of the vibration rod used for eliminating the weld stress by vibration impact is a semicircular prolate rectangular vibration rod tip.

Technical Field

The invention relates to the technical field of welding, in particular to a welding repair method for cracks of a circular saw blade.

Background

At present, the circular saw blade is widely applied to cutting processing of steel, aluminum, stone, wood and the like. Generally, the thickness of the circular saw blade is between 2.0mm and 17mm, and the diameter is between 300mm and 5200 mm; the circular saw blade is made of carbon tool steel, alloy tool steel or spring steel. The circular saw blade is structurally characterized by large diameter and thin thickness, and the material of the circular saw blade is characterized by high strength, rigidity and hardness, high carbon content and alloy content, easy hardening and poor weldability.

Due to the factors of the structure and material characteristics of the circular saw blade, penetrating cracks are easily generated at certain parts of the circular saw blade in the heat treatment and leveling and shaping manufacturing processes, and the circular saw blade is scrapped due to the fact that the crack position of the cracks is uncertain, and the length and the shape of the cracks are irregular, as shown in figure 1. If the circular saw blade can be repaired by welding, the rejection rate can be effectively reduced.

As is known to all, carbon tool steel, alloy tool steel and spring steel have poor weldability, and a large and thin circular saw blade structure is easy to crack in the welding process, so that the biggest problem of welding repair of the circular saw blade is how to solve the problem of crack generation in the welding process. The carbon tool steel, the alloy tool steel and the spring steel have great difficulty when being melted and welded, because the materials have large hardening tissue tendency and large welding stress, so the cold crack sensitivity is great, and the forming condition of the welding cold crack is hardening tissue, restraint stress and diffused hydrogen, so the processes of preheating and slow cooling are usually adopted, and high-quality welding materials are selected to reduce the hardening tissue tendency and the welding stress, thereby avoiding the generation of cracks, but the successful experience of the preheating temperature of the workpiece before welding is required to be more than 400 ℃, but if the circular saw blade is welded under the high-temperature preheating condition of more than 400 ℃, a welder is difficult to approach the circular saw blade to carry out continuous construction operation, particularly the welding of the circular saw blade with large diameter, and unless a heat insulation construction rack is built, the great inconvenience and trouble are brought to the repairing of the circular saw blade, thereby the welding operation difficulty is increased, the repairing period is prolonged, and the repairing cost is improved, the method is also one of the main reasons for repairing the crack defects of the circular saw blade by no one at present, so that the key for solving the problem is how to reduce the preheating temperature on the premise of ensuring that the defects such as cracks are not generated in the welding process, but an effective method for solving the problem does not exist so far, and the method for repairing the cracks of the circular saw blade by welding at a lower preheating temperature still falls into the blank.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for welding and repairing the cracks of the circular saw blade, which can be used for welding and repairing at a lower preheating temperature and can avoid the cracks from being generated by welding, and has high practical value and economic benefit.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a welding repair method for circular saw blade cracks is characterized in that: the welding material is a flat welding rod which can realize the welding of a narrow electrode conveying method and the welding of a wide electrode conveying method; welding a narrow groove; eliminating weld stress by vibration impact; welding backing weld seams and filling weld seams by adopting a narrow-direction strip conveying method, and welding cover weld seams by adopting a wide-direction strip conveying method; the preheating temperature of the circular saw blade is 100 ℃, and the welding repair temperature is kept at 80-100 ℃.

The core of the technical scheme of the invention is to reduce welding heat input and eliminate welding restraint stress, so as to achieve the effects of reducing hardened tissues and reducing welding restraint stress and reduce crack sensitivity. The flat welding electrode is selected as a welding material, a narrow groove welding mode and a vibration impact method are adopted to eliminate weld stress, and under the condition of preheating temperature of 100 ℃, the welding repair of the crack defect of the circular saw blade cannot generate cracks and the defect influencing the quality of the circular saw blade, so that the technical requirement of the welding repair of the crack defect of the circular saw blade is met. Based on this, compared with the prior art, the invention has the following beneficial effects:

(1) the method for manually arc welding by adopting the welding rod has the advantages of flexible and convenient operation, is more suitable for the welding of the actual conditions of uncertainty of the cracking position of the circular saw blade, the length of cracks and irregular shape, and has the obvious effects of strong operability and low repair welding cost.

(2) The flat welding electrode has absolute advantages for welding the narrow-gap groove, and the welding of the narrow and small groove is easier to realize than the welding of a round stick electrode, so that the welding crack sensitivity and the welding defect are more favorably reduced, meanwhile, the welding efficiency is obviously improved, the welding repair period is shortened, the using amount of welding materials is saved, and the electric energy consumption cost is reduced.

(3) The combined welding process for eliminating the weld stress by adopting the narrow and small groove welding mode and the vibration impact can obviously reduce the sensitivity of welding crack cracking, thereby effectively solving the problem of overhigh preheating temperature, realizing the welding repair of the crack defect of the circular saw blade under the condition of 100 ℃ preheating temperature without generating cracks and influencing the quality of the circular saw blade, realizing the technical requirement of the welding repair of the crack defect of the circular saw blade, and simultaneously ensuring that the welding operation is as simple, convenient and feasible as common welding.

(4) The welding repair method for the saw blade cracks achieves the aim of welding repair of the scrapped saw blade, has high practical value, economic benefit and certain social significance, fills a method for welding the easily-cracked steel at a lower preheating temperature, adopts a combined welding process of welding with flat welding rods, eliminating welding seams by adopting a narrow and small groove welding mode and vibration impact, is simple and convenient to weld at the lower preheating temperature of 100 ℃, and embodies the novelty, the innovativeness and the practicability of the patent.

Preferably, the further technical scheme of the invention is as follows:

the flat welding rod is a low-hydrogen type welding rod with similar color and luster of weld metal and saw blade metal, high toughness and tensile strength which is 10 MPa-50 MPa higher than the saw blade metal, and the cross section of the welding core is 2mm multiplied by 4 mm.

The welding groove is formed by polishing the upper surface of the circular saw blade along the direction of the through cracks by using an angle grinding wheel, when the thickness of the saw blade is less than or equal to 6mm, the groove is in a single-side U shape, the width of the groove is the same as the thickness of the saw blade, the thickness of the truncated edge is 1-1.5 mm, a forced forming pad is adhered, and the back surface of the circular saw blade is formed by single-side welding; when the thickness of the saw blade is larger than 6mm, the groove is a double-sided symmetrical U-shaped groove, the width of the groove is 6mm, the front side and the back side are symmetrically welded and formed, the thickness of the truncated edge of the welding groove is 1.5-2 mm, and the rest height of the welding seam of the cover surface is smaller than 1.5 mm.

The vibration shock is adopted to eliminate the weld stress, and the end of the vibrating rod is a semicircular prolate rectangular vibrating rod end.

Drawings

FIG. 1 is a schematic view of a circular saw blade and crack progression;

FIG. 2 is a schematic view of a single U-shaped welding groove;

FIG. 3 is a schematic view of a double U-shaped welding groove;

FIG. 4 is a schematic view of a vibration impact welding apparatus;

FIG. 5 is a schematic view of a vibrating rod;

FIG. 6 is a schematic view of a flat electrode;

FIG. 7 is a schematic view of a narrow-direction electrode transportation mode of a flat welding electrode;

FIG. 8 is a schematic view of a wide-direction electrode transportation mode of the flat welding electrode;

FIG. 9 is a schematic top view of a circular saw blade crack weld repair in accordance with an embodiment of the present invention;

FIG. 10 is a schematic front view of a circular saw blade crack weld repair in accordance with an embodiment of the present invention;

FIG. 11 is a schematic view illustrating repair of a single U-shaped welding groove during welding according to an embodiment of the present invention;

FIG. 12 is a schematic top view of a circular saw blade crack weld repair in accordance with another embodiment of the present invention;

fig. 13 is a schematic view illustrating repair of welding of a double U-shaped welding groove in another embodiment of the present invention.

In the figure: the welding device comprises a circular saw blade 1, a crack 2, a crack stop hole 3, a welding groove 4, a hoop 5, an electric heating mould 6, a heat preservation quilt 7, a heat preservation cover 8, a forced forming pad 9, a flat welding rod 10, a backing welding seam 11, a filling welding seam 12, a cover welding seam 13, an electromagnetic suction base 14, an up-down vibrating device 15, a vibrating rod 16, a main shaft 17, a lifting positioning ring 18, a rotating sleeve 19, a rotating joint 20, a telescopic arm 21, a vibrating switch 22 and a magnetic switch 23.

Detailed Description

In order to make the technical solution of the present invention better understood by those skilled in the art, the following detailed description of the present invention will be made with reference to the accompanying drawings.

The following embodiments of the invention have to meet the following technical requirements:

(1) the welding strength cannot be lower than that of the base material of the circular saw blade;

(2) the welding can not be cracked and any defect influencing the quality is generated;

(3) the repaired welding seam metal has the color similar to that of a circular saw blade matrix.

The welding method of the following embodiment is a manual arc welding method, and the reason for selecting manual welding is that the method has the advantages of flexible and convenient operation compared with automatic welding, and is more suitable for the actual conditions of uncertainty of the cracking position of the circular saw blade, length of cracks and irregular shape.

The reason why the flat welding rod is selected for the circular saw blade welding repair in the following examples is that it is more suitable to perform welding in a narrow gap groove than a round stick welding rod, and the welding groove is designed to be smaller.

The following embodiment adopts a narrow groove welding mode and a method for eliminating weld stress by vibration impact, and is a combined welding process. The welding method of the narrow groove and the small groove is characterized in that the welding groove is shown in the figures 2 and 3, the welding groove is formed by grinding along the trend of the penetrating cracks on the circular saw blade by using an angle grinding wheel, and the method is characterized in that: when the thickness of the saw blade is less than or equal to 6mm, the saw blade is polished into a single-sided U-shaped groove, the width of the groove is the same as the thickness of the saw blade, the thickness of the truncated edge is 1-1.5 mm, and the back of the saw blade is formed by single-sided welding (the back is provided with a forced forming pad); when the thickness of the saw blade is larger than 6mm, the saw blade is polished into a double-sided symmetrical U-shaped groove, the width of the groove is 6mm, the thickness of a truncated edge is 1-2 mm, the front side and the back side are symmetrically welded, and the surplus height of a cover surface welding line is smaller than 1.5 mm. The welding of the narrow groove is an effective way for reducing the section of the welding seam, and the filling amount of the welding seam is obviously reduced, so that the welding heat input is reduced, the quenching tissue tendency and the restraint stress of the welding seam are reduced, the sensitivity of welding crack cracking can be effectively reduced, and as a result, the temperature of a circular saw blade is kept within the range of 80-100 ℃ under the condition that the preheating temperature is 100 ℃, the crack can not be generated in normal welding, the problem of overhigh preheating temperature is well solved, and meanwhile, the welding operation is as simple, convenient and feasible as common welding.

The method for eliminating the stress of the welding seam by vibration impact is shown in figures 4 and 5, a vibration impact welding seam device is used, the vibration impact principle is similar to that of an impact electric drill, the mode of impacting the welding seam is similar to that of a manual hammering stress elimination method, the difference is that the end part of a hammer head which is hammered by hand is usually a round head, the end of a vibrating rod is a semicircular prolate rectangle, the effect is more stable, moderate and powerful than the impact force of the manual hammering method on the welding seam, the impact area of the welding seam is larger and uniform, the contraction stress (tensile stress) of the welding seam is counteracted by extending the welding seam to two sides (compressive stress) through the up-and-down vibration striking method, the sensitivity of the welding seam can be obviously reduced, and the possibility of generating the cold crack of the welding joint with low restraint stress is low according to the cold crack generation condition judgment.

The welding material of the following embodiment is flat welding rod, the structure of the flat welding rod is shown in figure 6, the flat welding rod can realize two welding modes of narrow-direction rod conveying method and wide-direction rod conveying method because the cross section of the welding rod is flat, the rod conveying mode of the flat welding rod is shown in figures 7 and 8, the narrow-direction rod conveying method means that the narrow surface of the welding rod is welded along the groove direction of the welding seam (the welding seam is narrow) and is suitable for narrow gap welding and backing welding, the wide-direction rod conveying method means that the wide surface of the welding rod is welded along the groove direction of the welding seam (the welding seam is wide) and is suitable for cover surface welding and wide welding, therefore, the flat welding rod is easier to realize welding in the narrow gap groove than the round rod-shaped welding rod with the same specification (the cross section area of the welding rod is the same), therefore, the flat welding material realizes the technological scheme of the circular saw blade crack and narrow groove welding, and, the method is characterized in that a low-hydrogen type flat welding rod with the weld metal and the saw blade metal having similar color and luster, high toughness and tensile strength higher than the saw blade strength by 10-50 MPa is selected, and a flat welding rod (equivalent to a round rod-shaped welding rod with phi 3.2 mm) with the specification of welding core section thickness of 2mm multiplied by width of 4mm is selected in consideration of the width and welding efficiency of a welding groove, the flat welding rod with the specification can be well welded in the welding groove with the width of 6mm, and the round rod-shaped welding rod with the same specification of phi 3.2mm needs to be welded with the width of at least more than 10 mm.

Example 1:

referring to fig. 2 to 11, in the present embodiment, the circular saw blade 1 has a thickness of 6mm, a diameter of Φ 2200mm, and is made of carbon tool steel, and the cracks 2 are formed during the leveling and shaping process of the circular saw blade, and the directions of the cracks are irregular.

The welding repair method for the circular saw blade cracks is carried out according to the following steps:

the welding method comprises the following steps: a direct current welding machine is selected and the manual electric arc welding with reversed polarity is adopted.

Welding materials: the low-hydrogen high-toughness flat welding rod 10 with the weld metal and the saw blade metal having similar colors is selected, the tensile strength of the deposited metal of the flat welding rod is 830MPa, the specification of the welding rod is 2mm multiplied by 4mm, the welding rod has good welding process performance and crack resistance, the drying temperature of the welding rod before welding is 300 ℃, the temperature is kept for one hour, and then the welding rod is placed into a heat-preserving container to be taken along with welding.

(1) Derusting and deoiling: the steel wire brush is adopted to clean the periphery of the crack 2 on the circular saw blade 1 within 100mm, and dirt which influences the welding quality such as oil rust and the like cannot exist.

(2) Drilling a crack stop hole: and (3) drilling the crack-stopping hole 3 at the end of the crack 2 by adopting a drill bit, wherein the crack-stopping hole 3 can effectively prevent the end of the crack 2 from extending and expanding, and the drill bit with the diameter of 6mm is selected to drill the crack-stopping hole 3 at the end of the crack 2.

In the embodiment, one end of the crack 2 starts from the edge of the central circle of the circular saw blade 1, the other end of the crack stops at the base body of the circular saw blade 1, and the crack stop hole 3 is positioned at the end of the crack 2 on the base body of the circular saw blade 1.

(3) And (3) grinding a groove: and (3) grinding and welding the groove 4 along the crack trend by adopting an angle grinder, wherein the groove 4 is of a single-side U shape, the width of the groove 4 can ensure that the flat welding rod can be normally welded in the groove, the designed width of the groove 4 is 6mm, and the thickness of the truncated edge is 1 mm-1.5 mm.

(4) Preheating the circular saw blade: firstly, sticking a forced forming pad 9 on the back of a crack 2 on a circular saw blade 1, wherein the purpose of the forced forming pad 9 is to more easily realize single-side welding back forming, then putting the circular saw blade 1 stuck with the forced forming pad 9 on an electric heating mould 6, wherein the electric heating mould 6 is also a welding mould, covering the circular saw blade 1 with a heat preservation cover 7, then covering the circular saw blade 1 with the heat preservation cover 8 to start preheating, wherein the preheating temperature is 100 ℃, the heat preservation cover 7 is kept for 2 hours, an opening is left at the crack part, and a wide seam can be opened to facilitate welding construction.

(5) The welding process comprises the following steps: and (3) removing the heat-insulating cover 8, uncovering a seam from the heat-insulating quilt 7 on the repaired part of the crack 2, continuously covering the heat-insulating quilt 7 on other parts, keeping the electric heating mould 6 in a continuously heating state, then welding in the groove 4, and vibrating and impacting the welded seam to eliminate welding stress.

Firstly, point-fixing welding: the gap at the root of the welding groove 4 is firmly subjected to sectional spot welding by adopting a flat welding electrode 10 narrow-direction electrode conveying mode, the length of a spot welding seam is 8-10 mm, and the two ends of the welding seam are firmly subjected to spot welding.

Backing welding: and backing welding is carried out on the welding groove by adopting a narrow electrode conveying mode of the flat welding electrode 10, and a backing welding seam 11 is welded by adopting a single-side welding back forming and intermittent welding mode.

Filling and welding: filling welding is carried out on the welding groove in a narrow electrode conveying mode of the flat welding electrode 10, the filling welding line 12 is used for fully welding the welding line once in an intermittent welding mode, the welding line of two ends is fully welded at first, then the middle part is welded, and vibration impact is carried out on the filling welding line after welding is finished so as to eliminate welding stress.

Welding the cover surface: the welding groove is subjected to cover welding by adopting a wide electrode conveying mode of the flat welding electrode 10, the cover welding line 13 is welded by adopting a continuous welding mode, the surplus height of the cover welding line is less than 1.5mm, the defects of undercut and pits are not allowed to exist, and the cover welding line is subjected to vibration impact after welding is finished so as to eliminate welding stress.

Eliminating weld stress by vibration impact: as shown in fig. 4 and 5, the vibration impact welding seam device includes an electromagnetic suction base 14, an up-down vibration device 15 and a vibration rod 16, a main shaft 17 is vertically disposed on the electromagnetic suction base 14, a lifting positioning ring 18 and a rotary sleeve 19 are mounted on the main shaft 17, the up-down vibration device 15 is connected with the rotary sleeve 19 through a rotary joint 20 and a telescopic arm 21, so that the up-down vibration device 15 can swing left and right and can stretch in length, the vibration rod 16 is disposed on the up-down vibration device 15, and in addition, the vibration impact welding seam device is further provided with a vibration switch 22 and a magnetic switch 23. Specifically, the operation method of the vibration impact welding seam device comprises the following steps: firstly, a vibration impact welding seam device is placed beside a welding seam on a circular saw blade 1, a magnetic switch 23 is pressed down to be electrified, an electromagnetic suction base 14 is enabled to tightly suck the upper surface of the circular saw blade 1, an up-and-down vibration device 15 is moved by hands to enable a vibration rod 16 to be aligned above the welding seam, the up-and-down position of the vibration rod 16 is determined by adjusting a lifting positioning ring 18, the up-and-down vibration device 15 is held by a hand and the vibration switch 22 is pressed to be electrified, the vibration rod 16 starts to vibrate and strike the welding seam, the vibration switch 22 is released to be powered off and stop striking, the striking welding seam track is completed by manually moving the up-and-down vibration device 15, and the left-and-right swinging length and stretching of the up-and-down vibration. By the vertical vibration striking method, the welding meat extends towards two sides (compressive stress) to offset the shrinkage stress (tensile stress) of the welding seam, the welding crack sensitivity can be obviously reduced, and the probability of generating cold cracks of the welding joint with low restraint stress is very low according to judgment of cold crack generation conditions.

(6) Circular saw blade heat preservation slow cooling: and covering the welded circular saw blade 1 with a heat preservation cover 8 for heating and heat preservation, stopping heating after the temperature is heated to 100 ℃, and then cooling to room temperature along with the furnace.

(7) Polishing the welding line: and polishing, repairing and flattening the weld joints on the front side and the back side.

(8) Quality inspection: and (4) carrying out flaw detection on the repaired welding seam by using ultrasonic waves, and judging that the repaired welding seam is qualified if any defect is not found.

In the welding process, the surface temperature of the circular saw blade 1 is always kept within the range of 80-100 ℃ through the measurement of a surface thermometer, the welding seam has no cracking phenomenon, after the circular saw blade 1 subjected to welding repair is subjected to secondary integral leveling and grinding processing, no welding defect is found through ultrasonic inspection, and the circular saw blade is judged to be a qualified product through final inspection of the product.

Example 2:

referring to fig. 2 to 13, in the present embodiment, the circular saw blade 1 has a thickness of 10mm and a diameter of Φ 3600mm and is made of alloy tool steel, and the crack 2 is formed by cracking during the quenching process of the circular saw blade, and the crack is irregular.

The welding repair method for the circular saw blade cracks is carried out according to the following steps:

the welding method comprises the following steps: a direct current welding machine is selected and the manual electric arc welding with reversed polarity is adopted.

Welding materials: the low-hydrogen high-toughness flat welding rod 10 with the weld metal and the saw blade metal having similar colors is selected, the tensile strength of the deposited metal of the flat welding rod is 850MPa, the specification of the welding rod is 2mm multiplied by 4mm, the welding rod has good welding process performance and crack resistance, the drying temperature of the welding rod before welding is 300 ℃, the temperature is kept for one hour, and then the welding rod is placed into a heat-preserving container to be taken along with welding.

(1) Derusting and deoiling: the steel wire brush is adopted to clean the periphery of the crack 2 of the circular saw blade 1 within 100mm, and dirt which influences the welding quality such as oil rust and the like cannot exist.

(2) Drilling a crack stop hole: and a drill bit with the diameter of 6mm is adopted to drill the crack-stopping hole 3 at the end of the crack 2, and the crack-stopping hole 3 can effectively prevent the end of the crack 2 from extending and expanding.

In the embodiment, one end of the crack 2 starts from the base body of the circular saw blade 1, the other end extends to the end part of the saw teeth, and the crack stop hole 3 is positioned at the end of the crack 2 on the base body of the circular saw blade 1.

(3) And (3) grinding a groove: and (3) polishing and welding the groove 4 along the crack trend by adopting an angle grinder, wherein the groove 4 is in a double-sided symmetrical U shape, the width of the groove 4 is 6mm, and the thickness of the truncated edge is 1.5-2 mm.

It should be noted that in this embodiment, the cracks 2 extend to the saw-tooth end, and in order to prevent the cracks 2 from being dislocated, opened or contracted during the welding process, after the groove 4 of the circular saw blade 1 is ground, the clamp 5 is installed at the saw-tooth end with the cracks 2, and is firmly spot-welded with the circular saw blade 1.

(4) Preheating the circular saw blade: the circular saw blade 1 is placed on an electric heating mould 6, the electric heating mould 6 is also a welding mould, a heat preservation quilt 7 is used for covering the circular saw blade 1, then a heat preservation cover 8 is covered to start preheating, the preheating temperature is 100 ℃, the heat preservation is carried out for 2.5 hours, an opening is left in the crack 2 part of the heat preservation quilt 7, and a wide seam can be uncovered, so that the welding construction is facilitated.

(5) The welding process comprises the following steps: and (3) removing the heat-insulating cover 8, uncovering a seam from the heat-insulating quilt 7 on the crack repairing part, continuously covering the heat-insulating quilt 7 on other parts, keeping the electric heating mould 6 in a continuously heating state, welding in the groove 4, and vibrating and impacting the welded seam to eliminate welding stress.

Firstly, point-fixing welding: the gap at the root of the welding groove 4 is firmly subjected to sectional spot welding by adopting a narrow electrode conveying mode of the flat welding electrode 10, the length of a spot welding seam is 10-15 mm, and the two ends of the welding seam are firmly subjected to spot welding.

Backing welding: and backing welding is carried out on the welding groove by adopting a narrow electrode conveying mode of the flat welding electrode 10, and a backing welding seam 11 is welded by adopting a single-side welding back forming and intermittent welding mode.

Filling and welding: filling welding is carried out on the welding groove in a narrow electrode conveying mode of the flat welding electrode 10, the filling welding line 12 is used for fully welding the welding line once in an intermittent welding mode, the welding line of two ends is fully welded at first, then the middle part is welded, and vibration impact is carried out on the filling welding line after welding is finished so as to eliminate welding stress.

Welding the cover surface: the welding groove is subjected to cover welding by adopting a wide electrode conveying mode of the flat welding electrode 10, the cover welding line 13 is welded by adopting a continuous welding mode, the surplus height of the cover welding line is less than 1.5mm, the defects of undercut and pits are not allowed to exist, and the cover welding line is subjected to vibration impact after welding is finished so as to eliminate welding stress.

Welding the back of the turnover circular saw blade: and after one side is welded, the other side is welded by hoisting and overturning the circular saw blade 1, the welding beading, welding slag and incomplete penetration defects of the backing weld on the back side are removed by using a grinding wheel, then filling welding is carried out according to the step 3), and cover welding is carried out according to the step 4).

The vibration impact welding device and the operation method thereof adopted after welding in the embodiment are the same as those in embodiment 1, and are not described again here.

(6) Circular saw blade heat preservation slow cooling: and covering the welded circular saw blade 1 with a heat preservation cover 8 for heating and heat preservation, stopping heating after the temperature is heated to 100 ℃, and then cooling to room temperature along with the furnace.

(7) Polishing the welding line: the clamp 5 on the circular saw blade 1 is removed, and then the weld joints on the front side and the back side are polished, repaired and leveled.

(8) Quality inspection: and (4) carrying out flaw detection on the repaired welding seam by using ultrasonic waves, and judging that the repaired welding seam is qualified if any defect is not found.

In the welding process, the surface temperature of the circular saw blade 1 is always kept within the range of 80-100 ℃ through the measurement of a surface thermometer, the welding seam has no cracking phenomenon, the circular saw blade after welding repair is subjected to secondary integral leveling and grinding processing, no welding defect is found through ultrasonic inspection, and the circular saw blade is judged to be a qualified product through final inspection of the product.

Example 3:

in this embodiment, the circular saw blade has a thickness of 8mm, a diameter of 3000mm, a material of spring steel, a groove opening width of 6mm, a blunt edge thickness of 1.5mm, a tensile strength of 800MPa, and a welding rod specification of 2mm × 4mm, and is welded and repaired according to the method of embodiment 2, and the circular saw blade is determined to be qualified through a weld inspection.

In conclusion, the welding repair of the circular saw blade cracks is well applied in production by adopting the process method, and practice proves that the qualified rate of the welding repair is 100% as long as the process method is strictly operated and constructed, but sometimes, a welder has the defect of welding undercut due to improper operation, and if the welder finds that the welding repair can be carried out immediately, the error can be made up, and the repair quality cannot be influenced.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.