Hot insert tooth fixing drill bit body and heat treatment method thereof

Abstract

The invention discloses a hot-embedded tooth-fixing drill bit body and a heat treatment method thereof, and belongs to the technical field of heat treatment of rock drilling tools. Comprising the following steps that a bar is sawed into a blank with the required length according to needs, and annealing is conducted at the temperature of 750-770 DEG C; the drill bit body subjected to finish machining is placed in a molten salt bath furnace in a suspended mode, the temperature is increased to 890-910 DEG C, and constant-temperature heat preservation is conducted for 15-35 min; the drill bit body is put into a constant-temperature quenching device with the oil temperature ranging from 40 DEG C to 60 DEG C to be subjected to oil quenching, the drill bit body shakes back and forth in oil for 110 s to 130 s, too high oil temperature and non-uniform oil temperature are avoided, then the drill bit body stands for 290 s to 310 s, and the drill bit body is taken out and suspended for air cooling; the drill bit body is put into a box-type furnace to be heated to 850-870 DEG C, and the drill bit body is discharged out of the furnace to be air-cooled; and the drill bit body treated in the third step is quenched and tempered. According to the method, the heat treatment hardness is uniform, the treated drill bit body is good in abrasion resistance and high in tooth fixing strength, the fixed teeth are not prone to cracking or falling, the effect that all indexes of the drill bit body reach the drill bit body hardness and the stable structure is achieved, the actual problem is solved, and the product quality is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen storage alloy powder, in particular to a hot-set fixed-tooth drill bit body and a heat treatment method thereof. Background Art

[0002] The heat treatment process of steel includes annealing, normalizing, quenching, tempering and surface heat treatment. Tempering includes quenching and tempering and aging. Tempering of steel: The quenched steel is reheated to a certain temperature according to the desired mechanical properties, and carbon precipitates in the form of finely distributed cementite. As the tempering temperature increases, the carbide particles increase, the yield point and tensile strength decrease, the hardness and brittleness are reduced, and the elongation and shrinkage increase. Its purpose is to eliminate the internal stress caused by quenching in order to obtain the expected mechanical properties.

[0003] The domestic rock drilling tool industry uses cold setting, hot setting, welding and other tooth fixing methods to produce column tooth alloy drill bits. When the hot setting tooth fixing method is used, the drill body needs to be heat treated, the hole is drilled, and then heated to a certain temperature. The operator uses tweezers or other tools to align the fixed tooth with the alloy hole on the drill body, and then uses a copper hammer to quickly knock the fixed tooth into the hole, using the characteristics of thermal expansion and contraction of the steel body to achieve the purpose of fixing the tooth. The tooth fixing operation process must be fast and the time must be strictly controlled. The current heat treatment method is difficult to grasp due to the large furnace loading capacity. The phenomenon of insufficient hardness caused by uneven heating often occurs. In addition, the quenching medium is uneven, resulting in excessive tissue stress. In addition, the workpieces made by the current heat treatment method have uneven hardness and uneven stress, which causes large deformation of the workpiece and even cracking. Improper holding time will also cause coarse grains and severe oxidation and decarburization, affecting the quenching quality. Therefore, the heat treatment of the drill body brings many inconveniences to the actual production and directly affects the quality of the product's fixed teeth. Summary of the invention

[0004] The object of the present invention is to provide a hot-setting tooth drill bit body and a heat treatment method thereof, so as to solve the problems that the drill bit body is not wear-resistant and is easy to crack and lose teeth during hot-setting tooth operation.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A hot-set tooth drill bit body, wherein the material of the drill bit body comprises the following components by mass percentage: 0.38%-0.45% carbon, 0.17%-0.37% silicon, 0.50%-0.80% manganese, 0.90%-1.20% chromium, 0.15%-0.25% molybdenum, an allowable residual content of sulfur ≤0.035%, an allowable residual content of phosphorus ≤0.035%, an allowable residual content of nickel ≤0.30%, an allowable residual content of copper ≤0.30%, and the balance is iron.

[0007] The heat treatment method of a hot-set fixed tooth drill bit body is characterized by comprising the following steps: step 1: annealing treatment

[0008] The bars are sawn into blanks of required length according to the needs, annealed at 750℃-770℃, furnace cooled to 390-410℃ and then air cooled;

[0009] Step 2: Quenching

[0010] Place the finely processed drill body in the melted salt bath furnace in mid-air, heat it to 890℃-910℃, and keep it at a constant temperature for 15min-35min; place the drill body in a constant temperature quenching device with an oil temperature of 40℃-60℃ for oil quenching, shake the drill body back and forth in the oil for 110-130s to avoid excessive oil temperature and uneven oil temperature, then let it stand for 290-310s, take it out and hang it for air cooling;

[0011] Step 3: Normalizing

[0012] The drill bit body processed in step 2 is placed in a box furnace and heated to 850°C-870°C, and then air-cooled after being taken out of the furnace;

[0013] Step 4: Tempering

[0014] The drill bit body treated in step 3 is heated to 840°C-860°C, then tempered at 500-520°C, and then cooled in the furnace;

[0015] Step 5: Shot peening

[0016] The drill body after the tempering treatment in step 4 is shot peened to eliminate the residual stress on the surface of the drill body again. The fixed hole is processed in the drill body by drilling first and then reaming. The reserved interference of the hole is 0.024mm-0.045mm. Then the tooth fixing treatment is carried out: the drill body is heated to 200-220℃, and then the tooth installation operation is carried out.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] 1. The process of the present invention is simple and easy to operate. In the quenching step, the constant temperature holding time is strictly controlled to eliminate the disadvantages of coarse grains and serious oxidation decarburization. In addition, after the drill body is placed in the quenching medium, it is better to move rather than to be static. Static cooling medium plus static workpieces are prone to cause uneven hardness and stress. The present invention maintains a quenching medium temperature of 40°C-60°C and makes the drill body shake back and forth in the oil for 110-130s to keep the quenching medium temperature uniform. By controlling the above various conditions, the comprehensive performance of the drill body after heat treatment by the method of the present invention is greatly improved, and its strength, plasticity and toughness are good, and it has good comprehensive mechanical properties;

[0019] 2. The heat treatment method of the present invention has uniform hardness, and the drill bit body after treatment has good wear resistance, high fixed tooth strength, and is not easy to crack or fall off. The various indicators of the drill bit body achieve the effect of drill bit body hardness and structural stability, which solves practical problems and greatly improves product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the process route diagram of the present invention; DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the specific data in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0022] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] The comprehensive performance of the drill body after heat treatment of the present invention is adjusted to a great extent, and its strength, plasticity and toughness are good, and it has good comprehensive mechanical properties. After quenching and tempering treatment, tempered troostite is obtained. Tempered troostite is formed when martensite is tempered. It can be distinguished by magnification of 500-600 times or more under an optical phase microscope. It is a composite structure with carbide (including cementite) spherules distributed in the ferrite matrix. It is also a tempered structure of martensite, which is a mixture of ferrite and granular carbide. At this time, the ferrite has basically reached a carbon-free supersaturation, and the carbide is also a stable carbide. It is a balanced structure at room temperature. The hardness and wear resistance of the drill body after quenching are greatly improved, and the strength, toughness and fatigue strength of the metal are also improved. When commonly used steel is heated above the critical temperature, the original structure at room temperature will be completely or mostly transformed into austenite. The steel is then immersed in oil and quickly cooled, and the austenite is transformed into martensite. Compared with other structures in steel, martensite has the highest hardness. The purpose of tempering is to eliminate quenching stress, transform the steel structure into a relatively stable state, maintain high hardness and wear resistance of the quenched workpiece, and reduce quenching residual stress and brittleness. The plasticity and toughness of the steel can be improved without reducing or appropriately reducing the hardness and strength of the steel to obtain the desired performance.

[0024] In the following embodiments and comparative examples, the material of the drill bit body includes the following components by mass percentage: carbon 0.38%-0.45%, silicon 0.17%-0.37%, manganese 0.50%-0.80%, chromium 0.90%-1.20%, molybdenum 0.15%-0.25%, sulfur allowable residual content ≤0.035%, phosphorus allowable residual content ≤0.035%, nickel allowable residual content ≤0.30%, copper allowable residual content ≤0.30%, and the balance is iron.

[0025] Example 1

[0026] like Figure 1 As shown, this embodiment provides a heat treatment method for a hot-set fixed-tooth drill bit body, comprising the following steps:

[0027] Step 1: Annealing: Saw the bar into blanks of required length as required, anneal at 750℃, cool to 390℃ in the furnace and then air cool (cool in air);

[0028] Step 2: Quenching treatment: Place the finely processed drill body in a molten salt bath furnace, heat it to 890°C, and keep it at a constant temperature for 15 minutes; place the drill body in a constant temperature quenching device with an oil temperature of 40°C for oil quenching, and shake the drill body back and forth in the oil for 110 seconds to avoid excessive oil temperature and uneven oil temperature, then let it stand for 290 seconds, take it out and hang it for air cooling;

[0029] Step 3: Normalizing treatment: put the drill bit body treated in step 2 into a box furnace and heat it to 850°C, then take it out of the furnace and air cool it;

[0030] Step 4: Tempering treatment: Heat the drill bit body treated in step 3 to 840°C, then temper it at 500°C, and cool it in the furnace.

[0031] Example 2

[0032] This embodiment provides a heat treatment method for a hot-set fixed-tooth drill bit body, comprising the following steps:

[0033] Step 1: Annealing: Saw the bar into blanks of required length as required, anneal at 760℃, cool to 400℃ in the furnace and then air cool;

[0034] Step 2: Quenching treatment: Place the finely processed drill body in a molten salt bath furnace, heat it to 900°C, and keep it at a constant temperature for 25 minutes; place the drill body in a constant temperature quenching device with an oil temperature of 50°C for oil quenching, and shake the drill body back and forth in the oil for 120 seconds to avoid excessive oil temperature and uneven oil temperature, then let it stand for 300 seconds, take it out and hang it for air cooling;

[0035] Step 3: Normalizing treatment: put the drill bit body treated in step 2 into a box furnace and heat it to 860°C, then take it out of the furnace and air cool it;

[0036] Step 4: Tempering treatment: Heat the drill bit body treated in step 3 to 850°C, then temper it at 510°C, and cool it in the furnace.

[0037] Embodiment 3,

[0038] This embodiment provides a heat treatment method for a hot-set fixed-tooth drill bit body, comprising the following steps:

[0039] Step 1: Annealing: Saw the bar into the required length of blanks as needed, anneal at 770℃, cool to 410℃ in the furnace and then air cool;

[0040] Step 2: Quenching treatment: Place the finely processed drill body in a molten salt bath furnace, heat it to 910°C, and keep it at a constant temperature for 35 minutes; place the drill body in a constant temperature quenching device with an oil temperature of 60°C for oil quenching, and shake the drill body back and forth in the oil for 130 seconds to avoid excessive oil temperature and uneven oil temperature, then let it stand for 310 seconds, take it out and hang it for air cooling;

[0041] Step 3: Normalizing treatment: put the drill bit body treated in step 2 into a box furnace and heat it to 870°C, then take it out of the furnace and air cool it;

[0042] Step 4: Tempering treatment: Heat the drill bit body treated in step 3 to 860°C, then temper it at 520°C, and cool it in the furnace.

[0043] Comparative Example 1

[0044] This comparative example provides a heat treatment method for a hot-set fixed-tooth drill bit body, comprising the following steps:

[0045] Step 1: Annealing: Saw the bar into blanks of required length as required, anneal at 760℃, cool to 400℃ in the furnace and then air cool;

[0046] Step 2: Quenching treatment: Place the finely processed drill body in a molten salt bath furnace, heat it to 870°C, and keep it at a constant temperature for 10 minutes; quench the drill body in water or oil at room temperature, and keep the drill body shaking back and forth for 120 seconds, then let it stand for 300 seconds, take it out and hang it in air cooling;

[0047] Step 3: Normalizing treatment: put the drill bit body treated in step 2 into a box furnace and heat it to 830°C, then take it out of the furnace and air cool it;

[0048] Step 4: Quenching and tempering treatment: Heat the drill bit body treated in step 3 to 820°C, then temper it at 450°C, and air cool it.

[0049] Comparative Example 2

[0050] This comparative example provides a heat treatment method for a hot-set fixed-tooth drill bit body, comprising the following steps:

[0051] Step 1: Annealing: Saw the bar into blanks of required length as required, anneal at 760℃, cool to 400℃ in the furnace and then air cool;

[0052] Step 2: Quenching treatment: Place the finely processed drill body in a molten salt bath furnace, heat it to 930°C, and keep it at a constant temperature for 10 minutes; quench the drill body in water or oil at room temperature, and keep the drill body shaking back and forth for 120 seconds, then let it stand for 300 seconds, take it out and hang it in air cooling;

[0053] Step 3: Normalizing treatment: put the drill bit body treated in step 2 into a box furnace and heat it to 890°C, then take it out of the furnace and air cool it;

[0054] Step 4: Quenching and tempering treatment: Heat the drill bit body treated in step 3 to 880°C, then temper it at 450°C, and air cool it.

[0055] From the mechanical performance index data of the drill body of the above embodiments and comparative examples, it can be concluded that the performance indexes of the drill body of Embodiment 1, Embodiment 2 and Embodiment 3 are compared with the drill body of the prior art comparative examples 1 and 2, the tensile strength is increased by about 30%, the yield strength is increased by about 20%, and the impact energy is increased by about 20%.

[0056] The drill bodies of the above embodiments and comparative examples are shot peened: the alloy tooth holes are processed, and the drill body after the tempering treatment in step four is shot peened to eliminate the residual stress generated on the surface of the drill body again. The fixed holes are processed in the drill body by drilling first and then reaming, and the reserved interference of the holes is 0.024mm-0.045mm. The tooth fixing treatment is then performed: the drill body is heated to 200-220℃, and then the tooth installation operation is performed. The service life is tested using the same drilling rig, the same drilling process and the same drilling medium. It can be seen from the service life data that the drilling depths of Embodiment 1, Embodiment 2 and Embodiment 3 are all higher than those of Comparative Examples 1 and 2, and are about 20% higher on average.

[0057] It can be seen from the mechanical performance index data and service life data of the drill body of the above embodiments and comparative examples that the best effect is obtained in embodiment 2, that is, when the temperature is raised to 900°C in a salt bath furnace, kept at a constant temperature for 25 minutes, the oil temperature is 50°C, shaken for 120 seconds, and left to stand for 300 seconds, the hardness and wear resistance of the drill body after quenching are greatly improved under this condition, and the strength, toughness and fatigue strength of the metal are improved at the same time. The performance index of the drill body treated under this condition is the best and the service life is the longest.

Claims

1. A hot-set fixed-tooth drill bit body, characterized in that: The material of the drill body includes the following components by mass percentage: carbon 0.38%-0.45%, silicon 0.17%-0.37%, manganese 0.50%-0.80%, chromium 0.90%-1.20%, molybdenum 0.15%-0.25%, sulfur allowable residual content ≤0.035%, phosphorus allowable residual content ≤0.035%, nickel allowable residual content ≤0.30%, copper allowable residual content ≤0.30%, and the balance is iron.

2. A heat treatment method for a hot-set fixed-tooth drill bit body according to claim 1, characterized in that: The following steps are included: Step 1: Annealing The bars are sawn into blanks of required length according to the needs, annealed at 750℃-770℃, cooled to 390-410℃ in the furnace and then air-cooled; Step 2: Quenching Place the finely processed drill body in the melted salt bath furnace in mid-air, heat it to 890℃-910℃, and keep it at a constant temperature for 15min-35min; place the drill body in a constant temperature quenching device with an oil temperature of 40℃-60℃ for oil quenching, shake the drill body back and forth in the oil for 110-130s to avoid excessive oil temperature and uneven oil temperature, then let it stand for 290-310s, take it out and hang it for air cooling; Step 3: Normalizing The drill bit body treated in step 2 is placed in a box furnace and heated to 850°C-870°C, and then air-cooled after being taken out of the furnace; Step 4: Tempering The drill bit body treated in step 3 is heated to 840°C-860°C, then tempered at 500-520°C, and then cooled in the furnace; Step 5: Shot peening The drill body after the tempering treatment in step 4 is shot peened to eliminate the residual stress on the surface of the drill body again. The fixed hole is processed in the drill body by drilling first and then reaming. The reserved interference of the hole is 0.024mm-0.045mm. Then the tooth fixing treatment is carried out: the drill body is heated to 200-220℃, and then the tooth installation operation is carried out.

3. A heat treatment method for a hot-set fixed-tooth drill bit body according to claim 2, characterized in that: In step 2, the oil temperature in the constant temperature quenching device is 50°C; the drill body is suspended in a salt bath furnace and heated to 900°C, and kept at a constant temperature for 25 minutes; the drill body is shaken back and forth in the oil for 120 seconds, and then left to stand for 300 seconds.

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