Heat treatment equipment, heat treatment device, heat treatment method and application of broach

Abstract

The present application discloses a heat treatment equipment, a heat treatment device, a heat treatment method and an application of a broach. On the one hand, the present application provides a heat treatment equipment for a broach, including a vertical vacuum air quenching furnace, in which a first ventilator and a second ventilator are provided for introducing cooling gas into the tool in the furnace. The present application provides a heat treatment device for hanging and fixing the tool. On the other hand, the present application provides a heat treatment method for a broach, which uses the heat treatment equipment and heat treatment device for the broach, including preheating, quenching and tempering treatment. The present application also provides the application of the heat treatment method in the field of heat treatment of long rod processing broaches made of high-speed steel. The present application can make the high-speed steel broach not crack during heat treatment, with small deformation and qualified structure, and the hardness and other performance indicators of the broach can meet the technical requirements.

Description

Technical Field

[0001] The present application relates to the technical field of alloy heat treatment, and in particular to a heat treatment device, a heat treatment apparatus, a heat treatment method and an application of a broach. Background Art

[0002] A broach is a broach that completes cutting and broaches the workpiece into shape in one go under the action of pulling or pushing force. Broaches are often used for batch processing of round holes, spline holes, keyways, planes and formed surfaces, etc., and have the characteristics of high production efficiency and good processing consistency. The broach is a typical slender rod broach with a complex shape and multiple rows of teeth on the surface. The size and shape of each row of teeth increase and change from the cutting end to the cutting end. Therefore, the thickness of the broach blade and the base of the tool body are uneven, and the structure is also seriously asymmetric, which makes it difficult to heat treat the broach.

[0003] At present, there are two main heat treatment processes for broaches: salt bath heat treatment and vacuum heat treatment. Salt bath heat treatment is a heat treatment process that uses a salt bath furnace for heating and oil quenching; vacuum heat treatment is a heat treatment process that uses a vacuum furnace for heating and liquid quenching or gas quenching. Although the vacuum heat treatment process is more environmentally friendly, it is limited by the special structural characteristics of broaches, and the current heat treatment of broaches is still mainly salt bath heat treatment.

[0004] Salt bath heat treatment is not only highly polluting, but also difficult to control. It is very easy to cause oxidation and / or decarburization of alloy workpieces, as well as uneven heating of broaches. When broaches are heat treated by salt bath heat treatment, they are very easy to crack due to their complex structure. However, when broaches are heat treated by vacuum heat treatment, due to their complex structural characteristics, the technology is not mature at present, and they are prone to many technical problems such as cracking, unqualified structure and substandard hardness. In particular, when vacuum gas quenching heat treatment is used, a slight deviation in the process parameters will lead to coarse metallographic structure of the broach, high brittleness, uneven hardness, deformation and cracking of the broach, and many other problems.

[0005] Therefore, the art urgently needs to design heat treatment equipment and vacuum heat treatment process for high-speed steel broaches to solve the above technical problems. Summary of the invention

[0006] In order to solve at least one of the above technical problems, a vacuum heat treatment technology is developed to prevent high-speed steel broaches from cracking during heat treatment, to ensure that the microstructure is qualified, and to ensure that all performance indicators of the broaches meet the technical requirements. The present application provides a heat treatment equipment, a heat treatment device, a heat treatment method and an application for the broach.

[0007] In the first aspect, the present application provides a heat treatment equipment for a broach, wherein the heat treatment equipment is a vacuum furnace, and the vacuum furnace adopts a vertical vacuum air quenching furnace. The vertical vacuum air quenching furnace is provided with a first ventilation duct and a second ventilation duct for introducing cooling gas to the tool in the furnace; the first ventilation duct is arranged at the lower furnace door of the vertical vacuum air quenching furnace, and is evenly distributed along the axial direction of the furnace, and the lower furnace door is provided with multiple circles of first ventilation ducts; the second ventilation duct is arranged on the inner wall of the furnace of the vertical vacuum air quenching furnace, and is evenly distributed along the circumference of the furnace, and the inner wall of the furnace is provided with multiple layers of second ventilation ducts.

[0008] By adopting the above-mentioned technical scheme, the present application provides a first ventilation duct on the lower furnace door of the vertical vacuum air quenching furnace, and a second ventilation duct on the inner wall of the furnace, so that the tools mounted in the furnace are subjected to the longitudinal cooling gas from the lower furnace door and the lateral cooling gas from the inner wall of the furnace at the same time during quenching and tempering, thereby achieving the technical effect that the gas can surround the tools for heat exchange, so that all parts of the tools are evenly cooled, heat treatment distortion is reduced, and the consistency of the heat treatment performance of the tools is improved; the size, number and distribution position of the ventilation ducts are designed to further ensure that the tools are in full contact with the cooling gas, avoid blocking the cooling gas after multiple tools are mounted, and further improve the heat treatment effect.

[0009] Optionally, the lower furnace door is provided with m circles of first ventilation ducts, the inner wall of the furnace is provided with n layers of second ventilation ducts, 3≤m≤6 and m is an integer, 8≤n≤14 and n is an integer.

[0010] Optionally, the lower furnace door is provided with m circles of first ventilation ducts, the inner wall of the furnace is provided with n layers of second ventilation ducts, 3≤m≤6 and m is an integer, 8≤n≤14 and n is an integer, and m and n also satisfy: n=2m+2.

[0011] Optionally, the inner diameter of the first ventilation tube 3 is 100 mm.

[0012] Optionally, among the second ventilation ducts, the inner diameters of the second ventilation ducts 4 distributed in the first to third layers from top to bottom along the inner wall of the furnace are all 100 mm, and the inner diameters of the second ventilation ducts 4 in the remaining layers are all 80 mm.

[0013] Optionally, the lower furnace door is provided with a first ventilator, from the inside to the outside of the first to second circles

[0014] The number of first ventilators is 8, and the number of first ventilators in other circles is 12.

[0015] Optionally, in the multiple layers of second ventilation ducts provided on the inner wall of the furnace, the number of second ventilation ducts uniformly distributed radially along the circumference of the horizontal cross-section of the furnace in each layer is 12.

[0016] By adopting the above-mentioned technical scheme, in the present application, by controlling the number of circles of the first ventilation ducts distributed on the lower furnace door and the number of corresponding circles, and the number of layers of the second ventilation ducts distributed on the inner wall of the furnace and the number of corresponding layers, the tools mounted in the furnace are made to receive the longitudinal cooling gas from the lower furnace door and the cooling gas in the direction of the inner wall of the furnace during quenching and tempering, and the gas flow and pressure of the cooling gas meet the cooling requirements of the corresponding parts of the broach, thereby avoiding the situation where the difference in cooling gas flow in different directions is too large, resulting in inconsistent cooling rates of various parts of the broach, and can further improve the heat treatment effect.

[0017] In the second aspect, the present application provides a heat treatment device for a broach, the heat treatment device comprising an upper fixed plate and a chassis, and a supporting column fixedly arranged between the upper fixed plate and the chassis; the upper fixed plate comprises an outer ring and an inner plate with the same geometric center, a plurality of hanging rods are fixedly arranged between the outer ring and the inner plate, and the hanging rods are evenly arranged in the empty area between the outer ring and the inner plate; the chassis has the same main structure as the upper fixed plate, comprising an outer bottom ring and an inner chassis with the same geometric center, and a connecting rod adapted to the position of the hanging rod is fixedly arranged between the outer bottom ring and the inner chassis.

[0018] Furthermore, a limiting groove is provided on the hanging rod, and a hook hole for hanging a knife is provided on the inner wall of the limiting groove.

[0019] Furthermore, a limiting hole is provided on the connecting rod, and the limiting hole is arranged corresponding to the hook hole.

[0020] By adopting the above technical solution, the heat treatment equipment of the broach designed in this application adopts a specially designed heat treatment device, which can mount the tool on the hanging rod, and by setting a limit groove and a hook hole for hanging the tool on the hanging rod of the heat treatment device, and setting a limit hole coaxially corresponding to the hook hole on the connecting rod, the upper and lower ends of the tool are fixed in the heat treatment device, so that the tool is in a suspended and fixed state in the vacuum furnace. It can avoid the tool from contacting other objects, ensure that the cooling gas is in full contact with the tool, and ensure that the temperature of each part of the tool can be as uniform as possible during quenching and tempering cooling.

[0021] In a third aspect, the present application provides a heat treatment method for a broach, using the heat treatment equipment and heat treatment device for the broach, comprising the following steps:

[0022] S1, mounting the tool on the hanging rod (713) of the heat treatment device, and then aligning the heat treatment device (7) and installing the furnace;

[0023] S2, start the vertical vacuum gas quenching furnace, and perform two preheating treatments, the first preheating treatment temperature is not higher than 850°C, and the second preheating treatment temperature is not higher than 1050°C;

[0024] S3, heating the vertical vacuum gas quenching furnace to 1160°C~1240°C, keeping the temperature for 0.5h~3h, and then passing inert gas to cool down to below 50°C;

[0025] S4. Raise the temperature to 520℃~580℃ for tempering, temper 2~5 times, each tempering time is controlled to be 0.5h~3h, and pass inert gas to cool to room temperature after each tempering; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0026] By adopting the above-mentioned technical scheme, the heat treatment method of the present application, under vacuum conditions, adopts a process method of preheating twice, combined with quenching and tempering inert gas cooling, and adopts specific heat treatment parameters, which can effectively refine the metallographic structure of high-speed steel and make the metallographic structure distribution of the broach more uniform, and effectively improve the hardness and toughness of the broach while ensuring that the deformation of the broach is extremely small; the overall method step design of the present application, preheating, quenching and tempering treatments are all carried out under vacuum conditions, and the entire heat treatment process does not require furnace opening, which can effectively reduce the number of furnace openings and improve production efficiency; the present application adopts a vacuum gas quenching heat treatment process to replace traditional salt bath heat treatment, reduce pollution to the environment, and effectively improve the environmental friendliness of the process.

[0027] Optionally, in step S2, the first preheating treatment is to raise the temperature to 815°C~845°C and keep it warm for 0.5h~3h; the second preheating treatment is to raise the temperature to 1010°C~1040°C and keep it warm for 0.5h~3h.

[0028] Optionally, in step S3 and step S4, argon is used as the inert gas.

[0029] Optionally, in step S3 and step S4, the pressure of the inert gas for cooling is 2 bar to 6 bar, and the fan flow rate during cooling is controlled at 5000 to 16000 m 3 / h.

[0030] Optionally, in step S4, the temperature is raised to 540°C~580°C for tempering, and the tempering time is controlled to be 0.5h~3h each time. After each tempering, an inert gas is introduced to cool to room temperature, and tempering is performed 3~5 times; after tempering is completed, the broach is taken out of the furnace to complete the heat treatment of the broach.

[0031] In a fourth aspect, the present application provides the above-mentioned heat treatment method for broaches, which is applied in the field of heat treatment of long-rod processing broaches made of high-speed steel.

[0032] In summary, the present invention includes at least one of the following beneficial technical effects:

[0033] 1. The heat treatment equipment for the broach designed in the present application adopts a vertical vacuum air quenching furnace, and multiple circles of first ventilators are evenly distributed on the lower furnace door of the vertical vacuum air quenching furnace, and multiple layers of second ventilators are evenly distributed on the inner wall of the furnace of the vertical vacuum air quenching furnace, so that the tools in the furnace are simultaneously subjected to cooling gas from the axial and circumferential directions of the furnace, which can avoid blocking the cooling gas from each other when multiple tools are mounted, so that the tools are fully in contact with the cooling gas, ensuring that the temperature of various parts of the tool can be as uniform as possible during quenching and tempering cooling, effectively avoiding tool cracking during the heat treatment process, thereby further improving the heat treatment effect.

[0034] 2. The present application also improves the structure of the heat treatment device, and adopts a specifically designed heat treatment device to mount the tool. The tool can be mounted on a hanging rod so that the tool is suspended and fixed at the upper and lower ends in the vacuum furnace, which can avoid the tools from affecting each other during the heat treatment process. At the same time, the structure of the heat treatment device is also conducive to the circulation of cooling gas, which can ensure that the cooling gas is in full contact with the tool, thereby improving the heat treatment effect.

[0035] 3. The heat treatment method of the present application, during the quenching and tempering process, specifically designs the aperture size, number and position distribution of the first ventilator and the second ventilator in the vertical vacuum air quenching furnace, and controls the pressure and total flow rate of the cooling gas in the vertical vacuum air quenching furnace. At the same time, the structure of the heat treatment device is improved so that the cooling gas in the vacuum furnace can cool down the same batch of broaches that are vertically suspended, fixed at both ends and arranged at intervals according to specific air ducts, flow rates and pressures, so that each broach is evenly cooled at a preset cooling rate, which can effectively refine the metallographic structure of the high-speed steel and make the metallographic structure of the broach more evenly distributed, effectively improving the hardness and toughness of the broach while ensuring that the deformation of the broach is extremely small.

[0036] 4. The overall method step design of the present application is that preheating, quenching and tempering are all carried out under vacuum conditions. The entire heat treatment process does not require opening the furnace, which can effectively reduce the number of furnace openings and improve production efficiency.

[0037] 5. The present application adopts a heat treatment process of vacuum gas quenching, which replaces the traditional salt bath heat treatment, and has no oxidation decarburization process, thereby reducing pollution to the environment and effectively improving the environmental friendliness of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the structure of the vertical vacuum gas quenching furnace of the present application;

[0039] Figure 2 This is a schematic diagram of the structure of the heat treatment device of the present application;

[0040] Figure 3This is a schematic diagram of the distribution of ventilators on the lower furnace door of the vertical vacuum air quenching furnace in Example 1 of the present application;

[0041] In the figure: 1. vertical vacuum gas quenching furnace; 2. furnace chamber; 3. first ventilator; 4. second ventilator; 5. lower furnace door; 6. charge support rod; 7. heat treatment device; 71. upper fixed plate; 711. outer ring; 712. inner plate; 713. hanging rod; 72. chassis; 721. outer bottom ring; 722. inner chassis; 723. connecting rod; 73. supporting column; 74. limiting groove; 75. hook hole; 76. limiting hole; 8. heat exchanger; 9. fan. DETAILED DESCRIPTION

[0042] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0043] The present application designs a heat treatment equipment for a broach, including a vacuum furnace. The vacuum furnace adopts a vertical vacuum air quenching furnace 1. The vertical vacuum air quenching furnace 1 is provided with a first ventilation duct 3 and a second ventilation duct 4, which are used to introduce cooling gas into the tool in the furnace; the first ventilation duct 3 is arranged at the lower furnace door 5 of the vertical vacuum air quenching furnace 1, and is evenly distributed along the axial direction of the furnace chamber 2, and the lower furnace door 5 is provided with multiple circles of first ventilation ducts 3; the second ventilation ducts 4 are arranged on the inner wall of the furnace chamber 2 of the vertical vacuum air quenching furnace 1, and are evenly distributed along the circumference of the furnace chamber 2, and the inner wall of the furnace chamber 2 is provided with multiple layers of second ventilation ducts 4.

[0044] During the heat treatment process of the present application, after the tool is loaded into the furnace, it is in a vertical hanging state, and can be heated evenly during heating. When cooling gas is introduced for cooling, the cooling gas is ejected from the first ventilation duct 3 and the second ventilation duct 4. The cooling gas of the first ventilation duct 3 moves from the bottom to the top of the tool, and then moves to the top of the furnace through the peripheral area of ​​the upper fixed plate 71; the cooling gas of the second ventilation duct 4 is blown to the tool from the horizontal direction and then sucked away by the fan 9 on the top of the furnace. With this design, the cooling gas can quickly and evenly contact all parts of the entire broach, effectively ensuring the uniformity of cooling.

[0045] The present application designs a heat treatment device 7, which includes an upper fixed plate 71 and a bottom plate 72, and a supporting column 73 fixedly arranged between the upper fixed plate 71 and the bottom plate 72; the upper fixed plate 71 includes an outer ring 711 and an inner plate 712 with the same geometric center, a plurality of hanging rods 713 are fixedly arranged between the outer ring 711 and the inner plate 712, and the hanging rods 713 are evenly arranged in the empty area between the outer ring 711 and the inner plate 712; the bottom plate 72 has the same main structure as the upper fixed plate 71, including an outer bottom ring 721 and an inner bottom plate 722 with the same geometric center, and a connecting rod 723 adapted to the position of the hanging rod 713 is fixedly arranged between the outer bottom ring 721 and the inner bottom plate 722.

[0046] The number of the hanging rods 713 is preferably 8. This ensures that more tools can be mounted at one time, and also ensures that there is enough spacing between the tools to avoid the tools from contacting each other during the heat treatment process, which affects the heat treatment effect.

[0047] In a preferred embodiment of the present application, a limiting groove 74 is provided on the hanging rod 713, and a hook hole 75 for hanging the tool is provided on the inner wall of the limiting groove 74. After the tool is mounted, when the cooling gas is sprayed in, the limiting groove 74 can limit the hook, keep the tool fixed and stable, and effectively avoid the tool from colliding and contacting. The tool is mounted through the hook hole 75 at the top of the clamping part. The hook hole 75 can ensure that the mounted tool remains fixed and stable during the heat treatment process.

[0048] The connecting rod 723 is provided with a limit hole 76, which is arranged corresponding to the hook hole 75, so that the upper and lower ends of the tool are fixed in the heat treatment device 7, so that the tool is in a suspended and fixed state in the vacuum furnace.

[0049] Example 1

[0050] The heat treatment equipment for the broach of this embodiment includes a vacuum furnace, and the vacuum furnace is a vertical graphite vacuum gas quenching furnace.

[0051] The lower furnace door 5 of the vertical graphite vacuum air quenching furnace 1 in this embodiment is provided with a first ventilation duct 3 , a charge support rod 6 is provided on the lower furnace door 5 , and a heat treatment device 7 for mounting a tool is provided on the upper part of the charge support rod 6 .

[0052] The first ventilation ducts 3 on the lower furnace door 5 are evenly arranged in a circular array along the axial direction of the furnace. The first ventilation ducts 3 are arranged in three circles on the upper surface of the lower furnace door 5. The number of the first ventilation ducts 3 in the innermost circle is 8, the number of the first ventilation ducts 3 in the middle circle is 8, and the number of the first ventilation ducts 3 in the outermost circle is 12.

[0053] The vertical vacuum gas quenching furnace of this embodiment has second ventilators arranged on the inner wall of the furnace along the circumference of the furnace. In this embodiment, there are 8 layers of second ventilators 4 on the inner wall of the furnace from top to bottom, and each layer has 12 second ventilators 4 evenly distributed radially along the circumference of the horizontal cross section of the furnace.

[0054] The inner diameter of the first ventilation duct 3 provided on the lower furnace door 5 is 100 mm; the second ventilation duct 4 provided on the inner wall of the furnace 2 along the circumference of the furnace 2 has an inner diameter of 100 mm for the first to third layers from top to bottom along the inner wall of the furnace 2, and the inner diameters of the second ventilation ducts 4 corresponding to the remaining layers are all 80 mm, and the interval between each layer of the second ventilation ducts 4 provided on the inner wall of the furnace 2 is approximately 180 mm.

[0055] The heat treatment device of this embodiment includes an upper fixed plate 71 and a bottom plate 72, and a support column 73 fixedly arranged between the upper fixed plate 71 and the bottom plate 72. Both the upper fixed plate 71 and the bottom plate 72 are circular, and there are five support columns 73, one of which is arranged between the centers of the upper fixed plate 71 and the bottom plate 72, and the other four are evenly arranged along the outer ring 711 of the upper fixed plate 71 and the outer bottom ring 721 of the bottom plate 72. The upper fixed plate 71 includes an outer ring 711 and an inner plate 712 with the same geometric center, and eight hanging rods 713 are fixedly arranged between the outer ring 711 and the inner plate 712, and the hanging rods 713 are evenly arranged in the empty area between the outer ring 711 and the inner plate 712; the bottom plate 72 has the same main structure as the upper fixed plate 71, including an outer bottom ring 721 and an inner bottom plate 722 with the same geometric center, and eight connecting rods 723 corresponding to the positions of the hanging rods are fixedly arranged between the outer bottom ring 721 and the inner bottom plate 722.

[0056] Each hanging rod in this embodiment is provided with two limiting grooves 74, and the inner wall of each limiting groove 74 is provided with a hook hole 75 for hanging a tool. Correspondingly, each connecting rod 723 in this embodiment is provided with two limiting holes 76 corresponding to the hook hole 75.

[0057] This embodiment also designs a heat treatment method for a broach, using the above-mentioned heat treatment equipment and heat treatment device for the broach, comprising the following steps:

[0058] S1, mount the tool on the hanging rod of the heat treatment device, and then align the heat treatment device and install the furnace;

[0059] S2, start the vertical vacuum gas quenching furnace, and perform two preheating treatments, the first preheating treatment temperature is not higher than 850°C, and the second preheating treatment temperature is not higher than 1050°C;

[0060] S3, heating the vertical vacuum gas quenching furnace to 1160°C~1240°C, keeping the temperature for 0.5h~3h, and then passing inert gas to cool down to below 50°C;

[0061] S4. Raise the temperature to 520℃~580℃ for tempering, temper 2~5 times, and control the tempering time to 0.5h~3h. After each tempering, introduce inert gas to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0062] The inert gas used in the heat treatment method of this embodiment is argon.

[0063] In steps S3 and S4 of this embodiment, when the inert gas is introduced for cooling, the working pressure inside the furnace of the vertical vacuum air quenching furnace is controlled to be 2 bar to 6 bar, and the fan flow rate of the vertical vacuum air quenching furnace is controlled to be 5000 m 3 / h ~16000m 3 / h.

[0064] The following are Examples 2 to 10 of the present application.

[0065] Examples 2 to 10 of the present application use square keyway broaches as heat treatment workpiece samples, and the specific parameters of the broaches are: specification 20mm, elongation 50mm to 80mm, total length 1050mm, blade width 20mm, leading height 48.3mm. The material of the sample broach is W12Cr4V5Co5 high-speed steel.

[0066] Embodiments 2 to 10 of the present application all adopt the heat treatment equipment and heat treatment device of the broach in Embodiment 1, and argon is selected as the inert gas.

[0067] Example 2

[0068] The heat treatment method of the broach of this embodiment includes the following steps:

[0069] S1, mounting the tool on the hanging rod of the heat treatment device, and then aligning the heat treatment device and installing the furnace;

[0070] S2, start the vertical vacuum gas quenching furnace and perform two preheating treatments; the first preheating treatment is to heat up to 810℃~820℃ and keep warm for 0.5h; the second preheating treatment is to heat up to 1010℃~1020℃ and keep warm for 0.5h;

[0071] S3, heating the vertical vacuum quenching furnace to 1160°C~1180°C, keeping the temperature for 0.5h, and then cooling to room temperature by introducing argon gas;

[0072] S4. Raise the temperature to 550℃~560℃ for tempering, temper 3 times, each tempering time is controlled to 2h, and argon gas is passed after each tempering to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0073] In steps S3 and S4, when argon gas is introduced for cooling, the pressure is controlled at 2 bar to 3 bar, and the fan flow rate is controlled at 5000 m 3 / h ~6000m 3 / h.

[0074] Example 3

[0075] The heat treatment method of the broach of this embodiment includes the following steps:

[0076] S1, mounting the tool on the hanging rod of the heat treatment device, and then aligning the heat treatment device and installing the furnace;

[0077] S2, start the vertical vacuum gas quenching furnace and perform two preheating treatments; the first preheating treatment is to heat up to 820℃~830℃ and keep warm for 0.5h; the second preheating treatment is to heat up to 1020℃~1030℃ and keep warm for 0.5h;

[0078] S3, heating the vertical vacuum gas quenching furnace to 1200°C~1220°C, keeping the temperature for 0.5h, and then passing argon gas to cool to room temperature;

[0079] S4. Raise the temperature to 550℃~560℃ for tempering, temper 3 times, each tempering time is controlled to 2h, and argon gas is passed after each tempering to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0080] In steps S3 and S4, when argon gas is introduced for cooling, the pressure is controlled at 2 bar to 3 bar, and the fan flow rate is controlled at 5000 m 3 / h ~6000m 3 / h.

[0081] Example 4

[0082] The heat treatment method of the broach of this embodiment includes the following steps:

[0083] S1, mounting the tool on the hanging rod of the heat treatment device, and then aligning the heat treatment device and installing the furnace;

[0084] S2, start the vertical vacuum gas quenching furnace and perform two preheating treatments; the first preheating treatment is to heat up to 840℃~850℃ and keep warm for 0.5h; the second preheating treatment is to heat up to 1030℃~1040℃ and keep warm for 0.5h;

[0085] S3, heating the vertical vacuum gas quenching furnace to 1220°C~1240°C, keeping the temperature for 0.5h, and then passing argon gas to cool to room temperature;

[0086] S4. Raise the temperature to 550℃~560℃ for tempering, temper 3 times, each tempering time is controlled to 2h, and argon gas is passed after each tempering to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0087] In steps S3 and S4, when argon gas is introduced for cooling, the pressure is controlled at 2 bar to 3 bar, and the fan flow rate is controlled at 5000 m 3 / h ~6000m 3 / h.

[0088] Example 5

[0089] The heat treatment method of the broach of this embodiment includes the following steps:

[0090] S1, mounting the tool on the hanging rod of the heat treatment device, and then aligning the heat treatment device and installing the furnace;

[0091] S2, start the vertical vacuum gas quenching furnace and perform two preheating treatments; the first preheating treatment is to heat up to 840℃~850℃ and keep warm for 0.5h; the second preheating treatment is to heat up to 1030℃~1040℃ and keep warm for 0.5h;

[0092] S3, heating the vertical vacuum gas quenching furnace to 1220°C~1240°C, keeping the temperature for 0.5h, and then passing argon gas to cool to room temperature;

[0093] S4. Raise the temperature to 550℃~560℃ for tempering, temper 3 times, each tempering time is controlled to 2h, and argon gas is passed after each tempering to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0094] In steps S3 and S4, when argon gas is introduced for cooling, the pressure is controlled at 3.5 bar to 4.5 bar, and the fan flow rate is controlled at 10000 m 3 / h~11000m 3 / h.

[0095] Example 6

[0096] The heat treatment method of the broach of this embodiment includes the following steps:

[0097] S1, mounting the tool on the hanging rod of the heat treatment device, and then aligning the heat treatment device and installing the furnace;

[0098] S2, start the vertical vacuum gas quenching furnace and perform two preheating treatments; the first preheating treatment is to heat up to 840℃~850℃ and keep warm for 0.5h; the second preheating treatment is to heat up to 1030℃~1040℃ and keep warm for 0.5h;

[0099] S3, heating the vertical vacuum gas quenching furnace to 1220°C~1240°C, keeping the temperature for 0.5h, and then passing argon gas to cool to room temperature;

[0100] S4. Raise the temperature to 550℃~560℃ for tempering, temper 3 times, each tempering time is controlled to 2h, and argon gas is passed after each tempering to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0101] In steps S3 and S4, when argon gas is introduced for cooling, the pressure is controlled at 5 bar to 6 bar, and the fan flow rate is controlled at 15000 m 3 / h ~16000m 3 / h.

[0102] Example 7

[0103] The heat treatment method of the broach of this embodiment includes the following steps:

[0104] S1, mounting the tool on the hanging rod of the heat treatment device, and then aligning the heat treatment device and installing the furnace;

[0105] S2, start the vertical vacuum gas quenching furnace and perform two preheating treatments; the first preheating treatment is to heat up to 840℃~850℃ and keep warm for 3h; the second preheating treatment is to heat up to 1030℃~1040℃ and keep warm for 3h;

[0106] S3, heating the vertical vacuum quenching furnace to 1220°C~1240°C, keeping the temperature for 3 hours, and then passing argon gas to cool to room temperature;

[0107] S4. Raise the temperature to 550℃~560℃ for tempering, temper 3 times, each tempering time is controlled to 2h, and argon gas is passed after each tempering to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0108] In steps S3 and S4, when argon gas is introduced for cooling, the pressure is controlled at 5 bar to 6 bar, and the fan flow rate is controlled at 15000 m 3 / h ~16000m 3 / h.

[0109] Example 8

[0110] The heat treatment method of the broach of this embodiment includes the following steps:

[0111] S1, mounting the tool on the hanging rod of the heat treatment device, and then aligning the heat treatment device and installing the furnace;

[0112] S2, start the vertical vacuum gas quenching furnace and perform two preheating treatments; the first preheating treatment is to heat up to 830℃~840℃ and keep warm for 1h; the second preheating treatment is to heat up to 1020℃~1030℃ and keep warm for 1h;

[0113] S3, heating the vertical vacuum gas quenching furnace to 1180°C~1200°C, keeping the temperature for 0.5h, and then passing argon gas to cool to room temperature;

[0114] S4. Raise the temperature to 550℃~560℃ for tempering, temper 3 times, each tempering time is controlled to 2h, and argon gas is passed after each tempering to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0115] In steps S3 and S4, when argon gas is introduced for cooling, the pressure is controlled at 4 bar to 5 bar, and the fan flow rate is controlled at 12000 m 3 / h ~13000m 3 / h.

[0116] Example 9

[0117] The heat treatment method of the broach of this embodiment includes the following steps:

[0118] S1, mounting the tool on the hanging rod of the heat treatment device, and then aligning the heat treatment device and installing the furnace;

[0119] S2, start the vertical vacuum gas quenching furnace and perform two preheating treatments; the first preheating treatment is to heat up to 840℃~850℃ and keep warm for 0.5h; the second preheating treatment is to heat up to 1030℃~1040℃ and keep warm for 0.5h;

[0120] S3, heating the vertical vacuum gas quenching furnace to 1220°C~1240°C, keeping the temperature for 0.5h, and then passing argon gas to cool to room temperature;

[0121] S4. Raise the temperature to 520℃~550℃ for tempering, temper 5 times, each tempering time is controlled to 2h, and argon gas is passed after each tempering to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0122] In steps S3 and S4, when argon gas is introduced for cooling, the pressure is controlled at 3.5 bar to 4.5 bar, and the fan flow rate is controlled at 10000 m 3 / h~11000m 3 / h.

[0123] Example 10

[0124] The heat treatment method of the broach of this embodiment includes the following steps:

[0125] S1, mounting the tool on the hanging rod of the heat treatment device, and then aligning the heat treatment device and installing the furnace;

[0126] S2, start the vertical vacuum gas quenching furnace and perform two preheating treatments; the first preheating treatment is to heat up to 840℃~850℃ and keep warm for 0.5h; the second preheating treatment is to heat up to 1030℃~1040℃ and keep warm for 0.5h;

[0127] S3, heating the vertical vacuum gas quenching furnace to 1220°C~1240°C, keeping the temperature for 0.5h, and then passing argon gas to cool to room temperature;

[0128] S4. Raise the temperature to 560℃~580℃ for tempering, temper twice, each tempering time is controlled to 2h, and argon gas is passed after each tempering to cool to room temperature; after tempering, take out of the furnace and complete the heat treatment of the broach.

[0129] In steps S3 and S4, when argon gas is introduced for cooling, the pressure is controlled at 3.5 bar to 4.5 bar, and the fan flow rate is controlled at 10000 m 3 / h ~11000m 3 / h.

[0130] Embodiment 11

[0131] Example 11 is based on Example 8, except that the distribution of the first ventilator 3 and the second ventilator 4 in the heat treatment equipment used in Example 11 is different from that in Example 8, as follows:

[0132] There are 6 circles of first ventilation ducts 3 evenly distributed on the lower furnace door 5 of the vertical vacuum air quenching furnace in Example 11, wherein the number of first ventilation ducts 3 from the first to the second circle from the inside to the outside is 8, and the number of first ventilation ducts 3 in the remaining circles is 12; correspondingly, there are 14 layers of second ventilation ducts 4 evenly distributed on the inner wall of the furnace 2 of the vertical vacuum air quenching furnace in Example 11, wherein the number of second ventilation ducts 4 evenly distributed radially along the circumference of the horizontal cross-section of the furnace in each layer is 12; the inner diameters of the first ventilation ducts 3 and the second ventilation ducts 4 are the same as those in Example 8.

[0133] Example 12

[0134] Example 12 is based on Example 11, with the difference that the number of first ventilation ducts 3 arranged on the lower furnace door 5 of the vertical vacuum air quenching furnace in Example 12 is changed to 5 circles, and the rest is the same as Example 11.

[0135] Embodiment 13

[0136] Example 13 is based on Example 11, with the difference that the number of first ventilation ducts 3 arranged on the lower furnace door 5 of the vertical vacuum air quenching furnace in Example 13 is changed to 7 circles, and the rest is the same as Example 11.

[0137] Comparative Example 1

[0138] This application uses a broach of the same type produced by Harbin First Tool Manufacturing Co., Ltd. as comparative example 1, and the broach is heat treated by salt bath.

[0139] Comparative Example 2

[0140] The difference between this comparative example and Example 8 is that a heat-treated material frame is used to load the broach.

[0141] Comparative Example 3

[0142] The difference between this comparative example and Example 8 is that in steps S3 and S4, the fan flow rate during cooling is 3500 m 3 / h ~4500m 3 / h.

[0143] Comparative Example 4

[0144] The difference between this comparative example and Example 8 is that in steps S3 and S4, the fan flow rate during cooling is 16500 m 3 / h ~17500m 3 / h.

[0145] Comparative Example 5

[0146] The difference between this comparative example and Example 8 is that step S4 is changed to: heating to 550°C~560°C for tempering, tempering once, the tempering time is controlled to be 2h, and argon gas is introduced after tempering to cool to room temperature; after tempering is completed, the tool is taken out of the furnace to complete the heat treatment of the broach.

[0147] Comparative Example 6

[0148] The difference between this comparative example and Example 8 is that the arrangement of the first ventilation ducts 3 on the lower furnace door of the vertical vacuum air quenching furnace is changed from three circles in Example 8 to only one innermost circle, and the number of first ventilation ducts 3 constituting the circumference is changed from 28 in Example 8 to 8.

[0149] Comparative Example 7

[0150] The difference between this comparative example and Example 8 is that the first ventilation duct 3 is not provided on the lower furnace door of the vertical vacuum air quenching furnace.

[0151] Hardness and dimensional deformation testing

[0152] The broach samples were heat treated using the processes of Examples 2 to 13 of the present application and the processes of Comparative Examples 1 to 7, respectively. The broaches obtained by the processes of Examples 2 to 13 of the present application, the broaches of Comparative Example 1, and the broaches obtained by the processes of Comparative Examples 2 to 7 were then subjected to performance tests, and the hardness and deformation corresponding to the head, middle, and tail of the broaches were tested, respectively. The results are shown in Table 1.

[0153] It can be seen from the data in Table 1 that the broaches made by the heat treatment equipment and devices and the heat treatment method in Examples 2 to 13 of the present application: The broaches made in Examples 2 to 11 of the present application have a Rockwell hardness of more than 66HRC and a deformation of less than 0.8mm. It can be seen that the broaches made by the heat treatment equipment and devices and the heat treatment method of the present application have high hardness and small deformation, and have good practical application significance; the broaches made in Examples 2 to 11 of the present application have no obvious difference in hardness compared with the broach of Comparative Example 1, but the deformation is smaller, and the preheating, quenching and tempering treatments in the heat treatment methods of Examples 2 to 11 of the present application are all carried out under vacuum conditions, and the entire heat treatment process does not require opening a furnace, and the production efficiency is higher; the present application adopts a vacuum heat treatment method to replace the traditional salt bath heat treatment method in Comparative Example 1, and there is no oxidation decarburization process, which significantly reduces pollution to the environment.

[0154] It can be seen from the data in Table 1 that the broaches obtained by the processes of Examples 2 to 11 of the present application have higher hardness and smaller deformation than those of Comparative Examples 2 to 7. It can be seen that the heat treatment method of the present application, in combination with the heat treatment equipment and heat treatment device of the present application, has obvious beneficial effects on hardness and deformation. Comparing Example 11 with Examples 12 and 13, it can be seen that the size, number and distribution position of the first ventilator and the second ventilator have a significant impact on the cooling effect of the broach during heat treatment. The unreasonable size, number and distribution position of the first ventilator and the second ventilator will lead to too small or too large air volume during cooling, which will lead to too slow or too fast cooling rate during heat treatment, and then significantly reduce the heat treatment effect, so that the hardness of the broach obtained is significantly lower or the deformation is significantly larger.

[0155] It can also be seen from the data in Table 1 that the broaches obtained by the processes of Examples 2 to 11 of the present application, the hardness and dimensional deformation of the broach of Example 8 are significantly better than those of the broaches of other examples, followed by the hardness and dimensional deformation of the broach of Example 5. It can be seen that the present application adjusts the heat treatment equipment and heat treatment device according to the material and shape of the broach, and optimizes the heat treatment parameters to achieve precise control of the internal metallographic structure, stress and hardness of the broach, so as to further improve the hardness of the broach and reduce the deformation of the broach while maintaining the stability of other properties of the broach, and solves the problem of easy deformation and cracking of the broach during use.

[0156] From the data in Table 1, it can be seen from the comparison of the data of Example 8 with the data of Comparative Examples 2 to 7 that the use of a conventional heat treatment frame will seriously affect the heat treatment effect of the broach; and if the air volume is too small or too large during cooling, the cooling rate will be too slow or too fast during the heat treatment process, thereby significantly reducing the heat treatment effect, resulting in the hardness of the obtained broach being significantly lower or the deformation being significantly larger.

[0157] Process stability testing

[0158] The heat treatment equipment, device and heat treatment method corresponding to Examples 2 to 13 of the present application, and the heat treatment equipment, device and heat treatment method corresponding to Comparative Examples 2 to 7 were used to heat treat the broach samples, and 100 broach samples were treated respectively. The treated samples were then tested for hardness, size deformation and ultrasonic flaw detection to screen out unqualified products (e.g., low hardness, large deformation or obvious cracks), and the qualified rate was calculated. The results are shown in Table 2.

[0159]

[0160] It can be seen from the data in Table 2 that the use of appropriate heat treatment parameters and appropriate cooling air volume can effectively improve the hardness of the broach after heat treatment, reduce the dimensional deformation and cracking probability of the broach, and improve the qualified rate of heat treatment. Comparing Example 8 with Comparative Examples 6-7, it can be seen that when the number and distribution position of the first ventilator meet the requirements, the qualified rate of the broach prepared will be significantly increased; comparing Example 11 with Examples 12 and 13, it can be seen that when the number and distribution position of the first ventilator and the second ventilator meet the requirements, the qualified rate of the broach prepared will also be significantly increased. Therefore, the reasonable setting of the first ventilator on the lower furnace door and the second ventilator on the inner wall of the furnace is conducive to meeting the cooling speed requirements of the broach and can improve the qualified rate of the product.

[0161] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A heat treatment method for a broach, characterized in that: The broach is heat treated using heat treatment equipment and a heat treatment device (7) disposed in the heat treatment equipment, the heat treatment equipment comprising a vacuum furnace, the vacuum furnace using a vertical vacuum air quenching furnace (1), the vertical vacuum air quenching furnace (1) being provided with a first ventilator (3) and a second ventilator (4) for introducing cooling gas into the tool in the furnace; The first ventilation ducts (3) are arranged at the lower furnace door (5) of the vertical vacuum gas quenching furnace (1) and are evenly distributed along the axial direction of the furnace (2); the lower furnace door (5) is provided with a plurality of circles of first ventilation ducts (3); The second ventilation ducts (4) are arranged on the inner wall of the furnace (2) of the vertical vacuum gas quenching furnace (1) and are evenly distributed along the circumference of the furnace (2). The inner wall of the furnace (2) is provided with multiple layers of second ventilation ducts (4); The lower furnace door (5) is provided with m circles of first ventilation ducts, and the inner wall of the furnace (2) is provided with n layers of second ventilation ducts (4), where 3≤m≤6 and m is an integer, and 8≤n≤14 and n is an integer; The inner diameters of the first to third layers from top to bottom along the inner wall of the furnace (2) are 100 mm, and the inner diameters of the second ventilation ducts (4) corresponding to the remaining layers are all 80 mm; The heat treatment device (7) is used for hanging a tool; the heat treatment device (7) comprises an upper fixed plate (71) and a bottom plate (72), and a support column (73) fixedly arranged between the upper fixed plate (71) and the bottom plate (72); the upper fixed plate (71) comprises an outer ring (711) and an inner plate (712) having the same geometric center; a plurality of hanging rods (713) are fixedly arranged between the outer ring (711) and the inner plate (712); the hanging rods (713) are evenly arranged in the empty area between the outer ring (711) and the inner plate (712); the bottom plate (72) has the same main structure as the upper fixed plate (71), comprises an outer bottom ring (721) and an inner bottom plate (722) having the same geometric center; a connecting rod (723) adapted to the position of the hanging rod (713) is fixedly arranged between the outer bottom ring (721) and the inner bottom plate (722); The heat treatment method comprises the following steps: S1, mounting the tool on the hanging rod (713) of the heat treatment device, and then aligning the heat treatment device (7) and installing the furnace; S2. Start the vertical vacuum gas quenching furnace and perform two preheating treatments. The first preheating treatment temperature is not higher than 850°C, and the second preheating treatment temperature is not higher than 1050°C. S3, heating the vertical vacuum gas quenching furnace to 1160°C~1240°C, keeping the temperature for 0.5h~3h, and then passing inert gas to cool down to below 50°C; S4, heating to 520℃~580℃ for tempering, tempering 2~5 times, each tempering time is controlled to be 0.5h~3h, and inert gas is introduced to cool to room temperature after each tempering; after tempering, the tool is taken out of the furnace and the heat treatment of the broach is completed; In step S2, the first preheating treatment is performed by heating the temperature to 815°C to 845°C and keeping the temperature for 0.5h to 3h; the second preheating treatment is performed by heating the temperature to 1010°C to 1040°C and keeping the temperature for 0.5h to 3h; In the steps S3 and S4, the pressure of the inert gas for cooling is 2 bar to 6 bar, and the fan flow rate during cooling is controlled at 5000 m3 / h to 16000 m3 / h.

2. The heat treatment method of a broach according to claim 1, characterized in that: The hanging rod is provided with a limiting groove (74), and the inner wall of the limiting groove (74) is provided with a hook hole (75) for hanging a knife.

3. The heat treatment method of the broach according to claim 2, characterized in that: The connecting rod (723) is provided with a limiting hole (76), and the limiting hole (76) is arranged corresponding to the hook hole (75).

4. The heat treatment method of a broach according to claim 1, characterized in that: In the steps S3 and S4, argon is selected as the inert gas.

5. The heat treatment method for broaches according to any one of claims 1 to 4, applied in the field of heat treatment of long-rod broaches made of high-speed steel.

Images