CN109097551B - Heat treatment deformation control process method for slender gear shaft - Google Patents

Abstract

The invention discloses a heat treatment deformation control process method for a slender gear shaft, which comprises the following steps: rough machining; after rough machining, performing stress relief annealing treatment on the part; hobbing, wherein hobbing is carried out on two ends of the part, and tooth surface grinding allowance is reserved; carburizing, and detecting the deformation direction and the deformation of the part after carburizing; pressurizing, straightening and quenching, namely selecting a pressurizing position according to the deformation direction and the deformation of the part, and correspondingly arranging a supporting component; placing a pressurizing weight at the upper end of the part corresponding to the pressurizing position; integrally hoisting the part, the supporting part and the pressure weight into a quenching furnace for heat preservation, and then integrally hoisting out quenching oil; and (4) carrying out low-temperature tempering stress relief treatment after quenching. Through the technical process, the support points are arranged in the quenching process, and the pressure quenching is carried out on the support points, so that the quenching deformation is effectively reduced, the qualified product rate is greatly improved, the rejection rate is obviously reduced, and the problem of deformation control of the long gear shaft with the large-span herringbone teeth is solved.

Description

Heat treatment deformation control process method for slender gear shaft

Technical Field

The invention relates to the technical field of heat treatment, in particular to a heat treatment deformation control process method for a slender gear shaft.

Background

For a gear shaft used in large heavy-duty engineering machinery equipment such as a fracturing pump in the petroleum industry, in order to ensure reliability and a long fatigue life, on one hand, a gear shaft tooth part needs to be subjected to carburizing and quenching treatment so as to improve tooth surface hardness. On the other hand, because the length of the part is longer, the diameter is smaller, and the length-diameter ratio (length/diameter) is more than 10, the deformation tendency in the heat treatment process of the part is larger, and because the herringbone teeth of the part are arranged at two shaft ends, the span is large, the gear module is smaller (the module is less than 8), and the depth of the carburized layer of the part is shallower, if the part is subjected to larger bending deformation, the situation that the hardness of the tooth surface is reduced or the hardness of the tooth surface is uneven can be caused because the deep grinding amount of the hardened layer of the tooth surface is larger after the tooth surface is ground. If the part is deformed by torsion, the centering error of the tooth parts at the two ends of the gear shaft is large, and even the part is finally scrapped.

In summary, the selection of a reasonable heat treatment process to prevent deformation, so as to make the stress release of the gear shaft uniform during and after heat treatment and reduce the bending and torsion deformation of the parts is a key point for successful manufacture of the pinion shaft and a difficulty of heat treatment, and is also a problem to be solved by those skilled in the art at present.

Disclosure of Invention

In view of the above, the present invention aims to provide a deformation control process for a heat treatment of an elongated gear shaft, which can effectively solve the problems of high rejection rate of parts due to the fact that the deformation of bending and torsion is large in the heat treatment process of the elongated gear shaft, and the depth and hardness of an effective hardened layer of a tooth surface cannot be guaranteed after subsequent finish machining.

In order to achieve the purpose, the invention provides the following technical scheme:

a deformation control process method for the heat treatment of an elongated gear shaft comprises the following steps:

rough machining;

after rough machining, performing stress relief annealing treatment on the part;

hobbing, wherein hobbing is carried out on two ends of the part, and tooth surface grinding allowance is reserved;

carburizing, and detecting the deformation direction and the deformation of the part after carburizing;

pressurizing, straightening and quenching, namely selecting a pressurizing position according to the deformation direction and the deformation of the part, and correspondingly arranging a supporting component; placing a pressurizing weight at the upper end of the part corresponding to the pressurizing position; integrally hoisting the part, the supporting part and the pressure weight into a quenching furnace for heat preservation, and then integrally hoisting out quenching oil;

and (4) carrying out low-temperature tempering stress relief treatment after quenching.

Preferably, in the above method for controlling deformation of a elongated gear shaft by heat treatment, the support member includes a support plate and a support block, and the selecting a pressing position and the correspondingly setting a support member specifically include:

and arranging a support flat plate, selecting a pressurizing position, and correspondingly arranging support blocks, wherein the support blocks are placed on the support flat plate.

Preferably, in the above-mentioned slender gear shaft heat treatment deformation control process method, the support block includes an upper support block and a lower support block which are oppositely arranged, grooves for clamping the parts are respectively formed on the upper support block and the lower support block, and the top of the upper support block is placed with the pressure weight for loading.

Preferably, in the above-mentioned elongated gear shaft heat treatment deformation control process, the grooves of the upper support block and the lower support block are both semicircular grooves, and the radius of the semicircular groove is consistent with the radius of the part at the corresponding support position.

Preferably, in the above method for controlling deformation of a slender gear shaft by heat treatment, the selecting a pressing position and the correspondingly setting a support block specifically include:

and the supporting blocks are respectively arranged at the journals at two ends of the part, the journals of the tooth parts at two ends and the middle position of the part, and the top end of each supporting block is pressurized to ensure that the axes of the tooth parts at two ends are consistent with the axis of the whole part.

Preferably, in the above-mentioned slender gear shaft heat treatment deformation control process, the height of the support block satisfies that the distance between the tooth part of the part and the support plate is within the range of 100-200 mm.

Preferably, in the above-mentioned slender gear shaft heat treatment deformation control process method, in the pressurizing, straightening and quenching treatment process, the temperature is increased and equalized in stages at 600 ± 100 ℃, then the temperature is increased to the quenching temperature of 780-880 ℃, and after the heat is preserved for the preset time, the quenching is performed.

Preferably, in the above-mentioned elongated gear shaft heat treatment deformation control process, the carburizing treatment of the part specifically includes:

and (3) carburizing the parts, wherein the carburization process is carried out by carrying out stage temperature equalization for 2-4 h at 600 +/-80 ℃, 700 +/-50 ℃ and 800 +/-50 ℃, then heating to 900 +/-20 ℃ for carburization, and cooling to 800-700 ℃ along with the furnace after carburization, and then discharging for air cooling.

Preferably, in the above method for controlling deformation of a elongated gear shaft by heat treatment, the stress relief annealing treatment of the part after the rough machining specifically includes:

after rough machining, the part is subjected to stress relief annealing treatment at 600 +/-100 ℃.

Preferably, in the above method for controlling deformation of a long and thin gear shaft by heat treatment, the step of performing low-temperature tempering stress relief treatment after quenching specifically includes:

and (3) performing low-temperature tempering stress relief treatment at 150-250 ℃ after quenching.

By applying the heat treatment deformation control process method for the slender gear shaft, rough machining is firstly carried out, and a finish machining allowance is reserved for a non-carburized quenching part. And (5) after rough machining, performing stress relief annealing treatment on the part. And then hobbing the two ends of the part, and reserving tooth surface grinding allowance. And performing carburizing treatment, and detecting the deformation direction and the deformation of the part after carburizing. And selecting a pressurizing position according to the deformation direction and the deformation amount of the part, and correspondingly arranging a supporting component. And placing a pressurizing weight at the upper end of the part corresponding to the pressurizing position to pressurize, then integrally hoisting the part, the supporting part and the pressurizing weight into a quenching furnace for heat preservation for preset time, integrally hoisting out quenching oil, and performing low-temperature tempering stress relief treatment after quenching. Through the technical process, the support points are arranged in the quenching process, and the pressure quenching is carried out on the support points, so that the quenching deformation is effectively reduced, the qualified product rate is greatly improved, the rejection rate is obviously reduced, and the problem of deformation control of the long gear shaft with the large-span herringbone teeth is solved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic flow diagram of a method for controlling deformation of an elongated gear shaft during heat treatment according to an embodiment of the present invention;

FIG. 2 is a schematic view of the parts pressing position and manner;

FIG. 3 is a schematic view of the support block configuration;

fig. 4 is a schematic view of the structure of the surface a-a in fig. 3.

The drawings are numbered as follows:

the supporting device comprises a first supporting block 11, a second supporting block 12, a third supporting block 13, a groove 2, a supporting flat plate 3 and a gear shaft 4.

Detailed Description

The embodiment of the invention discloses a heat treatment deformation control process method for a slender gear shaft, which is used for uniformly releasing stress during and after heat treatment of the gear shaft, reducing the bending and twisting deformation of parts and improving the qualified product rate.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a schematic flow chart of a heat treatment deformation control process method for an elongated gear shaft according to an embodiment of the invention.

In one embodiment, the invention provides a heat treatment deformation control process method for an elongated gear shaft, which comprises the following steps:

s1: and (5) rough machining.

Specifically, a reasonable processing route and stress relief treatment are designed according to the structural form of the part, the gear shaft 4 is roughly processed according to the process route, and a finish machining allowance is reserved for the non-carburized quenching part.

S2: and (5) after rough machining, performing stress relief annealing treatment on the part.

Because the part length is longer, and whole machining allowance is big, in order to prevent the machining stress that produces of too big processingquantity, after the part rough machining, carry out destressing annealing to the part earlier, carry out subsequent processing again. The machining stress of the parts is eliminated through stress relief treatment, so that the machining precision of the left and right end tooth parts is ensured, and the deformation generated by the release of mechanical stress in the heat treatment process is reduced.

S3: and (4) hobbing, wherein hobbing is carried out on two ends of the part, and tooth surface grinding allowance is reserved.

After the stress relief annealing of the parts, the semi-finish turning and the gear hobbing are performed, and for specific process procedures, process parameters and the like, reference is made to a conventional machining process of the elongated gear shaft 4 in the prior art, which is not specifically limited herein.

S4: and (4) carburizing, and detecting the deformation direction and deformation of the part after carburizing.

After the carburization treatment, size and deformation detection can be carried out on a lathe, and deformation detection data is collected to carry out arrangement analysis so as to research the deformation condition after carburization. And then calculating and analyzing the deformation trend of the part according to the deformation detection result. The specific calculation and analysis method can refer to a conventional deformation analysis mode in the prior art, and is not described herein again.

S5: and (5) pressurizing, straightening and quenching treatment. The process specifically comprises the following steps:

s51: selecting a pressurizing position according to the deformation direction and the deformation amount of the part, and correspondingly arranging a supporting component;

according to the deformation direction and the deformation amount of the part obtained by the detection in the step S4, the pressing position is selected, specifically, the position with the larger deformation amount can be used as a pressing position setting support part for supporting, the number of the pressing positions can be set as required, and the number is not limited specifically here.

S52: placing a pressurizing weight at the upper end of the part corresponding to the pressurizing position;

i.e., from the upper end of the part, and optionally placing a pressure weight to provide pressure for ease of operation. The weight of the specific pressure-added weight may be set as needed, and is not particularly limited herein, and preferably, the weight of the pressure-added weight is obtained by strength calculation. The strength of the part is calculated according to the diameter of the journal of the part, the pressure required by the bending deformation of the part at high temperature is calculated, and the pressurizing weight is correspondingly set so as to select a proper pressurizing object.

S53: integrally hoisting the part, the supporting part and the pressurized heavy object into a quenching furnace for heat preservation, and then integrally hoisting out quenching oil;

the parts are placed on the supporting part, the whole part is hoisted into a quenching furnace for quenching and heating after the parts are placed on the supporting part and the pressurized heavy objects are placed, and then the whole part is hoisted out for quenching and cooling, such as quenching oil. The oil groove is opened for stirring in the cooling process, and the parts are moved up and down and rotated to ensure uniform cooling and reduce deformation.

Specifically, the supporting component can be placed on the quenching clamping fixture, the supporting component, the part and the pressurized heavy object are integrally hoisted into the quenching furnace during hoisting, and the quenching oil is integrally hoisted after the temperature is kept for a period of time.

S6: and (4) carrying out low-temperature tempering stress relief treatment after quenching.

After quenching is finished, low-temperature tempering stress relief treatment is immediately carried out, then the hardness, the performance, the metallographic structure and the like of the part can be detected as required, the deformation amount is detected, and the subsequent processing alignment requirement is met.

By applying the heat treatment deformation control process method for the slender gear shaft, provided by the invention, the support points are arranged in the quenching process, and the pressure quenching is carried out on the support points, so that the quenching deformation is effectively reduced, the qualified product rate is greatly improved, the rejection rate is obviously reduced, and the problem of deformation control of the long gear shaft with the large-span herringbone teeth is solved.

Specifically, the support component includes support flat 3 and supporting shoe, then selects the pressurization position to the corresponding support component that sets up specifically includes: and arranging a support flat plate 3, selecting a pressurizing position, and correspondingly arranging a support block, wherein the support block is placed on the support flat plate 3. Firstly, the support flat plate 3 is kept horizontal, specifically, the support flat plate 3 can be placed on a quenching mould and kept horizontal, a support block is placed at a corresponding position on the support flat plate 3 according to a pressurizing position, then a carburized part is placed on the support block, the part is kept horizontal, and the pressurizing position is opposite to the support block. The support plate 3 needs to ensure enough design strength and machining precision requirements so that the part can keep a straight state in the quenching process, and the deformation of the part is reduced. According to the difference of the supporting positions of the supporting blocks for the parts, the heights of the supporting blocks are correspondingly set so as to meet the requirement that the supporting blocks horizontally support the parts, and the bottom surfaces of the supporting blocks are on the same horizontal plane under the condition that the axes of the tooth parts at the two ends of the parts are consistent with the axis of the whole part.

Further, the supporting shoe includes relative last supporting shoe and the bottom suspension fagging that sets up, offers the recess 2 that is used for the centre gripping part on going up the supporting shoe and the bottom suspension fagging respectively, and the top of going up the supporting shoe is placed the pressurization heavy object with the loading. Namely, a lower supporting block is arranged according to the pressurizing position, then the part is correspondingly placed on the lower supporting block, the position of the upper supporting block corresponding to the lower supporting block is placed on the part, a pressurizing weight is placed at the top of the upper supporting block, and the part is loaded through the upper supporting block. It should be noted that the shapes of the grooves 2 on the upper support block and the lower support block need to be correspondingly set according to the shapes of the corresponding pressurizing positions of the parts so as to well fit the parts, and the force loading is more uniform. Through the arrangement of the supporting block structure, a pressurized heavy object is convenient to place, namely pressurized straightening quenching is convenient, and the relative positions of the parts and the supporting block are not easy to loosen. According to the requirement, only the lower supporting block can be arranged, and the pressurizing heavy object is directly placed on the part to be loaded, but the placing is inconvenient.

Furthermore, the grooves 2 of the upper supporting block and the lower supporting block are semicircular grooves, and the radius of each semicircular groove is consistent with that of the part at the corresponding supporting position. And then go up the bracer and the bottom suspension splice can be fine support and the loading to the part, the part atress is even, places also comparatively steadily. Specifically, referring to fig. 3 and 4, the structure of the upper supporting block and the lower supporting block, fig. 3 is a schematic structural diagram of the supporting block; fig. 4 is a schematic view of the structure of the surface a-a in fig. 3.

In each of the above embodiments, selecting the pressing position and correspondingly setting the supporting block specifically includes: supporting blocks are respectively arranged at the journals at two ends of the part, the journals of the tooth parts at two ends and the middle position of the part, and the top ends of the supporting blocks are pressurized to ensure that the axes of the tooth parts at two ends are consistent with the axis of the whole part. According to the structure of the part, the tooth part is prevented from being supported, the tooth part is prevented from collapsing and deforming, the shaft neck close to the tooth part is selected for supporting, and meanwhile, the middle part of the part is supported. Namely, the journals at two ends of the part (phi A in figure 2) are respectively provided with a first supporting block 11, the journals at two teeth parts (phi B in figure 2) are respectively provided with a second supporting block 12, the middle position of the part (phi C in figure 2) is provided with a third supporting block 13, the two first supporting blocks 11, the two second supporting blocks 12 and the third supporting block 13 are matched with the corresponding positions in size, and the five-point pressurization is designed to ensure the consistency of the axes of the teeth parts at two ends and the axis of the whole part.

Further, the height of the supporting block meets the requirement that the distance between the tooth part of the part and the supporting plate is within the range of 100-200 mm. That is, the height design of each supporting block ensures that the tooth part has a distance of 100-200 mm from the supporting plate so as to ensure the flowing of the quenching medium and the quenching effect. For the position of the tooth tool withdrawal groove which needs to be supported, the thickness and the matching circular arc of the supporting plate are designed, so that the crush injury is avoided.

On the basis of the above embodiments, in the process of pressurizing, straightening and quenching treatment, temperature is increased and equalized in stages at 600 +/-100 ℃, then the temperature is increased to the quenching temperature of 780-880 ℃, and after heat preservation for a preset time, quenching and cooling are performed. Namely, the lifting appliance, the parts, the supporting component and the pressurized heavy object are integrally lifted into a carburizing quenching furnace for quenching and heating, the temperature is increased and equalized in sections at 600 +/-100 ℃ in the heating process, the heating stress is reduced, and then the temperature is increased to the quenching temperature of 780-880 ℃ for quenching and heating. After the quenching heating is finished, quenching oil is carried out, and the specific preset time can be set according to the conventional quenching process, and is not limited specifically here.

In each of the above embodiments, the part carburizing process specifically includes: and (3) carburizing the parts, wherein the carburization process is carried out by carrying out stage temperature equalization for 2-4 h at 600 +/-80 ℃, 700 +/-50 ℃ and 800 +/-50 ℃, then heating to 900 +/-20 ℃ for carburization, and cooling to 800-700 ℃ along with the furnace after carburization, and then discharging for air cooling. Namely, the carburization process adopts the steps of temperature equalization for 2-4 hours at 600 +/-80 ℃, 700 +/-50 ℃ and 800 +/-50 ℃, so that the thermal stress in the carburization heating process is reduced, and the bending deformation of parts is prevented.

Further, after rough machining, the stress relief annealing treatment of the part in the above embodiment specifically includes: after rough machining, the part is subjected to stress relief annealing treatment at 600 +/-100 ℃. Namely, the temperature range of the stress relief annealing treatment after the rough machining is 600 + -100 ℃, so as to effectively remove the stress.

Furthermore, after quenching, low-temperature tempering stress relief treatment is carried out, and the method specifically comprises the following steps: and (3) performing low-temperature tempering stress relief treatment at 150-250 ℃ after quenching. Namely, the temperature range of the low-temperature tempering stress relief after quenching is 150-250 ℃, so as to effectively relieve the stress.

The following description is given with reference to a specific embodiment.

The pinion shaft 4 is scrapped because the deformation of the pinion shaft is too large after carburization and quenching and the pinion shaft cannot be straightened. The total length of the gear shaft 4 is 2271mm, the maximum span of the left herringbone teeth and the right herringbone teeth is 1956mm, the span is large, and the heat treatment deformation control difficulty is great. By adopting the conventional carburizing and quenching process, the six gear shafts of 2 batches cannot be processed due to overlarge deformation, and the deformation rejection rate is close to 100%. By adopting the improved process, the quenching deformation is reduced by adopting a scheme of multi-point supporting and pressure quenching for the supporting part, the maximum jumping amplitude of the tooth part reaches more than 80%, the deformation of the middle part is within the range of 1-2 mm, and the subsequent processing requirements can be met. The improved process scheme successfully improves the qualified product rate from 0 to nearly 90 percent, and greatly reduces the rejection rate.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (4)

1. A heat treatment deformation control process method for an elongated gear shaft is characterized by comprising the following steps:

rough machining;

after rough machining, performing stress relief annealing treatment on the part;

hobbing, wherein hobbing is carried out on two ends of the part, and tooth surface grinding allowance is reserved;

carburizing, and detecting the deformation direction and the deformation of the part after carburizing;

pressurizing, straightening and quenching, namely selecting a pressurizing position according to the deformation direction and the deformation of the part, and correspondingly arranging a supporting component; placing a pressurizing weight at the upper end of the part corresponding to the pressurizing position; integrally hoisting the part, the supporting part and the pressure weight into a quenching furnace for heat preservation, and then integrally hoisting out quenching oil;

carrying out low-temperature tempering stress relief treatment after quenching;

the support component comprises a support flat plate and a support block, the pressurizing position is selected, and the support component is correspondingly arranged, and the method specifically comprises the following steps:

the supporting blocks are respectively arranged at the journals at two ends of the part, the journals of the toothed parts at two ends and the middle position of the part, the top ends of the supporting blocks are pressurized to ensure that the axes of the toothed parts at two ends are consistent with the axis of the whole part, and the supporting blocks are placed on the supporting flat plate;

in the process of pressurizing, straightening and quenching treatment, heating up to 600 +/-100 ℃ in a segmented manner and then keeping the temperature to be 780-880 ℃, and then quenching and cooling after keeping the temperature for a preset time;

the part carburizing treatment specifically comprises the following steps:

carburizing the parts, carrying out stage temperature equalization for 2-4 h at 600 +/-80 ℃, 700 +/-50 ℃ and 800 +/-50 ℃ in the carburizing process, then heating to 900 +/-20 ℃ for carburizing, and cooling to 800-700 ℃ along with the furnace after carburizing, and then taking out of the furnace for air cooling;

the supporting block comprises an upper supporting block and a lower supporting block which are oppositely arranged, grooves for clamping the parts are respectively formed in the upper supporting block and the lower supporting block, and the top of the upper supporting block is used for placing the pressurizing weight for loading;

the grooves of the upper supporting block and the lower supporting block are semicircular grooves, and the radius of each semicircular groove is consistent with that of the corresponding supporting position.

2. The heat treatment deformation control process method for the slender gear shaft according to claim 1, wherein the height of the supporting block is such that the distance between the tooth part of the part and the supporting plate is in the range of 100 to 200 mm.

3. The elongated gear shaft heat treatment deformation control process method according to claim 1 or 2, wherein the stress relief annealing treatment of the part after the rough machining specifically comprises:

after rough machining, the part is subjected to stress relief annealing treatment at 600 +/-100 ℃.

4. The elongated gear shaft heat treatment deformation control process method according to claim 3, wherein the low-temperature tempering stress relief treatment is performed after the quenching, and specifically comprises:

and (3) performing low-temperature tempering stress relief treatment at 150-250 ℃ after quenching.

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