Straightening device for carburized and quenched driving shaft
Patent Information
- Application Number
- CN202611142339.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-30
- Publication Date
- 2026-10-27
AI Technical Summary
[0005]为了解决上述技术问题，本发明提供一种主动轴渗碳淬火后的校直工装，以解决热处理后的硬度及层深要求均能达到，但是变形严重，因其表面硬度较高，很难对其进行校直，严重影响后续加工的问题
[0019]针对20CrMnTi主动轴渗碳淬火后表面硬度达50-56HRC、冷校直易开裂且难以变形的核心痛点，采用200℃低温预热+热态液压校直的组合方式，利用材料在该温度下塑性提升、脆性降低的特性，在不损伤表面硬度和渗碳层深度（0.6—0.8mm）的前提下，实现了热处理后变形轴的有效校直，消除了因变形导致的后续加工障碍。
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Figure CN122974753A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of seawater pump component manufacturing technology, and more specifically, it relates to a straightening tooling for a drive shaft after carburizing and quenching. Background Technology
[0002] The drive shaft is a key component connecting the prime mover (electric motor or diesel engine) and the pump impeller. It is mainly used to transmit power, provide support and positioning, drive the impeller to rotate, and work with shaft sealing devices such as mechanical seals to ensure the pump's sealing performance and operational safety.
[0003] The drive shaft is the core component of the seawater pump transmission system. It serves as the carrier of the impeller and transmits the entire load of the rotor. It generally needs to have characteristics such as high reliability, high wear resistance, high hardness, and high straightness.
[0004] The main production process of the core component, the drive shaft, is as follows: blank forging → normalizing → rough turning of the outer diameter and end face → drilling of the center hole → semi-finish turning and finish turning → carburizing and quenching → rough grinding and finish grinding → oil sealing → warehousing. The material used for the drive shaft is 20CrMnTi. After carburizing and quenching, the surface hardness is required to be 50-56HRC, the carburized layer depth is 06-0.8mm, and the straightness is ≤0.14mm. The hardness and layer depth requirements after heat treatment can be met, but the deformation is severe. Due to its high surface hardness, it is difficult to straighten it, which seriously affects subsequent processing. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a straightening fixture for a drive shaft after carburizing and quenching. This fixture addresses the issue that while the required hardness and depth of the heat-treated shaft can be achieved, severe deformation occurs, making it difficult to straighten due to the high surface hardness, which significantly impacts subsequent processing.
[0006] A straightening fixture for a drive shaft after carburizing and quenching includes a runout meter for detecting the runout of the drive shaft and a hydraulic straightening fixture for thermally straightening the heated drive shaft.
[0007] The eccentricity meter includes a first base, two center seats and a dial indicator. The two center seats are mounted on the upper surface of the first base and their axes coincide with each other. The dial indicator is set between the two center seats.
[0008] The hydraulic straightening fixture includes a second base, a portal frame, a manual hydraulic jack, and two V-shaped blocks. The portal frame is vertically fixed to the upper surface of the second base. The manual hydraulic jack is fixedly installed below the top crossbeam of the portal frame. The two V-shaped blocks are symmetrically arranged on the upper surface of the second base, and both V-shaped blocks are located directly below the manual hydraulic jack. This enables precise hot straightening of the high-hardness drive shaft after carburizing and quenching, solving the industry pain points of easy cracking and difficult deformation correction during cold straightening.
[0009] Preferably, the yaw meter also includes a guide rail, which is fixedly installed on the upper surface of the first base. Two center seats can be slidably installed on the guide rail along its length, which can flexibly adapt to the detection needs of drive shafts of different lengths and greatly improve the applicability and versatility of the tooling.
[0010] Preferably, each center seat has an axially retractable center installed at the end facing the other center seat, and the axes of the two centers are collinear, which can be used to quickly clamp the drive shafts with different diameters, ensure the coaxiality of the support, and shorten the preparation time before testing.
[0011] Preferably, the dial indicator is mounted on the first base via a height-adjustable vertical bracket. The probe of the dial indicator can be vertically abutted against the outer circular surface of the drive shaft to be measured. The height of the dial indicator can be precisely adjusted to adapt to workpieces of different diameters, ensuring that the runout detection data is accurate and reliable.
[0012] Preferably, the portal frame is welded and spliced from channel steel. The bottom of the portal frame is fixedly connected to the upper surface of the second base by welding, providing sufficient rigid support to stably withstand the huge reaction force during straightening and prevent the tooling from deforming and failing.
[0013] Preferably, the hydraulic straightening fixture also includes two return springs, which are symmetrically distributed on the left and right sides of the manual hydraulic jack, so as to realize the automatic reset of the jack head without manual operation, simplifying the straightening process and improving production efficiency.
[0014] Preferably, the upper end of each reset spring is fixedly connected to the top crossbeam of the portal frame via a lifting ring, and the lower end of the reset spring is fixedly connected to the movable pressure head connecting plate of the manual hydraulic jack. This makes the spring easy to install and disassemble, ensures a uniform and symmetrical reset force, avoids pressure head skew, and extends the service life of the tooling.
[0015] Preferably, the V-shaped pad is made of aluminum alloy material, and the upper surface of the V-shaped pad has a V-shaped groove, which effectively protects the surface of the drive shaft from being scratched, and at the same time has good thermal conductivity, which slows down the heat loss rate of the workpiece.
[0016] Preferably, the V-groove axes of the two V-shaped pads are collinear and intersect perpendicularly with the axis of the movable pressure head of the manual hydraulic jack, ensuring that the force direction is perpendicular to the axis during straightening, avoiding lateral bending and significantly improving straightening accuracy.
[0017] Preferably, each center seat is equipped with a locking handle. The locking handle is used to lock the center seat in any sliding position on the guide rail, quickly lock the center seat position, prevent displacement during the test, and ensure stable runout test results.
[0018] Compared with the prior art, the present invention has the following beneficial effects:
[0019] Addressing the core challenges of 20CrMnTi drive shafts, such as surface hardness reaching 50-56 HRC after carburizing and quenching, easy cracking during cold straightening, and difficulty in deformation, a combination of 200℃ low-temperature preheating and hot hydraulic straightening was adopted. Utilizing the material's increased plasticity and reduced brittleness at this temperature, effective straightening of the deformed shaft after heat treatment was achieved without damaging the surface hardness and carburized layer depth (0.6-0.8 mm), eliminating subsequent processing obstacles caused by deformation.
[0020] The straightening accuracy is high and exceeds the technical requirements. The radial runout is accurately quantified and detected by using a runout meter and a dial indicator, and the high point of deviation is accurately located as the force target point. Combined with the controllable and uniform force application method of the hydraulic jack and the stable support and positioning of the V-shaped pad, the straightness of the drive shaft after straightening can be stably reached ≤0.1mm, which is better than the original technical requirement of ≤0.14mm, and fully meets the high-precision assembly requirements of the seawater pump drive shaft.
[0021] The tooling has a simple structure, low manufacturing cost, and strong applicability. The complete tooling adopts a combination of a general-purpose eccentric gauge and a self-made simple hydraulic tooling. The main body of the hydraulic tooling consists of a portal frame welded from channel steel, a standard manual hydraulic jack, and aluminum alloy pads. There is no need to purchase expensive special straightening equipment, and the on-site production is simple and inexpensive. At the same time, the sliding center seat of the eccentric gauge can be adapted to drive shafts of different lengths, which has good versatility.
[0022] It is easy to operate and has high production efficiency. It is suitable for standardized straightening processes in mass production. The operation steps are simple and easy to master. Workers can independently complete the entire process of testing, heating, straightening, and re-inspection after simple training. Moreover, the hydraulic straightening has stable force and fast action. The return spring can realize the automatic reset of the jack head, which greatly shortens the straightening time of a single piece and can meet the efficiency requirements of mass production.
[0023] After straightening, the dimensions are stable and there is no risk of springback. The combination of hot straightening and low-temperature aging treatment can effectively eliminate the residual internal stress generated during the straightening process, prevent the drive shaft from springback deformation during subsequent rough grinding, fine grinding and long-term use, ensure the long-term stability of the part's dimensional accuracy, and improve the operational reliability of the seawater pump transmission system. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the yaw meter structure of the present invention;
[0025] Figure 2 This is a schematic diagram of the hydraulic straightening fixture structure of the present invention.
[0026] In the figure, the correspondence between the component names and the attached drawing numbers is as follows: 1. First base; 2. Guide rail; 3. Center seat; 4. Dial indicator; 5. Second base; 6. Portal frame; 7. Manual hydraulic jack; 8. Lifting ring; 9. Return spring; 10. V-shaped pad. Detailed Implementation
[0027] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.
[0028] Please see Figure 1 and Figure 2 This invention provides a straightening fixture for a drive shaft after carburizing and quenching. It consists of two independent parts: a runout meter for detecting radial runout and a hydraulic straightening fixture for hot straightening. The runout meter includes a first base 1, two center seats 3, and a dial indicator 4. The first base 1 is made of gray cast iron HT200, and its upper surface is ground to a high-precision plane with a flatness ≤0.02mm / m. The two center seats 3 are symmetrically mounted on the upper surface of the first base 1, with their mounting axes strictly coincident and a coaxiality error ≤0.02mm. The dial indicator 4 is a mechanical dial indicator with an accuracy of 0.01mm, fixedly set in the intermediate detection area between the two center seats 3. The hydraulic straightening fixture includes a second base 5, a gantry frame 6, and a manual hydraulic jack 7. The second base 5 is made of Q235 steel plate with a thickness of ≥20mm, and two V-shaped pads 10. The portal frame 6 is a vertically set rigid portal structure, with its bottom fully welded to the upper surface of the second base 5. The manual hydraulic jack 7 is a standard vertical jack with a rated load of 10 tons. The cylinder body is fixed to the center of the top crossbeam of the portal frame 6 by bolts, and the movable pressure head is vertically downward. The two V-shaped pads 10 are symmetrically arranged on the upper surface of the second base 5, and the whole is located within the projection range directly below the movable pressure head of the manual hydraulic jack 7. This achieves precise hot straightening of the 20CrMnTi material drive shaft after carburizing and quenching, solving the problems of easy cracking during cold straightening and difficulty in correcting deformation under high hardness. After straightening, the surface hardness and carburized layer depth are not damaged.
[0029] The yaw meter also includes a guide rail 2, which is a high-precision rectangular linear guide rail. It is fixedly installed along the length of the first base 1 by multiple sets of countersunk bolts. The bottom of the two center seats 3 is machined with a sliding groove that matches the guide rail 2. The sliding groove and the guide rail 2 are fitted with an H7 / h6 clearance, allowing the center seats 3 to slide freely along the length of the guide rail 2 without clearance. This enables continuous stepless adjustment of the distance between the two center seats. It can be adapted to drive shafts of different lengths without changing the tooling, greatly improving the applicability and versatility of the tooling.
[0030] Each center seat 3 has an axial mounting hole at one end facing the other center seat 3, into which a Morse taper 2 telescopic center is slidably mounted. An adjusting screw is connected to the tail of the center; rotating the screw causes the center to extend or retract axially, with a travel of 5-20mm. The tips of the two centers are strictly collinear, with a coaxiality error ≤0.01mm. This allows for quick clamping of drive shafts with different shaft diameters and center hole depths, ensuring coaxial support without repeated alignment and significantly reducing preparation time before testing.
[0031] The dial indicator 4 is mounted on the first base 1 via a height-adjustable vertical bracket. The vertical bracket consists of a bottom fixed base and a cylindrical upright, on which a sliding gauge clamp is fitted. The dial indicator 4's rod is locked and fixed by the gauge clamp. The probe is a spherical probe, which can vertically abut against the outer circular surface of the drive shaft to be measured. The height of the dial indicator can be precisely adjusted to adapt to drive shafts of different diameters, ensuring that the probe makes perpendicular contact with the workpiece surface and that the contact force is uniform, thus guaranteeing the accuracy and repeatability of the runout detection data.
[0032] The portal frame 6 is constructed from two uprights and a top crossbeam. Both the uprights and crossbeam are made of No. 10 hot-rolled channel steel, with the channel steel openings facing outwards. All joints are continuously and fully welded, with a weld leg height ≥ 6mm. The overall verticality of the frame is ≤ 0.03mm / m, ensuring no skewing under load. While maintaining sufficient rigidity and strength, it significantly reduces tooling manufacturing costs and weight, can stably withstand the enormous reaction force during straightening, and remains deformation-free over long-term use.
[0033] The hydraulic straightening fixture also includes two return springs 9, which are cylindrical helical tension springs made of 65Mn material. They are symmetrically distributed on the left and right sides of the manual hydraulic jack 7, with the spring axes parallel to the jack axis. Each spring has a rated tension of 60N, sufficient to reset the jack head. After the manual hydraulic jack is depressurized, the spring tension automatically and quickly resets the movable head, eliminating the need for manual lifting of the head, simplifying the straightening operation and improving batch production efficiency.
[0034] Each return spring 9 has its upper end attached to an internally threaded lifting ring 8, which is bolted to a pre-drilled threaded hole on the lower surface of the top beam of the portal frame 6. The lower end of each return spring 9 is attached to the connecting plate of the movable pressure head of the manual hydraulic jack 7. The connecting plate is made of 10mm thick No. 45 steel plate and is threadedly connected to the movable pressure head. This facilitates the installation and removal of the return springs, ensures uniform and symmetrical return force on both sides, prevents the pressure head from skewing and jamming during return, extends the service life of the tooling, and reduces maintenance costs.
[0035] The V-shaped pad 10 is milled from 6061-T6 aluminum alloy and is in the shape of a rectangular block. The upper surface of the V-shaped pad 10 has a 90° V-groove, and both sides of the V-groove are precision ground and polished, with a surface roughness Ra≤1.6μm. The hardness of the aluminum alloy is lower than that of the hardened drive shaft, effectively protecting the machined surface of the workpiece from scratches. Simultaneously, the good thermal conductivity of aluminum alloy slows down the rate of heat loss from the workpiece, extending the effective straightening window.
[0036] The V-groove axes of the two V-shaped pads 10 are strictly collinear, with a straightness of ≤0.02mm; and this axis intersects perpendicularly with the axis of the movable pressure head of the manual hydraulic jack 7 in the same vertical plane, with a perpendicularity error of ≤0.02mm; the center of the jack pressure head coincides with the line connecting the midpoints of the two V-grooves, ensuring that the pressure direction during straightening is perpendicular to the axis of the drive shaft and acts on the midpoint, avoiding lateral bending and torsional deformation, significantly improving straightening accuracy and batch consistency.
[0037] Each center seat 3 is equipped with a locking handle on its side. The locking handle consists of a plastic handle head with anti-slip texture and an M8 threaded rod. A copper top block is embedded at the end of the threaded rod. Rotating the handle can cause the copper top block to press against the side of the guide rail 2, thereby locking the center seat 3 in any sliding position of the guide rail 2. This enables quick locking and unlocking of the center seat position, preventing displacement of the center seat during the testing process and ensuring the stability and accuracy of the runout test results.
[0038] Working principle:
[0039] The first step is to mount the drive shaft to be calibrated on the runout gauge: the two ends of the drive shaft are supported coaxially by the centers of the two center seats 3. If the lengths of the drive shafts are different, the center seats 3 can be slid along the guide rail 2 to adjust the spacing and then be fixed with the locking handle; rotate the drive shaft so that the probe of the dial indicator 4 is perpendicular to the outer surface of the drive shaft, record the radial runout value throughout the process, and accurately mark the position of the highest point of runout deviation, providing a precise force target point for subsequent calibration.
[0040] The second step is to place the drive shaft marked with the high point into a heat treatment furnace, heat it to 200℃ and hold it at that temperature for an appropriate time to make the drive shaft reach a uniform temperature. By utilizing the characteristics of 20CrMnTi material at this temperature, which increases plasticity and reduces brittleness, the problem of high surface hardness (50-56HRC) and easy cracking after cold straightening after carburizing and quenching is solved.
[0041] The third step is to remove the heated drive shaft and quickly place it in the V-grooves of the two V-shaped pads 10 of the hydraulic straightening fixture; adjust the circumferential position of the shaft so that the pre-marked high point of deviation is vertically upward and strictly aligned with the axis of the movable pressure head of the manual hydraulic jack 7, ensuring that the axes of the V-grooves of the two V-shaped pads 10 are collinear and perpendicularly intersecting with the axis of the jack pressure head, ensuring accurate force direction during straightening and avoiding lateral deformation.
[0042] Fourth, manually operate the lever of the manual hydraulic jack 7 to drive the movable pressure head to move slowly downward, applying uniform and controllable pressure to the out-of-tolerance high point of the drive shaft; the portal frame 6 welded from channel steel serves as a rigid force support, bearing the huge reaction force generated during the straightening process and ensuring the overall stability of the tooling; after maintaining the pressure for 3-5 seconds, slowly open the jack's pressure relief valve. At this time, the two symmetrically arranged return springs 9 are suspended from the top of the portal frame 6 through the upper lifting ring 8, and automatically pull the movable pressure head of the jack back to the initial position after the pressure is released, completing one straightening action.
[0043] Fifth, after the drive shaft has cooled to room temperature naturally, re-clamp it back into the runout tester and use dial indicator 4 to check the radial runout again to confirm whether the straightness meets the requirement of ≤0.1mm. If there is still a deviation, repeat the heating, clamping, and straightening steps above until the accuracy is qualified.
[0044] The sixth step is to perform low-temperature aging treatment on the straightened drive shaft to eliminate residual internal stress generated during the hot straightening process, prevent springback deformation of the parts during subsequent processing and use, and ultimately stabilize the dimensional accuracy and straightness of the parts to meet the technical requirements of the seawater pump drive shaft.
[0045] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.
Claims
1. A straightening fixture for a drive shaft after carburizing and quenching, characterized in that: This includes a runout meter for detecting the runout of the drive shaft and a hydraulic straightening fixture for thermally straightening the heated drive shaft. The sway gauge includes a first base (1), two center seats (3) and a dial indicator (4). The two center seats (3) are mounted on the upper surface of the first base (1) and their axes coincide with each other. The dial indicator (4) is set between the two center seats (3). The hydraulic straightening fixture includes a second base (5), a portal frame (6), a manual hydraulic jack (7), and two V-shaped pads (10). The portal frame (6) is vertically fixed to the upper surface of the second base (5). The manual hydraulic jack (7) is fixedly installed below the top crossbeam of the portal frame (6). The two V-shaped pads (10) are symmetrically arranged on the upper surface of the second base (5), and both V-shaped pads (10) are located directly below the manual hydraulic jack (7).
2. The straightening fixture for a drive shaft after carburizing and quenching as described in claim 1, characterized in that, The yaw meter also includes a guide rail (2), which is fixedly installed on the upper surface of the first base (1). Two top seats (3) can be slidably installed on the guide rail (2) along the length of the guide rail (2).
3. The straightening fixture for a drive shaft after carburizing and quenching as described in claim 2, characterized in that, Each of the top seats (3) has an axially retractable top at one end facing the other top seat (3), and the axes of the two tops are collinear.
4. The straightening fixture for a drive shaft after carburizing and quenching as described in claim 3, characterized in that, The dial indicator (4) is mounted on the first base (1) via a height-adjustable vertical bracket, and the probe of the dial indicator (4) can be perpendicularly pressed against the outer circular surface of the active shaft to be measured.
5. The straightening fixture for a drive shaft after carburizing and quenching as described in claim 4, characterized in that, The portal frame (6) is made of channel steel welded together, and the bottom of the portal frame (6) is fixedly connected to the upper surface of the second base (5) by welding.
6. The straightening fixture for a drive shaft after carburizing and quenching as described in claim 5, characterized in that, The hydraulic straightening fixture also includes two return springs (9), which are symmetrically distributed on the left and right sides of the manual hydraulic jack (7).
7. The straightening fixture for a drive shaft after carburizing and quenching as described in claim 6, characterized in that, The upper end of each return spring (9) is fixedly connected to the top beam of the portal frame (6) via a lifting ring (8), and the lower end of the return spring (9) is fixedly connected to the movable pressure head connecting plate of the manual hydraulic jack (7).
8. The straightening fixture for a drive shaft after carburizing and quenching as described in claim 7, characterized in that, The V-shaped pad (10) is made of aluminum alloy material, and a V-shaped groove is provided on the upper surface of the V-shaped pad (10).
9. The straightening fixture for a drive shaft after carburizing and quenching as described in claim 8, characterized in that, The V-groove axes of the two V-shaped pads (10) are collinear and intersect perpendicularly with the movable pressure head axis of the manual hydraulic jack (7).
10. The straightening fixture for a drive shaft after carburizing and quenching as described in claim 9, characterized in that, Each center seat (3) is provided with a locking handle, which is used to lock the center seat (3) in any sliding position of the guide rail (2).