JP2014162933A - Method and device for heat treatment of shaft parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for heat treatment of shaft parts capable of uniformly cooling in axial symmetry and suppressing heat deformation.SOLUTION: A method for heat treatment of shaft parts comprises: a hardening step of heating a jig 51 having a plurality of rectified cylindrical bodies 50 in which shaft parts 1 are inserted, and then promoting decomposition of a vapor film formed in the shaft parts 1 with a vapor film formed in the rectified cylindrical bodies 50 by immersing the jig 51 into an oil 15 in an oil tank 11, so as to harden the shaft parts 1; a bubble supply step of detecting a temperature of the oil in the oil tank, and promoting decomposition of the vapor film formed in the surface of the shaft parts 1 by supplying bubbles of an inert gas from a lower part of the jig 51 in the oil tank 11 when the detected temperature is equal to or more than a predetermined temperature; a bubble supply stop step of stopping supplying bubbles when the temperature of the oil 15 is less than the predetermined temperature; and a step of carrying the jig 51 out of the oil tank 11 after the elapsed time after stopping supplying bubbles exceeds a predetermined time.

Description

  The present invention relates to a heat treatment method and a heat treatment apparatus for a shaft component, and more particularly to a technique for suppressing or preventing deformation of a shaft component that occurs during oil quenching.

  A shaft component such as a CVT pulley used for a continuously variable transmission is required to be processed into an axially symmetric uniform shape for accuracy.

  A shaft part that is a workpiece may be deformed (shaft of the shaft) in an oil quenching process that is one of the machining processes. In this case, in order to correct the deformation of the shaft component, there is a method of correcting by a press or the like, but this leads to a decrease in the strength of the shaft component and an increase in cost, so it is important to prevent the deformation during oil quenching. ing. One of the factors causing deformation of the shaft parts during oil quenching is uneven cooling during oil quenching, and uniform cooling that is axisymmetric is required to eliminate the uneven cooling.

  However, in the conventional heat treatment method or heat treatment apparatus for shaft parts, the shaft parts are set in a dedicated jig, and the shaft parts are heated together with the special jig to a high temperature in a heating furnace, and then upward from below. The shaft parts were soaked in oil for quenching that forcedly generated convection to quench the shaft. Therefore, the oil flow velocity distribution tends to be non-uniform, and the oil flow varies due to the influence of the shaft parts, resulting in an imbalance in the cooling speed on the surface of the shaft parts, resulting in uneven cooling and deformation of the shaft parts. Was invited.

  In addition, as related technology, when a steel pipe is hardened with an inner surface flow that flows inside the steel pipe and an outer surface flow that flows outside the steel pipe by covering the steel pipe with a cylindrical cover in the immersion layer and injecting a cooling medium into the cover. In addition, the steel pipe support plate that supports the steel pipe within the cover further changes the outer surface flow into a swirl flow that swirls along the outer peripheral surface of the steel pipe, thereby achieving uniform hardening of the steel pipe (Patent Document 1). However, since this technique has a structure in which a support plate is in contact with the outer peripheral surface of a steel pipe and inhibits the collapse of a vapor film formed on the surface during oil quenching, it cannot be applied to shaft parts.

  On the other hand, as shown in FIG. 8, the change in oil temperature during oil quenching includes a vapor film stage in which a vapor film is first generated on the surface of the workpiece and gradually cools down, and then the surroundings of the workpiece. There are three stages, a boiling stage in which the oil boils and drops rapidly, and finally a convection stage in which the temperature gradually drops while causing convection, and as a method of promoting the collapse of the vapor film in the first vapor film stage, ( 1) There is a method of applying vibration to the jig that supports the shaft component, (2) a method of arranging a dummy work below the shaft component, etc., but the method (1) requires a special device. This method can not rectify the oil, but will be disturbed.

JP 2010-84172 A

  The objective of this invention is providing the heat processing apparatus of the shaft components which can perform uniform cooling of axisymmetric and can suppress a deformation | transformation.

  In the heat treatment method for a shaft part according to one aspect of the present invention, after heating a jig having a plurality of flow straightening cylinders into which the shaft parts are inserted, the jig is immersed in oil in an oil tank to form a flow straightening cylinder. A quenching process in which the steam film formed on the shaft component is accelerated by the formed steam film to quench the shaft component, and the temperature of the oil in the oil tank is detected, and the detected temperature is equal to or higher than a predetermined temperature. A bubble supplying step of supplying bubbles of an inert gas from below the jig in the oil tank to further promote the collapse of the vapor film formed on the surface of the shaft component, and the detection temperature of the oil is predetermined. A bubble supply stop process for stopping the supply of bubbles when the temperature falls below the temperature, and a process for unloading the jig from the oil tank after the elapsed time after the bubble supply stop exceeds a predetermined time. Yes.

  It is preferable that the oil in the oil tank is configured to generate an upward flow that rises in the oil tank in which the jig is immersed and a downward flow that descends around the upward flow.

  A heat treatment apparatus for a shaft component according to another aspect of the present invention includes a plurality of rectifiers for accelerating the collapse of the vapor film formed on the surface of the shaft component by inserting the shaft component and the vapor film formed on the surface. A jig having a cylindrical body, an oil tank storing oil for immersing the jig to quench the shaft component, a transport mechanism for carrying the jig into and out of the oil tank, and the jig in the oil tank. A bubble generator that generates bubbles of inert gas to promote the collapse of the vapor film formed on the surface of the shaft component in the jig, and the temperature of the oil in the oil tank Generating a bubble from the bubble generating device when a detected temperature detected by the temperature sensor is equal to or higher than a predetermined temperature, and then generating a bubble when the oil temperature falls below a predetermined temperature. Stop And a control device for measuring the immersion time of the shaft component from the time when the generation of bubbles is stopped and causing the jig to carry out the jig from the oil tank when the immersion time is equal to or longer than a set time. ing.

  Preferably, an oil circulation mechanism is provided in the oil tank for forcibly generating an upward flow that rises in the oil tank and a downward flow that descends around the upward flow. .

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the shaft component heat processing method and shaft component heat processing apparatus which can perform axisymmetric uniform cooling and can suppress thermal deformation.

It is a perspective view which shows one Embodiment of the heat processing apparatus of the shaft components with which this invention is applied. It is a sectional side view which shows the jig | tool used at the time of the oil quenching of shaft components. It is a schematic plan view of a jig. It is sectional drawing which shows the rectification | straightening cylinder which covers the outer periphery of shaft components. It is sectional drawing which shows the example of the internal peripheral surface shape of a rectification | straightening cylinder. It is a flowchart for demonstrating the heat processing method of shaft components. It is a graph for demonstrating the temperature of the oil at the time of oil quenching, and the change of the oil around a shaft component. It is a graph which shows the relationship between the clearance gap between a shaft component and a rectification | straightening cylinder, and the flow velocity of oil.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1 and 2, the heat treatment apparatus 10 for the shaft component 1 is for inserting the shaft component 1 and promoting the collapse of the vapor film formed on the surface of the shaft component 1 by the formed vapor film. A jig 51 having a plurality of rectifying cylinders 50 and an oil tank 11 storing oil 15 for carrying the jig 51 and quenching the shaft component 1 are provided. In addition, the heat treatment apparatus 10 is provided below the jig 51 in the oil tank 11, and a conveyance mechanism 12 that carries the jig 51 into and out of the oil tank 11 in order to quench the oil of the shaft component 1. In order to promote the collapse of the vapor film formed on the surface of the shaft component 1, a bubble generating device 13 that generates bubbles of an inert gas such as nitrogen gas is provided.

  Here, the shaft component 1 and the jig 51 will be described. The shaft component 1 is a CVT pulley used in, for example, a continuously variable transmission (CVT), and a fixed flange 3 for the pulley is integrally provided at one end of the shaft 2 as shown in FIG. By adjusting the width between the movable flange for the pulley (not shown) that is slidably attached to the shaft 2 and the fixed flange 3, the CVT pulley can change the belt winding diameter to enable stepless speed change. Yes.

  As shown in FIGS. 2 to 3, the jig 51 includes a plurality of rectifiers so that the fixing flanges 3 of the shaft component 1 adjacent to the upper part and the middle part of the rectangular frame 52 made of a metal frame do not interfere with each other. The cylindrical body 50 is arranged in a planar honeycomb shape with a support frame 53 in a state where the height is different. The rectifying cylinders 50 are arranged with their heights changed alternately so that the fixing flanges 3 of the adjacent shaft parts 1 do not buffer each other.

The rectifying cylinder 50 is formed of a metal having heat resistance and corrosion resistance. The length of the rectifying cylinder 50 is longer than the length of the shaft 2 of the shaft part 1 as shown in FIG. 4, and the gap Sa between the rectifying cylinder 50 and the shaft 2 of the shaft part 1 is 10 to 30 mm, Preferably, it is about 10 to 20 mm. The reason for this will be described with reference to FIG. FIG. 7 shows a flow of 0.5 m / sec on one half (left side) and 0.25 m / sec on the other half (right side) with respect to the central axis of the shaft part 1. It shows the result of calculating the flow velocity by the fluid analysis when there is no rectification cylinder 50 and when the gap Sa is 10 mm, 20 mm, and 30 mm. The analysis conditions are: oil (quenched oil) temperature: 150 ° C., specific gravity: 810.3 kg / m ³ , viscosity: 6.21 mm ² / s, oil flow rate (upward): left side is 0.50 m / s, right side is 0 .25 m / s, shaft diameter of shaft part 1 is 40 mm.

  In the absence of the rectifying cylinder 50, a large difference appears between the left and right sides. On the other hand, by providing the rectifying cylinder 50, a nearly uniform flow was obtained. However, if the gap Sa is increased, the effect is reduced, the flow velocity is lowered, and the cooling performance is impaired. Therefore, the gap Sa is preferably about 10 to 20 mm.

  Moreover, it is preferable that the upper end portion of the flow straightening cylinder 50 is provided with a protruding portion 54 as a spacer that secures a gap Sb for oil to flow between the fixed flange 3 of the shaft component 1. The gap Sb formed by the protrusion 54 is preferably about 10 mm.

  Further, in order to make the flow of oil around the shaft of the shaft component 1 uniform, a spiral groove 55 or a spiral projection is provided on the inner peripheral surface of the rectifying cylinder 50 as shown in FIG. It is preferable that

  Next, the heat treatment apparatus 10 will be described. The heat treatment apparatus 10 includes an oil tank 11 that carries the jig 51 and quenches the shaft part 1, and a transport mechanism 12 that carries the jig 51 into and out of the oil tank 11 in order to quench the shaft part 1. ing. The oil tank 11 is filled with quenching oil 15. The transport mechanism 12 is provided on the upper part of the oil tank 11 via a gantry 16. The transport mechanism 12 includes a metal flange 17 that moves up and down with the jig 51 placed thereon.

  Prior to oil quenching, the jig 51 is carried into the gantry 16 from one side of the gantry 16 (right side in FIG. 1), and after the oil quenching, the jig 51 is placed on the other side of the gantry 16 (left side in FIG. 1). In order to carry it out from the tank, conveying roller conveyors 19 and 20 are provided on the upper wall 18 of the oil tank 11 and the bottom of the flange 17. In this case, the roller conveyors 19 and 20 are installed, for example, above the floor of the factory, and the oil tank 11 is installed below the floor. On the carry-in side of the roller conveyors 19 and 20, a heating furnace (not shown) is provided for housing the shaft component 1 together with the jig 51 and heating it to a predetermined temperature (for example, 850 ° C.).

  The ceiling portion 11 a of the oil tank 11 is provided with an opening 21 through which the jig 51 is carried into and out of the oil tank 11 together with the flange portion 17 by the transport mechanism 12. In the oil tank 11, a space S for securing the jig 51 together with the flange portion 17 and performing oil quenching is secured as indicated by a virtual line. Below this space S, that is, below the jig 51 in the oil tank 11, in order to promote the collapse of the vapor film formed on the surface of the shaft component 1 in the jig 51, bubbles of inert gas, for example, nitrogen gas The bubble generating device 13 is provided to generate and supply the shaft component 1 in the jig 51 to the shaft component 1.

  The bubble generating device 13 has a flat box shape, and an infinite number of holes 22 for generating bubbles are formed on the upper surface thereof. In addition, in order to accelerate | stimulate collapse of the vapor | steam film | membrane formed in the surface of the shaft component 1 and the rectification | straightening cylinder 50, it is preferable that the hole part 22 is made into the fine diameter which produces | generates a fine bubble. A nitrogen gas cylinder 30 that is a gas supply source is connected to the bubble generation device 13 via a gas supply pipe 23 that is piped so as to penetrate the bottom 11 b or the side surface of the oil tank 11 in a liquid-tight manner. Is provided with an electromagnetic valve 24 which is an on-off valve for turning on and off the supply of nitrogen gas. In addition, as a gas supply source of the bubble generating device 13, a nitrogen pipe for replacing gas in an emergency of the heat treatment apparatus can be used.

  In the oil tank 11, forcibly generating an ascending flow that raises the quenching oil 15 along the central portion in the oil tank 11 and a descending flow that descends along the peripheral side portion in the oil tank 11. An oil circulation mechanism 25 is provided. The oil circulation mechanism 25 includes a flow path 26 provided so as to form a downward flow along the peripheral side portion in the oil tank 11, and an agitator (screw) 27 that is a flow generator disposed in the flow path 26. And is composed mainly of.

  In order to automatically quench the shaft component 1, a temperature sensor 28 for detecting the temperature (oil temperature) of the oil 15 in the oil tank 11 is provided in the oil tank 11, and the detected temperature detected by the temperature sensor 28 is Bubbles are generated from the bubble generating device 13 when the temperature is higher than a predetermined temperature, the generation of bubbles is stopped when the temperature of the oil 15 is lower than the predetermined temperature, and the immersion time of the shaft component 1 after the supply of bubbles is stopped is measured. And the control apparatus 29 which carries out the jig | tool 51 from the oil tank 11 by the conveyance mechanism 12 when immersion time is more than setting time is provided.

  Next, the operation of the shaft component heat treatment apparatus having the above-described configuration or the shaft component heat treatment method will be described with reference to the flowchart of FIG.

  First, the agitator 27 is rotated to circulate the oil 15 in the oil tank 11 along the flow path 26 (S1). Next, by driving the transport mechanism 12, the flange portion 17 is lowered, and the jig 51 heated to a predetermined temperature (for example, 850 ° C.) in advance is lowered into the oil tank 11 (S 2), and the shaft component 1 is quenched. To start. In addition, the temperature of the oil in the oil tank 11 is 150 degreeC, for example.

  Since the shaft component 1 is immersed in the oil 15 together with the rectifying cylinder 50 of the jig 51 and the shaft component 1 and the rectifying cylinder 50 are heated to a high temperature, a vapor film is generated on the surface thereof, and the rectifying cylinder 50 The collapse of the vapor film formed on the surface promotes the collapse of the vapor film on the surface of the shaft component 1.

  The temperature (oil temperature) of the oil 15 in the oil tank 11 is measured by the temperature sensor 28 and input to the control device 29, and it is determined whether or not the oil temperature is lower than a predetermined temperature (S4). That is, when the temperature is lower than the predetermined temperature, the measurement of the oil temperature is repeated again.

  When the oil temperature rises to a predetermined temperature or higher, it is determined as YES, the electromagnetic valve 24 of the bubble generating device 13 is opened, and supply of bubbles from the bubble generating device 13 is started (S5). With the passage of time, the oil temperature in the oil tank 11 decreases with the cooling of the shaft component 1.

  Next, it is determined whether or not the oil temperature is lower than a predetermined temperature (S7). If NO, that is, if the predetermined temperature is exceeded, the temperature of the oil temperature is repeated.

  When the oil temperature falls and falls below a predetermined temperature, it is determined YES, the electromagnetic valve 24 of the bubble generating device 13 is closed, and the supply of bubbles is stopped (S8). The immersion time after the jig 51 is lowered into the oil tank 11 and immersed in the oil 15 is measured (S9), and it is determined whether the immersion time is longer than the set time (S10). The soaking time measurement is repeated.

  When the immersion time exceeds the set time, it is determined as YES, the transport mechanism 12 raises the jig 51 from the oil tank 11 (S11), and the heat treatment of the shaft component 1 is completed. As described above, the jig 51 in which the shaft component 1 is inserted into the rectifying cylinder 50 is sequentially supplied to the flange portion 17 of the transport mechanism 12 and the above-described heat treatment is repeated.

  In the heat treatment method, when the shaft component heated to a high temperature is immersed in oil, first, as shown in FIG. 8, a vapor film stage is formed in which a vapor film is formed on the surfaces of the shaft component 1 and the rectifying cylinder 50, and about 800 ° C. To about 600 ° C. After the vapor film stage, the oil around the shaft parts and the rectifying cylinder becomes a boiling stage, and the temperature rapidly drops from about 600 ° C. to about 300 ° C. Then, after the boiling stage, when the oil around the shaft parts and the rectifying cylinder is in the convection stage, the temperature is gradually lowered and the temperature of the quenching oil reaches around 150 ° C., the next heat treatment may be started.

  According to the shaft component heat treatment method and the shaft component heat treatment apparatus configured as described above, the flow of oil around the shaft component 1 can be made uniform, and the collapse of the vapor film on the surface of the shaft component 1 can be promoted. Therefore, axisymmetric cooling can be performed uniformly, deformation (axial bending) can be suppressed or prevented, correction after heat treatment is unnecessary, and high-quality shaft parts 1 with high strength can be provided at low cost. It becomes possible.

  The present invention is not limited to the embodiment described above, and various design changes can be made within the scope of the present invention. For example, in the embodiment, the quenching oil is configured to generate an upward flow that is raised along the central portion in the oil tank and a downward flow that is lowered along the peripheral side portion in the oil tank. Further, it may be configured to generate an upward flow that rises in the oil tank and a downward flow that descends around the upward flow. Therefore, depending on the size of the oil tank, a plurality of regions for forming the upflow and the downflow may be provided and a plurality of jigs may be processed.

  Further, only an upward flow is formed in the oil tank 11, and the raised quenching oil is transferred to another container by overflowing the oil tank 11, etc., and returned to the bottom of the oil tank 11 after foreign matter removal, oil component adjustment, temperature adjustment, etc. It is possible to make a circulation.

DESCRIPTION OF SYMBOLS 1 Shaft component 10 Heat processing apparatus 11 Oil tank 12 Conveyance mechanism 13 Bubble generation apparatus 25 Oil circulation mechanism 28 Temperature sensor 29 Control apparatus 50 Rectification cylinder 51 Jig

Claims (4)

After heating a jig having a plurality of flow straightening cylinders into which shaft parts are inserted, a vapor film formed on the shaft parts by a vapor film formed on the flow straightening cylinders by immersing the jigs in oil in an oil tank A quenching process that accelerates the collapse of the shaft and quenches the shaft parts,
The temperature of the oil in the oil tank is detected, and when the detected temperature is equal to or higher than a predetermined temperature, an inert gas bubble is supplied from below the jig in the oil tank to be formed on the surface of the shaft component. A bubble supply process that further promotes the collapse of the vapor film;
A bubble supply stop step for stopping supply of bubbles when the detected temperature of the oil falls below a predetermined temperature;
A step of unloading the jig from the oil tank after an elapsed time after the bubble supply has stopped exceeds a predetermined time; and
A heat treatment method for a shaft part, comprising: In the heat processing method of the shaft components according to claim 1,
A method for heat-treating a shaft component, wherein the oil in the oil tank generates an upward flow that rises in the oil tank in which the jig is immersed and a downward flow that descends around the upward flow. A jig having a plurality of rectifying cylinders for promoting the collapse of the vapor film formed on the surface of the shaft component by inserting the shaft component and the vapor film formed on the surface;
An oil tank storing oil for immersing the jig and quenching the shaft component;
A transport mechanism for carrying the jig in and out of the oil tank;
A bubble generating device that is provided below the jig in the oil tank and generates bubbles of an inert gas to promote the collapse of a vapor film formed on the surface of the shaft component in the jig;
A temperature sensor for detecting the temperature of oil in the oil tank;
The bubble is generated from the bubble generating device when the detected temperature detected by the temperature sensor is equal to or higher than a predetermined temperature, and then the bubble generation is stopped when the oil temperature falls below a predetermined temperature. A control device for measuring the immersion time of the shaft component from the time of the occurrence of the occurrence, and when the immersion time is equal to or longer than a set time, the jig transports the jig out of the oil tank,
A heat treatment apparatus for shaft parts, comprising: In the heat processing apparatus for a shaft part according to claim 3,
The oil tank is provided with an oil circulation mechanism for forcibly generating an upward flow that rises in the oil tank and a downward flow that descends around the upward flow in the oil tank. Heat treatment equipment.

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