JP7376439B2 - Workpiece processing method - Google Patents

Description

The present invention relates to a reduction gear device and a workpiece processing method.

Patent Document 1 describes a flexible mesh type speed reduction device. In this speed reduction device, a rolling element is disposed between the casing and the output flange, and the output flange is rotatably supported by the casing via the rolling element. The output side flange body is provided with a rolling surface on which the rolling elements roll, as well as a hole into which a bolt is screwed.

Japanese Patent Application Publication No. 2011-112214

A component having a rolling surface, such as the output side flange body of Patent Document 1, is required to have a highly hardened rolling surface in order to improve fatigue strength. To achieve this, generally a surface hardening process such as deep hardening is used that can harden the entire workpiece to be heat treated.

In a member with a hole such as the above-mentioned output side flange body, drilling for providing a hole in the workpiece may be performed after surface hardening treatment. In this case, if the entire workpiece is hardened by quenching, problems such as shortened tool life will occur during drilling. No reduction gear device has yet been proposed that takes into account the workability of the workpiece that is the material for the holed member.

The present invention has been made in view of these circumstances, and an object of the present invention is to provide a reduction gear device that has good workability during machining of a workpiece that is a material to be machined into a member with a hole.

One aspect of the present invention relates to a speed reduction device. The speed reducer includes a rolling surface on which rolling elements roll and a holed member provided with a hole, and the holed member includes a base material region and a surface side from the base material region. A hardened surface layer having a higher hardness than the base material region is provided in the hardened surface layer, and the hardened surface layer is provided with a surface layer region and a hardness transition region in order from the surface in a vertical depth direction, and in the depth direction When the amount of change in Vickers hardness per 0.1 mm is defined as the amount of change in hardness, the surface layer region is continuous from the surface to the hardness transition region and includes a portion where the amount of hardness change is 0 or more, The transition region includes a portion where the hardness continuously decreases in the depth direction and the amount of change in hardness is −60 or less, and the rolling surface is provided on the surface of the surface layer region, and the rolling surface is provided on the surface of the surface layer region, A portion is provided in the base material region.

Another aspect of the present invention relates to a method for processing a workpiece. This method is a method for processing a workpiece that is a material for a member with holes, in which the member with holes is provided with a rolling surface on which the rolling element rolls and a hole portion, and the rolling element of the workpiece is provided with a rolling surface and a hole portion. A hardening process in which a surface hardening layer is provided by quenching the part that is to become a surface by irradiating a laser beam, and a hardening process that leaves a base material region without hardening the part that is to become a hole in the workpiece; and a drilling step of drilling a hole in the base material region at a location where the hole is to be formed.

According to the present invention, it is possible to provide a reduction gear device with good workability during machining of a workpiece that is a material to be machined into a member with a hole.

It is a sectional view showing a reduction gear device of a 1st embodiment. FIG. 2 is an enlarged view showing the rolling element of FIG. 1 together with surrounding structures. It is a figure which shows typically the hardness distribution of the 1st carrier member of 1st Embodiment. It is a graph which shows an example of the hardness distribution of the 1st carrier member of 1st Embodiment. It is another graph which shows an example of the hardness distribution of the 1st carrier member of 1st Embodiment.

Hereinafter, in the embodiments and modified examples, the same components are denoted by the same reference numerals, and redundant explanations will be omitted. Further, in each drawing, for convenience of explanation, some of the constituent elements are omitted as appropriate, and the dimensions of the constituent elements are illustrated with enlarged or reduced dimensions as appropriate. In addition, separate components that have something in common are distinguished by adding "first, second" etc. to the beginning of the name and "-A, -B" etc. to the end of the code, and are referred to collectively. In some cases, these are omitted.

FIG. 1 is a sectional view showing a reduction gear device 10 according to the first embodiment. The speed reduction device 10 of the present embodiment is a flexible mesh type speed reduction device that rotates the external gear 22 meshing with the internal gear 24 while bending and deforming it, thereby causing the external gear 22 to rotate and outputting its rotation component.

The speed reducer 10 mainly includes a casing 12, a pair of carriers 14, a plurality of rolling elements 16, a vibration generator 18, a vibration generator bearing 20, an external gear 22, an internal gear 24, Equipped with

The casing 12 is a cylindrical member, and a pair of carriers 14 are arranged inside the casing 12. The pair of carriers 14 are rigid cylindrical members. The pair of carriers 14 are arranged at intervals in the axial direction X, which will be described later, and the vibrating body 18 is arranged inside thereof.

One carrier 14 (carrier on the right side in the figure; hereinafter referred to as input carrier 14-A) is non-rotatably assembled to the casing 12 with bolts 26. The input carrier 14-A is connected to a drive device such as a motor by a bolt (not shown) screwed into a bolt hole 28.

The other carrier 14 (the carrier on the left side in the figure; hereinafter referred to as output side carrier 14-B) is rotatably supported by the casing 12 via rolling elements 16. The output side carrier 14-B functions as an output section for outputting the rotation input from the drive device to the driven device to be driven. Hereinafter, the direction along the rotation center line La of the output side carrier 14-B will be described as the axial direction X. Details of the casing 12, output side carrier 14-B, and rolling elements 16 will be described later.

The vibration generating body 18 is a cylindrical member, and its cross-sectional shape is formed into an elliptical shape. The vibration generating body 18 is rotatably supported on both sides by a pair of carriers 14 via bearings 30 . A drive shaft of a drive device is connected to the vibrator 18 .

The vibration generator bearing 20 is arranged between the vibration generator 18 and the external gear 22. The vibration generator bearing 20 rotatably supports the external gear 22 with respect to the vibration generator 18 .

The external gear 22 is arranged on the outer peripheral side of the vibrator 18 . The external gear 22 is a flexible annular member. The external gear 22 is deflected into an elliptical shape by the vibration generator 18 via the vibration generator bearing 20 . The external gear 22 has an annular base portion 22a, and a first external tooth portion 22b and a second external tooth portion 22c integrally formed on the outer peripheral side of the base portion 22a. The first external tooth portion 22b and the second external tooth portion 22c are arranged in the axial direction X. When the vibration generating body 18 rotates, the external gear 22 changes its meshing position with the internal gear 24 in the circumferential direction, and flexibly deforms to match the shape of the vibration generating body 18.

The internal gear 24 is a rigid annular member. The internal gear 24 is arranged on the outer peripheral side of the external gear 22. The internal gear 24 includes a first internal gear 24-A in which the first external tooth 22b of the external gear 22 internally meshes, and a second internal gear 24-A in which the second external tooth 22c of the external gear 22 internally meshes. 2 internal gear 24-B. The external teeth 22b and 22c are internally meshed with the internal gear 24 at both sides in the longitudinal direction of the vibrating body 18. The first internal gear 24-A has a number of internal teeth greater than the number of external teeth of the first external tooth portion 22b by 2i (i is a natural number of 1 or more), and the second internal gear 24-B has a The number of internal teeth is the same as the number of external teeth of the tooth portion 22c. The first internal gear 24-A is integrally formed with the input carrier 14-A, and the second internal gear 24-B is integrally formed with the output carrier 14-B.

The operation of the above reduction gear device 10 will be explained.
When the drive shaft rotates, the vibrator 18 rotates together with the drive shaft. When the vibrating body 18 rotates, the external gear 22 is continuously bent and deformed to match the shape of the vibrating body 18 while changing the meshing position with the internal gear 24 in the circumferential direction. The first external gear 22b rotates relative to the first internal gear 24-A by an amount corresponding to the difference in the number of teeth with the first internal gear 24-A every time the vibrator 18 rotates once. (rotate). At this time, the rotation of the vibrator 18 is reduced by a reduction ratio according to the difference in the number of teeth with the first internal gear 24-A, and the external gear 22 rotates.

The first external toothed portion 22b rotates integrally with the second external toothed portion 22c in the same phase. Since the second internal gear 24-B has the same number of teeth as the second external toothed portion 22c, the relative meshing position with the second external toothed portion 22c changes before and after one revolution of the vibration generator 18. It rotates synchronously with the same rotational component as the first external toothed portion 22b. The rotational component of the first external gear 22b is transmitted to the output carrier 14-B via the second internal gear 24-B. As a result, the rotation of the vibrator 18 is decelerated and output from the output side carrier 14-B to the driven device.

The configuration around the rolling element 16 will be explained.
FIG. 2 is an enlarged view showing the rolling element 16 of FIG. 1 together with its surrounding structure. The plurality of rolling elements 16 cooperate with the output carrier 14-B and a portion of the casing 12 to form a bearing. The rolling elements 16 of this embodiment cooperate with the output side carrier 14-B and a part of the casing 12 to form a cross roller bearing. The plurality of rolling elements 16 are provided at intervals in the circumferential direction around the rotation center line La of the output side carrier 14-B. The rolling elements 16 of this embodiment are cylindrical rollers that serve as cross rollers of a cross roller bearing. The plurality of rolling elements 16 are arranged alternately in the circumferential direction, with those whose rolling axes extend toward one side of the axial direction X toward the rotation center line La and those whose rolling axes extend toward the other side of the axial direction X. .

The output side carrier 14-B and the casing 12 are arranged with a plurality of rolling elements 16 in between. The output side carrier 14-B is arranged on the inner circumferential side, and the casing 12 is arranged on the outer circumferential side. The output side carrier 14-B includes a cylindrical first carrier member 32 and a cylindrical second carrier member 34 connected to the first carrier member 32 by spigot fitting or the like.

A V-shaped groove 36 is formed in the first carrier member 32 and the casing 12 at locations facing each other in the radial direction. Each of the pair of inner surfaces of the V-shaped groove 36 of the first carrier member 32 becomes a first rolling surface 38-A on which the rolling element 16 rolls. Each of the pair of inner surfaces of the V-shaped groove 36 of the casing 12 becomes a second rolling surface 38-B on which the plurality of rolling elements 16 roll. The first rolling surface 38-A and the second rolling surface 38-B are provided at locations facing each other in the radial direction with the plurality of rolling elements 16 in between.

The first carrier member 32 is a first holed member in which a first hole 40-A is provided in addition to the first rolling surface 38-A described above. The first rolling surface 38-A is formed on the outer peripheral surface of the cylindrical portion of the first carrier member 32. The first hole 40-A is provided at a position shifted to one side in the axial direction X from the first rolling surface 38-A. A female thread is formed in the first hole 40-A of this embodiment, into which a bolt (not shown) for connecting to a driven device is screwed.

The casing 12 is a second holed member in which a second hole 40-B is provided in addition to the second rolling surface 38-B. The second rolling surface 38-B is formed on the inner peripheral surface of the cylindrical portion of the casing 12. The second hole portion 40-B is provided at a position shifted from the second rolling surface 38-B to the other side in the axial direction X. A female thread is formed in the second hole 40-B of this embodiment, into which a bolt 26 for assembling the input side carrier 14-A is screwed.

The first carrier member 32 and the casing 12 allow the rolling elements 16 to roll on the first rolling surface 38-A of the first carrier member 32 and to roll on the second rolling surface 38-B of the casing 12. The relative rotation occurs as the moving body 16 rolls. At this time, the first carrier member 32 also serves as an inner ring for the rolling elements 16, and the casing 12 also serves as an outer ring for the rolling elements 16. The first carrier member 32 and the casing 12 function as a first member and a second member that are rotatable relative to each other as the rolling elements 16 roll.

The first carrier member 32 is provided with a first rolling surface 38-A and a first hole 40-A as part of a single member. In the casing 12, the second rolling surface 38-B and the second hole 40-B are provided as part of a single member. This means that the rolling surface 38 and the hole 40 are not individually provided in separate members, but are provided as part of an integrally molded product (single member).

Here, in this embodiment, there is a feature regarding the hardness distribution of each of the first carrier member 32 and the casing 12. This hardness distribution is common to both the first carrier member 32 and the casing 12. Hereinafter, the hardness distribution of the first carrier member 32 will be mainly explained, and the explanation of the hardness distribution of the casing 12 will be omitted.

FIG. 3 is a diagram schematically showing the hardness distribution of the first carrier member 32. As shown in FIG. The first carrier member 32 is made of, for example, a mechanical structural alloy steel material such as chromium molybdenum steel material (SCM material in JIS), that is, metal. The first carrier member 32 is subjected to surface hardening treatment by laser hardening, and a surface hardening layer 44 is provided in addition to the base material region 42 .

The base material region 42 is an unhardened region that has not been subjected to hardening treatment. The base material region 42 is a region having the hardness of the base material itself of the workpiece, which is the material to be processed by the first carrier member 32 .

The surface hardening layer 44 is provided closer to the surface than the base material region 42 . The surface hardening layer 44 is a region hardened by performing surface hardening treatment by quenching, and has higher hardness than the base material region 42. The hardened surface layer 44 is provided with, for example, a hardened structure containing martensite or the like as a main phase. The surface hardening layer 44 is provided only on a portion of the entire surface of the first carrier member 32 that includes the rolling surface 38 and is not provided on the peripheral portion that includes the hole 40 .

FIG. 4 is a graph showing an example of the hardness distribution of the first carrier member 32. As shown in FIG. This graph shows the relationship between the depth from the surface of the hardened surface layer 44 and the Vickers hardness. This graph shows the hardness distribution of the first carrier member 32 of Examples 1 and 2, which will be described later. In this graph, when the direction perpendicular to the surface (rolling surface 38) of the surface hardening layer 44 is the depth direction Pa, the Vickers hardness measured at multiple locations from the surface of the surface hardening layer 44 toward the depth direction Pa is shown. is plotted. Vickers hardness is measured by a method according to JIS Z2244.

The numbers attached to the measurement points in the graph indicate the amount of change in Vickers hardness from the measurement points adjacent to the surface side (hereinafter referred to as the amount of change in hardness). The amount of change in hardness indicates the amount of change in Vickers hardness per 0.1 mm with respect to the depth direction Pa of the surface hardening layer 44 and base material region 42.

The surface hardening layer 44 is provided with a surface layer region 46 and a hardness transition region 48 in this order from the surface of the surface hardening layer 44 toward the depth direction Pa (see also FIG. 3). The surface layer region 46 is continuous from the surface of the surface hardening layer 44 to the hardness transition region 48 . The hardness transition region 48 is continuous from the surface layer region 46 to the base material region 42. In the hardness transition region 48, the hardness continuously decreases in the depth direction Pa (that is, the amount of change in hardness never becomes 0 or more), and the hardness changes from the hardness of the surface layer region 46 to the hardness of the base material region 42. This is the area where the transition occurs.

The hardness transition region 48 includes a portion where the hardness rapidly decreases from the surface of the hardened surface layer 44 toward the depth direction Pa, and includes a portion where the amount of change in hardness is at least −60 or less, and usually −100 or less. The hardness transition region 48 is a region including a portion where the hardness change is at least -60 or less, usually -100 or less, and the hardness change changes from a value of 0 or more to a negative value in the depth direction Pa. This is the area starting from the point where the change occurs. In the hardness transition region 48, the amount of change in hardness is, for example, −200 or more and less than 0. The length of the hardness transition region 48 in the depth direction Pa is, for example, in the range of 0.3 mm to 0.8 mm. The presence of the hardness transition region 48 where the hardness rapidly decreases in this way makes it easier to reduce the total hardened layer depth, which is the depth from the surface of the surface hardened layer 44 to the base material region 42.

The surface layer region 46 is a region existing between the surface of the surface hardening layer 44 and the hardness transition region 48 . In order to specify this, the surface layer region 46 is conditioned to include a portion where the amount of change in hardness is 0 or more. Furthermore, even when the amount of change in hardness becomes a negative value, the surface layer region 46 has a larger amount of change in hardness (absolute value), so the hardness does not decrease as rapidly as in the hardness transition region 48. The surface layer region 46 can also be considered to be a region where the amount of change in hardness is at least greater than −60. Due to the existence of such a surface layer region 46, a region having a higher hardness than the base material region 42 is located between the surface of the surface hardening layer 44 and the hardness transition region 48, and the depth of the effective hardening layer having the required hardness is increased. This makes it easier to ensure safety.

The surface layer region 46 is also a region where there is no significant increase or decrease in Vickers hardness and contributes to ensuring the depth of the effective hardened layer having the required hardness. To achieve this, in the surface layer region 46, the first difference value Δ, which is the difference between the maximum value and the minimum value of Vickers hardness, is 100 or less, and the amount of change in hardness is in the range of more than −60 + 60 or less. The maximum and minimum values of Vickers hardness herein refer to the maximum and minimum values when the Vickers hardness of the surface layer region 46 is measured in units of 0.1 mm in the depth direction Pa.

The surface layer region 46 has a Vickers hardness that is, for example, at least 1.5 times the Vickers hardness at the starting position of the base material region 42 in order to ensure the depth of the effective hardened layer with the required hardness. Further, the surface layer region 46 is provided within a range of at least 0.2 mm from the surface of the surface hardening layer 44 in order to ensure the depth of the effective hardening layer. The lower limit of the Vickers hardness of the surface layer region 46 is not particularly limited, but from the viewpoint of ensuring sufficient fatigue strength, it is preferably 600 or more, for example. The upper limit of the Vickers hardness of the surface layer region 46 is not particularly limited, but is, for example, 800 or less.

The base material region 42 starts from a location where the amount of change in hardness switches from a negative value to a value of 0 or more in the depth direction Pa from the hardness transition region 48 . In the base material region 42, the hardness does not significantly increase or decrease toward the depth direction Pa. From this relationship, in the base material region 42, for example, the second difference value Δ, which is the difference between the maximum value and the minimum value of Vickers hardness, is 50 or less, and the amount of change in hardness is −50 or more and +50 or less. Therefore, the base material region 42 can be considered to start from the point where the amount of change in hardness becomes -50 or more and +50 or less toward the depth direction Pa from the place where the amount of change in hardness in the hardness transition region 48 becomes -60 or less. good. The hardness of the base material region 42 is not particularly limited, but is, for example, in the range of 250 to 400 Hv.

The above conditions regarding hardness may be satisfied in the range from the center portion 38a (see FIG. 3) of the rolling surface 38 in the width direction Pb toward the depth direction Pa. The width direction Pb herein refers to a direction perpendicular to the depth direction Pa of the rolling surface 38 in a cross section of the first carrier member 32 taken along the rotation center line La (see FIG. 1).

In the first carrier member 32 described above, the rolling surface 38 is provided on the surface of the surface layer region 46, and the first hole 40-A is provided in the base material region 42. In other words, the first hole 40-A is provided only in the base material region 42 and not in the hardened surface layer 44. Therefore, regarding the workpiece to be processed into the first carrier member 32, drilling can be performed to provide the first hole 40-A in the low hardness base material region 42 instead of the high hardness hardened surface layer 44. For this reason, the workability during processing of the work is improved.

Moreover, since the surface hardened layer 44 is provided with a surface layer region 46 in which the hardness does not decrease sharply in the depth direction Pa, it becomes easier to ensure the depth of the effective hardened layer. Moreover, since the surface hardened layer 44 is provided with a hardness transition region 48 where the hardness rapidly decreases toward the depth direction Pa, it becomes easier to reduce the total hardened layer depth. Therefore, by bringing the hole portion 40 close to the rolling surface 38, it becomes possible to design the first carrier member 32 to be smaller. In the example of this embodiment, by bringing the hole 40 closer to the rolling surface 38 in the axial direction, it becomes possible to design the first carrier member 32 to be smaller in the axial direction. As a result, it becomes easy to achieve not only good workability when processing the workpiece described above, but also a sufficient effective hardened layer depth of the surface hardened layer 44 and miniaturization of the first carrier member 32 in a well-balanced manner.

Further, the first carrier member 32 is provided with the first rolling surface 38-A and the first hole 40-A as part of a single member. Therefore, the above-mentioned effects can be obtained without increasing the number of parts of the speed reducer 10.

Next, preferred conditions for the hardness distribution of the first carrier member 32 will be explained.
The depth from the rolling surface 38 on the surface of the surface layer region 46 to the starting point of the hardness transition region 48 (hereinafter referred to as transition start depth) is preferably in the range of 0.5 mm to 1.5 mm. If this transition start depth is less than 0.5 mm, the starting point of the hardness transition region 48 will be too shallow, and there is a risk that the depth of the effective hardened layer will be insufficient. If the transition start depth exceeds 1.5 mm, the starting point of the hardness transition region 48 becomes too deep, and the distance from the rolling surface 38 to the hole 40 becomes too deep to ensure workability during machining of the workpiece. There is a possibility that it will be long. If this transition start depth condition is satisfied, the above-mentioned workability during processing of the workpiece, sufficient effective hardening layer depth of the surface hardening layer 44, and miniaturization of the first carrier member 32 can be achieved in a better balance. It becomes easier to realize.

The distance from the rolling surface 38 on the surface of the surface layer region 46 to the starting point of the base material region 42, that is, the depth from the rolling surface 38 to the end point of the hardness transition region 48 (hereinafter referred to as transition end depth) is preferably in the range of 0.8 mm to 2.0 mm. If the transition end depth is less than 0.8 mm, the end point of the hardness transition region 48 will become too shallow, and there is a risk that the depth of the effective hardened layer will be insufficient. If this transition end depth exceeds 2.0 mm, the end point of the hardness transition region 48 will be too deep, and the distance from the rolling surface 38 to the hole 40 will be too deep to ensure workability during machining of the workpiece. may become longer. If this transition end depth condition is satisfied, the above-mentioned workability during processing of the workpiece, sufficient effective hardening layer depth of the surface hardening layer 44, and miniaturization of the first carrier member 32 can be achieved in a better balance. It becomes easier to realize.

FIG. 5 is another graph showing an example of the hardness distribution of the first carrier member 32. As shown in FIG. This graph shows the hardness distribution of the first carrier member 32 of Examples 3 and 4 and Reference Examples 1 and 2, which will be described later. Although details will be described later, in Examples 1 to 4, laser hardening is used as the surface hardening treatment for the rolling surface 38 of the first carrier member 32. On the other hand, Reference Example 1 uses nitriding treatment, and Reference Example 2 uses induction hardening.

The conditions of the transition start depth and transition end depth described above can be satisfied by using laser hardening as the surface hardening treatment. When nitriding treatment is used as the surface hardening treatment, as shown in Reference Example 1, only a very shallow range from the rolling surface 38 of the first carrier member 32 in the depth direction Pa is hardened. In this case, the surface layer region 46 no longer exists in the surface hardening layer 44. Further, in this case, the transition start depth is in the range of 0.1 mm to 0.2 mm, and the transition end depth is in the range of less than 0.8 mm, neither of which conditions can be satisfied. When induction hardening is used as the surface hardening treatment, as shown in Reference Example 2, hardening is performed over a very deep range from the rolling surface 38 of the first carrier member 32 in the depth direction Pa. In this case, the transition start depth and the transition end depth are greater than 2.0 mm, and neither condition can be satisfied. Although not shown, when induction hardening is used as the surface hardening treatment, the transition start depth and the transition end depth become 5.0 mm or more. In order to ensure workability during machining of the workpiece, the distance from the rolling surface 38 to the hole 40 becomes too long.

Note that the above-mentioned surface hardening layer 44 is provided over the entire circumference of the rolling surface 38 of the first carrier member 32. Such a hardened surface layer 44 can be obtained by water-cooling the work simultaneously with laser hardening, as will be described later.

Next, a method of processing a workpiece that is a material for the first carrier member 32 will be described.
This processing method includes a hardening step of hardening the workpiece and a drilling step of drilling the workpiece. The workpiece to be processed by this processing method is prepared by cutting or the like. The workpiece to be processed has a shape in which there is no hole 40 in the portion of the first carrier member 32 that should become the hole 40 .

The hardening process uses laser hardening, which hardens the workpiece using laser light. In the hardening process, the workpiece is rotatably supported around the rotation center line La by a rotating jig (not shown). A portion of the workpiece that is to become the rolling surface 38 is irradiated with laser light of a predetermined output from a laser head. The output of the laser beam is set so as to obtain a temperature increase that exceeds the quenching temperature depending on the composition of the workpiece. The laser head irradiates a laser beam over the entire length of the portion of the workpiece in the width direction Pb that is to become the rolling surface 38 . In this state, by rotating the workpiece around the rotation center line La at a predetermined rotational speed, the portion of the workpiece that is to become the rolling surface 38 is hardened in the circumferential direction. As a result, a hardened surface layer 44 is provided in the portion of the workpiece that is to become the rolling surface 38 from the surface toward the depth direction Pa. At this time, the portion of the workpiece that is to become the hole portion 40 is not irradiated with laser light so as not to be hardened, and the base material region 42 is left.

The hardness distribution of this surface hardened layer 44 depends on the composition of the workpiece. Therefore, a workpiece having a composition that satisfies the hardness distribution under the conditions described above is prepared. The composition of this workpiece is, for example, chromium molybdenum steel such as SCM440 and AISI4150, but is not limited to these and may be determined through experimental studies.

In the hardening process of the present embodiment, the workpiece is hardened so that a surface hardening layer 44 is provided all around the portion that is to become the rolling surface 38 of the workpiece. To achieve this, a workpiece rotating at a predetermined rotational speed is irradiated with laser light of a predetermined output to harden it and cool it with water. The rotational speed and output are set to a sufficiently high rotational speed and a sufficiently high output so that an elevated temperature state in which heating is performed by a ring-shaped coil can be obtained in a pseudo manner. Water cooling is performed to ensure the cooling rate necessary for hardening, since self-cooling, which is a characteristic of laser hardening, becomes less effective due to the use of high-output laser light. The rotation speed, the output power of the laser beam, and the water cooling conditions may be determined by, for example, experimental studies.

In the drilling step, a base material region 42 located at a portion of the workpiece hardened in the hardening step that is to become a hole is drilled. In the drilling process of this embodiment, a tap is used to drill a hole in a portion of the workpiece to form a female thread. At this time, since the base material region 42 is provided in the portion of the workpiece that is to become the hole, workability during machining of the workpiece is improved.

In addition, in the quenching step, an absorbing material with excellent heat absorption rate may be applied to the surface of the portion of the workpiece that is to become the rolling surface 38, and then the absorbing material may be irradiated with laser light. This absorbent material is, for example, graphite. As a result, it is possible to increase the amount of heat absorption at the part that should become the rolling surface 38 of the workpiece, and the above-mentioned transition start depth and transition end depth can be deepened with respect to the holed member obtained through the drilling process on the workpiece. can.

Examples of the present invention will be described below. The examples are merely illustrative to suitably explain the present invention, and are not intended to limit the present invention in any way.

First, a workpiece having the outer shape of the first carrier member 32 described above was manufactured as a prototype. The prototype workpieces include a workpiece using SCM440 as Examples 1, 3, and 4 and Reference Examples 1 and 2, and a workpiece using AISI4150 as Example 2.

Multiple types of surface hardening treatments were applied to the rolling surface 38 of the prototype workpiece. In Examples 1 and 3, the workpiece was hardened by being rotated and heated by laser hardening to a temperature higher than the hardening temperature, and then cooled by water cooling. In Examples 2 and 4, surface hardening treatment by laser hardening was performed under the same conditions as in Examples 1 and 3, except that graphite was applied as an absorbent to the rolling surface 38 of the workpiece. In Reference Example 1, the rolling surface 38 of the workpiece was subjected to surface hardening treatment by nitriding using a fluorine-based gas. In Reference Example 2, the rolling surface 38 of the workpiece was subjected to surface hardening treatment by induction hardening. This induction hardening was performed by heating at a temperature equal to or higher than the hardening temperature and then cooling with water.

From the surface-hardened workpiece, test pieces were cut out from a plurality of locations in the depth direction Pa from the rolling surface 38, and the plurality of test pieces were subjected to a Vickers hardness test.

FIG. 4 shows the test results of Examples 1 and 2. FIG. 5 shows the test results of Examples 3 and 4 and Reference Examples 1 and 2. As shown in FIGS. 4 and 5, in Examples 1 to 4 in which laser hardening was performed, the surface hardening layer 44 is provided with a surface layer region 46 and a hardness transition region 48 that satisfy the hardness distribution described above. Note that the first difference value Δ between the maximum value and the minimum value of the Vickers hardness of the surface layer region 46 is 44.4, 97.3, 35.8, and 50.1 in Examples 1 to 4, respectively.

Examples of embodiments of the present invention have been described above in detail. The embodiments described above are merely specific examples for carrying out the present invention. The content of the embodiments does not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of constituent elements may be made without departing from the idea of the invention defined in the claims. It is possible. In the above-mentioned embodiment, contents that allow such design changes are explained with the notations such as "in the embodiment" and "in the embodiment", but the design does not include such notations. This does not mean that changes are not allowed. Further, the hatching added to the cross section of the drawing does not limit the material of the hatched object.

Although the speed reduction device 10 has been described using a flexible mesh speed reduction device as an example, its type is not particularly limited. For example, it may be an eccentric oscillation type reduction gear or the like, or it may be a reduction gear including any one of a planetary gear mechanism, an orthogonal axis gear mechanism, a parallel axis gear mechanism, and the like. Moreover, although the cylindrical flexural mesh speed reduction device has been described as an example, the type of the flexural mesh speed reduction device is not particularly limited. For example, the internal gear may be applied to a cup-shaped or top hat-shaped flexible mesh reduction gear.

Although the casing 12 and the first carrier member 32 have been described as an example of the holed member provided with the rolling surface 38 and the hole 40, the specific example is not limited thereto. Further, although an example has been described in which both the first member and the second member disposed with the rolling element 16 in between are members with holes, it is sufficient that at least one of them is a member with holes.

The above conditions regarding the hardness distribution of the holed member can be satisfied by appropriately setting the composition of the workpiece and the heat treatment conditions when laser hardening is used as the surface hardening treatment. The conditions regarding the hardness distribution herein refer to numerical conditions regarding the provision of the above-mentioned surface layer region 46 and hardness transition region 48 in the surface hardening layer 44, and the transition start depth and transition end depth. The heat treatment conditions herein refer to, for example, the output (kW) of the laser beam irradiated onto the workpiece, and the conditions regarding whether or not an absorbing material is applied to the surface of the workpiece. When the output of this laser beam is increased, the range that is hardened from the rolling surface of the holed member in the depth direction Pa increases, making it easier to increase the transition start depth and transition end depth. Further, when an absorbent material is applied to the surface of the workpiece, it becomes easier to increase the transition start depth and the transition end depth compared to the case where no absorbent material is applied. Conditions for satisfying the above-mentioned hardness distribution of the holed member may be determined through experiments, analysis, etc., taking such matters into consideration.

In the embodiment, laser hardening has been described as an example of the surface hardening treatment applied to the holed member, but the present invention is not limited thereto. This surface hardening treatment continues from the surface of the holed member to the hardness transition area, and includes the surface area where the hardness change amount is 0 or more, and the hardness continuously decreases in the depth direction, and the hardness changes. Any material that can provide a hardness transition region including a portion where the hardness is -60 or less may be used.

DESCRIPTION OF SYMBOLS 10... Reduction device, 16... Rolling element, 38... Rolling surface, 40... Hole, 42... Base material region, 44... Surface hardening layer, 46... Surface layer region, 48... Hardness transition region.

Claims (1)

A method of processing a workpiece that is a material for a member with a hole,
The holed member is provided with a hole,
A part of the workpiece is hardened by irradiating it with laser light to provide a hardened surface layer,
a quenching step of leaving a base material region without quenching the part of the workpiece that should become the hole;
a drilling step of drilling the base material region in a portion of the workpiece that is to become a hole,
In the hardening step, a surface layer region and a hardness transition region are provided in order from the surface in a vertical depth direction, and when the amount of change in Vickers hardness per 0.1 mm with respect to the depth direction is defined as the amount of change in hardness, The hardness transition region includes a portion where the hardness continuously decreases in the depth direction and the hardness change amount is -60 or less, and the depth from the surface of the surface layer region to the hardness transition region is Quenched to less than 1.5 mm,
When the direction perpendicular to the surface of the hardened surface layer is defined as the depth direction, the portion of the workpiece that should become the hole is a position that overlaps the surface in the depth direction, or the hole is bored. A method of processing a workpiece located at a position overlapping the surface hardening layer in the direction.

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