JP2013164168A - Eccentric swing type reduction gear and method for manufacturing eccentric body shaft of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend a life span of an eccentric body shaft of an eccentric swing type reduction gear and to improve durability of the eccentric swing type reduction gear itself.SOLUTION: In an eccentric swing type reduction gear 12, external gears 24A, 24B are internally meshed with an internal gear 28 via eccentric bodies 22A, 22B of an eccentric body shaft 20 while they are swung eccentrically or with warpage. A granular carbide having a maximum granular diameter of lower than 4 μm is deposited on a surface of the eccentric body shaft 20.

Description

  The present invention relates to an eccentric oscillating speed reducer and a method of manufacturing the eccentric body shaft.

  Patent Document 1 discloses an eccentric rocking type speed reducer. This reduction device includes an external gear, an eccentric body shaft having an eccentric body, an eccentric body bearing disposed between the external gear and the eccentric body, and an internal gear.

  In this type of reduction gear, the eccentric body shaft is rotated by the rotation of the input shaft, and the external gear is eccentrically or flexibly oscillated through the eccentric body of the eccentric body shaft by the rotation of the eccentric body shaft. Internally mesh with the gear. This internal meshing causes relative rotation between the internal gear and the external gear in accordance with the difference in the number of teeth of the internal gear and the external gear. The rotation is constrained and the relative rotation component is output from the other side.

JP 2008-267571 A

  In this type of eccentric oscillating type speed reducer, the rolling element of the bearing arranged between the external gear and the eccentric body is subjected to a dynamic fluctuation torque when the external gear is eccentrically oscillated. B) Roll contact directly on the eccentric body axis. For this reason, the eccentric body shaft is in a severe condition in terms of durability, and the actual situation is that the life of the eccentric body shaft is a major factor that determines the life of the entire speed reducer.

  However, there have been few examples in which the mechanism related to the durability of the eccentric body shaft has been examined and studied in detail. For this reason, in manufacturing the eccentric body shaft, the conventional curing processing example P in FIGS. The actual situation was that only a general surface hardening treatment as shown in FIG.

  The present invention was made on the basis of knowledge obtained as a result of exploring the mechanism related to the durability of the eccentric body shaft in such a situation, and greatly extends the life of the eccentric body shaft. The task is to further improve the durability of the dynamic reduction gear.

  The present invention includes an external gear, an eccentric body shaft having an eccentric body, an eccentric body bearing disposed between the external gear and the eccentric body, and an internal gear, and the eccentric body shaft. In an eccentric oscillating type speed reducer in which the external gear is engaged with the internal gear while being eccentrically or flexibly oscillated through the eccentric body, a maximum particle size of less than 4 μm is formed on the surface layer portion of the eccentric body shaft. This problem is solved by adopting a structure in which the granular carbides are deposited.

  The present invention has been made on the basis of knowledge that has clarified the mechanism of deterioration (damage / wear) of the eccentric body shaft that has not been verified at all. Since the specific problem itself that is focused on is not a publicly known one, the specific problem and the principle of its solution will be described in detail later.

  According to the present invention, the life of the eccentric body shaft of the eccentric oscillating speed reducer can be greatly extended, and the durability of the eccentric oscillating speed reducer itself can be greatly improved.

(A) A graph showing the relationship between the height of rise of indentation and the life before applying the thermal load for testing and after (B) applying the same. List of performance, specifications, etc. of various curing processes (however, P is conventional) Explanatory drawing showing one aspect (hypothesis) of the mechanism that the eccentric body shaft is damaged and worn Sectional drawing which shows the eccentric rocking | fluctuation type reduction gear which shows an example of embodiment of this invention Sectional drawing which follows the arrow VV line of FIG. Time chart showing an example of application of heat load of various curing processes in the manufacturing process of the eccentric body shaft of the eccentric oscillating speed reducer (P is conventional) Organization chart schematically showing martensite

  In the embodiment of the present invention, as a conclusion, attention is paid to the size of the raised height of each indentation in the indentation test conducted before and after the thermal load that changes the material properties to the eccentric body axis. doing.

  That is, in the embodiment of the present invention, the bulge height generated as a result of performing the bulge test of the indentation before applying a thermal load that changes the material characteristics of the eccentric body shaft to the eccentric body shaft is A1, A ratio of A2 / A1 with respect to the eccentric body axis is 1.0 when the rising height resulting from the swell test of the indentation after applying the heat load to the eccentric body axis is A2. A curing process having the following characteristics is performed.

  As a result, it is possible to obtain an ideal qualitative characteristic that the durability is rather improved (over time) by use, and the durability of the eccentric body shaft can be greatly extended. .

  In the embodiment of the present invention, attention is also paid to the change in the Vickers hardness before and after the thermal load that changes the material characteristics is applied to the eccentric body axis from another viewpoint.

  Specifically, in an embodiment of the present invention, an external gear, an eccentric shaft having an eccentric body, an eccentric bearing disposed between the external gear and the eccentric body, and an internal gear In the eccentric oscillating speed reducer, the material of the eccentric body shaft is engaged with the internal gear while being eccentrically or flexibly oscillated through the eccentric body of the eccentric body shaft. When the Vickers hardness of the eccentric body shaft before applying a thermal load whose characteristics change is HV1, and when the Vickers hardness of the eccentric body shaft after applying the thermal load is HV2, The above-mentioned problem is also solved by the fact that the curing process in which the change of HV1-HV2 is suppressed to less than 60 HV is performed.

  That is, with this configuration as well, the durability of the eccentric body shaft can be dramatically extended as described above.

  In addition, by performing one of the processes corresponding to the above-described curing process, granular carbides having a maximum particle size of less than 4 μm are deposited on the surface layer portion of the eccentric body shaft, thereby the eccentric body shaft. Durability can be extended dramatically.

[Specific problems of the present invention and the solution principle]
The present invention has been made on the basis of knowledge that has clarified the mechanism of deterioration (damage / wear) of the eccentric body shaft that has not been verified at all. Since the specific problem itself focused on is not a publicly known one, before describing the embodiment, first, the specific problem focused on in the present invention and the principle of the solution will be described in detail.

  As one of the mechanisms (causes) of deterioration of the eccentric body shaft, the inventors have a gear between the eccentric body E of the eccentric body shaft and the eccentric body bearing (rolling body thereof) R as shown in FIG. When a foreign matter such as wear particles D is mixed, a small indentation M is generated on the surface of the eccentric body E (FIG. 3 (A) → (B)), and stress is concentrated on the edge of the indentation M (FIG. 3 ( B)), a mechanism of developing to surface peeling H was estimated (FIG. 3C). If this estimation is correct, when the indentation test (the test for examining the height of the indentation when the Vickers hardness test is performed at a test load of 30 kgf) is performed, the smaller the indentation height, Since the indentation is unlikely to occur), stress concentration is unlikely to occur, and the life should be extended.

  However, as shown in FIG. 1 (A), an experimental result has been obtained that even with an eccentric body shaft having substantially the same bulge height in the indentation test, there may be a large difference in life, and the bulge height of the indentation is obtained. Is not simply affecting the lifespan (not just the raised height of the indentation is low).

  Here, in this test example (and an embodiment to be described later), a Vickers hardness test with a test load of 30 kgf is performed as an indentation swell test, but if the indentation can be formed on the eccentric body shaft, the test is performed. A load and a test method are not limited to this, For example, it is good also as test loads other than 30 kgf, and you may make it perform a Rockwell hardness test. In addition, as shown in FIG. 3, the indentation height refers to the distance between the rolling surface and the top of the raised portion, and more specifically, in this test example (and an embodiment described later), The average value of the raised heights at the two points is set as the raised heights A1 and A2. However, the method for determining the height of the indentation is not limited to this, and for example, a specific height of one point may be employed, or an average value of three or more points may be employed. .

  On the other hand, in the process of elucidating and observing the mechanism of the deterioration of the eccentric body shaft, the inventors, once the eccentric body shaft of this kind of speed reducer starts to deteriorate, the progress of the deterioration becomes faster. I noticed a strange phenomenon. About this cause, inventors made the following hypotheses.

  That is, normally, the radial clearance between the eccentric body shaft, the rolling element of the eccentric body bearing, and the external gear is set to about −10 μm to 10 μm. In applications such as robot joints where accuracy is required, about −3 μm to 3 μm may be required. Furthermore, since there is a strong demand for industrial machines in recent years to increase the working speed, the rotational speed of the eccentric body shaft is also greatly increased. For this reason, the DmN value, that is, the value of the rotational speed (rpm) of the eccentric body shaft × the pitch circle diameter (mm) of the rolling element of the eccentric body bearing is often used at 10,000 or more. The situation is very severe (the eccentric body shaft becomes very hot during the operation of the speed reducer). Therefore, the inventors have stated that "the eccentric shaft of the new speed reducer and the eccentric shaft of the speed reducer after the deterioration begins to progress by use (due to the heat generated during operation of the speed reducer) I guessed that there is a change in the material properties of the eccentric body shaft. "

  In other words, the inventors have the situation after the eccentric body shaft becomes very hot due to the operation of the speed reducer and the material characteristics of the eccentric body shaft change due to the thermal load, or before the material characteristics change. It was speculated that the “after” situation might be greatly related to the life of the eccentric body shaft.

  Then, in order to verify this hypothesis, in the same way as during the operation of the reduction gear, in order to change the material properties of the eccentric body shaft by the thermal load, the predetermined test heat is intentionally changed (relative to the new eccentric body shaft). A load (for example, a thermal load for testing that is exposed to 300 ° C. for 3 hours) was applied, and an indentation test was performed at “before” and “after” when the thermal load for testing was applied.

  Then, as shown in the P column of FIG. 2, in the case of the eccentric shaft of the conventional speed reducer, the indentation test before applying the test thermal load was only a rise of 2.6 μm, In the indentation test after applying the test thermal load, it was confirmed that the swell height increased (softened) to 4.2 μm.

  This experimental result is consistent with the inventor's feeling that once the deterioration starts, the speed of the deterioration will increase. It was also supported that the speculation that there was a change in the properties of the material with the eccentric body axis after the load due to was applied. And as FIG.1 (B) shows, it was recognized that the bulge height in the impression test after giving the heat load for a test has a clear negative correlation with the lifetime of an eccentric body axis | shaft.

  Therefore, the inventors have described this and that in the previous FIG. 1 (A), “the raised height in the indentation test (in the state where no thermal load for testing is applied) is not necessarily correlated with the life”. Considered in combination, the height of the indentation height A1 at the beginning of a new product (before the thermal load due to the use of the reducer) and the height A2 in the indentation test after the thermal load is applied are the eccentricity. It was newly speculated that it might have a great influence on the life of the shaft. From this point of view, when a similar test was carried out for many curing processes, including a curing process that has never been adopted for this type of eccentric body shaft, When the "treatment" is performed, the raised height A2 in the indentation test after application of the test thermal load is rather smaller than the uplift height A1 in the indentation test before application of the test thermal load ( It has been confirmed that there are processing examples (for example, first to fifth curing processing examples in FIGS. 2 and 6 described later) in which a characteristic of A2 / A1 ≦ 1) is obtained. And when the hardening process which has this tendency was performed, as seen in FIG. 2 mentioned later, it was confirmed that the lifetime has extended greatly (lifetime 1.44-3.13 times of the past).

  Therefore, the present invention focuses on the situation after the eccentric body shaft becomes very hot due to the operation of the reduction gear and the material characteristics of the eccentric body shaft change due to the thermal load. In other words, as a result of an indentation test after applying a thermal load for testing that changes the material characteristics of the eccentric body shaft, more specifically, as a result of comparing indentation tests performed before and after applying the thermal load for testing Pay attention to. In other words, the eccentric body shaft is not a stance in which a curing treatment is performed in which the height A1 of the indentation in the indentation test in a normal state (especially in a state where no thermal load for test is applied) is suppressed, but for testing. The stance of keeping the height A2 of the indentation after applying a thermal load low, more specifically, the height A2 of the indentation in the indentation test conducted after applying the thermal load for testing, It is characterized by performing a curing process (a curing process that satisfies A2 / A1 ≦ 1) that is smaller than the swell height A1 in the indentation test before applying the test heat load.

  The characteristic that satisfies this relationship (A2 / A1 ≦ 1) is, in short, that “when a thermal load is applied through the use of a speed reducer, the bulge due to the impression becomes smaller”. The tendency that indentation is less likely to occur with continued use is a very favorable qualitative tendency for an eccentric body shaft that is subjected to a significant thermal load during operation of the speed reducer.

  The inventors also focused on the change in the Vickers hardness (Vickers hardness) HV before and after the material characteristics of the eccentric body shaft change due to the thermal load from a viewpoint different from the height of the indentation. For the purpose of verification, the relationship between the change in the Vickers hardness (HV2-HV1) and the life in “front (HV1)” and “rear (HV2)”, which gives the test body the same thermal load as described above on the eccentric body axis. investigated.

  Then, as shown in FIG. 2, when a specific curing process (curing process 1 to 5) is performed on the eccentric body shaft, before and after applying a test heat load compared to the conventional curing process (that is, It was confirmed that the decrease in Vickers hardness (HV2-HV1) before and after the change in the material characteristics of the eccentric body shaft was small (in FIG. 2, since the numerical value of HV2-HV1 is shown, it is negative) It is a numerical value). And when the hardening process which has this tendency was performed, it was confirmed that the lifetime has extended greatly (life of 1.44-3.13 times the conventional).

  Therefore, in the present invention, the situation after the eccentric body shaft becomes very hot due to the operation of the speed reducer and the material characteristics of the eccentric body shaft change due to the thermal load, more specifically, the material characteristics of the eccentric body shaft Pay attention to the change in the Vickers hardness of the eccentric body shaft before and after applying the thermal load for testing to the extent that changes. In other words, it is not a stance of simply performing a curing process (especially under a condition in which a test thermal load is not applied) on the eccentric body shaft, but suppresses a decrease in Vickers hardness before and after applying the test thermal load. Such a curing process (a curing process that suppresses a change in Vickers hardness to less than 60 Hv) is performed.

[Example of reducer to which the present invention is applied]
Hereinafter, an example of a more specific embodiment of the present invention will be described in detail.

  FIG. 4 is a cross-sectional view showing an example of an eccentric oscillating speed reducer according to the embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along line VV in FIG.

  The eccentric oscillating speed reducer 12 includes external gears 24A and 24B, an eccentric body shaft 20 integrally including eccentric bodies 22A and 22B, and the external gears 24A and 24B and the eccentric bodies 22A and 22B. There are rollers (eccentric bearings) 26A, 26B disposed between them and an internal gear 28, and the external gears 24A, 24B are eccentrically oscillated via the eccentric bodies 22A, 22B of the eccentric body shaft 20. However, it is in mesh with the internal gear 28. The output is taken from the first and second carriers 32 and 34 as the rotation components of the external gears 24A and 24B. Details will be described below.

  The input shaft 14 can be connected to an output shaft of a motor (not shown). A sun gear 16 is integrally formed at the tip of the input shaft 14. The sun gear 16 meshes simultaneously with a plurality (three in this example) of transmission gears 18.

  Each transmission gear 18 is incorporated into a plurality of (three in this example) eccentric body shafts 20 and can drive the three eccentric body shafts 20 simultaneously and in the same direction. Each eccentric body shaft 20 is integrally provided with eccentric bodies 22A and 22B at a phase of 120 ° side by side in the axial direction. Further, the eccentric bodies 22A and the eccentric bodies 22B that are in the same position in the axial direction of the respective axes are incorporated so as to be rotatable in the same direction with the same phase.

  Between the external gear 24A and the three eccentric bodies 22A, a roller (rolling element) 26A constituting an eccentric body bearing is disposed. Between the external gear 24B and the three eccentric bodies 22B, a roller (rolling element) 26B constituting an eccentric body bearing is also arranged. The external gears 24A and 24B can be internally meshed with the internal gear 28 while eccentrically swinging via the eccentric bodies 22A and 22B of the eccentric body shaft 20, respectively.

  First and second carriers 32 and 34 are arranged on both axial sides of the external gears 24A and 24B. The first and second carriers 32 and 34 are connected to each other via a carrier pin 34A and a bolt 40 which are formed by press-fitting from the second carrier 34 side, and the whole is rotated to the casing 30 via bearings 36 and 38. Supported as possible.

  The internal gear 28 is integrated with the casing 30 and includes roller-shaped pins 28P as “internal teeth”. The pin 28P can mesh with the external gears 24A and 24B, respectively.

  Next, the operation of the eccentric oscillating speed reducer 12 will be described.

  When the input shaft 14 rotates, the three eccentric body shafts 20 are simultaneously decelerated and rotated through the transmission gear 18 meshing with the input shaft 14. As a result, the eccentric bodies 22A and 22B integrally mounted on the eccentric body shafts 20 rotate in the same phase, and the external gears 24A and 24B are inscribed in the internal gear 28 and 120 degrees each. Oscillating and rotating while maintaining the phase difference. Since the internal gear 28 is integrated with the casing 30 and is in a fixed state, when the eccentric body shaft 20 rotates, the external gears 24A and 24B swing and rotate via the eccentric bodies 22A and 22B. A phenomenon occurs in which the meshing positions of the gears 24A and 24B and the pin 28P, which is the internal tooth of the internal gear 28, sequentially move.

  At this time, since the number of teeth of the external gears 24A and 24B is slightly smaller than the number of teeth of the internal gear 28, the movement of the meshing position causes a difference in the number of teeth with respect to the internal gear 28 in a fixed state. The phases of the external gears 24A and 24B are shifted (spinned) by the corresponding amount. Therefore, the eccentric body shaft 20 revolves around the input shaft 14 at a speed corresponding to the rotation component, and the first and second carriers 32 and 34 supporting the eccentric body shaft 20 correspond to the revolution speed. Rotates at speed. Since the first and second carriers 32 and 34 are connected via the bolt 40 and the carrier pin 34A, the first and second carriers 32 and 34 are integrated (one large lump). It rotates slowly and drives a not-shown counterpart machine (driven machine) connected through the bolt hole 42.

  As in this embodiment, when the casing 30 (internal gear 28) is fixed, the relative displacement between the external gears 24A and 24B and the internal gear 28 is changed to the first and second carriers 32 and 34 side. When the rotation of the first and second carriers 32 and 34 is constrained, the relative displacement can be reduced through the swinging (rotation constrained) of the external gears 24A and 24B. It can be taken out as rotation on the casing 30 side (frame rotation).

  Here, the radial gap between the eccentric body 22A (22B) -the rolling element 26A (26B) -external gear 24A (24B) of the eccentric bearing (the radial gap between the eccentric body-rolling element and the rolling element-external gear). In this embodiment is set to about -3 μm to 3 μm, and the absorption margin for manufacturing errors is extremely small. Moreover, since the eccentric body shaft rotates at a high speed, the value of DmN value, that is, the rotational speed (rpm) of the eccentric body shaft × the pitch circle diameter (mm) of the rolling element of the eccentric body bearing is 10,000. It is in a state of exceeding. Under this condition, the eccentric body shaft 20 is constantly subjected to “high-speed fluctuating load torque” when the external gears 24A and 24B are swung and rotated via the eccentric bodies 22A and 22B and the rolling elements 26A and 26B. . For this reason, the eccentric body axis | shaft 20 exists in the very severe condition thermally (it becomes very high temperature).

  Therefore, in the present embodiment, a specific curing process is performed on the eccentric body shaft 20. In order to facilitate understanding, first, a comparative example P of this type of eccentric body shaft curing process will be described for comparison purposes.

  As shown by P in FIG. 6, the eccentric body shaft (20) has been conventionally cured by the following method. Here, the material of the eccentric body shaft subjected to the curing treatment P is iron (Fe), C: 0.18 to 0.23% by weight, Si: 0.15 to 0.35% by weight, Mn: 0 .60 to 0.90 wt%, P: 0.030 wt% or less, S: 0.030 wt% or less, Ni: 0.25 wt% or less, Cr: 0.90 to 1.20 wt%, Mo: Containing 0.15 to 0.25% by weight.

[Previous Curing Treatment Example P]
a) The eccentric body axis is 1203 K (absolute temperature: 930) together with a material containing carbon (a solid material such as charcoal, a gas material such as natural gas or petroleum gas, or a liquid material). C.) for 8.1 ksec (135 minutes).
b) The heating temperature is lowered to 1103 K (830 ° C.), and this state is maintained for 1.8 ksec (30 minutes). c) Putting the eccentric body shaft into oil (or water) and quenching (quenching).
d) Heat again to tempering temperature of 443 K (170 ° C.) and maintain for 7.2 ksec (120 minutes) and temper.

  By the above treatment, carbon penetrates and diffuses into the surface layer portion of the eccentric body axis, and the carbon content of the surface layer portion becomes about 0.8 to 0.9% by weight.

  As shown in the column labeled P in FIG. 2, the processing depth of the eccentric body shaft processed in this conventional curing processing example P is about 0.4 mm, and the new product after the curing processing The raised height of the indentation test in the state (particularly in a state where no heat load for testing was applied) was 2.6 μm. Here, the treatment depth of the curing treatment is the depth of the layer cured to a desired hardness or higher, that is, the effective cured layer depth, and this curing treatment example P (the same applies to the curing treatment examples 1 to 5). In FIG. 5, the depth of the layer having a Vickers hardness of 513 (Hv) or more from the surface of the eccentric body axis is used. However, the index of the “effective hardened layer depth” is not limited to the depth of the layer hardened to Vickers hardness of 513 (Hv) or more, and the layer effectively hardened before and after the hardening treatment. What is necessary is just to select a numerical value suitably for specifying, and hardening from the eccentric body axis | shaft surface of the part into which carbon (carbon and nitrogen in the hardening processing examples 1 and 2 demonstrated below) penetrate | invaded and diffused. The processing depth may be used.

  Moreover, in this embodiment, after performing each hardening process (hardening process P, 1-5), after giving the grinding | polishing process to the eccentric body shaft surface, an indentation rise test and the measurement of various numerical values shown in FIG. 2 are performed. Is going.

  The martensite width was 5 μm. In addition, the martensite width | variety here means the width | variety of the block grain boundary shown with the code | symbol W1 in the schematic diagram of the martensite shown in FIG. In FIG. 7, the thick dotted line indicates the packet grain boundary, and the thick solid line indicates the old γ grain.

  The inventors gave a heat load for testing to the eccentric body shaft subjected to the above-described curing treatment P by subjecting it to 300 ° C. for 3 hours, which is considered to change the material properties of the eccentric body shaft intentionally. An indentation test was performed on an eccentric body shaft subjected to a test heat load. As a result, the height of the swell was actually increased to 4.2 μm as described above. This corresponds to a state in which A2 / A1, which will be described later, is as high as 4.2 / 2.6 = 1.61. When this state is converted from the results of separate examination from the viewpoint of “hardness change” of Vickers hardness, the Vickers hardness of the eccentric body shaft before application of the test heat load is HV1, and the test heat load is applied. When the Vickers hardness of the eccentric body shaft after HV2 is HV2, the change of HV1 to HV2 with respect to the eccentric body shaft can be understood as 65 HV (softened). (As described above, in FIG. 2, since the numerical value of HV2-HV1 is described, it is a negative numerical value). In such a situation, it is natural that deterioration due to damage or wear proceeds faster.

  On the other hand, in the course of this research, when similar tests were conducted for various curing processes that have not been performed on the eccentric body shafts in the past, at least the following five curing process examples 1 to 5 were reversed. Characteristics, that is, “the bulge height resulting from the bulge test of the indentation before applying the test thermal load is A1, the bulge resulting from the bulge test of the indentation after applying the thermal load for the test” It was confirmed that when the height is A2, it has a characteristic that the relationship of (A2 / A1 ≦ 1) is established. From another point of view, it was confirmed that “the change in the Vickers hardness of the eccentric body shaft before and after applying the test heat load is suppressed to less than 60 HV”. Hereinafter, it demonstrates in order.

[Curing treatment example 1 according to this embodiment]
In the curing processing example 1, the following processing was performed. Here, the material of the eccentric body shaft subjected to the curing processing example 1 is the same as that of the eccentric body shaft subjected to the curing processing example P.
1a) The eccentric body shaft is heated to 1203 K (930 ° C.) for 10.8 ksec (180 minutes) in an atmosphere containing carbon-containing gas and NH ₃ gas (ammonia gas).
1b) The heating temperature is lowered to 1133 K (860 ° C.) and maintained for 1.2 ksec (20 minutes).
1c) Putting the eccentric body shaft into oil (or water) and quenching (quenching).
1d) Reheat to tempering temperature of 553 K (280 ° C.) and maintain for 1.8 ksec (30 minutes) and temper.

  By the above processing, carbon and nitrogen enter and diffuse into the surface layer portion of the eccentric body shaft.

  In addition, the heating temperature and heating time in each of the above-described curing treatments and each of the curing treatments described below do not necessarily have to be accurate in units of 1 ° C. and units of 1 minute. Characteristic that the height of indentation after application of thermal load is kept low, characteristic that the relationship of A2 / A1 ≦ 1 is established), or characteristic relating to Vickers hardness (eccentricity before and after applying the thermal load for testing) If the characteristic that the change in the Vickers hardness of the body axis is suppressed to less than 60 HV is obtained, it can be adjusted as appropriate. Further, the material heated together with the eccentric body axis is not limited to the above gas.

  According to this curing treatment example 1, the characteristics (A2 / A1 = 2.7 / 2.7 = 1) were obtained as shown in FIG. The hardness change after application of the test heat load is only -29 HV (that is, the change in Vickers hardness before and after application of the test heat load is 29 HV), which is 1.59 times that of the conventional curing treatment P. Life span was obtained.

[Curing treatment example 2 according to this embodiment]
In the curing process example 2, the following process was performed. Here, the material of the eccentric body shaft to which the curing treatment example 2 is applied is iron (Fe), C: 0.33 to 0.38 wt%, Si: 0.15 to 0.35 wt%, Mn: 0.60 to 0.90 wt%, P: 0.030 wt% or less, S: 0.030 wt% or less, Ni: 0.25 wt% or less, Cr: 0.90 to 1.20 wt%, Mo : 0.15 to 0.3% by weight.
2a) The eccentric body axis is set to 1213K (in an atmosphere containing carbon and NH ₃ gas).
930 ° C.) for 14.4 ksec (240 minutes).
2b) The heating temperature is lowered to 1133 K (860 ° C.) and maintained for 1.2 ksec (20 minutes).
2c) Putting the eccentric body shaft into oil (or water) and quenching (quenching).
2d) Reheat to tempering temperature of 553 K (280 ° C.) and maintain 1.8 ksec (30 minutes) and temper.

  The point that carbon and nitrogen penetrate and diffuse into the surface layer portion of the eccentric body shaft by the above processing is the same as in the curing processing example 1, but according to the main curing processing example 2, the processing depth is the processing of the curing processing example 1. It becomes 1.6 mm deeper than the depth (0.8 mm).

  In this curing treatment example 2, as shown in FIG. 2, the characteristics of (A2 / A1 = 2.4 / 2.5 = 0.96 ≦ 1) were obtained. The hardness change after application of the test heat load is −28 HV (that is, the change in Vickers hardness before and after application of the test heat load is 28 HV), and the lifetime is 2.10 times that of the conventional curing treatment P. was gotten. Moreover, in this hardening process example 2, the residual austenite of the eccentric body shaft surface layer part greatly exceeds 10 volume% and is 19 volume%, which also contributes to the improvement of the life of the eccentric body shaft.

[Curing treatment example 3 according to this embodiment]
In the curing processing example 3, the following processing was performed. Here, the material of the eccentric body shaft subjected to the curing processing example 3 is the same as that of the eccentric body shaft subjected to the curing processing example P.
3a) Eccentric body axis is set to 1203K (930 ° C.) together with a material containing carbon (a solid material such as charcoal, a gas material such as natural gas or petroleum gas, or a liquid material). 16.2 ksec (270 minutes) heating.
3b) The heating temperature is lowered to 1103 K (830 ° C.) and maintained for 1,8 ksec (30 minutes).
3c) Putting the eccentric body shaft into oil (or water) and quenching (quenching).
3d) Reheat to a low tempering temperature of 443 K (170 ° C.) and maintain for 7.2 ksec (120 minutes) and temper.

  The point that carbon penetrates and diffuses into the surface layer portion of the eccentric body shaft by the above processing is the same as in the curing processing example P. However, according to the main curing processing example 3, the processing depth is the processing depth of the curing processing example P. It becomes about 0.8 to 1.2 mm deeper than (0.4 mm). Here, the processing depth (0.4 mm) of the curing processing example P means that on the eccentric body axis (in the speed reducer in which the eccentric body shaft subjected to each curing processing is used). Since the maximum shear stress is generated in the radial shear stress distribution when the roller of the eccentric body roller rolls, it is almost equal to the depth at which the maximum shear stress is generated. In the radial shear stress distribution when the roller of the bearing rolls, the hardening treatment is performed to a position deeper than the depth at which the maximum shear stress is generated. More specifically, the curing process is performed to a depth that is twice or more the depth at which the maximum shear stress is generated.

  In the curing treatment example 3, as shown in FIG. 2, the characteristics of (A2 / A1 = 3.2 / 3.3 = 0.96 ≦ 1) were obtained. The hardness change after application of the test heat load is -56 HV (that is, the change in Vickers hardness before and after application of the test heat load is 56 HV), which is 2.21 times the life of the conventional curing treatment P. was gotten. Moreover, in this hardening process example 3, the martensite width | variety of the eccentric body axis | shaft surface layer part is as small as 4 micrometers, and this also contributes to the lifetime improvement of an eccentric body axis | shaft. That is, the lifetime can be improved by setting the martensite width in the material of the eccentric body axis surface layer to 4 μm or less.

[Curing treatment example 4 according to this embodiment]
In the curing process example 4, the following process was performed. Here, the material of the eccentric body shaft subjected to the curing treatment example 4 is the same as that of the eccentric body shaft subjected to the curing processing example P.
4a) Eccentric body axis is set to 1203K (930 ° C.) together with a material containing carbon (a solid material such as charcoal, a gas material such as natural gas or petroleum gas, or a liquid material). Heat for 38.4k seconds (640 minutes).
4b) The heating temperature is lowered to 1103 K (830 ° C.) and maintained for 1.8 ksec (30 minutes).
4c) Putting the eccentric body shaft into oil (or water) and quenching (quenching).
4d) Heat again to a low tempering temperature of 443 K (170 ° C.) and maintain 7.2 ksec (120 minutes) and temper.

  The point that carbon penetrates and diffuses into the surface layer portion of the eccentric body axis by the above processing is the same as in the curing processing example P. However, according to the present curing processing example 4, the processing depth is the processing depth of the curing processing example P. It becomes about 1.2 to 1.6 mm deeper than (0.4 mm). That is, also in the present curing processing example 4, a position deeper than the depth at which the maximum shear stress is generated in the radial shear stress distribution when the rollers of the eccentric body bearing roll on the eccentric body shaft, specifically, Is cured to a depth that is at least three times the depth at which the maximum shear stress is generated.

  In the curing treatment example 4, as shown in FIG. 2, the characteristics of (A2 / A1 = 3.2 / 3.9 = 0.82 ≦ 1) were obtained. The change in hardness after applying the test heat load is −32 HV (that is, the change in Vickers hardness before and after applying the test heat load is 32 HV). The lifetime of 1.44 times that of the conventional curing process P was obtained.

[Hardening treatment example 5 according to this embodiment]
In the curing processing example 5, the following processing was performed. Here, the material of the eccentric body shaft subjected to the curing treatment example 5 is the same as that of the eccentric body shaft subjected to the curing processing example P.
5a) In an atmosphere depressurized to 10 kPa or less, together with a hydrocarbon gas (for example, methane, propane, ethylene, acetylene, etc.), the eccentric body shaft is heated to 1223 K (950 ° C.) for 24.6 ksec (410 minutes). .
5b) After lowering the heating temperature by gas cooling, the temperature is raised again to 1123 K (850 ° C.) and maintained for 6.3 ksec (105 minutes).
5c) After the temperature was temporarily lowered by gas cooling, the heating temperature was increased again to 1123 K (850 ° C.) and maintained for 1.8 ksec (30 minutes).
5d) Putting the eccentric body shaft into oil (or water) and quenching (quenching).
5e) Reheat to a low tempering temperature of 443 K (170 ° C.) and maintain for 7.2 ksec (120 minutes) and temper.

  By the above processing, carbon penetrates and diffuses into the surface layer portion of the eccentric body shaft. In the present curing treatment example 5, a larger amount of carbon (carbon having an Acm saturated carbon amount or more) than during the curing treatment example P is being processed. Since it is supplied, the carbon content of the surface layer is about 1.2 to 2.5% by weight. Further, in the present curing treatment example 5, a large amount of granular (specifically spherical) metal carbide precipitates in the martensitic structure of the eccentric body axis surface layer portion. Moreover, the area ratio which the said granular carbide accounts in the surface layer part of an eccentric body axis | shaft is 15-25%. In addition, the point which the atmosphere which heats an eccentric body axis | shaft is not restricted to the above is the same as having demonstrated in the example of another hardening process.

  In this curing treatment example 5, as shown in FIG. 2, the characteristics of (A2 / A1 = 2.7 / 3.1 = 0.87 ≦ 1) were obtained. The change in hardness after applying the test heat load is -29 HV (that is, the change in Vickers hardness before and after applying the test heat load is 29 HV). A lifespan of 3.13 times that of the conventional curing process was obtained. In the curing treatment example 5, the treatment depth is as high as 1.4 mm, and when the roller of the eccentric body roller rolls on the eccentric body shaft as in the above-described curing treatment example 3 and the curing treatment example 4. The fact that the hardening treatment is performed to a position deeper than the depth at which the maximum shear stress is generated in the shear stress distribution in the radial direction also contributes to the improvement of the life of the eccentric body shaft. Moreover, in this hardening process example 5, the remaining amount austenite of the eccentric body shaft surface layer portion is 14%, which exceeds 10%, which contributes to the improvement of the life of the eccentric body shaft as in the case of the above-described curing process example 2. Yes.

  Furthermore, in the present curing treatment example 5, fine granular carbides that were not seen in the other curing treatment examples described above are deposited on the surface layer portion of the eccentric body shaft, and as a result, compared with other curing treatment examples. In addition, a significant improvement in service life has been obtained. Here, the granular carbide preferably has a maximum particle size of less than 4 μm (the maximum particle size of the granular carbide obtained in the present curing treatment example 5 is 1 to 2 μm), and the particle shape is spherical. It is preferable (the particle shape of the granular carbide obtained in the present curing treatment example 5 is spherical), and the area ratio of the granular carbide in the surface layer portion of the eccentric body shaft is preferably 15 to 25%.

  The inventors have confirmed the existence of the above five curing treatment examples 1 to 5, but of course they should not be limited to these examples. However, in at least these five curing treatment examples 1 to 5, if a thermal load is applied to the eccentric body shaft by use of a speed reducer, the eccentric body shaft becomes rather difficult to rise due to the change in material characteristics. Such characteristics can be obtained. As a result, as shown in FIG. 2, a life much longer than the life time obtained by the conventional curing process is obtained.

  In the present invention, the test thermal load is a test load that is applied to the eccentric body shaft during use of the speed reducer, and what should be the base is loaded according to the actual usage mode. Heat load. However, since the purpose is to apply a thermal load to the extent that the material characteristics of the eccentric body shaft change as in the case of using the speed reducer, the heat load actually applied to the speed reducer is not necessarily There is no need to link. In short, the qualitative tendency of the raised heights A1 and A2 can be grasped if the heat load changes the material characteristics of the eccentric body shaft. Rather, the heat load for the test is more severe than the actual heat load, for example, the condition that it is higher than the low-temperature tempering temperature (150 ° C. to 200 ° C.). There is a tendency to make comparison easier. In this sense, it can be said that the conditions adopted by the inventors, such as “exposure to 300 ° C. for 3 hours”, is an appropriate heat load in which a qualitative tendency is prominent. In other words, the eccentric body shaft hardening process according to the present invention is not limited to the hardening process by “heat treatment” in the first place. In short, as a result, the curing process in which the above relationship (A2 / A1 ≦ 1) is established, the curing process in which the height of the indentation after applying the test heat load is suppressed, and before applying the test heat load For example, a mechanical curing process such as shot peening can be used for a curing process in which the change in the Vickers hardness of the eccentric body shaft afterwards is suppressed to less than 60 HV, or a curing process in which fine granular carbides are deposited on the surface layer portion of the eccentric body shaft. The specific treatment method such as a curing treatment appropriately combining an electrical curing treatment such as induction hardening is not limited. In this sense, the above term, that is, “low temperature tempering temperature” does not mean the tempering temperature itself when the eccentric body shaft itself is actually heat-treated.

  Further, the specific speed reduction structure of the eccentric oscillating speed reducer according to the present invention is not limited to the above example. For example, only one eccentric body shaft is provided at the central portion in the radial direction of the speed reducer. A speed reduction structure in which the external gear is oscillated and rotated via an eccentric body of an eccentric body shaft arranged in the center of the machine may be used. Further, it may be a so-called bending-meshing type eccentric oscillating speed reducer in which the external gear is in mesh with the internal gear while being bent. In this case, the shaft integrally provided with the eccentric body (non-circular body) for bending the external gear can be regarded as the “eccentric body shaft” according to the present invention.

  From another viewpoint, the present invention is an external gear, an eccentric body shaft having an eccentric body, an eccentric body bearing disposed between the external gear and the eccentric body, An eccentric oscillating type speed reducer having an internal gear meshingly engaged with the internal gear while eccentrically or flexibly oscillating the external gear via an eccentric body of the eccentric body shaft. What has been subjected to a curing process such that the raised height resulting from the raised test of the indentation after applying a thermal load to the shaft is smaller than the eccentric body shaft subjected to the conventional curing process P It can also be understood as.

DESCRIPTION OF SYMBOLS 12 ... Eccentric rocking type reduction gear 14 ... Input shaft 16 ... Sun gear 18 ... Transmission gear 20 ... Eccentric body shaft 22A, 22B ... Eccentric body 24A, 24B ... External gear 26A, 26B ... Roller (Eccentric body bearing)
28 ... Internal gear

Claims (9)

An external gear, an eccentric shaft having an eccentric body, an eccentric bearing disposed between the external gear and the eccentric body, and an internal gear, the eccentric body shaft having an eccentric body An eccentric oscillating type speed reducer in which the external gear is engaged with the internal gear while being eccentrically or flexibly oscillated,
An eccentric rocking-type speed reducer, characterized in that granular carbide having a maximum particle size of less than 4 μm is deposited on a surface layer portion of the eccentric body shaft. In claim 1,
An eccentric oscillating speed reducer, wherein the granular carbide has a spherical shape. In claim 1 or 2,
The eccentric oscillating speed reducer, wherein the area ratio of the granular carbide in the surface layer portion of the eccentric body shaft is 15 to 25%. In any one of Claims 1-3,
The total radial clearance between the eccentric body shaft, the eccentric body bearing, and the external gear is −10 μm to 10 μm, and the rotational speed of the eccentric body shaft and the pitch circle diameter of the rolling body of the eccentric body bearing An eccentric oscillating speed reducer characterized by having a product of 10,000 rpm · mm or more. An external gear, an eccentric shaft having an eccentric body, an eccentric bearing disposed between the external gear and the eccentric body, and an internal gear, the eccentric body shaft having an eccentric body An eccentric oscillating type speed reducer in which the external gear is engaged with the internal gear while being eccentrically or flexibly oscillated,
The eccentric rocking-type speed reducer, wherein the retained austenite in the surface layer portion of the eccentric body shaft is 10% or more. In any one of Claims 1-5,
Nitrogen penetrates and diffuses into the surface layer of the eccentric body shaft. An external gear, an eccentric shaft having an eccentric body, an eccentric bearing disposed between the external gear and the eccentric body, and an internal gear, the eccentric body shaft having an eccentric body In the manufacturing method of the eccentric body shaft of the eccentric oscillating speed reducer in which the external gear is engaged with the internal gear while being eccentrically or flexibly oscillated,
The manufacturing method of the eccentric body axis | shaft characterized by including the procedure which deposits the granular carbide | carbonized_material below a maximum particle size of 4 micrometers in the surface layer part of the said eccentric body axis | shaft. In claim 7,
The procedure for precipitating the granular carbide is to heat the eccentric body shaft together with the carbon-containing material, and infiltrate the carbon into the surface layer portion of the eccentric body shaft until the carbon content becomes 1.2 to 2.5%. The manufacturing method of the eccentric body axis | shaft characterized by including the procedure to diffuse. In claim 7 or 8,
The manufacturing method of the eccentric body axis | shaft characterized by including the procedure which penetrates and diffuses nitrogen in the surface layer part of the eccentric body axis | shaft.

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