JP6057943B2 - Rolling tool manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a rolling tool.

  As a technique for improving the wear resistance of a rolling tool, a technique for performing nitriding treatment on the surface of a base material is known (Patent Document 1). According to such nitriding treatment, for example, the surface hardness is improved by diffusing nitrogen on the surface of high-speed steel or die steel, but the surface hardness is about 1400 HV at the maximum, and sufficient improvement in wear resistance is achieved. I couldn't plan.

  On the other hand, by coating TiN on the surface of the base material by CVD, it is possible to secure a surface hardness of up to about 1700 HV and improve wear resistance, but the coating temperature is high speed steel or die steel. Since the tempering temperature is exceeded, the hardness of the base material decreases. Therefore, the difference in hardness between the base material and the coating layer is increased, and the coating layer is likely to be peeled off, so that the durability is not sufficient.

  On the other hand, since the coating at a relatively low temperature is possible by adopting the PVD treatment, it is possible to suppress the decrease in the hardness of the base material and to prevent the coating layer from peeling off.

JP 2002-192282 A (for example, paragraph 0013)

  However, the above-described coating by the PVD treatment has a problem that the workpiece is slipped because the friction coefficient of the coating layer is low. When the work piece slips, it is necessary to perform the rolling process by pressing the rolling tool against the work piece, which causes a decrease in durability of the rolling tool.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing a rolling tool that can suppress slippage of a workpiece.

Method for producing a rolling tool of claim 1, wherein in order to achieve this object is achieved by a method for producing a rolling tool having a rolling surface for rolling the predetermined shape of the workpiece is plastically deformed, A preparation step of forming a target composed of at least one metal element in the third period and the fourth period of the periodic table and Al and having an Al content set to 30 wt% or more and 75 wt% or less, and the preparation process wherein performs PVD processing by using a target with an arc ion plating method after, and a processing step of forming a coating layer by coating a coating material on the rolling surface, in the processing step, the drop on the surface Rett Is formed on the rolled surface .

Method for producing a rolling tool according to claim 2 is a method of manufacturing a rolling tool according to claim 2, wherein, in said processing step, the coating layer thickness is set to and the range 4μm over 0.5μm the formed on the rolling surface.

Method for producing a rolling tool according to claim 3 is a method of manufacturing a rolling tool according to claim 1 or 2, wherein the rolling surface, chamfer and rolling direction rear side of the chamfer at least provided with a finishing portion provided continuously to, and in the processing step, the coating layer in which the droplets are distributed, you formed chamfer of said rolling surface.

According to the method for manufacturing a rolling tool according to claim 1, since a coating layer is formed on the rolling surface by coating the coating material by PVD treatment, the surface hardness is increased and the wear resistance is increased. Can be improved.

  On the other hand, in such a coating layer, where the friction coefficient is low, the droplets are dispersedly arranged on the surface thereof, so that the droplets can bite into the surface of the workpiece and the slippage of the workpiece can be suppressed. In particular, since the droplet has a triangular pyramid shape, it is possible to achieve both the biting property and the separation property with respect to the surface of the workpiece and to improve the rolling performance.

In addition , arc ion plating is used for the PVD treatment, and at least one metal element in the third period and the fourth period of the periodic table and Al are included, and the Al content is 30 wt% or more and 75 wt%. Since a target set to not more than% is used, it is easy to generate triangular pyramid-shaped droplets on the surface of the coating layer. As a result, the rolling performance can be improved.

According to the manufacturing method of the rolling tool according to claim 2, in addition to the effects of the manufacturing method of the rolling tool according to claim 1, thickness of the coating layer is set to and the range 4μm over 0.5μm Therefore, the drop performance can be improved by setting the droplets to a size suitable for the rolling process.

  That is, when the thickness dimension of the coating layer is smaller than 0.5 μm, the droplets cannot be sufficiently dispersed and arranged, and the slip of the workpiece cannot be sufficiently suppressed, while the thickness of the coating layer When the dimension is larger than 4 μm, the number of droplets becomes excessive and the rolling resistance increases.

According to the manufacturing method of the rolling tool of Claim 3 , in addition to the effect which the manufacturing method of the rolling tool of Claim 1 or 2 show | plays, a droplet is disperse | distributed to the biting part in a rolling surface. Since it arrange | positions, the slip of the workpiece rolled by the biting part can be suppressed and the improvement of rolling accuracy can be aimed at. On the other hand, since the droplets are not formed in the finished portion, the rolling resistance of the workpiece is reduced while taking advantage of the property that the surface of the coating layer by PVD treatment is smooth. Smoothing can be obtained.

(A) is a front view of the rolling tool which is one Embodiment of this invention, (b) is a side view of a rolling tool. (A) is a front view of a biting part, (b) is the elements on larger scale of the rolling tool which expanded and showed the IIb part of Fig.2 (a). It is the partial expansion front perspective view which expanded and looked at the biting part of a rolling tool. It is the table | surface which showed the test result of the tool life test.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1A is a front view of a rolling tool 1 according to an embodiment of the present invention, and FIG. 1B is a side view of the rolling tool 1.

  The rolling tool 1 is a tool for rolling a plurality of tooth profiles by plastically deforming the outer peripheral surface of a cylindrical shaft-shaped material (hereinafter referred to as a workpiece). The workpiece is sandwiched between the opposing surfaces of the pair of rolling tools 1. In addition, in FIG. 1, one rolling tool 1 fixed to a rolling machine (not shown) is illustrated among a pair of rolling tools 1 which perform a rolling process, and this one rolling tool Illustration of the other rolling tool 1 translated in parallel with respect to 1 is omitted.

  The rolling tool 1 is formed in a substantially rectangular parallelepiped shape from a metal material such as alloy tool steel, cold die steel or high-speed tool steel suitable for rolling, and one surface thereof (FIG. 1 (a) on the front side of the paper surface, (B) The upper side is provided with a rolling tooth profile surface 2 for rolling a plurality of tooth profiles on the outer peripheral surface of the workpiece. A coating layer is formed on the rolling tooth profile surface 2 by PVD processing, which will be described later, and the rolling tool 1 starts from the rolling direction start end side (the right side in FIGS. 1A and 1B) and the terminal end side (see FIG. 1A ), (B) toward the left side), a chamfered portion 2a, a finish portion 2b, and a relief portion 2c are successively provided.

  The biting part 2a is a part for allowing the rolling tooth profile surface 2 of the rolling tool 1 to bite against the outer peripheral surface of the workpiece. This biting part 2a is predetermined toward the finishing part 2b side (FIG. 1 (a), (b) left side) from the rolling direction start end side (FIG. 1 (a), (b) right side) of the rolling tool 1. Further, an anti-slip process is performed on the surface of the biting portion 2a by forming a droplet 4 (see FIG. 3) to be described later. . Therefore, the biting portion 2a can gradually bite the plurality of processing teeth 3 engraved on the biting portion 2a on the outer peripheral surface of the workpiece without sliding the workpiece.

  The finishing portion 2b is a portion for finishing a plurality of tooth profiles rolled on the workpiece by the biting portion 2a, and is approximately the lower end surface of the rolling tool 1 (lower side in FIG. 1 (b)). They are formed in parallel. The relief portion 2 c is a portion for discharging the workpiece finished by the finishing portion 2 b from the rolling tooth profile surface 2 of the rolling tool 1. The relief portion 2c is formed so as to be inclined downward at a predetermined inclination angle κ2 from the end of the finishing portion 2b toward the end of the rolling tool 1 in the rolling direction (left side in FIG. 1B).

  Next, the biting portion 2a of the rolling tooth profile surface 2 will be described with reference to FIGS. Fig.2 (a) is a front view of the biting part 2a. In FIG. 2A, a part of the rolling tool 1 in the longitudinal direction is omitted.

  As shown in FIG. 2A, a plurality of processing teeth 3 are engraved on the biting portion 2a. The processing teeth 3 are continuously engraved in the rolling direction (FIG. 2 (a) left-right direction) while having a constant pitch corresponding to the outer peripheral dimension of the workpiece. They are engraved in a state of being lined up in a direction substantially perpendicular to the direction (vertical direction in FIG. 2A). The workpiece is relatively rolled and moved on the biting portion 2a (finishing portion 2b and relief portion 2c) from the start side to the end side in the rolling direction, so that a plurality of tooth profiles are formed on the outer peripheral surface thereof. Is rolled.

  FIG. 2B is a partially enlarged front view of the rolling tool 1 showing the IIb portion of FIG. 2A enlarged, and FIG. 3 is an enlarged view of the biting portion 2a of the rolling tool 1. It is a partial expansion front perspective view. In FIG. 3, the enlarged droplet 4 is shown in a schematic view. A large number of droplets 4 are formed on the surface of the biting portion 2a, as shown in FIGS.

  The droplet 4 is a particle protruding in a triangular pyramid shape from the surface of the coating layer applied to the rolling tool 1. The droplet 4 is formed as a by-product when the coating is performed by the PVD process, and the frequency of formation increases as the thickness dimension of the coating layer increases, and the individual external shape also increases. Here, the thickness dimension of the coating layer is preferably set to 0.5 μm or more and 4 μm or less. Thereby, the droplets 4 are formed with a size and frequency suitable for the rolling process, and the rolling performance of the rolling tool 1 can be improved.

  That is, when the thickness dimension of the coating layer is smaller than 0.5 μm, since the droplets 4 are small and cannot be sufficiently dispersed and arranged, the workpiece cannot be sufficiently prevented from slipping. On the other hand, when the thickness dimension of the coating layer is larger than 4 μm, the number of droplets becomes excessive and the rolling resistance increases.

  In the present embodiment, the thickness dimension of the coating layer is set to 2.2 μm. In this case, many droplets 4 formed on the surface of the biting portion 2a of the rolling tool 1 have an area ratio (the bottom area of the droplet 4) of about 15% to 40% with respect to the area of the biting portion 2a. Are formed on the surface of the rolling tool 1 substantially uniformly (see FIG. 2B).

  In addition, the droplet 4 is the largest, and the bottom surface has a circumscribed circle diameter of 8 μm and a height of 4 μm, and the majority has a bottom surface size of a circumscribed circle diameter of about 3 μm and a height of 1. It is formed to 5 μm (see FIG. 3). Thus, since the droplet 4 is small, it can suppress that the ductility of a to-be-processed object falls by the droplet 4. FIG. In addition, if the thickness dimension of a coating layer increases from the formation mechanism of the droplet 4 mentioned later, the magnitude | size and height of the bottom face of a droplet will increase proportionally.

  Here, it is also conceivable to perform anti-slip processing by forming a recess in the rolling tool 1. However, in this case, there is a problem that stress concentration occurs in the recessed portion and the rolling tool 1 is likely to crack. On the other hand, since the anti-slip process in this embodiment forms a convex part in the rolling tool 1, even if the stress applied to the rolling tool 1 becomes excessive, the non-slip process part (drop in this embodiment) It can suppress that let 4) becomes a starting point of a crack.

  Next, a method for manufacturing the droplet 4 will be described. The manufacturing method of the droplet 4 mainly includes a preparation process for manufacturing a target used when performing the PVD process by the arc ion plating method and a processing process for performing the PVD process using the manufactured target.

  First, in the preparation step, a target composed of at least one metal element of the third period and the fourth period of the periodic table and Al is formed by the HIP manufacturing method (hot isostatic pressing method). The HIP manufacturing method is a process in which a high temperature and an isotropic pressure are simultaneously applied to an object to be processed. In this embodiment, an isotropic pressure is set to Ti and Al using Ar gas as a pressure medium. By adding to the contained powder, a target formed from a TiAl alloy is manufactured.

  The target is preferably set to have an Al content of 30 wt% or more and 75 wt% or less, and particularly preferably 40 wt% or more and 60 wt% or less. Thereby, since an arc can be concentrated between Al and another metal element, the droplet 4 can be easily formed on the surface of the rolling tool 1 in the PVD process described later. In the present embodiment, the target is set to have an Al content of 50 wt% and a Ti content of 50 wt%. Next, a processing process performed following the preparation process will be described.

  The processing step is performed inside the arc ion plating apparatus. The arc ion plating apparatus is a box-shaped apparatus capable of forming the inside of the apparatus in a vacuum state, a target that generates metal ions by arc discharge, and a rotary table that rotates the rolling tool 1 and negatively charges it. And a reaction gas introduction hole which is a passage for the reaction gas introduced into the interior.

  In the processing step, first, the rolling tool 1 is placed on a rotary table, and after the inside of the arc ion-plating apparatus is evacuated, the rolling tool 1 is heated and the rolling tool 1 is negatively charged. Next, while rotating the rolling tool 1 by rotating the rotary table, nitrogen gas is introduced from the reaction gas introduction hole, and metal ions of Ti and Al are generated by evaporating the target by arc discharge. The positively charged nitrogen gas and metal ions are attracted to the negatively charged rolling tool 1 and receive electrons from the rolling tool 1 to form a coating layer (formed from TiAlN on the rolling tool 1). (Hereinafter referred to as “TiAlN coating”).

  In this embodiment, the TiAlN coating is formed in two stages. First, in the first stage, a TiAlN coating is formed by performing PVD treatment on the finishing portion 2b and the relief portion 2c of the rolling tool 1 with a mask attached to the biting portion 2a of the rolling tool 1. The By forming this TiAlN coating, the surface hardness and wear resistance of the rolling tool 1 are improved, but the friction coefficient of the rolling tool 1 is reduced. In order to perform the corresponding anti-slip processing, in the subsequent second stage, the mask attached to the chamfered portion 2a is peeled off and the mask is attached to the finished portion 2b and the escape portion 2c. The TiAlN coating and the droplet 4 are formed on the biting portion 2a. Note that the order of the first stage and the second stage described above may be reversed.

  Next, the formation mechanism of the droplet 4 will be described. In the treatment process described above, when the target is heated by arc discharge, the arc concentrates on the boundary between Ti and Al, so that the Al before evaporation is ejected as a lump, and the ejected Al lump is turned off. It adheres to the tool 1. A triangular pyramid-shaped droplet 4 is formed by newly adhering Al or TiAl to the adhered lump of Al.

  The size of the droplet 4 varies depending on at which stage the Al lump which is the nucleus of the droplet 4 adheres to the rolling tool 1. That is, the droplet 4 that grows with the Al lump adhering to the rolling tool 1 in the initial stage of the above-described processing process as a nucleus grows greatly, and the Al lump adhering to the rolling tool 1 at the end of the processing process becomes the nucleus. The grown droplet 4 becomes a small one. Therefore, the size (the size and the height of the bottom surface) of the droplet 4 can be adjusted by adjusting the timing at which the lump of Al is attached to the rolling tool 1 in the processing step.

  Here, in the second stage of the treatment process in the present embodiment, the arc discharge condition is set to a condition in which Al is easily ejected as a lump from the target. On the other hand, in the first stage of the treatment process, the arc discharge condition is set to a condition in which Al is not easily ejected from the target as a lump (evaporation is easy).

  Thereby, since the droplet 4 can be easily formed in the biting part 2a of the rolling tooth profile surface 2, the anti-slip function can be improved. Moreover, since it can suppress that the droplet 4 is formed in the finishing part 2b and the escape part 2c, while taking advantage of the characteristic that the TiAlN coating is smooth, the rolling resistance is reduced and the rolling of the workpiece is performed. The surface can be smoothed. That is, it is possible to achieve both improvement of the anti-slip function and suppression of rolling resistance.

  In addition, it is difficult to form the convex part of the same shape and the same posture as the droplet 4 (triangular pyramid shape tapered in the height direction) by another method. For example, when forming a convex portion by hitting a triangular pyramid-shaped particle on the rolling tool 1, it is difficult to manipulate the posture of the triangular pyramid-shaped particle (for example, a posture in which the tip is directed in the height direction, The shape of the convex portion formed on the rolling tool 1 is sparse. On the other hand, according to the present embodiment, the droplet 4 grows in the height direction (the front side in FIG. 2 (b)) with the Al lump attached to the rolling tool 1 as a nucleus, and thus the droplet 4 Can be easily formed into a triangular pyramid shape tapered in the height direction.

  Next, with reference to FIG. 4, the result of the tool life test performed using the rolling tool 1 configured as described above will be described. FIG. 4 is a table showing the test results of the tool life test. This tool life test is a test for measuring the life of the rolling tool 1, and it is determined that the life is over when the variation of the overpin diameter of the spline rolled onto the workpiece exceeds a predetermined reference value. is there. Here, as described above, when the anti-slip process applied to the biting portion 2a is worn, the rolling tool 1 slides the workpiece during the rolling process, and is rolled into the workpiece. The overpin diameter of the spline becomes worse. Therefore, the tool life test described below can be rephrased as an anti-slip durability test performed on the rolling tool 1.

  In the life test, a rolling tool 1 (hereinafter referred to as “the product A of the present invention”) in which the TiAlN coating of the present invention is formed with a thickness of 2.2 μm and a conventional rolling tool that is not coated (hereinafter referred to as “the present invention product A”). And “conventional product B”). The difference between the product A of the present invention and the conventional product B is only whether or not the TiAlN coating is formed, and other shapes, dimensions, materials, and the like are the same. The workpiece is a cylindrical shaft-shaped material formed of stainless steel (SUS301), and a M10 × 1.5 bolt shape is formed by rolling.

  In the life test, every time the continuous rolling process of 3000 workpieces is completed, 10 final rolled products are sampled, and the average value of the overpin diameter variation obtained by measuring the 10 final rolled products is a standard. The lifetime was judged by whether or not the value was satisfied.

  First, when the number of rolling processes is 15000, both the product A of the present invention and the conventional product B roll the spline to the workpiece with good accuracy, and the same is true when the number of rolling processes is 18000. It was the result.

  Next, when the number of rolling processes was 21,000, the measurement result of the rolled product rolled with the conventional product B exceeded the reference value, and the conventional product B reached the end of its life. In the conventional product B, the test was continued until the number of rolled products was 24,000. However, the measurement result of the rolled product was greatly deteriorated, and the surface of the bite portion was so worn that it could be visually confirmed. Was progressing.

  On the other hand, the product A of the present invention satisfies the standard value of the measurement result of the rolled product even when the number of rolling processes reaches 36,000, and then the life of the product when the number of rolling processes is 39000. Was confirmed. Also at this time point, no peeling was observed in the coating formed by the PVD process, and it was confirmed that the droplet 4 was formed in close contact with the surface of the biting portion 2a.

  From the test results, the product life of the product A of the present invention was improved by 180% compared to the conventional product B. Here, in the product A of the present invention, the wear resistance of the rolling tool 1 is improved by forming a TiAlN coating on the surface of the biting portion 2a by PVD treatment. Further, the formation of a large number of droplets 4 on the TiAlN coating improves the anti-slip function of the biting portion 2a. The TiAlN coating and the droplet 4 are considered to have a synergistic effect, and the tool life is greatly improved.

  That is, for example, if a TiAlN coating is only formed on the rolling tool 1 and a portion having an anti-slip function such as a droplet 4 is not formed, a gap between the work piece and the rolling tool 1 is formed during rolling. Slip occurs. In this case, in order to suppress the slip of the workpiece, it is necessary to increase the pressure applied to the workpiece from the rolling tool 1 in the biting portion 2a (for example, to reduce the inclination angle κ1), and at the time of rolling The load applied to the rolling tool 1 becomes excessive. Therefore, the TiAlN coating is peeled off early, and the tool life of the rolling tool 1 is shortened.

  On the other hand, in the product A of the present invention, the droplets 4 are projected in a triangular pyramid shape, so that the workpiece is easily eroded and easily detached (peeled) from the workpiece. That is, since the droplet 4 is tapered toward the tip, the rolled tooth profile surface 2 can be easily eaten on the surface of the workpiece, and the rolled tooth profile surface 2 is separated from the workpiece. The resistance at the time of making it can be suppressed. Thereby, while being able to suppress the slip of the workpiece at the time of a rolling process, the separation property of a workpiece can be improved. Therefore, since the workpiece does not slide on the biting portion 2a during the rolling process, the pressure generated between the rolling tool 1 and the workpiece can be properly maintained. Therefore, since peeling of the TiAlN coating can be suppressed, the tool life of the rolling tool 1 can be improved.

  In addition, when anti-slip processing is performed by disposing a lump on the rolling tool 1 by thermal spraying or the like, the separation resistance between the lump disposed by spraying and the workpiece is low, so that the rolling resistance can be increased. There is a problem that the surface of the workpiece is roughened. On the other hand, the droplet 4 of the present embodiment has a high work piece separation property as described above, so that the rolling resistance is reduced or the surface of the work piece becomes rough while ensuring the anti-slip function. Can be suppressed.

  As described above, since the droplet 4 is projected in a triangular pyramid shape, the droplet 4 formed on the drive side (opposite side to the workpiece during rolling) of the machining tooth 3 is particularly covered. The processed material can be easily eaten. Therefore, compared to the droplet 4 formed on the coast side of the machining tooth 3 (the trailing surface side with respect to the workpiece during rolling), the frequency of forming the droplet 4 formed on the drive side is increased, By increasing the size of the let 4, it is possible to improve the anti-slip function during rolling.

  Further, the droplet 4 formed on the coast side of the processing tooth 3 can be easily removed (peeled) from the workpiece. This is because the droplet 4 is formed in a tapered shape (triangular pyramid shape) and the height of the droplet 4 is set to 4 μm or less. Therefore, on the coast side of the processed tooth 3, the peeling of the droplet 4 can be suppressed, the durability of the anti-slip function by the droplet 4 can be improved, and the surface of the workpiece can be suppressed from becoming rough. it can.

  The present invention has been described based on the above embodiment, but the present invention is not limited to the above embodiment, and various modifications can be easily made without departing from the spirit of the present invention. Can be inferred.

  In the above embodiment, the case where a target containing Ti and Al is used has been described. However, the present invention is not necessarily limited thereto. For example, a target containing one or more of Ti, Al, Cr, B, and Si may be used.

  In the above embodiment, the case where the droplets 4 are uniformly formed on the biting portion 2a has been described, but the present invention is not necessarily limited thereto. For example, the frequency with which the droplets 4 are formed or the size of the droplets 4 may be changed along the rolling direction. In this case, for example, compared to the droplet 4 formed on the end side (finished portion 2b side) of the biting portion 2a, the frequency of forming the droplet 4 formed on the start end side is increased, or the droplet 4 By increasing the size, the anti-slip function at the initial stage of rolling can be improved. For example, the droplet 4 may be formed in a part of the biting portion 2a. In this case, for example, the droplet 4 is formed only in the rolling direction starting end side of the biting portion 2a (for example, the region on the starting end side of each region obtained by dividing the biting portion 2a into three parts), so that the workpiece is formed. The period during which a smooth region (region in which the droplets 4 are not formed) in the rolling tooth profile surface 2 is rolled can be lengthened. Therefore, the surface of the rolled product can be further smoothed.

  In the above embodiment, the case where the droplet 4 is formed only on the biting portion 2a has been described, but the present invention is not necessarily limited thereto. For example, the droplet 4 may be formed on the finishing portion 2b or the relief portion 2c, or may be formed on the entire surface of the rolling tooth profile surface 2. In this case, even if the workpiece is a material having a particularly low frictional resistance, it can be rolled well, and the degree of freedom in selecting the workpiece can be improved.

1 Rolling tool 2 Rolling tooth profile (rolling surface)
2a Chamfered part 2b Finishing part 4 Droplet

Claims (3)

In the manufacturing method of a rolling tool provided with a rolling surface that plastically deforms a workpiece and rolls a predetermined shape,
A preparatory step of forming a target composed of at least one metal element of the third period and the fourth period of the periodic table and Al and having an Al content set to 30 wt% or more and 75 wt% or less;
Its performs PVD processing by arc ion plating method using the target after the preparation step, and a step of forming a coating layer by coating a coating material on the rolling surface,
In the processing step, a method for manufacturing a rolling tool is characterized in that a coating layer in which droplets are dispersed and disposed on the surface is formed on the rolling surface . The processing in the step, the manufacturing method of the rolling tool of claim 1, wherein the forming the coating layer thickness is set to a range below 0.5μm or more and 4μm in the rolling surface. The rolling surface includes at least a biting portion and a finish portion continuously provided on the rear end side in the rolling direction of the biting portion,
In the processing step, the production of rolling tool according to the coating layer in which the droplets are distributed in claim 1 or 2, characterized that you formed chamfer of said rolling surface Way .