JP2012052582A - Machining method for hole inner face and tool used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and inexpensively form fine irregularities that are smoothly repeated in both of a circumferential direction and a longitudinal direction of a hole and which is advantageous for retaining oil and abrasion resistance, by using a tool with fineness in boring of a hole inner face with a rotating tool.SOLUTION: In a method for machining the inner face of the hole 1, the tool 2 advances and cuts the inner face of the hole 1 for receiving a sliding member, in the longitudinal direction of the hole 1, while being rotated, to machine the inner face of the hole 1, and the machining is performed such that changes in increase and decrease of cutting depth produced in the circumferential direction of the inner face of the hole 1 are caused at multiple points depending on rotation of the tool 2, and a machining start point S and a machining end point B are regulated to be shifted in the circumferential direction of the inner face of the hole 1 due to one rotation of the tool 2, thus solving the problem.

Description

  The present invention relates to a processing method for obtaining a predetermined inner surface structure of a hole inner surface, and a processing tool used for the processing method.

  The inner surface structure of the hole greatly affects the fitting characteristics and sliding characteristics with the pins and shafts it receives and supports. With these intent, Patent Document 1 below biases the roughness of the inner peripheral surface of the piston pin hole that supports the piston pin between the primary machining axis and the secondary machining axis of the piston pin hole machining tool. This discloses a technique for changing the longitudinal direction and the circumferential direction of the pin hole. Thereby, even if the high surface pressure portion and the low surface pressure portion of the pin hole are mixed in the longitudinal direction or the circumferential direction, the surface roughness of a desired size can be formed for each corresponding portion, and the low surface pressure portion In addition to improving the lubricating oil retention capability, the wear resistance of the high surface pressure region can be improved.

  Patent Document 2 below discloses a piston for an internal combustion engine in which streaking is finished in a regular band shape along the inner surface of the pin hole on the inner surface or the outer surface of the piston pin hole or on both the inner and outer surfaces. Is disclosed. As a result, when the piston slides in the cylinder bore, the piston pin is deformed by a compressive stress such as a gas force or an inertial force from the piston, thereby reducing the compressive stress applied to the inner surface of the pin hole. I am doing so. Further, the contact area between the piston and the pin hole is reduced, and seizure can be prevented without increasing the surface pressure of the pin hole surface. Furthermore, the piston pin can be prevented from coming off due to wear or deformation of the streak.

  Further, Patent Document 3 below discloses a piston / piston pin / connecting rod constituent unit in which at least one of bearings for a piston pin or a crankshaft is roughened by a laser beam in an area that receives at least a high load. Yes. Thereby, the oil holding capacity of the bearing is enhanced.

  Patent Document 4 below discloses a piston in which a plurality of crater-like depressions are provided on the surface of two piston pin holes provided in the piston skirt in order to receive the piston in the piston skirt. Thus, the oil storage volume is increased by the plurality of crater-shaped depressions, and the lubricant, particularly the engine oil, is collected so that a sliding membrane or cushion can be formed. As a result, based on the relative movement of the piston within the piston pin hole, sticking can be effectively prevented, while at the same time, the piston pin hole has important characteristics for the piston.

  Further, in Patent Document 5 below, a large number of fine recesses are formed on the sliding surface of at least one member that slides relatively in the presence of lubricating oil. A low friction sliding member is disclosed in which a second minute recess having a smaller width and depth in the sliding direction than the first minute recess is formed. As a result, the oil retention on the sliding surface is improved by mixing the two types of minute recesses, and the friction generated on the sliding surface can be reduced. In particular, since one of the two kinds of minute recesses is smaller in width and depth in the sliding direction than the other, friction can be reduced without causing direct contact due to a decrease in load capacity. In this document, the minute concave portion indicates an extremely small concave portion on the order of microns.

  Patent Document 6 below discloses a piston for an internal combustion engine in which a high-hardness thin film fired from a gas phase is formed on the peripheral surface of a pin hole on which a piston pin slides. Thereby, the peripheral surface of the pin hole is strengthened by this thin film, and the peripheral surface of the pin hole can be prevented from being worn even when subjected to stress due to bending of the piston pin or frictional force due to sliding.

  On the other hand, since the following Patent Document 7 is used to process the inner surface while the rotating processing tool advances in the longitudinal direction of the hole, since it is performed with the blade at the tip of the shaft-shaped main body protruding long, chatter is likely to occur. By providing a concave groove at the tip of the tool body, the tip becomes lighter, increasing the natural frequency of the tool itself, and increasing the discrepancy between the natural frequency of the mechanical system including the tool and the frequency of the external force. While preventing chattering, by providing a concave groove, it is possible to secure a thickness in the direction in which the main component of the cutting force acts, and leave a part that functions as a rib against the back component of the cutting force Such a technique is disclosed.

JP-A-3-246354 Japanese Patent Laid-Open No. 5-5460 Special table 2004-508501 gazette Special table 2007-504411 JP 2007-321860 A JP-A-2-218848 JP 11-285906 A

  However, in order to make the inner surface of the hole into a desired surface structure, a special secondary process in which the machining axis as described in Patent Document 1 is biased after the primary process as the hole process is described in Patent Document 2. A strip-shaped streak process on a specific portion with a cutting tool such as, a laser process as described in Patent Document 3, a shot peening process as described in Patent Document 4, and two types of fine patterns as described in Patent Document 5 Performing the process of forming the recesses requires a special secondary process, which increases the processing cost and increases the part cost. In addition, since the boundary between the concaves and convexes is sharp, stress at the time of sliding of the pin concentrates on this part, so that there is a concern that wear resistance is reduced and partial seizure occurs.

  In addition, since the film forming process described in Patent Document 6 is to form a film from a gas phase using a material having high hardness such as nickel and molybdenum, the processing cost is increased in terms of materials, processing equipment, and processing work. Since it is more bulky, the cost of the parts is further increased.

  The technique described in Patent Document 7 does not realize a hole inner surface structure that is advantageous for oil retention and wear resistance even if the processing accuracy can be improved by suppressing vibration of the processing tool.

  In view of such problems, the present invention is advantageous for oil retention and wear resistance, which are smoothly repeated in both the circumferential direction and the longitudinal direction of the hole by skillfully using the processing tool in processing with the rotary processing tool on the inner surface of the hole. It aims at providing the processing method of the inner surface of a hole which forms fine unevenness | corrugation easily and cheaply, and the processing tool used for this.

  In order to solve the above-mentioned problems, the inner surface processing method according to the present invention processes the inner surface of the hole by cutting the inner surface of the hole receiving the sliding member in the longitudinal direction of the hole while the processing tool rotates. There are a plurality of cutting depth increase / decrease changes that occur in the circumferential direction of the hole inner surface due to the rotation of the processing tool, and these increase / decrease changes depend on the machining start point and machining by one rotation of the tool. It is characterized by being controlled so as to deviate in the circumferential direction of the inner surface of the hole from the end point.

  The characteristics and regularity of the vibration of the rotating tool can be intentionally controlled by the material of the tool and the combination of materials. By combining this with the rotation speed and feed of the tool, cutting by the vibration of the tool is performed. The width of the increase / decrease of the quantity, that is, the amplitude and the period can be arbitrarily controlled. Moreover, the processing result of the inner surface of the hole produced by manipulating the amplitude and cycle of the vibration of the processing tool can be measured and confirmed by, for example, a three-dimensional shape measuring instrument.

  From these, as in the above configuration, there are a plurality of changes in the cutting depth that occur in the circumferential direction of the hole inner surface due to the rotation of the processing tool, and this increase / decrease change occurs at the start point and end point of one rotation of the tool. It can be processed while being regulated so as to be displaced in the circumferential direction. By this processing method, in the circumferential direction of the hole, the change period of the deep valley of the cutting and the shallow peak of the cutting is shifted between the machining start point and the machining end point, and in the longitudinal direction of the hole, An inner surface structure of holes in which valleys are alternately arranged is obtained.

  In the above, the hole is a piston pin hole of a piston, a pin hole of a connecting rod, or a through hole of a crankshaft.

  The processing tool used in the method for processing the inner surface of the hole of the present invention has a main body extending in a substantially columnar shape from the attachment portion to the mechanical system to the tip having the blade, and the main body is moved from its midway position to the attachment portion side. It is characterized by a combination structure of a base side material made of a general structural material and a tip material made of a super hard material on the tip side, and the base member and the tip material are integrated by a joint portion such as brazing. .

  And, by combining the vibration characteristics of the low frequency with large amplitude due to the general structural material of the base side material, and the vibration characteristics of high frequency with small amplitude due to the cemented carbide of the tip side material according to their occupation length ratio, Number of increase / decrease changes in the cutting depth generated in the circumferential direction of the inner surface of the hole due to the rotation of the processing tool, and deviation in the circumferential direction of the inner surface of the hole between the processing start point S and the processing end point F by one rotation of the processing tool. Can easily set the vibration characteristics to regulate

  According to the hole inner surface processing method of the present invention, there are a plurality of deep valleys of cutting and shallow peaks of cutting in the cutting streak by the processing tool in the circumferential direction of the hole inner surface, and smoothly connected to each other. And the valley part are shifted from the starting point and the ending point of one rotation of the processing tool, and the peak part is not aligned in the longitudinal direction of the hole but is shifted in the circumferential direction. For this reason, the ridgeline formed by overlapping the ridges is spiral, so that the oil retained in the valleys is difficult to escape and seizure due to metal touch is less likely to occur.

  Further, the roundness of the inner surface of the hole can be ensured by the arrangement in which the crests are not aligned in the longitudinal direction of the hole but shifted in the circumferential direction to form a spiral. From these, in addition to having high fitting characteristics, wear resistance is improved and partial seizure can be avoided.

  In addition, since a desired recess can be formed by one-pass processing, it is easy to connect the crests and troughs smoothly, and the processing is simple and requires only a short time, thus reducing processing costs and product costs. .

It is explanatory drawing which sees typically the relationship between the piston pin hole of a piston, and the processing tool to rotate about the processing method of the hole inner surface which concerns on embodiment of this invention. One example of the internal structure of the piston pin hole obtained by the processing method is schematically shown, wherein (a) is a transverse sectional view, (b) is a longitudinal sectional view, and (c) is a perspective view. It is explanatory drawing which sees typically the relationship between the piston pin hole of a piston, and the processing tool to rotate about the processing method of the hole inner surface of a comparative example. It is sectional drawing which shows typically one example of the internal structure of the piston pin hole obtained by the same processing method, (a) is a cross-sectional view, (b) is a longitudinal cross-sectional view, (c) is a perspective view.

  The hole inner surface processing method according to the embodiment of the present invention will be described together with a comparative example with reference to FIGS. 1 to 4 for understanding of the present invention. The following description is a specific example of the present invention and does not limit the items described in the claims.

  The hole inner surface processing method according to the present embodiment receives a sliding member as shown in FIG. 1, and the hole 2 as shown by the arrow in FIG. It is a processing method of the inner surface of the hole for processing the inner surface of the hole 1 by cutting in the longitudinal direction.

  By the way, the processing tool used for such a processing method receives and supports the piston pin that connects the connecting rod to the piston head 21 so as to be slidable, for example, like the processing tool 20 of the comparative example shown in FIG. Used for machining the inner surface of the piston pin hole 22. In this case, since the piston pin hole 22 penetrates two places on the diameter line of the peripheral wall of the piston head 21, the length of the diameter + α of the piston head 21 from the base portion attached to the spindle of the cutting machine to the blade 20a at the tip end. is required.

  + Α approaches the blade 20a of the processing tool 20 into the pair of piston pin holes 22 from one side thereof, and securely moves the outer stroke of the hole for safely entering and starting the processing, and the piston pin hole 22 on the other side. Includes out-of-hole stroke to finish cutting. The processing tool 20 processes the piston pin hole 22 in a state of protruding from the main shaft by the length.

  As described above, the processing tool 20 that protrudes and rotates long and is cut by the blade at the tip vibrates due to the natural frequency, processing conditions, and the like of the processing tool 20 as disclosed in Patent Document 7. Although this vibration varies depending on the configuration of the vibration system including the mechanical system to which the processing tool 20 is attached and the processing conditions, the specific vibration is generated in the specific vibration system and processing conditions. According to the vibration of the processing tool 20, for example, as shown in the comparative example of the present invention shown in the cross-sectional view of FIG. Concave and convex portions are formed in which the portion 23a and the shallow cut portion 23b are continuously repeated in the circumferential direction.

  Such vibration characteristics and regularity of the processing tool 20 may impair the roundness of the inner surface of the piston pin hole 22 as described above. More specifically, in the comparative example shown in FIGS. 3 and 4, the phase of the crests and valleys of the machining start point S and the machining end point F by one rotation of the processing tool 20 coincide with each other. As shown in the cross-sectional view of FIG. 4 (a), the valley portion 23a and the peak portion 23b are substantially continuous in the longitudinal direction of the pin hole. As a result, the roundness of the processed hole is impaired.

  This means that the valleys 23a and the peaks 23b of the cutting streak 23 are lined up in the longitudinal direction of the piston pin hole 22 as shown in the longitudinal sectional view of FIG. The roundness of the inner surface of the pin hole 22 is reduced. In order to emphasize this and make it easy to understand, FIG. 4A shows a simple form in which four valleys 23a and four peaks 23b are alternately connected in the circumferential direction. The distance 23d between the peak 23b and the valley 23a is about 1.5 μm.

  For this reason, since the peak part 23b and the trough part 23a which make a support surface are located in a line with the axial direction of a hole, the oil hold | maintained at the trough part 23a is easy to escape, and it is easy to produce a metal touch. In addition, since the peak portion 23b is less dispersed in the circumferential direction and the roundness is low, the fitting characteristics with the piston pin and the sliding characteristics are adversely affected.

  However, the present inventor has come to the present invention paying attention to the fact that the influence of the cutting state on the inner surface of the hole due to the vibration of the rotating working tool is regularly repeated. That is, in the hole inner surface processing method according to the present embodiment, as shown in FIG. 2A, the cutting depth h generated in the circumferential direction along the cutting streak 3 formed on the inner surface of the hole 1 by the rotation of the processing tool 2. There are a plurality of changes in the increase / decrease, and the increase / decrease change is controlled so as to be shifted in the circumferential direction of the inner surface of the hole 1 at the machining start point S and the machining end point F by one rotation of the processing tool 2. The cutting depth h (distance between the crest and trough) is about 1 μm or less or 2 μm or more.

  That is, the machining is performed by adjusting the vibration of the machining tool 2 so that the machining start point S and the machining end point F are different in the phase of the increase / decrease period of the cutting depth h in the circumferential direction. As a more specific example, when a certain machining start point S is started from the top of the cutting peak, the processing end point F rotated once in the circumferential direction ends at the bottom of the valley (in this case, the position The phase difference is 90 degrees).

  The characteristic and regularity of the vibration of the rotating processing tool 2 can actively manage its natural frequency by the material or combination of materials of the processing tool 2. In addition, by combining the natural frequency, the number of rotations of the processing tool 2 and the processing conditions such as feed, the width of increase / decrease of the cutting amount due to the vibration of the processing tool 2, that is, the amplitude and the period can be arbitrarily manipulated. .

  The machining state of the inner surface of the hole 1 produced by manipulating the amplitude and period of vibration of the processing tool 2 can be measured and confirmed by a widely known and widely used three-dimensional shape measuring instrument.

  From these, as in the present embodiment, there are a plurality of increase / decrease changes in the cutting depth h generated in the circumferential direction of the inner surface of the hole 1 due to the rotation of the processing tool 2, and the processing start point S by one rotation of the processing tool 2. And the machining end point F can be regulated and cut so as to be displaced in the circumferential direction.

  As a result, the connection state between the deep valley 3a and the shallow peak 3b of the cut in the circumferential cut striation 3 and the hole between the valley 3a and the peak 3b between the adjacent cut stripes 3 are obtained. The circumferential displacement of the inner surfaces of the holes 1 aligned in the longitudinal direction, that is, the amount of displacement, can be set in an array state in which the phase is shifted at the machining start point and the machining end point. This cutting state is shown in the transverse sectional view of FIG. 2A, the longitudinal sectional view of FIG. 2B, and the perspective view of FIG. FIG. 2A shows that the machining start point S and the machining end point F do not coincide with each other, and the phase is shifted. Moreover, in FIG.2 (b), the blade 2b was shown.

  Thereby, there are a plurality of deep valleys 3a and shallow peaks 3b which are cut by the cutting streak 3 by the processing tool 2 in the circumferential direction of the inner surface of the hole 1 as shown in FIG. The valleys 3 a and the peaks 3 b are connected to each other, and the peaks 3 b are not aligned in the longitudinal direction of the hole 1 because the machining start point S and the machining end point F are rotated by one rotation of the processing tool 2.

  Further, since the crests 3b are not aligned linearly in the longitudinal direction of the holes 1 but are sequentially displaced in the circumferential direction, the oil held in the troughs 3a is difficult to escape, and the metal touch is difficult to touch. Moreover, since all the peaks and valleys are arranged in a continuous manner in the hole inner surface area in a spiral manner, the roundness of the inner surface of the hole 1 can be ensured even if peaks and valleys are formed during cutting. From these, in addition to having high fitting characteristics, wear resistance is improved and partial seizure can be avoided. In addition, since a desired recess can be formed by one-pass processing, it is easy to smoothly connect the crest 3b and the trough 3a, and the processing is simple and requires a short time. To reduce.

  More specifically, the valleys 3a and the peaks 3b are alternately and smoothly connected along the cutting line 3 in the circumferential direction of the inner surface of the hole 1 to form a recess formed by the valley 3a. At this time, it corresponds to the adjacent pitch P of the cutting streak 3, that is, the feed pitch P when the processing tool 2 advances in the longitudinal direction of the hole 1 while rotating.

  Therefore, it is set as the arrangement | sequence set to the maximum cutting width Bmax at the time of the cutting streak 3 making the trough part 3a and making a hollow. However, due to the circumferential displacement between the valley 3a and the mountain 3b in the adjacent cutting streak 3 (half-cycle displacement in the illustrated example in FIG. 2C), as shown in FIG. It becomes a three-dimensional array.

  As a result, in the cut striations 3 adjacent at a pitch P equal to the maximum cutting width Bmax, the valley portion 3a having the maximum cutting width Bmax and the peak portion 3b having the minimum cutting width Bmin are adjacent to each other. FIG. 2C shows a state where the maximum cutting width Bmax and the minimum cutting width Bmin are adjacent to each other.

  In the comparative example shown in FIG. 4 (b), the crests 23b and the troughs 23a of the cutting trace are linearly aligned in the length direction of the hole, so that the crests are adjacent to the crests and the troughs are Only adjacent. That is, in FIG. 4C, the maximum cutting width Bmax and the minimum cutting width Bmin are not adjacent to each other, and the maximum cutting width Bmax and the minimum cutting width Bmin are adjacent to each other. Therefore, the peak portions 23b that are difficult to become oil retaining portions are continuous.

  On the other hand, in the present invention, as shown in FIG. 2 (c), the trough 3a serving as the oil retaining portion has a hole in the portion where the crest 23b shown in FIG. Since they are alternately arranged in the length direction, the arrangement density of the valley portions 3a is almost doubled as compared with the conventional example.

  Such a hole 1 to be machined is effective when applied to a pin hole of a connecting rod and a crankshaft through hole (not shown) in addition to a piston pin hole for connecting a connecting rod of a piston 4 illustrated in FIG. .

  In the present embodiment, the cutting tool 3 has a cutting streak 3 formed by cutting and proceeding in the longitudinal direction of the hole 1 while the processing tool 2 rotates, and the cutting streak 3 corresponding to one rotation of the processing tool 2 is provided. In this case, the generated cutting depth h has a plurality of increase / decrease changes, and the phase of the increase / decrease change is shifted in the circumferential direction between the machining start point S and the machining end point F by one rotation of the processing tool 2. It also provides an internal structure of the hole 1 that receives the moving member.

  As shown in FIG. 1, the processing tool 2 used in the hole inner surface processing method as described above generally extends in a substantially columnar shape from an attachment portion 2a to a mechanical system 6 such as a main shaft of a cutting machine to a tip having a blade 2b. The main body 2c has a basic configuration. The main body portion 2c in such a basic configuration is a combination structure of a base side material 2d made of a general structural material on the attachment portion 2a side and a tip side material 2e made of a super hard material on the tip side from the middle position. Yes.

  Then, it is assumed that the base side member 2d and the tip side member 2e are joined and integrated by a joint 5 such as brazing.

  As a result, the low-frequency vibration characteristic with a large amplitude due to the general structural material of the base side material 2d of the processing tool 2 and the low-frequency vibration characteristic with a small amplitude due to the cemented carbide material of the tip side material 2e have their occupation length ratio. The number of changes in the cutting depth generated in the circumferential direction of the inner surface of the hole 1 due to the rotation of the processing tool 2 and the processing start point S and the processing end point F by one rotation of the processing tool 2 of the increase / decrease change are combined. The vibration characteristic that regulates the circumferential shift (phase difference) of the inner surface of the hole 1 at and can be easily set.

  Note that the processing tool 2 of the present embodiment has a total length of about 80 mm to 100 mm, and the ratio of the length of the base side member 2d and the tip side member 2e was preferably 1: 2, but this is not the only case. It will never be done.

  The present invention has a deep cutting depth that can be formed along the cutting streak caused by the rotation of the processing tool when the processing tool that rotates the inner surface of the hole that receives and supports the sliding member proceeds in the longitudinal direction of the hole. Only by machining by regulating the amount of deviation between the trough and the crest by the number of circumferential sections between the trough and the crest having a shallow cutting depth, and the machining start point and machining end point by one rotation of the processing tool. An inner surface structure suitable for the combined characteristics and sliding characteristics can be realized easily and inexpensively.

DESCRIPTION OF SYMBOLS 1 Hole 2 Processing tool 2a Attachment part 2b Blade 2c Body part 2d Base side material 2e Tip side material 3 Cutting striation 3a Valley part 3b Mountain part 4 Piston 5 Joint part

Claims (3)

  A processing method of an inner surface of a hole for processing the inner surface of the hole by cutting the inner surface of the hole receiving the sliding member in the longitudinal direction of the hole while the processing tool rotates, and the inner surface of the hole by the rotation of the processing tool There are a plurality of cutting depth increase / decrease changes that occur in the circumferential direction of the tool, and the hole inner surface machining method is controlled so as to deviate in the circumferential direction of the hole inner surface at the start point and end point of one rotation of the tool .   The hole inner surface machining method according to claim 1, wherein the hole is a pin hole of a piston, a pin hole of a connecting rod, or a crankshaft through hole.   It has a main body extending in a columnar shape from the attachment part to the mechanical system to the tip with the blade, and this main body part from the middle position to the base side material made of the general structural material on the attachment part side, and the tip side material The structure according to claim 1, wherein the base side material and the tip side material are integrated by a joint part such as brazing. The processing tool used for the processing method of the hole inner surface of description.