JP2011036931A - Surface-machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-machining method capable of repairing a blow hole without destroying a casting by pressing a periphery of the blow hole by a spherical body even in the thin casting. <P>SOLUTION: By using a surface-machining device including a surface-machining tool including a pressing ball having a spherical surface for pressing an inner peripheral surface of the casting having a cylindrical part; a ball rolling means for pressing the inner peripheral surface by the spherical surface while rolling the pressing ball by relatively moving the pressing ball in a circumferential direction of the inner peripheral surface; and a feeding means for relatively moving the surface-machining tool and the casting in an axial direction of the casting, the number of the pressing balls included in the surface-machining tool, diameters of the pressing balls, a pushing-in amount of the pressing ball relative to the inner peripheral surface, a movement amount of the pressing ball by the ball rolling means and a movement amount of the pressing ball by the feeding means are adjusted to successively machine the inner peripheral surface in an axial direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for processing an inner peripheral surface of a casting having a cylindrical portion obtained by die casting or the like.

  One of the casting products is a cylinder block of an automobile engine. The cylinder block includes a plurality of cylindrical portions (cylinder bores) that accommodate the pistons. The cylinder block is made of a light and inexpensive aluminum alloy and is often cast by die casting. Since the cylinder block is worn with the piston and the fuel explodes, the cylinder liner is press-fitted into the cylindrical part. It is starting to take place. However, in casting, casting defects (cast holes) may be formed on the inner peripheral surface of the cylindrical portion. Such a cast hole is difficult to fill even if the inner peripheral surface is sprayed, and the airtightness between the cylinder block and the piston is impaired. Therefore, it is necessary to repair the cast hole on the inner peripheral surface prior to thermal spraying. As a method for repairing a casting hole formed in a casting, there is a repairing method in which a spherical tool is pressed against the surface of the casting to plastically deform the periphery of the casting hole.

  For example, Patent Document 1 (see FIG. 11B) describes a method in which a cast hole on the inner peripheral surface of a cylindrical casting W is crushed and removed by a sphere. A spherical body 64r is rotatably accommodated in a support block 65 attached to the tip of the rotary shaft 64b. A cylindrical casting W is fixed to the main shaft 64m of the lathe 64, and the tip end portion of the rotating shaft 64b is inserted therein. When the rotating shaft 64b is rotated and simultaneously moved in the axial direction, the sphere 64r moves in the axial direction while rotating along the inner peripheral surface of the casting W. At this time, the cast hole on the inner peripheral surface of the casting W is crushed by the spherical surface of the sphere 64r.

  Patent Document 2 (see FIGS. 8 and 9) describes a method of crushing and removing a cast hole on a seal surface of a cylinder block, which is an aluminum cast product, with a sphere. FIG. 8 shows a pressing tool 20 used to process the sealing surface. A ceramic sphere 25 is housed in a rotatable state at the tip of the pressing tool 20. When the pressing tool 20 is moved following the seal surface, the seal surface is plastically deformed to form a groove. In the same manner, the second groove is formed by plastic deformation in the same manner adjacent to this groove, and the center portion of the two grooves is similarly plastically deformed, so that the seal surface is deformed into a shallow groove shape, thereby forming a cast hole Crushing.

Japanese Patent Laid-Open No. 10-94869 JP-A-10-202492

  When the cast hole is crushed by using a tool including a sphere as described in Patent Document 1 and Patent Document 2, the sphere and the inner peripheral surface are in point contact with each other, so that the pressure is concentrated on the contact position. Therefore, when the inner peripheral surface of a casting having a thin cylindrical portion is plastically processed to crush the casting cavity, there is a problem that the outer surface of the casting is deformed or the casting is broken and the casting is destroyed. all right. However, conventionally, attention has not been paid to the fact that casting breakage can occur when processing a thin casting, and it has been clarified which casting conditions can be suppressed by adjusting the processing conditions. There wasn't.

  In view of the above problems, the present invention provides a surface processing method capable of repairing a casting cavity without destroying the casting by pressing the periphery of the casting cavity with a sphere even when the casting is thin. The purpose is to do.

The surface processing method of the present invention includes a surface processing tool including a pressing ball having a spherical surface that presses an inner peripheral surface of a casting having a cylindrical portion, and relatively moving the pressing ball in a circumferential direction of the inner peripheral surface. Surface processing comprising: ball rolling means for pressing the inner peripheral surface with the spherical surface while rolling the pressing ball; and feed means for relatively moving the surface processing tool and the casting in the axial direction of the casting. Using the device,
The thickness of the cylindrical portion is T [mm], the groove width of the groove formed on the inner peripheral surface by being pressed by the pressing ball is b [mm], the interval between adjacent grooves is p [mm], When the total pushing amount by the pressing ball is t [mm], 0 <p / b <1 and 0.018T ≦ t ≦ 0.0625T are satisfied, and the pressing load of the pressing ball is the thickness of the cylindrical portion. And the number of the pressing balls provided in the surface processing tool, the diameter of the pressing balls, and the pressing of the pressing balls into the inner peripheral surface so as not to exceed the upper limit value determined according to the deformation resistance of the material of the cylindrical portion The inner peripheral surface is sequentially processed in the axial direction by adjusting the amount, the amount of movement of the pressing ball by the ball rolling means, and the amount of movement of the pressing ball by the feeding means.

  According to the surface processing method of the present invention, even if the casting is thin, casting defects existing immediately below the surface can be efficiently crushed without destroying the casting. In the surface processing method of the present invention, by setting the local processing range (corresponding to the groove width b) performed by pressing the pressing ball to a range according to the material and thickness of the casting, the material flow range by surface processing ( The flow stress generation range) can be concentrated in the vicinity of the inner surface of the cylindrical portion so that the outer peripheral side is not deformed. As a result, the destruction of the casting such as deformation of the outer surface of the cylindrical portion or cracking of the cylindrical portion is suppressed.

  Furthermore, by setting the amount of movement of the pressing ball within the appropriate range and expanding the machining range in the axial direction of the casting (cylindrical part) without giving excessive irregularities or excessive machining to the inner circumferential surface, the inner circumferential surface It is possible to reliably and efficiently process casting defects existing in the steel.

  Furthermore, since the pressing ball presses the inner peripheral surface of the cylindrical portion while rolling, seizure between the pressing ball and the inner peripheral surface of the cylindrical portion is prevented even when the surface processing tool moves at a high speed.

  The inner peripheral surface pressed and processed by the pressing ball may be further processed. By repeatedly performing the surface processing method of the present invention a plurality of times, a smooth processed surface with small irregularities can be obtained in a wide range, and a relatively large cast hole can be effectively produced without increasing the amount of pressing once. Can be repaired.

It is the schematic explaining the repair method of the cast hole by the surface processing method of this invention. It is a drawing substitute photograph which shows the cylinder block and bore surface before a process. It is a figure which shows typically the surface processing apparatus which can be used for the surface processing method of this invention, Comprising: It is a top view of a surface processing apparatus. It is a figure which shows typically the surface processing apparatus which can be used for the surface processing method of this invention, Comprising: It is a front view which shows the external appearance of a surface processing apparatus. It is a graph which shows the relationship between pushing amount h and shaping | molding angle (theta) for every ball diameter of the used press ball | bowl. It is a graph which shows the relationship between the pushing amount h and the process groove width b for every ball diameter of the used press ball | bowl. It is a graph which shows the relationship between indentation amount h and indentation load for every ball diameter of the used press ball. It is a drawing substitute photograph which shows the bore surface of the cylinder block processed by the surface processing method of the reference example. It is a drawing substitute photograph which shows the bore surface of the cylinder block processed by the surface processing method of the comparative example. It is a drawing substitute photograph which shows the bore surface of the cylinder block processed by the surface processing method of this invention (Example 1). It is a drawing substitute photograph which shows the bore surface of the cylinder block processed by the surface processing method of this invention (Example 2). It is a drawing substitute photograph which shows the bore surface of the cylinder block processed by the surface processing method of this invention (Example 3). It is a drawing substitute photograph which shows the bore surface of the cylinder block processed by the surface processing method of this invention (Example 4). It is a drawing substitute photograph which shows the bore surface of the cylinder block processed by the surface processing method of this invention (Example 5). It is drawing substitute photograph which shows the cross section which cut | disconnected the axial direction so that the cylinder block processed by the surface processing method of this invention (Example 5) might pass the center of an artificial defect hole (casting hole). It is a drawing substitute photograph which shows the bore surface of the cylinder block processed by the surface processing method of the comparative example. It is a drawing substitute photograph which shows the bore surface of the cylinder block processed by the surface processing method of this invention (Example 6). It is a drawing substitute photograph which shows the cross section which cut | disconnected the axial direction so that the cylinder block processed by the surface processing method of this invention (Example 6) might pass the center of an artificial defect hole (casting hole). It is a graph which shows the opening diameter (measured value) of the artificial defect hole after a process with respect to the total pushing amount t.

  The best mode for carrying out the surface processing method of the present invention will be described below. Unless otherwise specified, the numerical range “x to y” described in this specification includes the lower limit x and the upper limit y.

  The surface processing apparatus of the present invention includes a surface processing tool having a pressing ball, ball rolling means, and feeding means, and processes an inner peripheral surface of a casting having a cylindrical portion. Below, a surface processing tool, a ball rolling means, and a feeding means are each demonstrated.

  The surface processing tool includes a pressing ball. Since the pressing ball has a spherical surface that presses the inner peripheral surface of the casting and rolls by the ball rolling means, the pressing ball preferably has a shape close to a true sphere. The pressing ball is preferably larger than the size (maximum diameter) of the opening of the casting hole opened on the inner peripheral surface of the cylindrical portion of the casting, and the ball diameter is practically a diameter of 2 mm or more. When the ball diameter is less than φ2 mm, it is difficult not only to efficiently repair the cast hole, but it may also be difficult to continuously process the surplus material deposited on the ball. Further, the ball diameter is preferably φ6 mm or less. This is because if the diameter exceeds 6 mm, the contact area between the spherical surface and the inner peripheral surface increases, and the pressing load of the pressing ball increases, and the casting is easily damaged.

  Moreover, there is no particular limitation on the material of the pressing ball, but it is preferable that the material is made of metal or ceramics which is superior in mechanical strength to the material of the processed part of the casting. Since the casting which is a workpiece is preferably made of a metal, particularly an aluminum alloy or a magnesium alloy used as a cylinder block, a pressed ball made of steel, ceramics or tool steel may be used.

  The pressing ball is held on the surface processing tool in a rollable state. The pressing ball holding mechanism may be a general mechanism conventionally used. There is no limitation on the number of pressing balls which one surface processing tool has, and one or a plurality of pressing balls may be used. However, since it is easy to balance the processing load for processing the inner peripheral surface of the cylindrical portion, it is preferable to use two or more pressing balls. Further, the configuration of the surface processing tool is not particularly limited, but the surface processing tool has a main body having a main shaft on which the pressing ball rolls by holding the pressing ball in a rollable manner and rotating relative to the casting. Is preferred. When there are a plurality of pressing balls, the center may be held so that the center thereof is disposed at the same position in the axial direction of the main body. At this time, the plurality of pressing balls may be held at equal intervals in the circumferential direction. The number of pressing balls held at the same position in the axial direction is preferably about 2 to 12, and it is preferable to arrange them at intervals so that the processing by the individual pressing balls does not interfere with each other. Furthermore, it is also possible to arrange the pressing balls at different positions in the axial direction. The inner peripheral surface can be pressed twice or more simply by moving the surface processing tool once in the axial direction in the cylinder.

  The ball rolling means moves the pressing ball relatively in the circumferential direction of the inner peripheral surface, and presses the inner peripheral surface with a spherical surface while rolling the pressing ball. The feeding means relatively moves the surface processing tool and the casting in the axial direction of the casting. The ball rolling means and the feeding means are preferably driven simultaneously. The ball rolling means preferably revolves the pressing ball around the central axis of the inner peripheral surface of the casting. The revolution speed of the pressed ball by the ball rolling means is not limited, but is preferably 30 to 1500 rpm, and more preferably 60 to 600 rpm. If it is less than 30 rpm, the casting hole is sufficiently repaired, but the processing efficiency is not good. Exceeding 1500 rpm is not preferable because the pressed ball may slip on the inner peripheral surface and may not easily roll. The feed amount in the axial direction by the feed means is not particularly limited. For example, the feed rate is preferably 0.5 to 30 mm / second, and more preferably 1 to 20 mm / second. If it is less than 0.5 mm / second, the casting hole is sufficiently repaired, but the processing efficiency is not good. If it exceeds 30 mm / second, depending on the ball diameter, the amount of indentation and the revolution speed, an unprocessed part may be generated and the cast hole cannot be repaired well, and the load on the surface processing tool and the surface processing apparatus is severe. This is not preferable.

  An outline of the surface processing method of the present invention using the above-described surface processing apparatus will be described with reference to FIG. FIG. 1 shows a state in which the inner peripheral surface Cs of the casting C is processed in the axial section of the casting C having a cylindrical portion. However, in FIG. 1, in order to simplify the description, the surface processing apparatus shows only the pressing ball. The ball B moves in the circumferential direction R of the inner peripheral surface Cs by the ball rolling means and in the axial direction P by the feeding means. The ball B moves in the axial direction P while moving in the circumferential direction R while pressing the inner peripheral surface Cs, and reaches the position indicated by B ′. When the inner peripheral surface Cs is pressed by the ball B, a groove extending substantially orthogonal to the axial direction is formed with a width b corresponding to the ball diameter of the ball B and the pushing amount h into the inner peripheral surface Cs. At this time, the surplus remaining due to being pushed into the ball B rises forward in the moving direction of the ball B. The surplus front (not shown) in the circumferential direction is sequentially crushed by the balls B as the balls B move in the circumferential direction R while rolling. On the other hand, the surplus D in the axial direction can be crushed when the ball B reaches the position indicated by B 'in FIG. By repeating this, the periphery of the casting hole opened in the inner peripheral surface is plastically deformed, and the casting hole is repaired.

  In the surface processing method of the present invention, the desired range of the inner peripheral surface of the cylindrical portion can be sequentially processed in the axial direction by moving the pressing ball in a spiral manner by the ball rolling means and the feeding means. When the desired range of the inner peripheral surface of the cylinder has been processed by sending the surface processing tool in one direction, the inner peripheral surface once processed may be processed again by sending it in the opposite direction. When performing the second and subsequent processing, change the amount of pressing by the pressing ball, change the revolution direction of the pressing ball by the ball rolling means, change the feed speed, change the phase of the pressing position, etc. May be.

  In the surface processing method of the present invention, the number of pressing balls provided in the surface processing tool, the diameter of the pressing balls, the pressing amount of the pressing balls with respect to the inner peripheral surface, the amount of movement of the pressing balls by the ball rolling means, and the pressing balls by the feeding means By adjusting the amount of movement and processing the inner peripheral surface in order in the axial direction, it is possible to repair the casting cavity while suppressing breakage of the casting. In the description of the surface processing apparatus, a desirable numerical range has already been described. However, if the following conditions are satisfied, the above range may be exceeded.

  The thickness of the cylindrical portion is T [mm], the groove width of the groove formed on the inner peripheral surface by the pressing ball is b [mm], the interval between adjacent grooves is p [mm], and the total of the pressing balls When the pushing amount is t [mm], the cast hole is repaired while only the inside of the cylindrical portion is deformed by adjusting the above processing conditions so as to be (1) to (3). Can do.

(1) 0 <p / b <1, and (2) 0.018T ≦ t ≦ 0.0625T, and (3) the pressing load of the pressing ball changes the thickness of the cylindrical portion and the material of the cylindrical portion. Do not exceed the upper limit required for resistance.

  Here, the thickness T is an actual measurement value of the thickness of the cylindrical portion of the casting before processing. The groove width b is a value corresponding to the diameter of the projected contact area that can be calculated from the radius of the pressing ball and the pressing amount h, and is found to match the width of the groove formed on the inner peripheral surface by processing. ing. The groove interval p is a value that changes in accordance with the amount of movement of the pressing ball, and in the axial cross section of the casting after processing, from the deepest position of one groove, the deepest groove adjacent to the groove This is an actually measured value of the axial distance to the position. The total pushing amount t is t = h when machining in the axial direction is performed only once. However, when machining in the axial direction is performed twice or more, the total pushing amount in each machining is a value. It is.

  Regarding (1), when p / b = 0, machining in the axial direction does not proceed. Moreover, in p / b> = 1, since a non-processed part is formed between two adjacent grooves, it is impossible to repair the cast hole located in the non-processed part. Preferably 0.1 ≦ p / b <1, more preferably 0.25 ≦ p / b ≦ 0.8.

  Regarding (2), when 0.018T> t, the effect of repairing the cast hole is reduced, and it is difficult to repair the cast hole whose opening on the inner peripheral surface exceeds φ2 mm. Preferably 0.02T ≦ t, and more preferably 0.025T ≦ t. In addition, when t> 0.0625T, the amount of pressing becomes excessive and molding becomes difficult. Preferably t ≦ 0.05T, and more preferably t ≦ 0.03T. Although depending on the ball diameter of the pressed ball, the upper and lower limits of the groove width b are naturally determined from the upper and lower limits of the range of the total pushing amount t. In addition, if the suitable range of the total pushing amount t is shown concretely, it is preferable that it is 0.13-0.5 mm further 0.15-0.4 mm.

  Regarding (3), the pressing load of the pressing ball is the product of the contact projected cross-sectional area where the pressing ball and the inner peripheral surface are in contact with the deformation resistance σ of the material of the cylindrical portion. The contact projected cross-sectional area is equal to the area of a circle having a diameter b [mm]. Therefore, the upper limit of the value of the groove width b is substantially defined by preventing the pressing load of the pressing ball from exceeding a certain value (upper limit value). The upper limit value to be compared is, for example, when the other side of the test piece is deformed when one surface of a test piece of the same material and the same thickness as the cylindrical part to be processed is pressed in the thickness direction, or the test piece Is the indentation load when breaking. Since the deformation resistance is a specific value corresponding to the type of metal, a known value may be used, but an actual measurement value may be used. In addition, if the suitable range of groove width b is shown concretely, it is preferable that they are 0.5-2.5 mm, 0.79-2 mm, and also 1.2-1.8 mm.

  Further, as (4), the relationship between the thickness T [mm] of the cylindrical portion and the groove width b [mm] of the groove is 0.098T ≦ b, 0.15T ≦ b, and further 0.18T ≦ b. preferable. 0.098T> b is not preferable because the width of the groove to be processed and the amount of pressing are too small and the processing efficiency and the effect of repairing the cast hole tend to be low. Moreover, it is preferable that b ≦ 0.325T and further b ≦ 0.25T. This is because when b> 0.325T, the processing load increases, so the range of deformation also increases and cracks are likely to occur in the cylindrical portion.

  (5) The number of balls used is preferably 2-12. This is because when the number increases, the processing areas of adjacent balls are likely to interfere with each other, or the entire load increases and the cylindrical portion is likely to be cracked.

  In addition, when processing is performed a plurality of times until the total indentation amount t is reached, the b / p and the indentation load of the pressing ball at each time are the above (1) and (3), and if necessary, (4) and / or Or it is necessary to satisfy the condition of (5).

  In the surface processing method of the present invention, if the thickness of the cylindrical portion and the processing conditions satisfy each of the above conditions, the casting hole can be repaired satisfactorily while suppressing breakage of the casting. However, if it is defined by specific values, the present invention is suitable for castings having a cylindrical portion with a thickness T of 5 to 12 mm, or 7 to 9 mm, which is easily broken by processing. The diameter of the cylindrical portion is not particularly limited, but the inner diameter is preferably 30 to 160 mm, 50 to 120 mm, and more preferably 70 to 90 mm. Further, the casting hole is sufficiently repaired by the surface processing method of the present invention if the diameter (maximum diameter) opened to the inner peripheral surface is φ2.5 mm or less, φ2 mm or less, or φ1.5 mm or less.

  As mentioned above, although embodiment of the surface processing method of this invention was described, this invention is not limited to the said embodiment. The present invention can be implemented in various forms without departing from the gist of the present invention, with modifications and improvements that can be made by those skilled in the art.

  Hereinafter, the present invention will be specifically described with reference to examples of the surface processing method of the present invention. In the processing example described below, the inner periphery of a cylinder block B made of aluminum die-casting (ADC12) having a cylindrical portion having a height of 140 mm, a thickness of 8 mm, and an inner diameter of 78.26 to 79.16 mm. Surface (bore surface) Bs was processed. In the bore surface Bs of the cylinder block B, an artificial defect hole having a depth of 2 mm was previously subjected to electric discharge machining in order to evaluate the effect of repairing the cast hole. As for the artificial defect hole, a diameter φ0.5 mm hole was formed 50 mm away from one end face of the cylinder block in the axial direction, a diameter φ1 mm hole was further formed 5 mm away, and a diameter φ2 mm hole was further formed 10 mm away. The artificial defect hole formed in the cylinder block B is shown in FIG. In addition, an artificial defect hole is formed in a circled portion in the lower left photograph of FIG. 2, and the upper right photograph is an enlarged photograph of the artificial defect hole.

<Surface processing equipment>
The surface processing apparatus used in the following processing examples will be described with reference to FIGS. FIG. 3 is a view of the surface processing apparatus as viewed from the drive shaft side, and FIG. 4 is a front view showing the appearance of the surface processing apparatus.

  The surface processing apparatus includes a surface processing tool 9 having a pressing ball, ball rolling means (not shown), and feeding means (not shown). The surface processing tool 9 is made of tool steel, and includes a main body portion 90 and a plurality of pressing balls 10 held on the main body portion 90 so as to be able to roll. The main body 90 includes a taper ring 91 that expands to one side in the axial direction, and a substantially bottomed cylindrical ball housing 92 having a plurality of through holes 95 that house the pressing balls 10. Twelve through-holes 95 are formed on the wall surface of the ball housing 92 and are arranged at equal intervals on the same circumference of φ79.26 mm (circumscribed circle) at the same position in the axial direction. The required number of the pressing balls 10 is accommodated in the through hole 95 from the inside of the ball housing 92 and is held by a taper ring 91 that is coaxially accommodated inside the ball housing 92. The taper ring 91 and the ball housing 92 have a drive shaft 90 a that is coaxially fixed on the other axial side of the main body 90. The drive shaft 90a is driven by a drive source (not shown) (milling machine MHA400II manufactured by Osaka Kiko Co., Ltd .: equivalent to a ball rolling means and a feed means), and rotates the main body 90 about the main shaft M toward one side in the axial direction. Move.

  In the following calculation and processing, a sphere made of tool steel having a ball diameter of φ2 mm, φ4 mm, and φ6 mm was used as the pressing ball 10. Then, the protrusion amount of the pressing ball 10 is changed according to the dimension of the through hole 95 and the outer diameter of the taper ring 91 at the abutting position, and the diameter of the circumscribed circle as the entire tool is determined. The pressing amount of the pressing ball 10 was changed.

<Calculation result>
In the processing of the bore surface Bs of the cylinder block B using the above surface processing apparatus, the forming angle θ, the processing groove width b, and the indentation load were calculated in various combinations of the ball diameter and the indentation amount of the press ball 10. . In addition, the ball diameter was made into three types, φ2 mm, φ4 mm, and φ6 mm. The indentation amount was 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, or 0.5 mm. Four pressing balls 10 are used at any ball diameter. The pressing ball was moved without lubrication at a rotational speed of the tool of 60 rpm and a feed speed of 0.5 to 4 mm / second.

The calculation results are shown in FIGS. 5 shows the relationship between the pushing amount h and the forming angle θ, FIG. 6 shows the relationship between the pushing amount h and the machining groove width b, and FIG. 7 shows the relationship between the pushing amount h and the pushing load. It is a graph shown for every ball diameter. The indentation load was calculated by calculating the contact projected area from the machining groove width b and using the deformation resistance σ of the ADC 12: 20 kgf / mm ² .

  When processing is performed with a pressing amount of h = 0.3 mm using a pressing ball having a ball diameter of φ2, θ = 45 ° (FIG. 5). When θ = 45 °, the accumulation of surplus material on the pressed ball increases. Therefore, when a pressed ball having a ball diameter of φ2 is used, the movement in the axial direction is stopped when the pressing amount h is 0.3 mm or more and machining is performed. Does not advance. Further, it is considered that the cylinder block B is cracked with a push-in amount of 0.3 mm or more when a press ball with a ball diameter of φ6 is used and with a push-in amount of 0.5 mm when a press ball with a ball diameter of φ4 is used. It is done. That is, if the processed groove width b exceeds 2.5 mm, the breakage is likely to occur (FIG. 6). From FIG. 7, this indicates that when a pressed ball with a ball diameter of φ6 is used, the push amount is 0.3 mm or more, and when a press ball with a ball diameter of φ4 is used, the push amount is 0.5 mm and the push load is 100 kg. It is for exceeding.

  When the pushing amount h is 0.1 m or less, not only φ2 mm but also φ0.5 mm artificial defect holes cannot be repaired sufficiently.

<Cylinder block machining>
Using the same surface processing apparatus as described above, the inner peripheral surface of the cylinder block B was processed under the processing conditions shown in Table 1. The surface processing apparatus was operated and a surface processing tool was inserted from one end side of the cylinder block B, and 90 mm from one end surface of the cylinder block B was sequentially processed in the axial direction. And the groove | channel space | interval was measured about the cylinder block B after a process. As schematically shown in FIG. 1, the axial distance from the deepest position of one groove to the deepest position of a groove adjacent to the groove was measured as the groove interval. Furthermore, the artificial defect hole on the inner peripheral surface was observed to evaluate the repair effect.

  Table 1 shows the groove spacing p of the bore surface after processing. The groove interval p can be calculated from the number of pressed balls and the tool feed speed. However, in actuality, the position of the processing groove formed after the second round is shifted from the calculated value due to the influence of the processing groove formed by making one turn of each press ball, the surplus, and the lubricant. It was adopted. Moreover, while showing the artificial defect hole after a process in FIGS. 8-18, Table 1 shows an evaluation result.

  For the artificial defect hole after processing, the maximum diameter of the surface opening was measured. In Table 1, it was evaluated that ○: an opening was not visually recognized, Δ: a small opening was present, and X: an opening having a half or more of the original size was present. FIG. 19 shows the opening diameter (measured value) of the artificial defect hole after processing with respect to the total indentation amount t regarding processing performed in the absence of lubricating oil (no lubrication).

  About Reference Example 1: FIG. 8 is a drawing-substituting photograph showing an artificial defect hole after processing. In FIG. 8, dark portions are groove portions formed by processing, and bright portions are unprocessed portions. Since Reference Example 1 is a processing example in which p / b exceeds 1, an unprocessed portion was observed. In addition, although the periphery of the φ2 mm artificial defect hole was repaired because there was evidence that it was pushed in by the pressing ball, it was predicted that none of the artificial defect holes were sufficiently repaired when located in the unprocessed part. The

  About Comparative Examples 1 and 2: In these comparative examples, even an artificial defect hole of φ0.5 mm could not be completely repaired. This is because the processing of these comparative examples satisfied the above condition (1) but did not satisfy the above condition (2).

  Examples 1 to 4 and Example 6: In these processing examples, a plurality of irregularities parallel to the circumferential direction are formed on the inner peripheral surface after processing, but because the processing satisfies the condition (1) above, There were no unprocessed parts. Moreover, in Example 4 and Example 6, sufficient repair was possible if it was an artificial defect hole of φ1 mm or less. FIG. 18 is a drawing-substituting photograph showing a cross section of the cylinder block processed in Example 6 cut in the axial direction so as to pass through the center of the artificial defect hole. In the artificial defect holes of φ0.5 mm and φ1 mm, it was confirmed that plastic deformation occurred in the opening and the opening was closed.

  About Example 5 Example 5 is an example in which processing was performed by pushing a total of 0.24 mm of pressing balls against the inner peripheral surface. In the processing, after the indentation of 0.1 mm, the protruding amount of the pressing ball of the surface processing tool was changed, and the pressing amount of the pressing ball was further changed by 0.1 mm. As a result, all the artificial defect holes could be sufficiently repaired to the extent that they can be used as a surface treatment before thermal spraying (FIG. 15). Furthermore, the surface roughness of the inner peripheral surface after processing was relaxed compared to other examples (FIG. 14).

  Moreover, FIG. 19 is a graph which shows the opening diameter of the artificial defect hole after a process with respect to the total pushing amount. Plotted on a substantially straight line are the results of Examples 2 to 4, 6 and Comparative Example 2 in which the surface treatment was performed once. It was found that as the total indentation amount increased, the opening diameter of the artificial defect hole of any size was reduced and the repair effect was improved. And from the graph of FIG. 19, it was found that in order to completely repair the φ2 mm artificial defect hole, the amount of pressing once must exceed 0.3 mm. However, in Example 5 in which machining was performed in a plurality of times, all the artificial defect holes could be completely repaired even though the total indentation amount was 0.24 mm. In other words, it was found that by performing the processing in a plurality of times, it is possible to sufficiently repair the cast hole with a small amount of pressing.

In any of the processing examples shown in Table 1, there was no problem that the cylinder block B was broken or the outside was deformed. This is because in any processing example, the indentation load calculated from the processing groove width b and the deformation resistance σ (using 20 kgf / mm ² ) did not exceed 100 kg, and the condition (3) was satisfied. (In Example 1, the indentation load is about 47.5 kg)

Claims (5)

A surface processing tool including a pressing ball having a spherical surface that presses an inner peripheral surface of a casting having a cylindrical portion, and while moving the pressing ball relative to the circumferential direction of the inner peripheral surface to roll the pressing ball Using a surface processing apparatus comprising ball rolling means for pressing the inner peripheral surface with the spherical surface, and a feed means for relatively moving the surface processing tool and the casting in the axial direction of the casting,
The thickness of the cylindrical portion is T [mm], the groove width of the groove formed on the inner peripheral surface by being pressed by the pressing ball is b [mm], the interval between adjacent grooves is p [mm], When the total pushing amount by the pressing ball is t [mm], 0 <p / b <1 and 0.018T ≦ t ≦ 0.0625T are satisfied, and the pressing load of the pressing ball is the thickness of the cylindrical portion. And the number of the pressing balls provided in the surface processing tool, the diameter of the pressing balls, and the pressing of the pressing balls into the inner peripheral surface so as not to exceed the upper limit value determined according to the deformation resistance of the material of the cylindrical portion Adjusting the amount, the amount of movement of the pressing ball by the ball rolling means, and the amount of movement of the pressing ball by the feeding means, and processing the inner peripheral surface in order in the axial direction.   The surface processing method according to claim 1, wherein the inner peripheral surface pressed and processed by the pressing ball is further processed.   The surface processing method according to claim 1 or 2, wherein a relationship between a thickness T [mm] of the cylindrical portion and a groove width b [mm] of the groove is 0.098T ≦ b ≦ 0.325T. The surface processing method according to claim 2, wherein the surface processing tool includes a plurality of the pressing balls arranged at different positions in the axial direction. The surface processing method according to claim 1, wherein the surface processing tool includes a plurality of the pressing balls arranged at equal intervals on a circumference perpendicular to the axial direction.