JP2008036750A - Turning method of metallic cylindrical member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the deterioration of machining accuracy caused by the deflection or the like of a smaller diameter cylinder when turning a metallic cylindrical member having a larger diameter cylinder at one end side and the smaller diameter cylinder at the other end side while fixing the inner peripheral surface of the larger diameter cylinder by a chuck. <P>SOLUTION: A chuck body 2 has a larger diameter cylinder fitting part 3 and a smaller diameter cylinder fitting part 5 so as to externally fit the metallic cylindrical member 101 in a manner of loose fitting. In the larger diameter cylinder fitting part 3, a rod 30 is provided therein, a plurality of openings 18 passing through the radial direction of a rotating shaft G are formed around the rotating shaft at intervals, and chuck pieces 40 are disposed so as to be displaceable in the radial direction of the shaft at the respective openings. The metallic cylindrical member 101 is fitted, the rod 30 is slid to the tip end side, the chuck pieces 40 are pushed to the outside on the outer peripheral surface of a taper at the tip 31 to fix the metallic cylindrical member 101 on the inner peripheral surface 103b of the larger diameter cylinder 103. Since the smaller diameter cylinder fitting part 5 is loosely fitted to the smaller diameter cylinder 105, the deflection of the smaller diameter cylinder can be prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is provided with a large-diameter cylindrical portion on one end side of itself, like a metal shell (metal body) used in the configuration of a spark plug of an automobile engine, and is concentric on the other end side with respect to the large-diameter cylindrical portion. Further, the present invention relates to a method for turning a metal cylindrical member having a small-diameter cylindrical portion with a processing machine.

  In the manufacture of small metallic cylindrical members (cylindrical products) such as metal shells used for spark plugs (spark plugs), semi-finished products that have been molded to a shape close to the product by cold forging (rolling) It is used as a material (material for machining), and it is completed as a part by processing a predetermined part such as an outer peripheral surface where accuracy is required with a processing machine (for example, a multi-axis automatic lathe). (Patent Document 1). FIG. 6 is a cross-sectional view of the metallic cylindrical member 101 that is a material before turning of the metal shell 101b constituting the spark plug 200 shown in FIG. A double hatched portion in FIG. 6 indicates a cutting allowance (machining allowance) in the turning process.

  The metal cylindrical member 101 shown in FIG. 6 has a large-diameter cylindrical portion 103 whose inner diameter is larger than the inner diameter of a small-diameter cylindrical portion 105 described later (for example, 12 mm) on the left side of the figure. On the right side of the large-diameter cylindrical portion 103, a small-diameter cylindrical portion 105 having an inner diameter smaller than the inner diameter of the large-diameter cylindrical portion 103 and an outer diameter smaller than the inner diameter of the large-diameter cylindrical portion 103 is concentric. is doing. However, the outer peripheral surface of the intermediate portion in the axis (axis) G direction of the large-diameter cylindrical portion 103 forms a polygonal portion (for example, hexagon) 108. The polygonal portion 108 is a tool locking portion for screwing when the plug is attached to the engine by a screwing method after being processed (finished product) and assembled as the spark plug 200 shown in FIG. Then, both sides sandwiching the processed polygonal portion 108 of the intermediate portion in the axis G direction of the large-diameter cylindrical portion 103 are set so that the thickness is reduced by machining in order to perform crimping when assembling as the spark plug 200. Has been. Moreover, the small diameter cylinder part 105 has comprised the comparatively long cylindrical shape, and the screw | thread is formed in the outer peripheral surface after rolling, for example by rolling.

When processing (turning) the outer peripheral surface of the small-diameter cylindrical portion 103 and the small-diameter cylindrical portion 105 in such a small metallic cylindrical member (workpiece) 101, as shown in FIG. The inner peripheral surface of the large-diameter cylindrical portion 103 is fixed by the chuck 1 for processing. This is because with such small parts, it is easier to fix the inner peripheral surface of the large-diameter cylindrical portion 103, the rotational blur is small, and the accuracy in processing is improved. In the fixing, for example, by pressing a plurality of chuck pieces (claws) 40 arranged at intervals in the circumferential direction with a rod 30 having a tapered tip, the pieces 40 are moved by the wedge action. A chuck having a structure in which the inner peripheral surface 103b (see FIG. 6) of the large-diameter cylindrical portion 103 is pressed and fixed by pushing to the outer peripheral surface side has been used (Patent Document 1).
JP 2002-11543 A

  In the above processing method, the inner peripheral surface of the large-diameter cylindrical portion 103 on one end side is fixed by the chuck 1, and under this state, the metal cylindrical member 101 is rotated to perform the required processing. In the processing of the metallic cylindrical member 101, the inner and outer peripheral surfaces (double hatched portions) of the distal end portion of the small diameter cylindrical portion 105 are also processed. For this reason, when the small-diameter cylindrical portion 105 connected to the other end side of the large-diameter cylindrical portion 103 is long, there are the following problems to be solved. This is because, in such a metallic cylindrical member 101, the fixing range by the chuck is relatively small (short), while the protruding amount of the small diameter cylindrical portion 105 protruding from the chuck becomes long. For this reason, when the metal cylindrical member 101, which is a workpiece, is rotated around the axis (rotation axis) G of the chuck 1 in such a fixed state for cutting, a particularly protruding tip of the small-diameter cylindrical portion 105 is provided. Since the shift portion is relatively greatly shaken, there is a problem that the processing accuracy of the outer peripheral surface is lowered, and the concentricity (coaxiality) of the inner diameters of the large diameter cylindrical portion 103 and the small diameter cylindrical portion 105 is decreased. there were.

  In addition, when the metal cylindrical member 101 is fixed to the chuck on the inner peripheral surface of the large-diameter cylindrical portion 103 in this way, the protruding amount of the small-diameter cylindrical portion 105 protruding from the chuck becomes long. The axis (axis) G of the member 101 tends to be tilted without being correctly aligned with the rotation axis G of the chuck and fixed to the chuck. That is, when fixing to the chuck, the metal cylindrical member 101 tends to be inclined although it is minute. Therefore, such a workpiece has a problem that not only the small-diameter cylindrical portion 105 swings along with the rotation of the chuck, but also the processing accuracy is easily lowered due to the centering failure in the chuck. Moreover, since the metal shell constituting the spark plug has a tendency that the small-diameter cylindrical portion 105 becomes longer and more recently, such a problem is serious in the metal cylindrical member used for such a metal shell. It has become to.

  An object of the present invention is to solve the above-described problems in the case of turning a metal cylindrical member as described above with the inner peripheral surface of the large-diameter cylindrical portion fixed to a chuck.

In order to achieve the above object, the turning method for a metal cylindrical member according to claim 1 includes a large-diameter cylindrical portion on one end side of the metal cylindrical member, and a concentric small-diameter on the other end side of the large-diameter cylindrical portion. When turning a metal cylindrical member provided with a cylindrical portion with a processing machine, to a chuck for fixing the metal cylindrical member,
The metal cylindrical member is externally fitted from the large-diameter cylindrical portion side, so that the large-diameter cylindrical portion is fitted to each inner peripheral surface of the large-diameter cylindrical portion and the small-diameter cylindrical portion with a gap fit. A chuck body having a joint portion and a small-diameter cylindrical portion fitting portion extending from the distal end side of the large-diameter cylindrical portion fitting portion toward the distal end is provided, and can be slid in the direction of the rotation axis inside the chuck body. And a rod having a tapered portion formed at a tip end portion thereof, and the large-diameter cylindrical portion fitting portion into which the large-diameter cylindrical portion of the metallic cylindrical member is fitted in the chuck body. And a plurality of openings penetrating in the radial direction of the rotating shaft at intervals around the rotating shaft, and a chuck piece is disposed in each opening so as to be displaceable in the radial direction of the rotating shaft. And the large-diameter tube portion fitting portion and the small-diameter tube portion fitting portion of the chuck body, Under the state where the large-diameter cylindrical portion and the small-diameter cylindrical portion of the metal cylindrical member are fitted with a clearance fit, the rod is slid toward the distal end side of the chuck body, and the tapered tapered portion closer to the distal end portion. The chuck piece is used to push the chucking piece outward in the radial direction on the outer circumferential surface of the metal plate, and to fix the metal cylindrical member on the inner circumferential surface of the large-diameter cylindrical portion by the pressing force. .

The metal cylindrical member turning method according to claim 2, wherein the metal cylindrical member has a convex portion projecting inwardly on an inner peripheral surface of the small-diameter cylindrical portion, and the convex portion is rearward. A tip end having a rear end portion facing toward the end side, the tip end of the small-diameter cylindrical portion fitting portion of the chuck main body or a portion near the tip end facing the front end side and capable of contacting the rear end facing portion The orientation part is formed,
In the state where the large-diameter cylindrical portion and the small-diameter cylindrical portion of the metal cylindrical member are fitted to the large-diameter cylindrical portion fitting portion and the small-diameter cylindrical portion fitting portion of the chuck main body with a clearance fit, The metal cylindrical member according to claim 1, wherein the metal cylindrical member is positioned in a rotational axis direction when the metal cylindrical member is fixed to the chuck by bringing the rear end facing portion into contact with a portion. This is the turning method. The metal cylindrical member is exemplified by a spark plug metal shell or a gas sensor metal shell.

  According to the present invention, when the metal cylindrical member is fixed to the chuck on the inner peripheral surface of the large-diameter cylindrical portion, and after the fixing, the small-diameter cylinder in the chuck body is provided on the inner peripheral surface of the small-diameter cylindrical portion. The part fitting part is in a state fitted with a gap fit. Thus, in the present invention, when the metal cylindrical member is fixed to the chuck, the small-diameter cylindrical portion fitting portion of the chuck main body is fitted to the inner peripheral surface of the small-diameter cylindrical portion with a gap fit. For this reason, it is possible to effectively prevent the axis of the metal cylindrical member from being inclined and fixed with respect to the rotation axis of the regular chuck. In addition, since the small-diameter cylindrical portion fitting portion in the chuck body is fitted with a clearance fit on the inner peripheral surface of the small-diameter cylindrical portion, the steady-reducing action of the small-diameter cylindrical portion during rotation can be obtained. It is also effective for preventing the small-diameter cylindrical portion from swinging when the cylindrical member rotates. Therefore, according to the present invention by fixing to such a chuck, the concentricity (coaxiality) of the large diameter cylindrical portion and the small diameter cylindrical portion is improved, and the processing accuracy is also improved. Thus, it is also effective in preventing a decrease in processing accuracy due to an increase in the size of the small diameter cylindrical portion.

  Embodiments of the present invention will be described in detail with reference to FIGS. However, in this embodiment, the metal cylindrical member 101 which is a workpiece is the same as that shown in FIG. 6, but the shape and structure thereof will be described in more detail based on FIG. That is, this metallic cylindrical member 101 is a material for manufacturing the metal shell 101b constituting the spark plug 200 of FIG. 8, and the inner diameter is large (for example, 12 mm) on the left end side of FIG. A large-diameter cylindrical portion 103 and a small-diameter cylindrical portion 105 formed on the right side of the large-diameter cylindrical portion 103 have an inner diameter smaller than that of the large-diameter cylindrical portion 103 and an outer diameter smaller than the inner diameter of the large-diameter cylindrical portion 103. Have concentricity. The large-diameter cylindrical portion 103 is based on a cylindrical shape, and the outer peripheral surface 108a of the intermediate portion in the axis G direction is a polygon (in this example, a hexagon).

  In such a metallic cylindrical member 101, the double hatched portion in FIG. 1 is a part to be turned. The large-diameter cylindrical portion 103 of the metallic cylindrical member 101 has a polygonal portion 108 in the form of leaving a polygonal portion 108 within a predetermined range at an intermediate portion in the axis G direction on the left side of the circular flange portion 107 at the right end. Both the left end side portion (rear end side portion) 109 and the middle side portion 110 in FIG. 1 are set so as to be thinner than the thickness of the polygonal portion 108 by turning. In addition, the polygon part 108 in the large diameter cylinder part 103 is a place which makes the tool latching part for screwing after assembling as the spark plug 200 after a process (finished product) as mentioned above.

  On the other hand, the small-diameter cylindrical portion 105 of the metallic cylindrical member 101 is formed in a straight tube (straight circular tube) shape, and the thin portions (the left end side portion 109 and the middle side portion 110) of the large-diameter cylindrical portion 103 are thick. It is set to be relatively thick. The outer diameter of the small diameter cylindrical portion 105 is formed to be smaller than the inner diameter of the large diameter cylindrical portion 103. And the convex part 106 which protrudes in a circumferential flange shape inwardly in the inner peripheral surface 105b of the small diameter cylinder part 105 is formed in the raw material. In the metallic cylindrical member 101 of FIG. 1, the small-diameter cylindrical portion 105 has a distal end surface (right end surface in FIG. 1) and a part of the outer peripheral surface of the portion near the distal end as shown by double hatching. Is set to be turned. In addition, since the screw is formed by rolling, for example, on the outer peripheral surface 105a of the small diameter cylindrical portion 105 in a post-turning process, a portion near the circular flange portion 107 of the small diameter cylindrical portion 105 is partially cut. Is set. Such a metal tubular member (material) 101 is made of steel or stainless steel as a material and is formed by a number of forging processes as described above.

  Next, the chuck 1 in each spindle (rotary shaft) of a processing machine (for example, a multi-axis automatic lathe) for turning such a metal cylindrical member (main metal fitting) 101 will be described with reference to FIGS. explain. The chuck 1 is configured as follows, with a chuck body (body) 2 concentrically provided on each spindle (not shown) in a multi-axis automatic lathe as a main body. The chuck body 2 has a cylindrical shape in which the tip side (the right end in FIG. 1) is closed. As shown in FIGS. 1 to 3, the chuck main body 2 is configured such that the metal cylindrical member 101 is externally fitted from the large-diameter cylindrical portion 103 side, whereby the large-diameter cylindrical portion 103 and the small-diameter cylindrical portion. A large-diameter cylindrical portion fitting portion 3 whose outer peripheral surface is formed in a cylindrical shape or a columnar shape having a different diameter so that the inner peripheral surfaces 103b and 105b of 105 are fitted with a clearance fit, and this large-diameter cylindrical portion fitting A small-diameter cylindrical portion fitting portion 5 extending concentrically from the distal end side of the portion 3 toward the distal end is provided.

  Among these, a center hole 9 is provided at the center of the distal end surface (the distal end surface of the closing portion) 7 of the small diameter cylindrical portion fitting portion 5. Between the large-diameter cylindrical portion fitting portion 3 and the small-diameter cylindrical portion fitting portion 5 in the axis G direction, the large-diameter cylindrical portion 103 and the small-diameter cylindrical portion 105 among the inner peripheral surface of the metallic cylindrical member 101 are provided. A tip-facing annular portion 14 corresponding to a tapered rear-end facing portion 104 (see FIG. 1) located at the boundary portion is formed. When the metal cylindrical member 101 is externally fitted to the chuck body 2, the tip-end-shaped annular portion 14 contacts the tapered rear end facing portion 104 of the metal cylindrical member 101 and is positioned in the axis G direction. It is formed to be.

  In addition, as shown in FIG. 2, chamfering is given along the circumferential direction at a portion near the outer periphery of the distal end surface 7 of the small diameter tubular portion fitting portion 5 to form a distal end facing portion 16. In this embodiment, the tip-facing portion 16 of the tip surface 7 of the small-diameter cylindrical portion fitting portion 5 is set so as not to contact the rear-end facing portion 106b of the convex portion 106 protruding from the inner peripheral surface 105b of the small-diameter cylindrical portion 105. However, as shown by a two-dot chain line in FIG. 2, it may be abutted and the positioning in the axis G direction may be performed by this abutment. That is, when the metal cylindrical member 101 is externally fitted and pushed to the left end side in FIG. The rear end facing portion 106 b of the convex portion 106 in the small diameter cylindrical portion 105 of the tubular member 101 is set so as to abut on the front end facing portion 16 at the outer peripheral portion of the distal end of the small diameter cylindrical portion fitting portion 5. Also good. At the time of this contact, the rear end facing portion 104 located at the boundary at the inner diameter between the large diameter cylindrical portion 103 and the small diameter cylindrical portion 105 does not contact the front end facing annular portion 14.

  Such a large-diameter cylindrical portion fitting portion 3 and a small-diameter cylindrical portion fitting portion 5 are formed on the inner peripheral surfaces 103b and 105b of the large-diameter cylindrical portion 103 and the small-diameter cylindrical portion 105 of the metallic cylindrical member 101 in the chuck. And the diameter of each outer peripheral surface is set so as to be externally fitted with gap fittings each holding a minute gap (for example, 0.03 mm in diameter difference). However, in the drawing, it is exaggerated and shown as a large gap.

  On the other hand, a cylindrical hole 20 is provided inside the chuck body 2 and is concentric with its axis (hereinafter also referred to as a rotation axis) G. However, in this embodiment, the portion of the hole 20 corresponding to the large-diameter cylindrical portion fitting portion 3 is formed in a tapered shape (conical truncated cone) to form a tapered tapered portion 21, and the depth is small. It is closed before reaching the tube portion fitting portion 5. A round rod-like rod 30 is arranged in the hole 20 so as to be slidable in the direction of the rotation axis G by a driving means (not shown), and a tip portion (tip-side portion) 31 is tapered. Has been. The shaft diameter of the rod 30 is slightly smaller than the inner diameter of the hole 20, and the taper of the tip 31 of the rod 30 is the same as the taper part 21 of the hole 20 of the chuck body 2.

  In addition, the peripheral wall portion of the large-diameter cylindrical portion fitting portion 3 in the chuck body 2 is provided with three or more openings 18 that penetrate the rotation shaft G in the radial direction at equal angular intervals around the rotation shaft G. (See FIG. 5). Each opening 18 has a substantially rectangular shape as shown in FIG. 4 when the chuck body 2 is viewed from the outer peripheral surface. In each opening 18, a chucking piece (claw) 40 is arranged in a loosely fitting manner with a minute gap around it so as to be displaceable in the radial direction with respect to the axis G of the rod 30. A cylindrical pin hole 42 having a predetermined diameter is bored in the chuck piece 40 along the direction of the axis G (parallel to the axis G) from the front end surface side (the right end surface side in FIG. 2). Then, in a state where the chuck piece 40 is fitted in the opening 18, the pin 45 driven into the annular portion 14 facing the distal end of the large-diameter cylindrical portion fitting portion 3 in the chuck body 2 from the distal end side along the axis G direction. Is inserted into the pin hole 42 so that the chuck piece 40 is not separated or dropped from the chuck body 2. The pin 45 has an outer diameter that is sufficiently smaller than the inner diameter of the pin hole 42 and does not reach the hole bottom end of the pin hole 42, and is fixed to the main body 2. In order to drive the pin 45, a concave groove 48 having a semicircular cross section is provided along the axis G at a corresponding portion of the outer peripheral surface of the small diameter cylindrical portion fitting portion 5. Accordingly, the chuck piece 40 is disposed in each opening 18 so as to be displaceable in the radial direction of the axis G of the rod 30 by the gap in the fitting of the pin hole 42 of the pin 45.

  When the chuck piece 40 is arranged in this manner with respect to each opening 18, a portion (outer peripheral surface portion) 46 along the outer peripheral surface 3 a side of the large-diameter cylindrical portion fitting portion 3 in the chuck piece 40. Is a curved surface having substantially the same radius as the outer peripheral surface 3 a of the large-diameter cylindrical portion fitting portion 3. And the site | part (inner peripheral surface site | part) 47 located in the inner peripheral surface (namely, taper taper part 21) side of the large diameter cylinder part fitting part 3 has the taper which substantially corresponds with the internal peripheral surface in the axis | shaft G direction. It is assumed that it has a flat surface. However, when the chuck piece 40 is disposed with respect to each opening 18, the inner peripheral surface portion 47 located on the inner surface side of the chuck piece 40 is always inside the large-diameter cylindrical portion fitting portion 3. It is formed so as to slightly protrude from the peripheral surface toward the axis G. On the other hand, when the chuck piece 40 is placed in a free state, that is, when the rod 30 is slid to the rear end side of the chuck body 2 and is displaced to the inner side (axis side) of the chuck body 2, The outer peripheral surface portion 46 is set so as not to protrude from the outer peripheral surface 3 a of the large diameter cylindrical portion fitting portion 3. On the other hand, when the rod 30 is slid to the tip end side of the chuck body 2, the chuck piece 40 is slightly pushed outward in the radial direction by the wedge action on the outer peripheral surface of the tapered end portion 31 of the taper shape. The metal cylindrical member 101 is pressed and fixed (supported) outward on the inner peripheral surface of the large-diameter cylindrical portion 103 by the extrusion.

  The rod 30 is slid (advanced) to the distal end side by the driving means (not shown) when the metal cylindrical member 101 is chucked. In other cases, the rod 30 is slid rearward and held at a predetermined position. The chuck piece 40 is set to be in a free state. Further, in this embodiment, the chuck piece 40 has an appropriate size on the peripheral edge (peripheral corner) of the outer peripheral surface portion 46 in contact with the inner peripheral surface of the large-diameter cylindrical portion 103 of the metal cylindrical member 101. Chamfering (R chamfering) is provided so that the inner peripheral surface 103b of the large-diameter cylindrical portion 103 of the metallic cylindrical member 101 is not damaged during chucking.

  When the metal cylindrical member 101 is turned by the multi-axis automatic lathe having the chuck 1 as the main shaft, when the metal cylindrical member 101 is fixed to the chuck 1, the large-diameter cylindrical portion fitting portion 3 and the small-diameter portion described above are used. The metal cylindrical member 101 is externally fitted to the chuck body 2 including the cylindrical portion fitting portion 5 from the large-diameter cylindrical portion 103 side, and the inner peripheral surfaces 103b of the large-diameter cylindrical portion 103 and the small-diameter cylindrical portion 105. , 105b are fitted into the large-diameter tube portion fitting portion 3 and the small-diameter tube portion fitting portion 5. This fitting is performed so that the axis G of the metal cylindrical member 101 coincides with the axis (rotation axis) G of the chuck body 2 and the metal cylindrical member 101 is moved in the left direction in FIG. Just move. At this time, the chuck piece 40 disposed below the chuck 1 does not protrude below the outer peripheral surface of the chuck body 2 because the internal space is in a vacuum even in the free state. The metal tubular member 101 is not hindered when it is externally fitted. After the metal tubular member 101 is externally fitted to the large-diameter cylindrical portion fitting portion 3 and the small-diameter cylindrical portion fitting portion 5 in the chuck main body 2 in this way, the rod 30 disposed inside the chuck main body 2 is attached. Slide to the tip side. By doing in this way, the metal cylindrical member 101 which is a workpiece is chucked.

  That is, when the rod 30 is slid to the tip end side, the chuck piece 40 disposed in each opening 18 is moved to the inner peripheral surface portion 47 of the chuck piece 40 by the outer peripheral surface of the tapered tapered tip portion 31 of the rod 30. It is pressed and pushed outward in the radial direction of the axis G by the wedge action. Thus, the metal cylindrical member 101 is fixed on the inner peripheral surface 103b of the large-diameter cylindrical portion 103 by the pressing force generated thereby (see the enlarged view of FIG. 2). Thus, in this embodiment, the chuck for turning the metal cylindrical member 101 is performed with a chuck having a unique chuck structure, and the metal cylindrical member 101 is fixed on the inner peripheral surface of the large-diameter cylindrical portion 103. Is done. In this state, the small-diameter cylindrical portion fitting portion 5 in the chuck body 2 is fitted inside the small-diameter cylindrical portion 105 with a clearance fit.

  That is, when the metal cylindrical member 101 is fixed to the chuck 1 by the inner peripheral surface 103b of the large diameter cylindrical portion 103, and after the fixing, the chuck main body 2 is provided on the inner peripheral surface 105b of the small diameter cylindrical portion 105. The small-diameter cylindrical portion fitting portion 5 is in a state of being fitted with a clearance fit. As a result, it is possible to effectively prevent the shaft G of the metallic cylindrical member 101 from being inclined and fixed with respect to the rotation axis G of the regular chuck 1 by the amount of the clearance fitting. In addition, since the small-diameter cylindrical portion fitting portion 5 of the chuck body 2 is fitted to the inner peripheral surface 105b of the small-diameter cylindrical portion 105 with a gap fit, the amount of protrusion of the small-diameter cylindrical portion 105 during rotation is increased. Even if is large, the steadying action can be obtained. Therefore, in the turning of the metallic cylindrical member 101, the concentricity (coaxiality) of the large diameter cylindrical portion 103 and the small diameter cylindrical portion 105 is improved, and the processing accuracy is improved.

  In the above-described embodiment, when the metal cylindrical member 101 is externally fitted to the chuck main body 2, the taper-shaped rear end of the metal cylindrical member 101 is placed on the annular portion 14 facing the front end of the chuck main body 2. Although the end facing portion 104 abuts and positioning in the axis G direction is performed, as described above, this positioning may be performed as follows. That is, as shown by a two-dot chain line in FIG. 2, the length of the small-diameter cylindrical portion fitting portion 5 in the direction of the axis G is the same as that of the small-diameter cylindrical portion fitting portion 5 when the metallic cylindrical member 101 is externally fitted. When the rear end facing portion 106 b of the convex portion 106 in the small diameter cylindrical portion 105 of the metal cylindrical member 101 is pushed toward the left end in FIG. You may set so that it may contact | abut to the direction part 16. FIG.

  If positioned in this way, the reference position in the axial direction at the time of processing is the rear end facing portion 106 b of the convex portion 106 in the small diameter cylindrical portion 105. That is, in this case, the metal cylindrical member 101 can maintain the processing accuracy with respect to the rear end facing portion 106b in the axial direction. Accordingly, the metal cylindrical member 101 is a spark plug metal shell, and the insulator (insulating cylinder) inserted and disposed therein is the rear end facing portion 106 b of the inner peripheral surface of the small diameter cylindrical portion 105. The positioning accuracy desired by the insulator in the axial direction can be improved.

  As for the gap fitting of the small-diameter cylindrical portion fitting portion 5 in the chuck main body 2 to the inner peripheral surface 105b of the small-diameter cylindrical portion 105 in the metal cylindrical member 101, to the extent that does not hinder smooth fitting, It can be said that the gap fitting with a sufficiently small gap is preferable in order to prevent the metal cylindrical member 101 from being inclined during fitting and to prevent shake during rotation. For this fitting, chamfering is given to the intersecting ridge formed by the tip of the outer peripheral surface of the large-diameter cylindrical portion fitting portion 3 and the outer peripheral edge of the tip-oriented annular portion 14 in the chuck body 2. Is preferred. In addition, chamfering is also applied to the outer peripheral edge (cross ridge between the outer peripheral edge and the outer peripheral surface of the small-diameter cylindrical portion fitting portion 5) of the distal-end-facing portion 16 near the outer periphery of the distal end surface 7 of the small-diameter cylindrical portion fitting portion 5. It is preferable to keep the fitting smooth.

  Accordingly, the metal cylindrical member 101 held by the chuck 1 is turned using a known processing machine (for example, a multi-axis automatic lathe). Thereafter, the outer peripheral surface 105a of the small-diameter cylindrical portion 105 is threaded and the ignition terminal is welded to the tip of the small-diameter cylindrical portion 105 to complete the metal shell 101b (part before assembling as a spark plug). Thereafter, it is used for assembling the spark plug. Then, in the assembly, as shown in FIG. 8, the left end side portion 109 of the large-diameter cylindrical portion 103 is inserted inside the metallic cylindrical member 101 by inserting an insulator 301 having an electrode or the like inserted therein. The thin-walled portion is bent inward, and simultaneously crimped so as to be compressed in the axial direction.

  The present invention is not limited to the above-described embodiment, and can be embodied with various design changes without departing from the gist thereof. For example, the number of chuck pieces in the chuck may be plural. Further, in the above description, the metal cylindrical member that is a workpiece is embodied in the case of a metal shell for a spark plug. However, in the turning method of the metal cylindrical member of the present invention, the metal cylindrical member that is a workpiece is made. The tubular member is not limited to this. That is, in addition to this, the metal shell 401 for the gas sensor 400 as shown in FIG. 9 includes a large-diameter cylindrical portion 403 on one end side of the gas sensor 400, and other than the large-diameter cylindrical portion 403. Of course, as long as the small diameter cylindrical part 405 is provided concentrically on the end side, it can be applied. The gas sensor 400 is for detecting an oxygen concentration in a gas to be measured such as exhaust gas discharged from an internal combustion engine or the like, and has an internal electrode (layer) and an external electrode (layer) on the inner and outer surfaces, respectively. A detection element 421 made of a hollow shaft (cylindrical) solid electrolyte with a closed end (lower end in the figure) and a metal shell 401 etc. attached to the exhaust gas pipe while holding the detection element 421 inside. ing. The gas sensor 401 is attached to an exhaust gas pipe of an internal combustion engine via a metal shell 401, and an internal electrode (reference electrode) on an inner peripheral surface (inner wall surface) of the detection element 421 is used as a reference gas (atmosphere), and an outer peripheral surface ( The external electrode (measurement electrode) on the outer wall surface is brought into contact with the exhaust gas, an electromotive force is generated between both electrodes corresponding to the oxygen concentration difference between the inner and outer surfaces of the detection element 421, and a signal based on this electromotive force is generated in the control circuit. It is used to control the air-fuel ratio by detecting the oxygen concentration in the exhaust gas. In FIG. 9, a protective cover (cap) 420 is attached to the small-diameter cylindrical portion 405, and the large-diameter cylindrical portion 403 surrounds terminal fittings 471, 491 and the like connected to the respective electrodes of the element 421. A protective cylinder 431 is attached to the inside and covers the inside.

  That is, according to the present invention, the metal cylindrical member includes a large-diameter cylindrical portion on one end side thereof, like a metal cylindrical member used for a metal shell for a spark plug or a gas sensor. A concentric small diameter cylindrical portion is provided on the other end side of the diameter cylindrical portion, and can be widely applied to the turning thereof. Therefore, the present invention can be widely applied to various small metal cylindrical members having such a configuration. Furthermore, in the above description, the multi-axis automatic lathe is embodied as an example in the processing machine, but it is only necessary to be able to turn a metal cylindrical member. Therefore, it can be applied to a chuck in a single-axis lathe as a matter of course. .

The half sectional view of the metal cylindrical member processed in an embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing of the state which fitted and fixed the metal cylindrical member to the chuck | zipper in the processing machine, and also the principal part enlarged view explaining embodiment of this invention. Sectional drawing of the principal part of the chuck | zipper in FIG. The figure which looked at the chuck | zipper of FIG. 3 from the outer peripheral surface of the top of a chuck | zipper. The AA line expanded sectional view of FIG. Sectional drawing of a metal cylindrical member. Sectional drawing of the state which fitted and fixed the metal cylindrical member to the chuck | zipper of the conventional processing machine. A half sectional view of a spark plug. Sectional drawing of a gas sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chuck of processing machine 2 Chuck main body 3 Large diameter cylinder part fitting part 5 Small diameter cylinder part fitting part 16 Tip direction part of small diameter cylinder part fitting part of chuck body 18 Rotation of large diameter cylinder part fitting part of chuck body Opening that penetrates in the radial direction of the shaft 30 Rod 31 Position near the tip of the rod 40 Chuck top 101, 401 Metal cylindrical member 103, 403 Large diameter cylindrical portion 103b of the metallic cylindrical member Inner peripheral surface of the large diameter cylindrical portion 105, 405 Small-diameter cylindrical portion 105b of the metallic cylindrical member Inner peripheral surface 106 of the small-diameter cylindrical portion The convex portion 106b of the inner peripheral surface of the small-diameter cylindrical portion The rear end facing portion 400 of the convex portion Gas sensor G axis (rotating shaft)

Claims (4)

When turning a metal cylindrical member provided with a large-diameter cylindrical portion on one end side of itself and having a small-diameter cylindrical portion concentrically on the other end side with respect to the large-diameter cylindrical portion, the metal cylinder To the chuck that fixes the member
The metal cylindrical member is externally fitted from the large-diameter cylindrical portion side, so that the large-diameter cylindrical portion is fitted to each inner peripheral surface of the large-diameter cylindrical portion and the small-diameter cylindrical portion with a gap fit. A chuck body having a joint portion and a small-diameter cylindrical portion fitting portion extending from the distal end side of the large-diameter cylindrical portion fitting portion toward the distal end is provided, and can be slid in the direction of the rotation axis inside the chuck body. And a rod having a tapered portion formed at a tip end portion thereof, and the large-diameter tubular portion fitting portion into which the large-diameter tubular portion of the metallic tubular member is fitted in the chuck body. And a plurality of openings penetrating in the radial direction of the rotating shaft at intervals around the rotating shaft, and a chuck piece is disposed in each opening so as to be displaceable in the radial direction of the rotating shaft. And the large-diameter tube portion fitting portion and the small-diameter tube portion fitting portion of the chuck body, Under the state in which the large-diameter cylindrical portion and the small-diameter cylindrical portion of the metal cylindrical member are fitted with a clearance fit, the rod is slid toward the distal end side of the chuck body, and the tapered tapered portion near the distal end portion The chuck piece is used to push the chucking piece outward in the radial direction on the outer circumferential surface of the metal plate, and to fix the metal cylindrical member on the inner circumferential surface of the large-diameter cylindrical portion by the pressing force. A method for turning a metal cylindrical member. The metallic cylindrical member has a convex portion projecting inwardly on the inner peripheral surface of the small diameter cylindrical portion, and the convex portion has a rear end facing portion facing the rear end side, A tip-facing portion is formed at the tip or near the tip of the small-diameter cylindrical portion fitting portion of the chuck body, the tip-facing portion facing the tip side and capable of contacting the rear-end facing portion,
In the state where the large-diameter cylindrical portion and the small-diameter cylindrical portion of the metal cylindrical member are fitted to the large-diameter cylindrical portion fitting portion and the small-diameter cylindrical portion fitting portion of the chuck main body with a clearance fit, The metal cylindrical member according to claim 1, wherein the metal cylindrical member is positioned in a rotational axis direction when the metal cylindrical member is fixed to the chuck by bringing the rear end facing portion into contact with a portion. Turning method.   The method of turning a metal cylindrical member according to claim 1 or 2, wherein the metal cylindrical member is a metal shell for a spark plug.   The metal cylindrical member turning method according to claim 1 or 2, wherein the metal cylindrical member is a metal shell for a gas sensor.

Images