81 results about "Shape fitting" patented technology

A hinge mechanism and an electronic device are provided. The hinge mechanism includes a hinge base and a swing arm assembly. The swing arm assembly includes a first rotating part, the first rotating part is provided with a first arc-shaped fitting surface and a second arc-shaped fitting surface disposed opposite to each other, and the hinge base includes a third arc-shaped fitting surface and a fourth arc-shaped fitting surface, the third arc-shaped fitting surface and the fourth arc-shaped fitting surface are disposed opposite to each other and spaced apart to form guide space. The first rotating part is disposed in the guide space, the first arc-shaped fitting surface is in a sliding fit with the third arc-shaped fitting surface, and the second arc-shaped fitting surface is in a sliding fit with the fourth arc-shaped fitting surface.

Disclosed are a method and apparatus devices for an acrylic display case wherein the two panels (walls or ceiling or even floor) are adjoined using substantially wedge-shaped (trapezoidal) fittings capable of easily snapping into slot cut-outs / notches in the acrylic panel walls (or ceiling or floor) before final screw-tightening. The wedge-shaped fittings are easily positioned (inserted by sliding-insertion, then push-snapped) into their receiving slots in their respective panel slots (before being screw-tightened from a screw coming from the perpendicular panel). The wedge-shaped fitting promotes “one direction insertion” and then ‘snaps into place’ in its panel slot due to the fitting's “substantially three layer (3-structure)” style shape. Each fitting has an inner (anchors inside the box) face section with a surface area slightly larger than its panel notch. This inner section is ultimately positioned inside the case, acting as an inner anchoring lip against the acrylic panel's inside wall (wall herein interchangeable with “panel, whether ceiling or side or floor). The fitting further comprises a tapered middle section that allows for easy sliding-insertion into the panel notch-slot, and then allows gentle pressing / pushing into place (until friction gives to the “snap” positioning). This seamless positioning is made possible due to the fitting's middle-section tapering. After insertion (smaller end of the wedge fitting is initially inserted into the wider end of the dovetail shaped slot), as the fitting is then pressed into its slot, the tapered middle structure is what allows the fitting to gently slide against the panel notch's edge until the fitting “snaps” into place when this friction is overcome. The fitting further comprises an outer face section which is substantially larger than its panel-slot. This fitting “outer face section” has the largest surface area of the fitting's three sections. Both the innermost and outermost “layers / structures” of the fitting function as “lip-rim anchors” to keep the fitting firmly in its panel-slot, while the trapezoidal “wedge shape” of the fitting allows efficient insertion and ultimately secure snap-placement.The remainder of the system comprises modular panels with optional cut-out slots, tabs, indentations and screw holes to build a wide variety of display cases.

The utility model relates to the technical field of medical instruments, and discloses a PICC adjustable skin expanding needle which comprises a needle body, the needle body comprises a needle point, a sliding piece is assembled on the needle body in a sliding mode, a limiting protruding block is arranged at the bottom of the sliding piece, a locking column is arranged on the limiting protruding block, a movable column is arranged on the locking column, a limiting piece is arranged on the movable column, and a through hole is formed in the middle of the sliding piece. Transverse compression gaps are formed in the locking column, the movable column and the limiting piece, an embedding groove is formed in the locking column, the movable column is sleeved with a buckling piece, and a wedge-shaped embedding block is arranged in the buckling piece. The diameter of the through hole is larger than that of the needle body. The embedding groove is located in the vertical direction of the compression gap. The side face of the limiting protruding block is in a circular arc shape. The device has the advantages that the position of the limiter is adjusted according to the subcutaneous fat thickness prompted by B-ultrasonic, and a better puncture effect is achieved for different patients.

The invention discloses an electric tower stay wire fitting, and relates to the technical field of stay wire fittings. In order to solve the problems that an existing wedge-shaped fitting is fixed only by abutting against a straight plate and slips off under the long-term wind action, the wedge-shaped fitting comprises a fitting body, the fitting body comprises a U-shaped bolt, the periphery of the U-shaped bolt is slidably connected with a stay wire block, and a stay wire channel and a conical block are arranged in the stay wire block; a wire pulling assembly and an abutting assembly are arranged in the wire pulling channel, and the wire pulling assembly comprises a fixing column and a sliding sleeve plate; the abutting assembly comprises a sliding groove, an abutting block, a connecting rod, an extending rod and a rotating piece. The extension rod is driven by the rotating piece to slide in the sliding groove, so that the abutting block is unfolded outwards, the stay wire is pushed to be tightly attached to the inner wall of the stay wire channel, and the contact area and friction force are increased. Through a mechanical expanding type fixing structure, the stay wire is effectively prevented from slipping under the long-term action of wind power, and the fixing stability of the stay wire of the electric tower is remarkably improved.

The utility model discloses a dental operating knife handle assembly which comprises a blade and a knife handle, a holding point according to the human engineering principle is arranged at the front end, close to the blade, of the knife handle, round protrusions are arranged on the two sides of the middle end of the knife handle, concave holding points are arranged opposite to the round protrusions, and a spoon head is arranged at the end, away from the blade, of the knife handle. The outer edge of the knife handle is arranged to be in the shape of a hand-shaped fitting curve. The dental scalpel is reasonable in structural design, an operator holds the scalpel handle in the working process, the outer edge of the scalpel handle is arranged to be in the shape of a hand fit curve, holding is convenient, the spoon head arranged at the rear end can be used for repairing false teeth in the false tooth machining process, the installation position of the false teeth can be slightly adjusted, and comfort, holding feeling and operability are improved when the dental scalpel is used.

The utility model provides a self-locking type retainer assembly which comprises a cylindrical retainer body and an elastic limiting piece, the retainer body is provided with a plurality of pockets for containing balls, the pockets are circumferentially distributed and axially arranged at intervals in two rows, each pocket comprises an upper portion and a lower portion, and the upper portion and the lower portion of the retainer body are provided with elastic limiting pieces. The upper part extends to the outer diameter of the frame body and is arranged in a barrel shape corresponding to the diameter of a roller, an upper opening communicated with the upper part is formed in the outer diameter of the frame body, the lower part is arranged in an arc shape attached to the roller, a lower opening communicated with the lower part is formed in the inner diameter of the frame body, and the elastic limiting piece is arranged at the outer diameter of the frame body and can limit the roller. Aiming at the defects in the prior art, the utility model provides the self-locking type retainer assembly which can be used for radial displacement of the roller and can axially and linearly move during working.

There are provided a positioning method and a positioning device that can position workpieces by a simple method and configuration. A positioning method includes: gripping at least one of first and second workpieces; obtaining point group data of the at least one gripped workpiece of the first and second workpieces; calculating a translation matrix of shape fitting point group data obtained by adjusting a position of the point group data to reference data in a position adjustment state of the first and second workpieces; calculating an inverse matrix based on the translation matrix; and positioning the first and second workpieces by moving the at least one gripped workpiece of the first and second workpieces based on at least one of the translation matrix and the inverse matrix.

The invention discloses a welding positioning device for an automobile seat backrest framework, and relates to the technical field of welding positioning, the welding positioning device comprises a case and a core driving assembly, guide sleeves are mounted on two sides of the top end of the case, the core driving assembly is mounted in a cavity of the case, and the core driving assembly comprises an air cylinder fixedly mounted in the middle of the top end of the case. According to the welding positioning device for the automobile seat backrest framework, on one hand, the chuck is driven to symmetrically clamp framework side plates through an inclined surface transmission structure of the inclined wedge and the roller shaft, and the shape fitting design of the lower electrode and the framework side plates is matched, so that the positioning gap of the framework side plates is effectively eliminated, and welding deviation is avoided; on the other hand, the nuts are accurately limited through the positioning grooves of the lifting plates, the sliding plates slide along the side grooves in a guiding mode in the feeding process, the coaxiality of the nuts and mounting holes of the framework side plates is ensured, the welding precision is improved from the framework positioning and nut positioning two dimensions, and the defects of insufficient welding, wrong welding and the like are reduced.

Provided is a lid unit that has superior cleanability of a water-stopping packing and that can maintain the seal achieved by the water-stopping packing well. A water-stopping packing (23) is composed of a ring-shaped elastic member that abuts against a protruding portion (6) that protrudes from the inside of a container main body (2) in its entirety in a state in which a lid main body is installed to the container main body (2), and has a ring-shaped fitting protrusion (23a) that fits into a fitting recess (24), an elastic flange portion (23b) that protrudes from the outer peripheral surface of the fitting protrusion (23a) in the entire diameter direction, and an elastic sleeve portion (23c) that protrudes from between the fitting protrusion (23a) and the elastic flange portion (23b) in the entire downward direction, and in a state in which the lower surface of the elastic flange portion (23b) is in contact with the surface of the protruding portion (6) on the entry side and the outer peripheral surface of the elastic sleeve portion (23c) is in contact with the surface of the protruding portion (6) on the top side, the inner peripheral surface of the elastic sleeve portion is continuously provided downward from the lower surface of the fitting protrusion.

The present application aims to obtain a car operating panel of an elevator in which the rigidity of a sleeve wall can be improved by a method other than increasing the plate thickness of the sleeve wall, and a sleeve wall fixing structure. To this end, the car operating panel of the elevator according to the present application includes a car operating panel main body provided in a car chamber of an elevator; a box-shaped box panel that houses the car operating panel main body; a sleeve wall of the car chamber that can open and close the box panel; a fixing portion fixed to the sleeve wall and formed with a fourth hole portion that opposes a third hole portion formed in an upper surface or a lower surface of the car chamber; a rod-shaped insertion member that passes through a first hole portion formed in the sleeve wall and a second hole portion formed in the box panel in a state in which the sleeve wall is closed; and a rod-shaped fitting member that passes through the fourth hole portion formed in the fixing portion in the state in which the sleeve wall is closed and fits with the third hole portion formed in an upper surface of the car chamber above the sleeve wall or a lower surface of the sleeve wall below the sleeve wall.

The application belongs to the technical field of automobile electrical connectors, and particularly relates to a high-adaptability automobile electrical connector, which comprises a terminal seat, a flip cover seat, a main shaft and multi-specification terminals, a plurality of specification connecting grooves and a bottom sliding connecting groove are arranged in the terminal seat; the flip cover seat is rotationally connected with the terminal seat through the main shaft and is provided with a T-shaped fitting groove; the multi-specification terminals comprise first, second and third terminals with different structures, each terminal is provided with a hooking part for hooking the main shaft, a limiting protrusion for preventing errors, a clamping protrusion for locking and a switching clamping position, the flip cover seat and the terminals are linked through the main shaft, mechanical interference between the T-shaped fitting groove and the terminal clamping part is utilized to realize synchronous compression, the limiting protrusions at different positions are matched with the corresponding sliding connecting grooves to realize physical error prevention, the application can realize compatible and stable connection of terminals of various specifications on a single base, and the adaptability, assembly error prevention performance and contact reliability in a vibration environment are significantly improved.

To provide a show case provided with a positioning structure defining relative positions of unit case bodies arranged in parallel, in which construction of the positioning structure in connection work can be more easily and reliably performed while suppressing a decrease in appearance design.SOLUTION: Unit case bodies 4 (4A, 4B) includes: a heat insulation box body 7 having a front wall 11; and a front exterior package 10 provided so as to cover a front surface of the front wall 11 across right and left ends. A positioning structure 43 provided between adjacent unit case bodies 4A, 4B includes: rail-shaped fitting parts 44 provided in right and left ends of the front exterior package 10 and formed in a right and left direction; and a connection body 45 fitted and mounted across the fitting parts 44, 44 of the unit case bodies 4A, 4B on an inner surface side of the front exterior packages 10, 10 of adjacent unit case bodies 4A, 4B. The front exterior package 10 is provided with a regulation structure 51 that regulates an entrance depth in the right and left direction of the connection body 45 with respect to the fitting parts 44.SELECTED DRAWING: Figure 1

The utility model discloses a motor laminated iron core separator structure, which comprises a separator body, one end of a tooth-shaped fitting area in the length direction is connected with the separator body, two sides of the other end of the tooth-shaped fitting area in the length direction extend to form extension sections, and a convex block and a concave block are arranged in the separator body. The protruding blocks and the concave blocks are formed on the separating sheet body through stamping, the protruding blocks and the concave blocks are arranged in the annular attaching area around the center of the separating sheet body at intervals, the protruding blocks and the concave blocks are arranged in the tooth-shaped attaching area at intervals, and a separating notch is formed in the end of the extending section. The protrusions enable the stator punching sheets to be in a circular range, so that the bonding area between the stator punching sheets and the separation sheet bodies is reduced, subsequent separation of the separation sheet bodies by each stator punching sheet group at the position is facilitated, and the effect of assisting separation of the stator punching sheet groups is further achieved.

The invention discloses an unsupervised polygonal structural member profile fitting method, which belongs to the technical field of railway infrastructure intelligent monitoring and computer vision, and comprises the following steps: acquiring a profile contour point set of a structural member in an image, and describing a straight line where the edge of the structural member is located by a slope parameter and a translation parameter corresponding to the slope parameter; constructing an objective function based on the distance between the contour point and the straight line, optimizing a slope parameter and a translation parameter, minimizing the objective function to train a neural network model, generating a slope parameter and a translation parameter corresponding to the predicted optimal straight line, and obtaining a contour point set corresponding to the contour image of the to-be-detected structural member. And generating an optimal slope parameter and an optimal translation parameter through the trained neural network model, generating an optimal straight line, and obtaining the appearance of the polygonal structural member through the intersection points between the straight lines. According to the invention, accurate fitting and state detection can be carried out on the appearance of the polygonal structural member, so that accurate and efficient real-time monitoring of railway infrastructures is realized.

The application discloses a curtain fabric and a weaving process thereof, which comprises a first area, a second area and a third area, and the first area, the second area and the third area are arranged in the order of one first area, one second area, one first area and one third area along the length direction of the fabric. The natural close effect is formed by the V-shaped fitting structure of the second area and the wave-shaped fitting structure of the third area. In the natural state, the adjacent second convex area spontaneously covers the second base cloth area, the adjacent third convex area completely covers the third base cloth area, the first convex area is twisted by connection to cover the first base cloth area, the light-shielding property of the fabric is ensured, the second convex area is arranged in a V shape, the loops of the second convex area are in the mutual holding state, the fiber cannot be pulled out, the third convex area is in a wave-shaped structure, the loops are continuously curved and held along the width direction of the fabric, the fiber is prevented from falling off through the structure self-locking, and the fiber floating and falling off is reduced.

The invention discloses a shape detection method, a shape detection device, a shape detection system and a storage medium, and belongs to the technical field of image processing. The shape detection method comprises the steps of performing shape detection on a to-be-detected image corresponding to a to-be-detected piece based on a shape detection model to obtain an initial detection result; screening the first detection shape according to the detection score to obtain a second detection shape; performing discrete sampling on the second detection shape to obtain a plurality of first sampling points; performing position optimization on the plurality of first sampling points based on the gradient of the to-be-detected image to obtain a plurality of corresponding second sampling points; and performing shape fitting on the plurality of second sampling points to obtain a third detection shape as a shape feature of the to-be-detected piece. Thus, for the to-be-detected image of the to-be-detected piece obtained in a complex scene, accurate shape features can be extracted, and then the precision of follow-up execution of industrial detection tasks such as positioning and size measurement of the to-be-detected piece is guaranteed.

The utility model provides a tandem thrombin determination kit, which relates to the technical field of medical detection kits and comprises a kit body, and four connecting short shafts are symmetrically and fixedly connected to one end of the kit body; the head ends of the four connecting short shafts are fixedly connected with a series-connection assembly, the series-connection assembly is integrally formed by two symmetrically-distributed U-shaped assembling sleeves, a row of arc-shaped connecting plates arranged between the two U-shaped assembling sleeves and a row of vertical force transmission plates arranged between the row of arc-shaped connecting plates, and a T-shaped sliding groove is formed between the two U-shaped assembling sleeves. A T-shaped connecting piece is integrally formed at the other end of the kit body, and the T-shaped connecting piece is slidably assembled and fixedly connected with the series-connection assembly through a T-shaped sliding groove. Through the mechanism for temporarily removing the positioning force, the positioning force can be temporarily removed when the kit body is assembled and disassembled, and the situation that the assembling and disassembling operation of the kit body is not smooth and wastes labor due to the fact that the positioning force needs to be overcome when the kit body is assembled and disassembled is avoided.

The utility model relates to a side punching mounting structure of a die. The side punching mounting structure comprises a die main body, a side punching module, a mounting contact surface, a strip-shaped binding surface and a clearance surface, according to the structure, the strip-shaped binding face is arranged between the die body and the side punching module through receding treatment, and the area of a contact face needing fine grinding is reduced. The strip-shaped binding face is arranged on the edge of the installation contact face in a shape-following mode, the perpendicularity of the strip-shaped binding face and the horizontal bottom face needs to be guaranteed, and the strip-shaped binding face is connected with the receding face and the mold body side through fillets. The receding depths of the receding faces are consistent, supporting is guaranteed, meanwhile, the assembling work time is shortened, and the assembling efficiency is improved. Compared with the prior art, the utility model has the advantages of high efficiency, stability, safety, long service life and the like.

This product is a holder used to attach a wire condenser (condenser) consisting of a cylindrical tube and multiple wires to, for example, the back of a refrigerator. The holder is made of a single molded piece, and its upper part has three horizontally reclined C-shaped fitting parts in the front-to-back direction for fitting and holding the cylindrical tube. The front part of the holder has horizontally reclined L-shaped latching pieces and elastically deformable clips, positioned above and below. The holder is fixed to the refrigerator or the like by the latching pieces engaging with the latching holes and the clips being inserted into and engaged with the clip holes.

This utility model discloses a separate collection bag for facilitating the separation of centrifuge cups and centrifuged materials. It includes a main bag body, an annular pleated section, a sealing structure, and an arc-shaped fitting section. The main bag body is cylindrical with a diameter of 7.4 cm, designed to accommodate centrifuge cups. The annular pleated section is located in the middle of the outer wall of the main bag body, extending upwards and elastically stretching to accommodate centrifuge cups of different heights. The sealing structure is connected to the top of the main bag body, with an opening diameter of 7.8 cm. The top edge is thickened to form a sealing reinforcement edge for tightening and sealing. Thus, the bottom arc-shaped fitting section matches the curvature of the centrifuge cup bottom, leaving a 1-3 mm elastic margin. During centrifugation, it fits the bottom of the cup, preventing solid residue. The annular pleated section and the 2 cm pleats on the outer wall of the sealing section work together to adjust the base height by 11 cm to accommodate different centrifuge cups. The 2-5 mm wide sealing reinforcement edge, combined with the pleat deformation, forms a tight seal to prevent leakage.

The present invention relates to the technical field of self-controlled self-priming pumps, and specifically relates to a self-controlled self-priming pump with adjustable position, including a pump body that can be conveniently adjusted to a horizontal state for use. The self-controlled self-priming pump with adjustable position further includes a horizontal adjustment assembly, which is pre-adjusted to a horizontal state and is used to provide horizontal support for the pump body after changing the position of the pump body, and a temporary support assembly, which is arranged outside the horizontal adjustment assembly. The temporary support assembly provides temporary support by fitting the bottom of the pump body, facilitating the horizontal adjustment assembly not to provide support for the pump body during the process of adjusting the level. In the present invention, by controlling the support screw to abut against the L-shaped fitting plate, the L-shaped fitting plate drives the assembled plate to rotate through the rotating shaft, and the linkage plate and the connecting block are coordinated through the rotating rod and the hinge to finely adjust the ring, and the ring is adjusted to a horizontal state, facilitating adjusting the pump body to a horizontal state before using the pump body in the later stage and then using it.

This invention discloses a dual-function cage structure for ultra-high temperature, high-speed all-ceramic ball bearings, belonging to the field of all-ceramic bearing technology. The cage is made of silicon nitride, silicon carbide, or zirconium oxide and includes a guiding structure and a lubrication and protection structure. The guiding structure is an arc-shaped fitting pocket for high-precision guidance. The lubrication and protection structure consists of an annular lubrication storage cavity, a gradient aperture slow-release channel, and a capillary transport structure connected in sequence to form a synergistic lubrication system, which can suppress high-temperature volatilization, overcome centrifugal oil spillage, provide quantitative slow release, and ensure precise oil supply. This invention achieves dual-function coupling of guidance and lubrication, reducing the friction coefficient by ≥35% and increasing service life by ≥60%. It is suitable for ultra-high temperature, high-speed, and extreme operating conditions in aerospace, high-end equipment, and other fields, and has high engineering application value.

1. Name of the product in this design: Counterweight base. 2. Purpose of this design: This product is used to provide counterweights for pole-shaped fittings in sports. 3. The key design feature of this product is its shape. 4. The image or photograph that best illustrates the design's key points: a 3D model.

The invention belongs to the technical field of knee joint arbor treatment equipment, and particularly relates to a knee joint force line appliance which comprises a body and a pressure mechanism, the body comprises a main body supporting frame, a thigh binding assembly and a shank binding assembly, and the thigh binding assembly and the shank binding assembly are in sliding connection with the main body supporting frame; after sliding in place, the main body supporting frame is fixed, and then the main body supporting frame is bound to the thigh and the shank respectively; the pressure mechanism is located between the thigh binding assembly and the shank binding assembly, and the pressure mechanism applies adjustable pressure to the key position of a force line to adjust the form of the force line of the lower limb joint, reduce and improve the development speed of gonitis lesion and reduce knee joint pain. Gradient pressure is applied to the outer side, the lower limb force line is guided to be corrected towards the outer side, and joint load redistribution is achieved. The structure of the device adopts an arc-shaped fitting design conforming to ergonomics, and it is ensured that a pressure acting point is accurately located at a key position of a knee joint force line.

The utility model discloses an anti-backpressure radial seam structure bracket assembly for a positive arch slotted rupture disk, which relates to the technical field of rupture disks, and comprises a positive arch slotted rupture disk, an upper lining film, a sealing film, a lower lining film and a novel backpressure-resistant bracket which are sequentially arranged from top to bottom and matched in shape, according to the radial seam structure bracket assembly for resisting back pressure of the forward-arch slotted rupture disk, the bracket supporting plate is arranged below the bracket radial seam in a spot welding mode, and when the bracket assembly is combined with the large-diameter forward-arch slotted rupture disk for use, the bracket can be prevented from integrally flying out along the circular seam to generate fragments; according to the utility model, the expandability is strong, and simple adjustment is carried out according to the bursting pressure, the back pressure and occasions with strict requirements on no fragments, so that the device can be used in different working conditions.

The invention relates to a straight line and circular arc combined convex shape optimization method for a cylindrical roller, and aims to solve the problems that in existing logarithmic shape modification fitting, circular arc segmentation connection points depend on experience setting, and adaptability is poor. According to the method, a corresponding line-arc combination curve model is constructed based on a logarithmic modification curve, and the line-arc combination curve is iteratively optimized through an optimization method to obtain an optimal line-arc combination curve, so that the optimal line-arc combination curve approaches the logarithmic modification curve. The modeling process comprises segmentation point setting, connection point generation, arc parameter solving and curve construction, the optimization target is to minimize fitting error quadratic sum, and the geometric rationality and convexity of the curve are constrained and guaranteed. The adopted optimization algorithm is a sequence least square quadratic programming (SLSQP) algorithm. According to the method, fitting precision and engineering applicability are remarkably improved, and the method has good universality and expansibility, is suitable for modification design of various roller bearings and has engineering application value.

The utility model discloses a machine part polishing clamp which comprises a supporting frame, the top of the supporting frame is fixedly connected with a positioning plate, the top of the positioning plate is fixedly connected with a matching piece, an inner cavity of the positioning plate is in threaded connection with a threaded rod, and the accessories are placed on the surface of the positioning plate, so that the matching piece is fixed to the surface of the positioning plate. Then a rotating handle is rotated to drive a threaded rod to rotate through a positioning plate, the threaded rod drives a moving plate to move towards a matching piece through a threaded sleeve, and the accessory is clamped and fixed in the moving process; a fourth sliding block is rotationally connected with a third sliding block, the third sliding block is rotationally connected with a second sliding block, and the second sliding block drives a first sliding block to rotate at the same time; and the first sliding block rotates through the moving plate, the fitting is fixed through the matching piece through continuous rotating adjustment, then the fitting is ground and machined through the grinding assembly, and therefore the purposes that the fixing effect is improved, the special-shaped fitting can be fixed, and displacement and vibration of the fitting in the machining process are avoided can be achieved.

Provided is a plug and a plug structure that can automatically correct a regular posture. A plug (10) has a square-shaped fitting portion (12) that extends in the front-rear direction. The square-shaped fitting portion (12) has four corners (15) at diagonal positions in the front-rear direction. The four corners (15) each have a chamfered portion (17) that expands outward toward the rear and decreases in width in the axis direction as it goes toward the rear. The chamfered portion (17) has a ridge line portion (18) that extends in the front-rear direction and protrudes outward. The ridge line portion (18) is inclined so as to approach in one direction of the axis direction as it goes toward the rear.