34results about How to "Uniform wall thickness" patented technology

This invention belongs to the field of drilling tool technology, specifically relating to a device for ensuring uniform rubber wall thickness after adhesive injection in a stator with equal wall thickness. The device includes inner and outer spiral positioning heads, a connecting rod, a base, a mandrel, an upper plug, a lower plug, an upper baffle, a lower baffle, a positioning bolt, an upper nut, a first nut, and a second nut. The inner and outer spiral positioning heads are connected to the base via the connecting rod. The inner side of each positioning head has an inner spiral that engages with the threaded surface of the mandrel. The upper plug is fitted onto one end of the mandrel, the upper baffle is fitted onto the mandrel and fixed by the upper nut, and the lower plug is fitted onto the other end of the mandrel. The first nut is threadedly connected to the other end of the mandrel and presses against the lower plug. The lower baffle is threadedly connected to the other end of the mandrel and fixed by the second nut. The positioning bolt passes through the side of the stator housing with equal wall thickness. This device ensures uniform rubber wall thickness after adhesive injection in the stator of a screw drilling tool with equal wall thickness, thus improving the service life of the stator.

The utility model discloses a plate spring support which comprises a support body used for connecting a girder and a plate spring body and a limiting assembly, the support body is provided with a side extending plate capable of supporting the bottom wall of the girder, the support body is provided with a first wall and a second wall which are arranged in parallel, and the first wall is perpendicular to the side extending plate and attached to the side wall of the girder. The limiting assembly is installed on the frame body and connected with the girder and the plate spring body. The weight of the support can be reduced while the structural strength is guaranteed, and the dead weight of the whole vehicle is reduced.

The application relates to the technical field of pipe extrusion, in particular to a power-saving furnace for seven-hole plum-blossom pipe extrusion forming with adjustable extrusion pipes, which comprises an extrusion furnace for melting materials and a pipe die set coaxially connected to the discharge end of the extrusion furnace, a storage rack is arranged outside the discharge end of the extrusion furnace, and a plurality of pipe die sets with different specifications are arranged for staggered sliding switching; the pipe die set is coaxially composed of an extrusion pipe, a pipe sleeve die and a plurality of pipe hole dies from outside to inside, a central shaft die is sleeved on the central shaft of the extrusion pipe, and a pipe material channel is formed between the extrusion pipe and the plurality of pipe hole dies and the central shaft die; and the plurality of pipe die sets are slidingly clamped on the storage shaft. The application can complete the quick disassembly of old dies and the accurate positioning and installation of new dies by suspending a plurality of pipe die sets with different specifications on the storage rack in a staggered mode; the technical effect that only the screw extrusion function needs to be stopped when plum-blossom pipes with different aperture specifications are replaced, and the extrusion furnace heating function does not need to be stopped is achieved; and the power-saving benefit is realized.

This invention relates to a method for preparing capillary seamless steel tubes, comprising the following sequential steps: S100. Selecting austenitic stainless steel seamless tubes as tube blanks, the outer diameter of the tube blanks being 8mm-15mm, the wall thickness being 0.5mm-1.2mm, and the wall thickness accuracy being ±0.015mm; S200. Using a drawing machine with a long mandrel, cold-drawing the tube blanks from S100, when the deformation compression rate of a single cold drawing is 30%-75%, performing internal and external surface cleaning and solution treatment; repeating the above treatment until a capillary seamless steel tube with an outer diameter of 3.8mm-4.2mm and a wall thickness of 0.125mm-0.3mm is obtained. Drawing the billet; wherein the hardness of the long mandrel is 780HV-860HV, and the diameter accuracy of the long mandrel is ±0.005μm; S300. Using a drawing machine with a moving mandrel, the moving drawing billet obtained in S200 is cold drawn. When the deformation compression rate of a single cold drawing is 30%-75%, the inner and outer surfaces are cleaned and solution treated; repeat the above treatment to obtain a capillary seamless steel tube with an outer diameter of 0.59mm-1mm, a wall thickness of 0.05mm-0.09mm, and a wall thickness accuracy of ±0.003mm; S400. The capillary seamless steel tube obtained in S300 is subjected to external grinding treatment to obtain the final product.

The invention discloses a plate pre-drawing and dieless mirror image loading composite forming process and a product, and belongs to the technical field of metal component forming and manufacturing. The method is used for solving the problems of cracking, ultra-poor thinning, low dimensional precision and the like in the forming process of the high-strength aluminum alloy thin-wall component with local continuous large-area bulge and local large wall angle characteristics in the aerospace field. According to the method, through two-stage area expansion distribution, the thinning amount of each stage is effectively controlled, and the cracking problem caused by one-time large deformation in a single process is avoided. And mirror images are cooperatively loaded on the local part of the plate to form a three-dimensional stress state, so that the forming limit is improved. And in-mold constraint aging synchronously realizes strengthening and shape righting, and is obviously superior to the traditional process.

The utility model provides an electronic throttle valve body which comprises a throttle valve shell and a throttle valve piece used for driving a throttle valve shaft to rotate, and a rotating shaft driving mechanism used for driving the throttle valve shaft to rotate is arranged in the shell. The rotating shaft driving mechanism comprises a direct-current motor, a motor gear, an intermediate gear, a sector gear assembly, a magnetic core assembly and a torsion spring, the direct-current motor is installed on one side of the throttle body, the motor gear is installed on an output shaft of the direct-current motor, the intermediate gear is rotatably installed on the throttle shell and meshed with the motor gear, and the sector gear assembly is connected with the magnetic core assembly. The sector gear is connected to the end of the throttle valve shaft through laser welding, the sector gear is meshed with the intermediate gear, the torsion spring is arranged on the sector gear in a sleeved mode, and the two ends of the torsion spring are fixed to sector gear limiting supporting legs. The electronic throttle valve body has the advantages of being simple in structure, low in cost, good in consistency of flow of a lower dead center of an assembly machine and flow of a default position, and capable of greatly improving reliability and stability of the electronic throttle valve body.

The application provides a design method and system for an internal-external flow coupling structure of a full-shield turbine rear support plate, which can ensure uniform wall thickness and stress distribution by respectively modeling cooling chambers for characteristic sections with different blade heights; the two-dimensional modeling of each characteristic section is defined according to the relative axial chord length position, offset distance and chamber length of each cooling chamber; the three-dimensional modeling of each cooling chamber is obtained through a skin method and Boolean operation; the positioning of film holes and impact holes in each characteristic section is determined through the relative arc length position of the inner cavity wall surface, the spatial positioning of each cooling hole is determined through the distance from the hub and the casing and the number of cooling holes, and the geometric configuration design of each cooling hole is completed in combination with the hole diameter and the inclination angle, and the three-dimensional cooling structure modeling is obtained by rounding the edges of each chamber, so that the design method and system have the advantages of fewer design variables, strong adaptability to blade shapes, high automation degree and the like, and are helpful to the efficient and agile design of a full-shield turbine rear support plate with an impact-film combined cooling structure.

The application discloses a 46120 type cylindrical battery shell drawing process, which comprises the following steps: drawing a blank with a diameter of 145mm-150mm and a thickness of 0.6mm±0.06mm, the drawing coefficient ranges from 0.54 to 0.56, the first concave die entering mode radius ranges from 7mm to 10mm, the first convex die radius ranges from 7mm to 10mm, the edge pressing mode is flat edge pressing, the edge pressing force ranges from 2.5T to 3.0T, and a hollow cylindrical first semi-finished product is formed after drawing. The 46120 type cylindrical battery shell drawing process can realize the forming of the cylindrical battery shell through four drawing processes, and greatly improves the drawing efficiency.

The utility model relates to the field of motors, in particular to a rotor casing, an external rotor motor and an electronic fan, the rotor casing comprises a cylindrical outer casing and a shaft sleeve assembly coaxially arranged in the outer casing, and an accommodating cavity is formed in the shaft sleeve assembly and used for mounting a rotating shaft of a rotor; the shaft sleeve assembly comprises a shaft sleeve body and a connecting part, the connecting part is arranged on the surface of the shaft sleeve body and extends outwards in the radial direction of the shaft sleeve body, the connecting part is welded and fixed to one end of the outer shell, and the connecting part is arranged at the end, adjacent to the outer shell, of the shaft sleeve body; the connecting part is in an annular plate shape, and an inner ring of the connecting part is welded and fixed with the surface of the shaft sleeve body. The integral stretching forming mode of the rotor casing in the prior art is changed into welding and fixing through the outer casing, the shaft sleeve body and the connecting part, high die cost and working hours are saved, unit price is reduced, and the rotor casing is high in product size consistency, uniform in wall thickness and small in unbalance amount.

The present application relates to the technical field of bellows preparation, and particularly relates to a cathode device for preparing an electrodeposited bellows and a preparation method, which comprises a frame body, a core mold assembly, a cathode wire assembly and a power transmission assembly. The frame body is internally provided with the core mold assembly, part of the cathode wire assembly and the power transmission assembly. The inner wall of the cylindrical groove of the frame body is provided with annular sawteeth. The core mold assembly comprises a horizontal connecting rod and a core mold body, the other end of the core mold body extends into the frame body, and each aluminum alloy core mold of the core mold body is detachably connected with a nylon external gear meshing with the annular sawteeth at the end away from the horizontal connecting rod. The present application can effectively control the rotating speed of a single core mold during the electrodeposition process, ensure the stable and uniform rotation of the core mold in the circumferential direction, thereby improving the imbalance of the circumferential current density and ion transmission conditions during the electrodeposition process, and ensuring that the prepared single-layer or multi-layer bellows has a uniform wall thickness in the circumferential direction.

This disclosure provides a cooling device for a battery assembly, the cooling device comprising: a cooling plate extending longitudinally along a first direction, the cooling plate including a cooling outer tube for conducting coolant; wherein the cooling outer tube is formed by bending and closing a single sheet material. Furthermore, this disclosure also provides a battery assembly and a vehicle.

The application relates to the technical field of sheath processing, and discloses a sheath forming device, which comprises a rack, a mounting rack arranged on the rack, a forming structure and a turnover structure for driving the forming structure to turn over, a lifting structure arranged on the rack and used for driving the mounting rack to lift, and a storage structure arranged below the forming structure and used for storing raw materials; the forming structure comprises a die plate arranged on the mounting rack, the die plate is provided with a forming column, the turnover structure comprises two mounting plates rotatably connected to the mounting rack, the die plate is arranged between the two mounting plates, and the mounting plates are provided with rotating structures used for driving the forming column to rotate, and the application has the effect of improving the yield of PVC sheaths.

The application discloses a torsion bar shaft, a lightweight anti-rolling torsion bar and a metal pipe hole processing technology. The torsion bar shaft comprises a metal pipe and a fiber layer which is bonded to the outer periphery of the metal pipe. The lightweight anti-rolling torsion bar comprising the torsion bar shaft further comprises torsion arms at both ends of the torsion bar shaft and an end connecting body. The torsion arms are formed by extending and bending the metal pipe of the torsion bar shaft. The end connecting body comprises a swing arm connecting part and a pull rod connecting part. The swing arm connecting part is connected with the end of the torsion arm, and the pull rod connecting part is connected with the pull rod. The metal pipe hole processing technology comprises the following steps: S1, performing cylindrical processing on a rod to be processed; S2, clamping the rod by reversing the direction, and drilling a hole one and a hole two which are communicated from the A end and the B end of the rod respectively; and S3, positioning and clamping the rod with the axis line one and the axis line two as the pipe hole axis lines, and performing turning on the outer periphery of the rod to make the wall thickness uniform.

The invention discloses a smelting and machining method for a high-toughness non-magnetic steel pipe in the field of petroleum drilling tools, and solves the problems existing in non-magnetic steel pipe manufacturing in the prior art. (1) high alloy components are adjusted again, the alloy element ratio is strictly controlled, the manganese element is highly controlled, and it is ensured that the steel is non-magnetic; the low-control chromium element ensures the corrosion resistance of the steel, and meanwhile, high chromium is prevented from forming ferrite to influence the magnetism; the nitrogen element is accurately controlled, and high nitrogen is prevented from generating cracks and low nitrogen is prevented from influencing magnetism; (2) a bar drilling process is replaced by an extrusion and cold rolling process in the processing process, so that the yield is improved, and time and processing cost are saved; carrying out gradient heating on the round billet through a secondary heating furnace; a two-pass rolling process is adopted, the wall thickness is increased and decreased in the first pass, and then the product performance is controlled through second-pass rolling. The technology has the technical advantages that the blank is subjected to hot extrusion forming and two-pass cold rolling, the pipe meeting the requirement is obtained, and the product obtained through the technology has the characteristic of high toughness on the non-magnetic basis.

This invention relates to the field of centrifugal molding technology, and more particularly to an energy-saving, high-efficiency centrifugal molding device for cement poles. The device includes a base, on which an annular steel mold is mounted. The annular steel mold comprises an upper steel mold and a lower steel mold, on which multiple first arc-shaped strips and multiple second arc-shaped strips are respectively installed; a first cover plate and a second cover plate, respectively disposed on both sides of the annular steel mold; a central sleeve fixedly connected to the first cover plate; and a rotating assembly disposed on the first cover plate. The central sleeve of this invention incorporates an air-bag compression vibration mechanism. Through a rotating shaft, the compression ball periodically compresses the air bag, generating high-frequency micro-vibrations that allow the concrete slurry to flow fully, effectively expelling internal air bubbles and pores. This significantly improves the density, impermeability, and frost resistance of the pole, extending its service life and benefiting the production of cement poles.

The application relates to a device and a method for preparing a fluorine-based glass optical fiber preform rod cladding hollow tube. In the device, by reducing the air pressure in a closed crucible environment and assisting with a constant rotation rate, dissolved gas in the glass liquid can be effectively removed, and a fluorine-based glass preform rod cladding hollow tube without bubbles, high uniformity and high interface quality can be automatically / semi-automatically prepared. The method has a short preparation period and is expected to be applied to the preparation of a fluorine-based optical fiber preform rod with a high-quality core-cladding structure.

The present application belongs to the field of aviation machining process, and relates to a method for controlling eccentric deformation of transmission shaft parts through a cold machining process. The method comprises the following steps: adjusting the axial size and radial size allowance of the part before heat treatment, at least ensuring the part position required by the penetration layer, and giving the allowance according to the penetration layer calculation size; adjusting the thin-wall shaft diameter position and the web position of the part structure before heat treatment; establishing the machining datum after heat treatment; designing the post-heat process, reasonably arranging the post-heat machining sequence, determining the alignment method and checking the run-out position, giving the alignment value, and refining the machining steps and allowance; determining the control method of the eccentricity of the part by post-heat turning machining; balancing the process control, adding a pre-balancing process, and adjusting the key position of the part before weight removal and the unbalance amount through local tolerance change.

The application relates to a flange pipe integrated processing device. The device comprises a rack, an outer die movably arranged on the rack, a forging table fixedly arranged on the rack and an inner rod rotatably arranged on the rack. The forging table is located at the limit position of the outer die movement, and the outer die and the inner rod are oppositely located on both sides of the forging table. A blank is arranged on the forging table close to one side of the outer die. The outer die reciprocally moves to act on the outside of the blank, and the inner rod rotates to act on the inside of the blank. The problems that welding processing leads to welding defects of the flange pipe and forging processing cannot be applied to batch production in the prior art are solved.

The invention provides a heat exchange device of a mixed TPMS structure and a construction method of the heat exchange device, relates to the field of heat energy engineering and new energy automobiles, and solves the problems that an existing TPMS heat exchanger adopts a fixed topology, heat exchange and flowing properties are difficult to collaboratively optimize under the same porosity and appearance, the energy efficiency is limited, and the service life is prolonged. And adaptive thermal management requirements under variable working conditions cannot be met. The method comprises the steps that two different TPMSD structures are selected, a basic topological unit of the mixed heat exchange core is constructed, and implicit functions corresponding to the two TPMS structures are extracted; according to the target heat exchange performance requirement, the weighting coefficients of the two TPMS structures are determined; based on the weighting coefficient and the implicit functions of the two TPMS structures, constructing a composite implicit function representing the variable coefficient mixed TPMS structure; and constructing a three-dimensional geometric model of the hybrid heat exchanger core based on the composite implicit function. The method and the device are used in the construction process of the mixed TPMS structure.

This invention discloses a positioning device for piercing tube blanks, including a tube blank, a receiving trough, and a positioning assembly. The positioning assembly includes a pusher, a guide plate, rollers, a conical mandrel, and a horizontally placed hub. Under the pusher, the tube blank enters the rollers and undergoes a slight diameter reduction process. The tube blank then enters the hub and is tangent to the hub. The upper end of the mandrel near the conical mandrel is tangent to the hub, while the lower end of the mandrel away from the conical mandrel is connected to a mandrel carriage. The mandrel carriage is equipped with a thrust seat to control the horizontal movement of the mandrel. The mandrel carriage pushes the conical mandrel to the piercing position. Under the action of the rotation source, the hub makes a circumferential motion while driving the tube blank to continue rotating forward. The mandrel carriage controls the thrust seat to slowly retract horizontally. The center of the tube blank and the rolling line of the mandrel always remain at the same horizontal line and will not shift due to vibration, ensuring uniform wall thickness after piercing.

A high-efficiency cooling manifold cone and differential pressure mold for differential pressure molds are disclosed. The manifold cone body comprises, from bottom to top, a frustum, a gating section, a riser, and a manifold cone tip. An annular water channel is provided inside the manifold cone body, including inlets and outlets located on both sides of the frustum. The annular water channel starts from one edge of the inlet, extends along the edges of the frustum, riser, and manifold cone tip, and circles to the other edge of the frustum and gating section, ultimately connecting to the outlet. This differential pressure casting mold can reduce aluminum adhesion to the manifold cone, improve product efficiency, reduce product deformation, and enhance product mechanical properties, thereby reducing costs.

This invention relates to a heating control system for metallic materials, belonging to the field of heating control technology for difficult-to-deform materials. It solves the problems of existing heating systems having a single temperature feedback source, poor temperature control accuracy, insufficient uniformity, and difficulty in adapting to complex working conditions. The system includes a heating module, a multi-source temperature sensing module, a power distribution module, a correction module, and a control module. The multi-source temperature sensing module acquires the real-time temperature of the heating module. The power distribution module performs initial power distribution based on the real-time temperature. The correction module corrects the initially distributed power, and the control system then performs power control. This achieves a heating system capable of adapting to ultra-high temperature environments and realizing precise and uniform temperature control in three-dimensional space.

The application relates to a novel injection mold structure of an electric connection copper bar shell, and relates to the technical field of injection molds. The injection mold structure comprises a mold core, a cavity is formed in the mold core, an electric connection copper bar is placed in the cavity, a U-shaped buckle with an abutting convex part is installed on the copper bar so that the copper bar is suspended in the cavity; a side pushing sliding block is arranged on the mold core, a contact part of the side pushing sliding block can be extended into the cavity and abut against the buckle; the electric connection copper bar is in a bent strip shape, at least one side pushing sliding block is arranged on one side of the long side; the mold core is provided with a sliding block mounting groove; an end sliding block is arranged at a narrow end surface of the cavity; reset springs are arranged in the side pushing sliding block and the end sliding block, the reset springs are provided with pushing moving parts, and bottom guide grooves are matched with mold guide rails; a limiting snap ring is further arranged on the mold core to fix the electric connection copper bar. The application can accurately position the electric connection copper bar, and guarantees the injection molding quality and stability.

The utility model relates to hard disk preparation technical field, concretely is a kind of glass sectional material processing equipment, including furnace bin, forming device, the forming device with the furnace bin intercommunication, the forming device includes: first forming piece, the first forming piece has at least one draw channel;The draw channel is set in furnace bin bottom, and with furnace bin intercommunication;Second forming piece, the second forming piece includes at least one fluid duct, the fluid duct with the draw channel coaxial, the fluid duct is inserted in furnace bin and is rotatably connected with furnace bin top, the bottom of fluid duct is located in draw channel, the fluid direction in fluid duct points to the draw channel to form the hollow portion of the glass sectional material.The utility model is provided with the fluid duct and draw channel, so that the hollow glass sectional material prepared, wall thickness is uniform, facilitates the processing of subsequent glass flake, improves the production efficiency of product and product qualification rate.

This invention discloses a lost-wax casting device for hollow turbine blades, comprising a sand box, a sand mold fixedly connected to the inner wall of the sand box, and protective frames connected to opposite sides of two sand boxes. An insert plate is fixedly connected to the bottom surface of the upper protective frame, and a fixed frame is fixedly connected to the top surface of the lower protective frame. The insert plate is inserted into the interior of the fixed frame. The upper protective frame is divided into two half-frames from the middle, and an adjustment component is connected between the two half-frames. A protective cover is fixedly connected to the top surface of the left half-frame. A protective plate is connected between the sand mold and the adjustment component, and side plates are fixedly connected between adjacent fixed frames. The protective plate limits the movement of the sand mold, preventing protrusions and ensuring a uniform wall thickness after casting, preventing unevenness. The top-mounted protective frame, divided into two half-frames, facilitates disassembly.

The utility model relates to the technical field of stamping die equipment, in particular to stamping die equipment capable of producing two parts at one time, which comprises a lower die holder, a lower die plate, an upper stripper plate and an upper die holder, a plurality of through holes corresponding to forming punches of the upper stripper plate are formed in a forming insert on the lower die plate, and the through holes are communicated with the upper die holder. The upper stripping plate can be driven by the upper die pressure device to drive the forming punch to move, so that the forming punch and a stamping material placed on the forming insert are stamped, and a required stamping shape is obtained through press fit; a first ejector rod is arranged on the lower die pressure device, the first ejector rod can be driven by the lower die pressure device to press out a stamping material through a through hole, then multiple times of stamping forming are conducted through a forming punch, the stamping die can be suitable for stamping products with thick walls, it is guaranteed that the wall thicknesses are uniform, and stripping can be conducted according to the sequence; and the mechanical properties such as strength and hardness of the product can be improved through multiple times of stamping, so that the yield of the product is improved.

This utility model discloses a wok stamping die, relating to the field of stamping die technology. It includes a die body and a die base for supporting and fixing the die body. The lower end of the die body is provided with a positioning block, and the middle position of the die base is provided with a positioning groove that matches the positioning block. Several positioning holes are arranged on the outer side of the positioning groove. These positioning holes are evenly distributed on a concentric ring with increasing diameter, centered on the center of the positioning groove. Positioning pins are threaded into the positioning holes. This utility model achieves a true "center-concentric" reference system by setting a positioning block at the lower end of the die body and providing a matching positioning groove and multiple sets of positioning holes and pins arranged in concentric rings on the die base. This ensures high concentricity and uniform wall thickness of the wok even after long-term use.

The invention discloses a pipe drawing and welding forming integrated manufacturing process for a plastic bucket. The process comprises the following steps that S1, a pipe drawing blank is prepared, specifically, a continuous plastic pipe is extruded through pipe drawing equipment; s2, a fixed-length cutting process: conveying the continuous plastic pipe extruded by the pipe drawing equipment to cutting equipment; s3, workpiece positioning and clamping are conducted, specifically, the cut barrel body blank, a preset base and a barrel cover are transferred to welding equipment; s4, inner side support arrangement; and S5, heating welding forming: passing through a heating structure of welding equipment. The problems that a traditional blow molding process is low in efficiency, uneven in barrel body wall thickness, high in mold cost, difficult in model changing and high in material loss and energy consumption are solved; through the modes of extrusion molding, fixed-length cutting and hot melting welding, efficient continuous production is achieved, it is guaranteed that the wall thickness of the barrel body is uniform, the structural strength is stable, no complex mold is needed, production of products of various specifications can be rapidly adapted, the production cost is remarkably reduced, and the device is especially suitable for large-size containers.

The present disclosure relates to the technical field of press machine, and particularly relates to a worktable structure suitable for a press machine. The present disclosure provides a worktable structure suitable for a press machine, which comprises a worktable, a bottom plate arranged in a forming area of a machine body, and a connecting base, the bottom plate is provided with a positioning mounting hole, and a main support plate along the width direction is symmetrically arranged at the bottom of the bottom plate near the end of the positioning mounting hole, the connecting base is arranged in the positioning mounting hole and supported on the main support plate, and the worktable is tightly mounted on the connecting base. Through the technical scheme of the present disclosure, the bottom plate does not need to be arranged as an over-thick structure plate body, the cost can be effectively reduced, and the uniform thickness of the machine body wall can be maintained.

The application discloses a kind of hollow shafts that are processed with bar to ensure uniform wall thickness, and the process of drilling hole is reversed, comprising the following steps: S1, cylindrical processing is carried out on the bar to be processed, so that any cross section is a circular surface and the center of the circle is located on the axis of the bar;S2, the bar is clamped by reversing, and the same drill is installed on one side of the machine tool to drill hole one and hole two from the A and B ends of the bar respectively, and the axis of hole one and the axis of hole two are on the same straight line;S3, the bar is positioned and clamped with the axis of hole one and the axis of hole two as the axis of the hollow shaft, so that the bar rotates around the axis of the hollow shaft and the outer periphery of the bar is turned to the standard wall thickness.