234 results about "Hard metals" patented technology

The invention relates to a milling burr (1) for an electrically or pneumatically operated hand-held tool for deburring, shaping, grinding and finishing iron-free surfaces, comprising: - a shank portion (2) and - a milling portion (4) made of a hard metal, in particular tungsten carbide, which adjoins the shank portion (2) and ends in a milling tip (6), wherein the milling portion (4) has a milling length (f) and a plurality of cutting edges (10) which are separated by mutually spaced main flutes (14) which have a main flute depth (h) and extend helically in a first twist direction (16) with a first twist angle (α) along the milling length (f), wherein each of the cutting edges (10) has a rake face (20) and a relief face (24) and a cutting edge (12) at the transition of rake face (20) and relief face (24), forming a rake angle (γ) and a relief angle (δ). The milling burr (1) according to the invention is characterized in that said relief face (24) is a first relief face (24) and said relief angle (δ) is a first relief angle (δ), wherein the first relief face (24) is adjoined in the circumferential direction of the milling portion (4) by a second relief face (26) which extends at a second relief angle (ε), and, in the region of the milling portion (4) with the largest diameter, the first relief angle (δ) is in the range from 6° to 20° and the second relief angle (ε) is in the range from 8° to 30°, and the second relief angle (ε) is greater than the first relief angle (δ). The invention also relates to the use of such a milling burr (1).

The utility model relates to the technical field of bearing processing, and discloses a cleaning machine for heat treatment of bearing steel balls, which comprises a cleaning box and supporting legs, a cleaning frame is arranged in the cleaning box, a driving motor is arranged at one end of the cleaning box, a screw rod is arranged in the cleaning box, one end of the screw rod is fixedly connected with the driving motor, and a cleaning mechanism is arranged at one end of the outer side of the screw rod; the cleaning mechanism comprises a cleaning frame, the lower end of the cleaning frame is in threaded connection with the lead screw, two sets of guide plates are arranged at one end of the cleaning frame and are arc-shaped hard plates, openings of the guide plates face the discharging baffle, one ends of the guide plates are fixedly connected with the cleaning frame, scrapers are arranged at the lower ends of the guide plates and are hard metal strips, and the lower ends of the scrapers are matched with the bottom face of the cleaning box. According to the steel ball cleaning device, by arranging the cleaning mechanism, the interior of the cleaning box can be cleaned through the cleaning mechanism after the steel balls are cleaned, oil dirt impurities are prevented from being attached to the inner wall of the cleaning box, the overall cleanliness of the interior of the cleaning box is improved, and follow-up use of equipment is facilitated.

The application discloses a kind of hard alloy cutter materials for deep hole machining, the cutter material is composed of the following weight percentage components: tungsten carbide: 75%~85%, wherein 0.2~0.4 μm superfine tungsten carbide particles account for 60%~80%, 0.4~0.8 μm tungsten carbide particles account for 20%~40%; Cobalt: 10%~15% titanium carbide: 2%~5%; Tantalum carbide: 1%~3%; Niobium carbide: 0.5%~2%; Vanadium carbide: 0.3%~1.0%; Chromium carbide: 0.2%~0.8%; Rare earth element: Y2O3 Or La2O3: 0.1%~0.5%. The application breaks through the bottleneck of high temperature wear, insufficient strength and short service life of traditional hard alloy in deep hole machining through three-dimensional innovation of component design, structure control and surface strengthening, and provides an efficient solution for precision deep hole machining of high hardness materials.

The present application provides a protective structure for the end of a packer rubber cylinder, including: a skeleton and a fixing ring, both of which are circular ring structures. The outer wall of the skeleton is provided with a plurality of protrusions along a circumferential array, and the outer surface of the protrusion has an external thread; the inner wall of the fixing ring has an internal thread, and when the fixing ring is coaxially connected to the skeleton, the internal thread on the fixing ring meshes with the external thread on the protrusion; it also includes a plurality of blades, each of which has a through hole at its root, and the blades are made of hard metal, and the blades are arranged along the circumferential array of the skeleton and enclosed to form a circular tube structure; the blades are sleeved on the outside of the protrusion through the through hole, and the top of the blade faces the same side of the skeleton, and the blades are swingingly arranged with the tangent of the skeleton passing through the protrusion as the axis, and the side of the blade overlaps with the side of the adjacent blade. This scheme completely covers the end of the rubber cylinder during the expansion of the rubber cylinder, provides sufficient support and sealing for the rubber cylinder, thereby effectively preventing the rubber cylinder from being damaged, and improving the sealing and pressure-bearing capacity of the rubber cylinder.

The utility model relates to the technical field of oil seals, and discloses a high-pressure-resistant rotary oil seal. The high-pressure-resistant rotary oil seal is arranged on the outer side of a rotary shaft in a sleeving mode, and a rubber body, a framework and a check ring are sequentially arranged from top to bottom in the axial direction of the rotary shaft. The upper surface of the framework is adhered to the lower surface of the rubber body, and the check ring is adhered to the lower surface of the framework; the framework is a plastic ring made of high-temperature-resistant and high-pressure-resistant hard plastic, and the check ring is a metal ring made of high-temperature-resistant and high-pressure-resistant hard metal. According to the high-pressure oil seal, a high-rigidity metal framework is replaced by the plastic framework, the service life of the high-pressure oil seal is greatly prolonged, a sealing piece is prevented from being extruded out of a gap through the cooperation of the plastic framework and the metal check ring, and the pressure bearing capacity of the whole oil seal structure is enhanced.

The utility model belongs to the technical field of sandwich panels, and particularly relates to an environment-friendly flame-retardant polyurethane sandwich panel which comprises a sandwich panel body, and a hard metal plate is wrapped outside the sandwich panel body. A flame-retardant isolation layer, a polyurethane foam layer and a polystyrene foam layer are further arranged in the sandwich panel body, and the flame-retardant isolation layer is arranged between the polyurethane foam layer and the polystyrene foam layer; the flame-retardant isolation layer comprises an aluminum honeycomb and a glass magnesium filler, and the glass magnesium filler is arranged in holes of the aluminum honeycomb; the left side and the right side of the laminboard body are provided with three connectors and three connecting grooves respectively, and the connectors are matched with the connecting grooves. According to the sandwich board, more environment-friendly and flame-retardant materials are adopted to serve as inner core filling, the heat preservation performance of the board is improved, meanwhile, the fireproof performance is improved, the overall weight of the board is reduced, and splicing and using are facilitated.

The invention relates to the field of hard alloy product production, in particular to a production method of a high-toughness and wear-resistant hard alloy. A production method of a high-toughness and wear-resistant hard alloy comprises the following steps that S1, raw materials including, by mass, 40%-45% of WC powder, 25%-35% of Fe powder, 3%-5% of Si powder, 0.95%-1.16% of C powder, 2.5%-3.2% of Ni powder, 9%-12% of Co powder, 1.75%-2.05% of Mo powder and 0.15%-0.3% of VC powder are taken, and the purities of all the powder components are all larger than 99%; s2, mixing the raw material powder in the step S1 with a ball milling medium according to a ratio, and mixing by adopting a wet ball milling process; s3, drying the slurry, and sieving to prepare granules; s4, pressing the granules into a hard alloy blank; s5, the hard alloy blank is sintered in a vacuum or low-pressure sintering furnace, and the sintering temperature is controlled to be 1180-1250 DEG C; and S6, after sintering is completed, a sintered body is cooled, precision machining is conducted according to requirements, and a product is obtained. The high toughness and wear resistance of the hard alloy material are remarkably improved.

A cladding process for depositing metal cladding onto a hollow metal substrate at ultra-high deposition rates, including: applying softer metal cladding as at least one annular band around a circumferential periphery of the hollow metal substrate using a plasma-arc welding device; circulating a liquid heat transfer medium through an interior space of the harder metal, hollow metal substrate such that an outer surface of the substrate to which metal cladding is to be applied is maintained at desired temperatures throughout the cladding applying step; and controlling temperature of the circulating liquid heat transfer medium to be within a predetermined temperature range. The hollow metal substrate is formed of a harder metal than the metal cladding.

The present invention provides a flexible drill pipe plug, which belongs to the technical field of tail pipe cementing in oil and gas fields. The plug comprises a core body made of elastic plastic material, a top cover is provided above the core body, a shrinkage tube and a socket are provided in sequence below the core body, and a colloid is commonly sleeved on the outside of the core body, the top cover and the shrinkage tube, the interior of the core body is sequentially penetrated by a plurality of frustum-shaped internal cavities along the axial direction from bottom to top, the interior of the core body is sequentially provided with a plurality of expansion joints made of hard metal material along the axial direction, the number of the expansion joints is consistent with the number of the internal cavities, the expansion joints of each level are slidably arranged in the expansion joints of the next level, the height of the expansion joints of each level are equal, and the expansion joints of each level correspond to the corresponding internal cavities one by one, when the flexible drill pipe plug passes through a continuous oil pipe wound on a large roller, the core body elastically bends along the curved continuous oil pipe without permanent deformation.

The invention provides a flexible drill rod rubber plug, and belongs to the technical field of oil and gas field tail pipe well cementation, the flexible drill rod rubber plug comprises a core body made of an elastic plastic material, a top cover is arranged above the core body, a contraction cylinder and a socket are sequentially arranged below the core body, and the core body, the top cover and the contraction cylinder are jointly sleeved with a rubber body; a plurality of cone-frustum-shaped inner through cavities are sequentially formed in the core body in the axis direction from bottom to top in a penetrating mode, a plurality of telescopic joints made of hard metal materials are sequentially arranged in the core body in the axis direction, the number of the telescopic joints is consistent with the number of the inner through cavities, and each stage of telescopic joint is arranged in the next stage of telescopic joint in a sliding mode. The height of each stage of telescopic joint is equal, and each stage of telescopic joint is in one-to-one correspondence with the corresponding inner through cavity; when the flexible drill rod rubber plug passes through a coiled tubing wound on a large roller, the core body is elastically bent along the bent coiled tubing, and permanent deformation is avoided.

The utility model relates to the technical field of hard alloy circular knives, and discloses a hard alloy circular knife edge burr detection device, which comprises a detection table and is characterized in that through the arrangement of a moving assembly, when a hard alloy circular knife is larger, the hard alloy circular knife can abut against a positioning block and drive a telescopic rod to contract; when the telescopic rod retracts, the fixed plate and the sliding block can be driven to move, when the sliding block moves, the toothed plate can be driven to move, when the toothed plate moves, the gear meshed with the top of the toothed plate can be driven to rotate, and when the gear rotates, the gear can abut against the inserting block to drive the inserting rod to swing upwards; when the gear rotates, the inserting rod resets under the action of the first volute spiral spring, so that the inserting block abuts against the surface of the gear again to be fixed, the situation that due to excessive clamping, a cutter body of the circular cutter is slightly deformed, and then the roundness and the flatness of a cutter edge are affected is prevented, the product quality is improved, and the rejection rate and the production cost are reduced.

The invention discloses a control system and a control method for 3D hard metal processing equipment, and the system comprises a processing unit which is configured to receive data from a sensor; the storage unit is used for storing a preset processing parameter set; the algorithm module is used for executing weighting calculation so as to dynamically adjust parameters in the processing parameter set based on the physical characteristics; and the output interface is used for transmitting the adjusted processing parameters to an execution mechanism of the 3D hard metal processing equipment. According to the invention, the data from the sensor can be received, and the processing parameters can be dynamically adjusted according to the data, so that the processing process is optimized. By introducing a weight distribution unit and weighting calculation based on historical data, the flexibility and adaptability of the system are improved, and the machining quality and efficiency are ensured. In addition, the user-friendly interface design enables the user to conveniently input or select the type of the to-be-processed material and the expected processing effect, and the usability and flexibility of the system are further improved.

The utility model discloses a limitable hard alloy processing clamping device which comprises a base, supporting seats and a fixed clamping plate, a bearing plate is rotatably connected to the upper end of the base, the supporting seats are arranged on the left side and the right side of the bearing plate in an attached mode, and the supporting seats move left and right on the bearing plate. A movable plate used for limiting is arranged at the lower end of the supporting seat, round covers are fixedly connected to the left side and the right side of the bearing plate correspondingly, and cooling fans are installed in the round covers. According to the limitable hard alloy machining clamping device, hard alloy of different sizes can be conveniently borne, the hard alloy is stably clamped by combining the fixed clamping plate, the bearing plate can rotate at the upper end of the base, the machining angle of the hard alloy is adjusted during machining, and the machining precision is improved. And in combination with a cooling fan, the machined hard alloy can be blown for heat dissipation and cooling, and operators are prevented from being scalded by the too high temperature of the hard alloy during material taking.

The application discloses a multi-blade hard alloy cutting tooth and application, which comprises a cylindrical base body, an upper outer cutting unit and a lower outer cutting unit are arranged on the outer wall of the cylindrical base body; an upper inner concave structure is arranged on the top surface of the cylindrical base body, and a lower inner concave structure is arranged on the bottom surface of the cylindrical base body; an upper inner cutting unit is arranged at the center of the upper inner concave structure, and a lower inner cutting unit is arranged at the center of the lower inner concave structure. The application realizes good cutting ability through a plurality of sharp cutting edges, improves stress concentration effect and thus improves cutting efficiency. The application is provided with the inner concave structure, so that the cutting tooth has good chip breaking capacity, can reduce the formation of long iron chips and prevent repeated crushing caused by the accumulation of iron chips at the bottom of the drill bit. The application can be mass-produced and avoids the unevenness of random broken hard alloy particles.

- The turntable has a short neck in the middle, with a hole perforated on the sides for attachment with the double reversible joint, inclined at an angle of (45°) degrees to the horizon, which rotate against each other and about an axis, No. (1) Figure No. (1,2,3). Made of hard metal.

The invention provides a method for measuring the content of impurity elements in inorganic oxide powder. The method comprises the following steps: uniformly mixing inorganic oxide powder to be detected with a volatile organic solvent by using glow discharge mass spectrometry to obtain a pasty mixed solution, then attaching the mixed solution to the surface of a soft or hard metal, and enabling the inorganic oxide to be attached to the surface of the metal without falling off after the mixed solution is dried, the device can be directly placed in a sample introduction device in a glow discharge mass spectrometer for glow discharge mass spectrometry determination, the state of inorganic oxide is stable in the determination process, the inorganic oxide is not prone to falling off, and stability testing is facilitated.

The invention relates to the field of materials engineering and relates to an AlN-based hard material layer on bodies of metal, hard metal, cermet or ceramics and to a method for the production thereof. The aim of the invention is to provide an AlN hard material layer which has improved hardness and wear resistance and can be produced in an inexpensive and time-efficient manner. According to the invention, an AlN-based hard material layer is provided, which is an individual layer or a multi-layered layer system, wherein at least the one layer or at least one layer of the multi-layered layer system is an AlN-based hard material layer with a hexagonal lattice structure that has a <002> texture and is oxygen-doped, wherein the oxygen doping is in the range of 0.01 at. % to 15 at. %. The hard material layer can be used as a wear-protection layer for cutting tools.

The invention relates to the technical field of vehicle-mounted backlight module structures, and discloses an ultrathin vehicle-mounted backlight module structure which comprises a die-casting shell and a display module, a groove body is formed in one side of the die-casting shell, and a step surface is arranged on the inner side of a port of the groove body; the display module comprises a reflecting film, a light guide plate, a diffusion film, a lower intensifying light, an upper intensifying light and a liquid crystal glass cover plate which are sequentially distributed from bottom to top, a middle rubber frame is bonded to the step face and wraps the outer side of the cover plate, and meanwhile the cover plate and the middle rubber frame are fixed through foam rubber. A traditional plastic rear shell is replaced by the die-casting shell, the die-casting shell is made of hard metal materials, the module die-casting piece and the plastic rear shell are combined into a whole, the die-casting piece is integrated, the front face bears the diaphragm, the back face structure is provided with a connecting structure to be connected with a vehicle body, and the die-casting shell guarantees the product strength and improves the overall heat dissipation effect.

The utility model discloses a baffle clamping device, a baffle mounting structure and a vehicle. The baffle clamping device comprises a front cover, a rear cover and at least two cushioning rubber pads. The front cover comprises a first clamping part, and the first clamping part is used for clamping the baffle; the rear cover comprises a second clamping part, and the second clamping part is used for clamping the baffle; the at least two cushioning rubber mats are arranged between the first clamping part and the second clamping part, the at least two cushioning rubber mats make contact with the baffle and are arranged on the two opposite sides of the baffle, and the first clamping part and the second clamping part are each provided with a groove used for containing the corresponding cushioning rubber mat. The cushioning rubber mat is arranged in the baffle clamping device, after the glass baffle is installed, the cushioning rubber mat makes contact with the glass baffle, isolation between hard metal and glass materials is achieved, the possibility of hard contact between the hard metal and fragile glass is greatly reduced, and the safety of the glass baffle is remarkably improved.

The utility model discloses an intelligent temperature control protector, which relates to the technical field of electrical components, and comprises an outer casing, a side cover, a circuit board and a mounting plate, the upper side of the circuit board is electrically connected with a microprocessor, a wireless receiving module and a temperature sensing module, and the upper side of the mounting plate is fixedly provided with an on-off protection mechanism and an access mechanism. When the interior of the electric appliance is overheated due to long-time heat supply, the temperature sensing module is arranged in the electric appliance, senses that the temperature exceeds a threshold value and sends an electric signal to the microprocessor, and the microprocessor controls the output shaft of the rectangular-axis motor to rotate reversely, so that the shifting piece is driven to rotate clockwise, and the rolling wheel rotates clockwise to be gradually separated from the soft metal strip; the soft metal strip is made of copper metal, has high toughness and is separated from the hard metal strip after being recovered to a horizontal state, and the hard metal strip is made of aluminum metal, so that a circuit of a temperature generation part of the electric appliance is disconnected, heat supply is not continued, and the electric appliance is protected.

A stud (100) for improving grip of a tyre (200). The stud (100) comprises a body (120) comprising a base flange (140) and a second part (130), the second part (130) being joined to the base flange (140), and a pin (110) protruding from the second part (130) in the longitudinal direction (Sz) of the stud (100). The pin (110) comprises hard metal or ceramic. The base flange (140) has a first cross-section having a first area (A140). The pin (110) has a second cross-section having a second area (A110). A ratio (A140 / A110) of the first area (A140) to the second area (A110) is 6.5 to 21. Moreover, the pin (110) protrudes a first height (H110) from the second part (130) such that a ratio (A140 / H110) of the first area (A140) to the first height (H110) is 20 to 50 mm2 / mm.

The invention discloses a cushion block composite layer for a semiconductor, a preparation method and a cushion block, the cushion block composite layer sequentially comprises a composite coating and a surface microstructure from a substrate close to beryllium copper to a position far away from the substrate, and the composite coating sequentially comprises a chromium transition layer, an alpha-diamond-like carbon layer and a self-lubricating layer doped with tungsten disulfide from a position close to the substrate to a position far away from the substrate. Hard metal carbide reinforced phase crystal grains are uniformly distributed in the alpha-diamond-like carbon layer; the surface micro-texture comprises a plurality of pits, and each pit is filled with a nano-particle solid lubricant; through the structure, the cushion block is compatible with the high process temperature, an additional cooling device is not needed, and the interface shear stress of the composite layer is reduced, so that the copper powder falling amount is greatly reduced, the hardness, the wear-resisting life, the wear-resisting particle penetrability and the high recognition accuracy of the cushion block are greatly improved, and the low friction coefficient of the surface is maintained; and the roughness is still kept at a lower level after the lead frame is carried for multiple times.

To provide a structural material of a resin foam base material which has a hard metal surface irrespective of a surface shape, is lightweight and has flame retardancy.SOLUTION: A structural material 20 has a sprayed metal layer 22 on the surface of a base material 21 composed of a resin foam subjected to flame-retardant treatment. The base material 21 is composed of a flame-retardant resin foam foam-molded by foamable resin beads coated with a flame retardant. The sprayed metal layer 22 contains an aluminum alloy. A resin undercoat 23 is provided on the surface of the base material 21, and the sprayed metal layer 22 is formed on the resin undercoat 23.SELECTED DRAWING: Figure 2

The invention discloses a light vehicle suspension component, and relates to the field of vehicle suspension components, the light vehicle suspension component comprises an anti-roll rod, the two ends of the anti-roll rod are connected with lining assemblies, and each lining assembly comprises a hard metal lining connected to the outer wall of the anti-roll rod in a sleeving mode. The universal assembly and the lining assembly are combined to serve as a connecting piece between the anti-roll rod and the frame, multi-angle rotation and power transmission can be achieved through the universal assembly, the universal assembly can be used for occasions where relative movement among components is allowed and torque or force is transmitted at the same time, the anti-roll rod is allowed to move relatively in multiple directions, and the anti-roll rod can rotate in multiple directions. Under the condition, in the same period, abrasion of the lining assembly and breakage of molecular chains can be relatively relieved, then the service life of the lining assembly is prolonged, then the material characteristics of the first flexible sleeve and the second flexible sleeve can be utilized, tiny displacement between the frame and the anti-roll bar is absorbed, stress concentration caused by rigid connection is avoided, and the service life of the anti-roll bar is prolonged. And roll control and comfort balance are optimized.

The instrument (10) according to the invention has an electrode (11) which is arranged in a gas-guiding lumen (16) and is held centered. The electrode (11) has an electrode body (22) which is made of a thermally stable material, such as hard metal, tungsten, steel, stainless steel, etc. The electrode (11) is equipped with a coating (23) which is made of a low-melting material, such as silver, a silver alloy or other low-melting metals. An adhesive layer (24), in particular a gold layer, can be provided between the coating (23) and the electrode body (22). This adhesive layer can contribute to the retraction of the coating (23) during the first commissioning and thus during the formation of the desired shape of the electrode (11) for operation.

The ground inserting type fertilizer applicator comprises a material conveying pipe and a shovel head, the material conveying pipe is a hard metal pipe, the upper end of the material conveying pipe is in threaded connection with a hopper, a second hinge frame is fixedly arranged on one side of the upper portion of the material conveying pipe, a pull handle is hinged to the second hinge frame, a pull rod is hinged to the lower side of the pull handle, and the other end of the pull rod is fixedly connected with a pull hook. The lower end of the conveying pipe is in threaded connection with the shovel head; the upper end of the movable part of the shovel head is connected with the drag hook, and the pull handle pulls the shovel head open through the pull rod and the drag hook. According to the fertilizer applicator, the shovel head is connected with the material conveying pipe through the thread structure, and the drag hook is connected with the movable part of the shovel head, so that the shovel head and the material conveying pipe are more conveniently detached, and after the shovel head and the material conveying pipe are detached, the legs of a user are not easily injured when the fertilizer applicator is taken to move, and the safety is relatively higher; and different shovel heads are easy to disassemble and replace, so that more use scenes can be met, and meanwhile, the damaged shovel head can be replaced and maintained more conveniently.

A tool component of a machine tool comprises a functional body having at least one functional surface and a support body which supports the functional body wherein the functional body has at least one surface for fixing or guiding the tool component within the machine tool, wherein the functional body is formed at least partially from a solid material. The tool component is characterized in that the structure of the support body adjoins the structure of the functional body, the functional body at least partially has a carrying structure having cavities, and the carrying structure is formed at least partially from a hard material, a hard metal or a hard alloy on a chromium-cobalt basis.

The utility model relates to a kind of hard alloy assembly pinch roll, belong to steel rolling equipment technical field.The pinch roll includes roll ring, base and cover plate;The base and cover plate are all ladder shaft structure, and are divided into thick section and thin section;The base is coaxially arranged with cover plate and thin section is opposite, is fixedly connected by fastener, and two thin sections butt joint form the roll ring installation groove extending in circumference;The base and cover plate central through hole are equipped with inner hole;The roll ring is set in base and cover plate outer, and the inner hole of roll ring is equipped with the convex extending in circumference, the convex and the roll ring installation groove shape are matched and there is radial and axial interference fit.The utility model realizes the consideration of economy and durability by assembly structure, and reduces the instability of non-integral structure by structural design.

The invention relates to a drilling tool, in particular a rock drilling tool (11), with a drilling section (15) for machining a workpiece, in particular comprising a hard metal, and with a shaft section (17) extending in particular along a longitudinal axis A, characterized by a transport recess (23) for transporting particles, in particular extending transversely to a longitudinal axis A.

The invention discloses a connecting bar and a battery module, the connecting bar comprises a first connecting section and a second connecting section, the first connecting section and the second connecting section are respectively made of hard metal materials, and two opposite ends of a buffer section in the extension direction are respectively connected with the first connecting section and the second connecting section; the buffer section comprises a plurality of soft metal foils which are stacked in the thickness direction of the buffer section. According to the connecting bar, stable connection between the connecting bar and the battery cell poles is achieved through the high-rigidity hard metal materials at the two ends, the fatigue stress between the battery cell columns under the vibration working condition is absorbed through the soft metal foil pieces with the good flexibility, and fatigue fracture of the connecting bar is avoided.