Patent Application
20070084538
The present invention relates to a method for producing a run flat tire supporting member to be provided inside a tire for allowing a running operation for a considerable distance in the state with the internal air pressure is reduced by the puncture, or the like, a run flat tire supporting member, and a pneumatic run flat tire.
As a pneumatic tire capable of run flat running, that is, a tire capable of running safely for a certain distance even in the case it is punctured so that the tire internal pressure becomes 0 Pa (hereinafter it is referred to as a run flat tire), a core type run flat tire with a core (supporting member) mounted as a rim portion in the tire air chamber is known (see for example the patent article 1).
The main constituent member of such a core (supporting member) is a ring shaped supporting member (shell). According to the production of the supporting member (shell), after cutting a metal plate like material by a predetermined length, a bending process into a ring like shape is applied and the both end parts in the longitudinal direction are bonded with each other so as to provide a cylindrical member, and a process such as a spinning process may be applied to the metal cylindrical member.
Here, since a large load is applied to the supporting member (shell) when run flat running, in the case the strength decline is generated due to the characteristic change of a welded part and the vicinity of the welded part, strength administration after processing or mounting has been troublesome.
In consideration to the above-mentioned facts, an object of the invention is to provide a production method for a run flat tire supporting member without a joint, a run flat tire supporting member without a joint, and a pneumatic run flat tire comprising the run flat tire supporting member.
A production method for a run flat tire supporting member of the invention according to claim 1 is a production method for a run flat tire supporting member capable of supporting the load when run flat running comprising; shaping a cylindrical member having a bottom part out of a flat plate metal material by deep drawing process, removing an opening part side and the bottom part side of the cylindrical member, and curving the cylindrical member into a shape comprising a projecting part with the axial direction middle part of the cylindrical member projecting to the outside in the radial direction.
According to the production method for a run flat tire supporting member of the invention according to claim 1, a run flat tire supporting member is shaped by shaping a cylindrical member having a bottom part out of a flat plate metal material by deep drawing process, after removing the opening part side and the bottom part side of the cylindrical member, and curving the cylindrical member into a shape comprising a projecting part with the axial direction middle part of the cylindrical member projecting to the outside in the radial direction. Accordingly, by removing the opening part side and the bottom part side of the cylindrical member after the deep drawing process, a cylindrical member without a joint can be obtained so that a run flat tire supporting member without a joint can be shaped.
A production method for a run flat tire supporting member of the invention according to claim 2 is a production method for a run flat tire supporting member capable of supporting the load when run flat running comprising; shaping a cylindrical member having a bottom part out of a flat plate metal material by deep drawing process, curving the cylindrical member into a shape comprising a projecting part with the axial direction middle part of the cylindrical member projecting to the outside in the radial direction, and removing an opening part side and the bottom part side of the cylindrical member curved into a shape comprising the projecting part.
According to the production method for a run flat tire supporting member of the invention according to claim 2, a run flat tire supporting member is shaped by shaping a cylindrical member having a bottom part out of a flat plate metal material by deep drawing process, curving the cylindrical member into a shape comprising a projecting part with the axial direction middle part of the cylindrical member projecting to the outside in the radial direction, and removing the opening part side and the bottom part side of the cylindrical member curved into a shape comprising the projecting part. Accordingly, by removing the opening part side and the bottom part side of the cylindrical member after the deep drawing process, a jointless cylindrical member can be obtained so that a jointless run flat tire supporting member can be shaped.
A production method for a run flat tire supporting member of the invention according to claim 3 is the production method for a run flat tire supporting member according to claim 1 or 2, and the curving to shape the cylindrical member further comprising; the cylindrical member is inserted into an inner circumferential side of a cylindrical shaping mold having an inner circumferential surface comprising a surface shape corresponding to the projecting part, filling an inner circumferential side of the cylindrical member with a liquid, pressurizing the liquid, and curving the cylindrical member by the liquid pressure to conform to the shaping surface.
According to the production method for a run flat tire supporting member of the invention according to claim 3, particularly in the case of using the cylindrical member according to claim 2 as the shaping material of the supporting member, that is, by forming the projecting part with the axial direction middle part projecting to the outside in the radial direction in the cylindrical member by the liquid pressure, leakage of the liquid provided to the inner circumferential side of the cylindrical member from the bottom surface side of the cylindrical member can be inhibited certainly at the time of pressurizing with a liquid, and thus a sealing work for the liquid provided in the cylindrical member or a sealing structure in the device for shaping the projecting part in the supporting member can be simplified.
A production method for a run flat tire supporting member of the invention according to claim 4 is the production method for a run flat tire supporting member according to claim 3, and the curving to shape the cylindrical member further comprising; providing the liquid sealed in an elastic bag member on the inner circumferential side of the cylindrical member, pressurizing the liquid together with the bag member so as to apply the liquid pressure onto the cylindrical member via the bag member.
A production method for a run flat tire supporting member of the invention according to claim 5 is the production method for a run flat tire supporting member according to claim 3 or 4, so as to set the bulge pressure P in a calculation value of formula (1) in the shaping with a value selected as a constant K in a range of 1.5 to 20:
P=K×S×T Formula(1)
wherein the bulge pressure as the maximum value of the liquid pressure to be applied to the cylindrical member by the liquid filled on the inner circumferential side of the cylindrical member is P (Kgf/mm2), the thickness of the cylindrical member is T (mm), the tensile strength of the metal material comprising the cylindrical member is S (Kgf/mm2), and the constant for determining the bulge pressure P is K (where K is a positive real number).
A run flat tire supporting member of the invention according to claim 6 is a run flat tire supporting member capable of supporting the load when run flat running comprises a projecting part projecting to the outside in the radial direction which is formed by curving an axial direction middle part of a jointless cylindrical member.
According to the run flat tire supporting member of the invention of claim 6, since a projecting part projecting to the outside in the radial direction is formed by curving the axial direction middle part of a jointless cylindrical member, a run flat tire supporting member without a joint can be provided. Therefore, the strength on the circumference of the run flat tire supporting member can be even so that unnatural deformation or rupture cannot be generated in an ordinary run flat running even without a firm welding required for a run flat tire supporting member with a joint.
A pneumatic run flat tire of the invention according to claim 7 comprises; a tire comprising a toroidal carcass spanning between a pair of bead cores, a side rubber layer configuring a tire side part and disposed on the outside in a tire axial direction of the carcass and a tread rubber layer configuring a tread part and disposed on the outside in a tire radial direction of the carcass, a tire size mounting rim for mounting the tire, and a supporting member disposed on the inside of the tire so as to be assembled on the rim together with the tire. The run flat tire supporting member is a run flat tire supporting member produced according to claim 3.
According to the pneumatic run flat tire of the invention according to claim 7, at the time the internal pressure of the pneumatic tire is lowered, run flat running is enabled by supporting the tread part by the supporting member disposed inside the pneumatic tire instead of the side rubber layer. When run flat running, the shock from the road surface is transmitted to the car body via the tread part, the supporting member and the rim. Accordingly, although the load and the vibration are applied to the run flat tire supporting member when run flat running, according to the invention, since the jointless run flat tire supporting member is used, the strength on the circumference of the run flat tire supporting member can be even so that unnatural deformation or rupture cannot be generated in an ordinary run flat running even without a firm welding required for a run flat tire supporting member with a joint.
A production device for a run flat tire supporting member of the invention according to claim 8 is a production device for producing a ring shaped run flat tire supporting member disposed inside a pneumatic tire so as to be assembled onto a rim together with the pneumatic tire comprises, a ring form shaping mold comprising a pressure shaping part, having a surface shape corresponding to a radial direction cross sectional shape of the supporting member formed on an inner circumferential surface thereof and a hollow part on the inner circumferential side of the pressure shaping part for inserting with a metal cylindrical member as the shaping material of the supporting member, a bag member made of an elastic and stretchable membrane material filled inside with a liquid for inserting into the hollow part on an inner circumferential side of the cylindrical member, and a pressurizing part for plastically deforming the cylindrical member to conform to the pressure shaping part by applying liquid pressure to the cylindrical member via the bag member while expanding the bag member towards the outer circumferential side by pressurizing the liquid in the bag member.
According to the production device for a run flat tire supporting member of the invention according to claim 8, since the cylindrical member can be plastically deformed to conform to the pressure shaping part in the shaping mold without contacting the liquid with the cylindrical member which is the shaping material to the supporting member by filling the inside of the bag member made of an elastic and stretchable membrane material with a liquid, inserting the bag member into the hollow part on the inner circumferential side of the cylindrical member, and applying the liquid pressure to the cylindrical member via the bag member while expanding the bag member towards the outer circumferential side by pressuring the liquid in the bag member with the pressuring part, the work for removing the liquid from the supporting member (hydro form shaping) shaped from the cylindrical member can be eliminated.
Moreover, since the liquid is sealed in the bag member in the production device, compared with one having a liquid directly filling the inside of the hollow part of the shaping mold, since the sealing member for preventing the liquid leakage from the inside of the hollow part can be eliminated, the part change accompanied by the deterioration or the sealing member can be eliminated.
Moreover, a production method for a run flat tire supporting member of the invention according to claim 9 is a production method for producing a run flat tire supporting member using the production device for a run flat tire supporting member according to claim 8, comprises; inserting the metal cylindrical member into the hollow part, inserting the bag member into the inner circumferential side of the cylindrical member that is in the hollow part, pressuring the liquid in the bag member inserted into the hollow part or a liquid filled inside the hollow part with the pressurizing part, and plastically deforming the cylindrical member to conform to the pressure shaping part by the liquid pressure.
According to the production method for a run flat tire supporting member of the invention according to claim 9, since the cylindrical member can be plastically deformed to conform to the pressure shaping part in the shaping mold without contacting the liquid with the cylindrical member which is the shaping material for the supporting member, adhesion of the liquid to the supporting member shaped from the cylindrical member (hydro form shaping) can be completely prevented, and thus generation of the rust or the chemical change on the supporting member surface by the influence of the adhered liquid can be prevented.
Moreover, the production method for a run flat tire supporting member of the invention according to claim 10 is a production method for producing a ring shaped run flat tire supporting member to be disposed inside a pneumatic tire so as to be assembled onto a rim together with the pneumatic tire comprises; inserting a metal cylindrical member as the shaping material for the supporting member into a hollow part provided on an inner circumferential side of a pressure shaping part in the ring form shaping mold, the pressure shaping part configuring a surface shape corresponding to a radial direction cross sectional shape of the supporting member and is formed on the inner circumferential side of the ring form shaping mold, inserting a bag member made of an elastic and stretchable membrane material and filled inside with a liquid into the hollow part on an inner circumferential side of the cylindrical member, pressurizing the liquid in the bag member with a pressuring part so as to apply the liquid pressure to the cylindrical member via the bag member, plastically deforming the cylindrical member to conform to the pressure shaping part, wherein, so as to set the bulge pressure P in a calculation value of formula (1) in the shaping with a value selected as a constant K in a range of 1.5 to 20:
P=K×S×T Formula (1)
wherein the bulge pressure as the maximum value of the liquid pressure to be applied to the cylindrical member by the liquid filled on the inner circumferential side of the cylindrical member is P (Kgf/mm2), the thickness of the cylindrical member is T (mm), the tensile strength of the metal material comprising the cylindrical member is S (Kgf/mm2), and the constant for determining the bulge pressure P is K (where K is a positive real number).
According to the production method for a run flat tire supporting member of the invention according to claim 10, particularly in the case a high strength metal material such as a high tension steel, a stainless steel and a ultra high tension steel is used as the material for the cylindrical member, by controlling the bulge pressure P to be applied to the cylindrical member to a calculation value of (K×S×T) by the pressuring means, the cylindrical member can be plastically deformed accurately to conform to the shape of the pressure shaping part so as to stably produce a supporting member having desired size accuracy and mechanical performance so that deterioration of the mechanical characteristics due to generation of the excessive distortion of the supporting member can be prevented.
Since the cylindrical member can be plastically deformed to conform to the pressure shaping part in the shaping mold without contacting the liquid with the cylindrical member, adhesion of the liquid to the supporting member shaped from the cylindrical member (hydro form shaping) can be completely prevented, and thus generation of the rust or the chemical change on the supporting member surface by the influence of the adhered liquid can be prevented.
Moreover, since a production device for shaping a supporting member, which has an appropriate output for a pressure shaping or the like can be selected accurately, increase of the production cost of the supporting member can be restrained effectively without selecting a device having an output higher than the required level.
As heretofore explained, according to a production method for a run flat tire supporting member of the invention, a run flat tire supporting member and a pneumatic run flat tire, a run flat tire supporting member without a joint can be produced so that the excellent effect of providing a run flat tire supporting member without a joint and a pneumatic run flat tire comprising the run flat tire supporting member can be provided.
FIGS. 5(A)(B)(C) are diagrams showing the production stages in the production method for a supporting member according to the first embodiment of the present invention. (A) is a perspective view showing a cylindrical member shaped by the deep drawing process. (B) is a perspective view showing a cylindrical member with the opening part side and the bottom part side cut off by the cutting process. (C) is a perspective view showing a shell (supporting member) shaped by the curving process.
FIGS. 6(A)(B) are diagrams showing the configuration of a pressure shaping device for producing a shell (supporting member) by the hydro form process in the production method for a supporting member according to the first embodiment of the invention. (A) is a cross sectional view showing the device state before starting the hydro form process of the shell (supporting member). (B) is a cross sectional view showing the device state during the hydro form process of the shell (supporting member).
FIGS. 7(A)(B)(C) are diagrams showing the production stages in the production method for a supporting member according to a second embodiment of the invention. (A) is a perspective view showing a cylindrical member shaped by the deep drawing process. (C) is a perspective view showing a cylindrical member with the opening part side and the bottom part side cut off by the cutting process. (B) is a perspective view showing a shell (supporting member) shaped by the curving process.
FIGS. 8(A)(B) are diagrams showing the configuration of a pressure shaping device for producing a shell (supporting member) by the hydro form process in the production method for a supporting member according to the second embodiment of the invention. (A) is a cross sectional view showing the device state before starting the hydro form process of the shell (supporting member). (B) is a cross sectional view showing the device state during the hydro form process of the shell (supporting member).
FIGS. 11 (A)(B) are cross sectional views showing the configuration of the pressure shaping device shown in
FIGS. 12(A)(B) are perspective views showing a supporting ring hydro form shaped by a pressure shaping device according to a fourth embodiment of the invention.
FIGS. 13(A)(B) are diagrams showing the production process for a supporting member according to a comparative example. (A) is a perspective view showing a cylindrical member obtained by welding the both end parts of a ring shaped material. (B) is a perspective view showing a shell (supporting member) shaped from the cylindrical member of
A run flat tire comprising a supporting member according to the first embodiment of the invention and the production method for the supporting member will be explained with reference to the drawings.
(Configuration of a Run Flat Tire Comprising a Supporting Member)
As shown in
As shown in
The leg part 28 provided as an elastic member is ring shaped in the longitudinal direction and a substantially rectangular in the cross sectional shape along the rotation axis O perpendicular to the longitudinal direction. As shown in
On the other hand, the shell 26 is formed with a thin plate having the cross sectional shape shown in
(Production Method for the Shell)
Next, the production method for the shell 26 in the run flat tire 10 provided as mentioned above will be explained.
The shell 26 is formed integrally with a metal material. As the metal material for the shell 26, an aluminum based, iron based, magnesium based or titanium based metal material can be used. Here, “based” is a concept that the material includes the metal as a base alloy, a material produced by plating the metal, a material produced by plating a metal provided the metal as the base alloy, or the like in addition to the metal itself. For example, in the case of the “iron based”, in addition to the iron itself, a carbon steel, and an iron-zinc alloy, furthermore, a zinc plated steel plate, a steel plate plated with an iron-zinc alloy, or the like are included,
In the case of using an aluminum based material, from the viewpoint of the strength and the shaping property, the aluminum alloys of the alloy number 5,000 series, 6,000 series and 7,000 series defined in the JIS are preferable. Moreover, in the case of using a high tension steel as the iron based material, from the viewpoint of the shaping property, those having a tensile strength of 380 N/mm2 or less are preferable.
—Deep Drawing Process—
The deep drawing process is a process of shaping a cylindrical member having a bottom part out of a flat plate like metal material by the deep drawing process.
By pressing down the punch 34 so as to push the convex part 34A into the hole 32B, the metal plate 30 portion initially on the dice surface 32A is drawn cylindrically so as to be processed by the deep drawing shaping. When the convex part 34A is pushed to a predetermined depth, the convex part 34A is contacted with the bottom surface 32C of the hole 32B via the metal plate 30 so that the metal plate 30 becomes a cylindrical member 36 having the bottom plate part 36B as shown in
Here, the cylindrical part 36A of the cylindrical member 36 shown in
As to the deep drawing process shown in
—Cutting Process—
The cutting process is a process for removing the opening part side and the bottom part side of the cylindrical member.
—Curving Process—
The curving process is a process for curving the cylindrical member into a shape comprising a projecting part with the axial direction middle part of the cylindrical member projecting to the outside in the radial direction.
In this process, a shell 26 comprising two convex parts 26A with the axial direction middle part projecting to the outside in the radial direction as shown in
The pressure shaping device 40 is provided with a thick cylindrical shaping mold 42 such that the shaping mold 42 comprises a pressure shaping part 42 A having the surface shape corresponding to the shape of the shell 26 (see
The pressure shaping device 40 has a fixed base 46 disposed below the shaping mold 42 such that a fixed plunger 48 is projected from the upper surface part of the fixed base 46. The fixed plunger 48 is fitted on the inner circumferential side of the cylindrical member 36 in the hollow part 44. A rubber seal ring 50 is mounted on the outer circumferential surface top end part of the fixed plunger 48 for sealing the gap with respect to the cylindrical member 36 inner circumferential surface. Thereby, the opening on the lower part side of the cylindrical member 36 can be sealed. In this state, the inside of the hollow part 44 is filled with a liquid L such as water and oil.
Moreover, in the pressure shaping device 40, an elevating base 52 movable along the height direction (in the upper and lower direction in the figure) is disposed above the shaping mold 42. A pressure plunger 54 is projected from the lower surface part of the elevating base 52. A rubber seal ring 56 is mounted also on the outer circumferential surface top end part of the pressure plunger 54 for sealing the gap with respect to the cylindrical member 36 inner circumferential surface.
At the time of shaping the shell 26 out of the cylindrical member 36 (see
On the other hand, in the case of shaping the shell 26 as shown in
(Function of the Shell and the Run Flat Tire)
Next, the function of the shell 26 produced as mentioned above and the run flat tire 10 comprising the shell 26 will be explained.
According to the run flat tire 10 shown in
The production method for a supporting member according to the second embodiment of the invention will be explained with reference to the drawings.
(Production Method for the Shell)
—Deep Drawing Process—
According to the production method for a supporting member according to this embodiment, as in the case of the first embodiment, the cylindrical member 36 shown in
—Curving Process—
The curving process is a process for shaping a cylindrical member 80 comprising two convex parts 26A, 26A by curving two points in the axial direction middle part of the cylindrical member 36 so as to be projected to the outer circumference side by the hydro form process.
As shown in
The pressure shaping device 82 has a fixed base 102 disposed below the shaping mold 84 such that a fixed plunger 10 is projected from the upper surface part of the fixed base 102. The fixed plunger 10 has the upper surface part thereof contacted with the bottom surface part of the cylindrical member 36 inserted into the hollow part 88. In this state, the inside of the cylindrical member 36 is filled with a liquid L such as water and oil.
In the pressure shaping device 82, an elevating base 94 movable along the height direction (in the upper and lower direction in the figure) by a hydraulic cylinder, or the like is disposed above the shaping mold 84. A pressure plunger 96 is projected from the lower surface part of the elevating base 94. Moreover, a ring like seal pressing member 98 is disposed on the outer circumferential side of the pressure plunger 96 in the pressure shaping device 82 such that the seal pressing member 98 can be moved along the height direction by a hydraulic cylinder, or the like. A rubber seal ring 100 is mounted on the inner circumferential surface of the seal pressing member 98 for sealing the gap with respect to the pressure plunger 96.
At the time of shaping the cylindrical member 80 comprising the two convex parts 26A, 26A out of the cylindrical member 36 (see
Then, the elevating base 94 is lowered so that the pressure plunger 96 is inserted into the inner circumferential side of the cylindrical member 36 in the hollow part 88. Thereby, the upper part side opening of the cylindrical member 36 is sealed as well as the liquid L filling the inside of the cylindrical member 36 is compressed so as to raise the liquid pressure. The pressure plunger 96 is lowered to the pressure position shown in
—Cutting Process—
The cutting process is a process for removing the opening part side and the bottom part side of the cylindrical member 80 comprising the two convex parts 26A, 26A.
The surfaces perpendicular to the central axis D of the cylindrical member 36 on the opening part 36D side (upper part in the figure) and the bottom plate part 36B side (lower part in the figure) of the cylindrical member 80 shown in
(Function According to the Production Method)
Next, the function of the production method for a supporting member according to the second embodiment as mentioned above will be explained.
According to the production method for a supporting member according to this embodiment, like the production method for a supporting member according to the first embodiment, a cylindrical member 80 without a joint can be obtained, and the cylindrical member 80 without a joint can be shaped into the shell 106.
By forming the two convex parts 26A, 26A with the axial direction middle part projecting to the outside in the radial direction in the cylindrical member 36 by the hydro form process without removing the opening part side and the bottom part side from the cylindrical member 36 after the deep drawing process, compared with the production method of the first embodiment, since the leakage of the liquid L filled to the inner circumferential side of the cylindrical member 36 from the bottom surface side of the cylindrical member 36 can certainly be inhibited at the time of the hydro form process, the sealing work for the liquid L filling the inside of the cylindrical member 36 at the time of the hydro form process and the seal structure of the pressure shaping device 82 can be simplified.
The third embodiment of the production method for a shell (supporting member) will be explained with reference to
As shown in
At the time of the cylindrical deep drawing process of the metal plate 30, first, the metal plate 30 is placed on the supporting surface 60A so that the circumference of the metal plate 30 is pressed and supported by the pressing member 58. Next, the punch 34 is lowered so as to push the metal plate 30 into the liquid pressure chamber 60B side. At the time, the liquid pressure of the liquid L in the liquid pressure chamber 60B is adjusted by the pump 62. Since the metal plate 30 is pressured on the outer circumferential surface of the punch 34 by the liquid pressure in the liquid pressure chamber 60B, it is shaped along the outer circumferential shape of the punch 34. Thereby, the metal plate 30 becomes a cylindrical member 36 without a joint as shown in
According to the shaping method using a liquid pressure to one of the molds as the method of this embodiment (counter liquid pressure method) or the method of using the liquid pressure instead of the punch 34 as shown in
Next, the configuration of the pressure shaping device 134 for producing the shell 26 of the supporting member 16 according to this embodiment will be explained.
As shown in
As shown in
According to this embodiment, the cylindrical member 36 is made of a metal material such as a high tension steel, a stainless steel and a ultra high tension steel into a thin cylindrical shape having a constant diameter corresponding to the maximum diameter of the shell 26. Specifically, the cylindrical member 36 is made of for example a high tension steel of a 50 Kgf/mm2 or more tensile strength with the thickness of about 0.8 mm to 1.8 mm. As shown in
As shown in
As shown in
Here, the bag member 154 is formed with a membrane material made of a vulcanized rubber such as NR, NBR, BR, IR, IIR, NOR, and EPDM as the material so as to have the sufficient elasticity and stretchability. Moreover, as the liquid L, various kinds of liquids such as water and oil can be used, and one having a low affinity with respect to the vulcanized rubber comprising the bag member 154 can be selected. The bag member 154 has the shape and the size set such that the outer diameter thereof is smaller than the inner diameter of the cylindrical member 36 in a state filled with the liquid L so as to be elastically deformed by the static pressure and the gravity as well as the volume is larger than the content volume of the cylindrical member 36 by a predetermined amount or more. Specifically, the difference of the volume of the bag member 154 and the content volume of the cylindrical member 36 is set according to the size of the bulge pressure at the time of the hydro form shaping to be described later. The material of the bag member 154 may be one other than the vulcanized rubber as long as it has the sufficient elasticity and the stretchability. For example, a urethane elastomer can be used. Moreover, the bag member 154 may have plural kinds of the materials laminated along the thickness direction.
(Operation and Function of the Pressure Shaping Device)
The operation and the function of the pressure shaping device 134 according to this embodiment having the above-mentioned configuration will be explained.
At the time of shaping the shell 26 out of the cylindrical member 36, the operator binds the split molds 139, 140 of the shaping mold 138 at the shaping position by the switching mechanism as well as sets the cylindrical member 36 in the hollow part 144 of the shaping mold 138 so as to complete the shaping preparation of the shell 26. After completing the shaping preparation, the pressure shaping device 134 lowers the elevating base 50 at the waiting position shown in
After inserting the bag member 154 into the cylindrical member 36, the pressure shaping device 134 further lowers the pressure plunger 152 by the hydraulic cylinder so as to compress the liquid L in the bag member 154 by the pressure plunger 152 for raising the liquid pressure of the liquid L. The pressured liquid L elastically deforms the bag member 154 so as to expand to the outer circumferential side according to the liquid pressure rise and presses evenly the outer circumferential surface part of the bag member 154 on the inner circumferential surface of the cylindrical member 36 as well as applying the liquid pressure to the cylindrical member 36 via the bag member 154.
The pressure shaping device 134 lowers the pressure cylinder to the pressure position to have the liquid pressure in the bag member 154 becomes a predetermined bulge pressure P by the hydraulic cylinder (see
After supporting the pressure plunger 152 at the pressure position for a certain time by the hydraulic cylinder, the pressure shaping device 134 returns the pressure plunger 152 to the waiting position shown in
The appropriate value of the bulge pressure P (Kgf/mm2) will be explained, which is applied on the cylindrical member 36 via the bag member 154 in the shaping process for the shell 26 mentioned above. The thickness of the cylindrical member 36 is T (mm), the tensile strength of the high tension steel comprising the cylindrical member is S (Kgf/mm2), and the constant for determining the bulge pressure P is K (K is a positive real number), the appropriate value of the bulge pressure P can be calculated by the below-mentioned formula (1) in the shaping process;
P=K×S×T Formula (1).
The constant K can be selected in a range of 1.5 to 20. It is preferable to select the constant K in a range of 2.0 to 15, and further preferably in a range of 2.0 to 10. By selecting optionally the constant K in the above-mentioned range even in the case the metal for the shell 26 is a metal other than the high tension steel, such as a stainless steel and a ultra high tension steel, the appropriate value of the bulge pressure P can be calculated based on the formula (1).
In the case the constant K is set at a value less than 1.5, the bulge pressure P in the shaping process is insufficient so that the plastic deformation of the cylindrical member 36 for accurately following the shape of the pressure shaping part 142 can be difficult, and thus the shell 26 shaped form the cylindrical member 36 cannot be produced stably by a predetermined size accuracy. Moreover, accompanied by the size accuracy decline of the shell 26, the shape strengthening function of the convex part 26A and the concave part 26B is lowered so that the strength along the shell 26 radial direction or the twisting direction may be insufficient.
On the other hand, in the case the constant K is set at a value larger than 20, the bulge pressure P in the shaping process is excessive so that a large internal distortion may be generated in the shell 26 shaped out of the cylindrical member 36.
Moreover, since a pressure shaping device 134 having a pressuring ability higher than the set value of the bulge pressure P needs to be installed on the production line of the shell 26, if the bulge pressure is set at an excessively large value, the scale of the pressure shaping device 134 becomes excessively large so as to raise the installation cost of the pressure shaping device 134 for causing the production cost increase of the shell 26. From this viewpoint, it is preferable to set the constant K at a value as small as possible within a range not to pose the adverse effect to the quality of the shell 26.
According to the pressure shaping device 134 according to this embodiment, the cylindrical member 36 can be deformed elastically to conform to the pressure shaping part 142 in the shaping mold 138 without contacting the liquid L with the cylindrical member 36 for the shell 26. This is caused by filling the inside of the bag member 154 with the liquid L, which is made of a membrane material having the elasticity and the stretchability, inserting the bag member 154 on the inner circumferential side of the cylindrical member 36 in the hollow part 144 of the shaping mold 138, and applying a predetermined bulge pressure to the cylindrical member 36 via the bag member 154 while expanding the bag member 154 to the outer circumferential side by pressuring the liquid L in the bag member 154 by the pressure plunger 154. The work for removing the liquid L from the shell 26 shaped out of the cylindrical member 36 can be eliminated.
As a result, since the adhesion of the liquid L to the shell 26 shaped out of the cylindrical member 36 can be prevented completely, generation of the rust or the chemical change on the shell 26 surface by the influence of the adhered liquid L can be prevented.
Moreover, according to the pressure shaping device 134 of this embodiment, since the liquid L is sealed in the bag member 154, compared with the pressure shaping device with the inside of the shaping mold directly filled with the liquid (see for example
Moreover, in the pressure shaping device 134 of this embodiment, in the case a high strength metal material such as a high tension steel, a stainless steel and a ultra high tension steel is used for the cylindrical member 36, by controlling the bulge pressure P to be applied to the cylindrical member 36 to the calculation value of (K×S×T), the cylindrical member 36 can be deformed plastically so as to accurately follow the shape of the pressure shaping part 142 in the shaping mold 138 so that the shell 26 having the desired size accuracy and mechanical performance can be produced stably as well as the mechanical characteristics decline by the generation of the excessive distortion of the shell 26 can be prevented. Moreover, since the pressure shaping device 134 having an appropriate output can be selected adequately for the hydro form shaping of the shell 26, the production cost increase of the shell 26 can be restrained effectively.
Moreover, according to the pressure shaping device 134 according to this embodiment, although the pressuring part inserting the pressure plunger 152 into the hollow part 144 by the hydraulic cylinder is used for pressuring the liquid L in the bag member 154. In addition to that, for example, preliminarily inserting the bag member 154 into the hollow part 144 and supplying the liquid L pressured by a high pressure pump, or the like may be employed as well. By measuring the liquid pressure of the liquid L in the bag member 154 with a pressure sensor and carrying out the feed back control of the liquid pressure based on the measurement result, the liquid pressure in the bag member 154 can be controlled accurately to the calculation value of (K×S×T).
(First Comparison Test)
For confirming the shell production efficiency by the production method of the present embodiments, the comparison test of the examples and the comparative examples shown below was carried out.
As the material for the shells to be produced in the examples and the comparative examples, a 2.3 mm plate thickness aluminum alloy (JIS alloy number 6061-O material) was used.
According to the production of the shell of the examples, the material was shaped to the cylindrical member 36 shown in
On the other hand, according to the production of the shell of the comparative example, as shown in
Here, according to the comparison of the production time per one piece of the shell 26 (see
In the first and second embodiments, the shape and the size of the metal plate 30 may be determined so as to have the flange part 36C after the deep drawing process to the minimum level.
Moreover, shaping of the cylindrical member 36 by the deep drawing process in the embodiments may be so-called large number taking. In the case the cylindrical member 36 can be taken by a large number in the production stage of the shell 26, the production time per one piece can further be shortened.
Furthermore, although the shell 26 comprising the two convex parts 26A, 26A is formed in the embodiment, the shape of the shell 26 to be shaped is not limited thereto, and it may be a shape comprising a projecting part with the axial direction middle part projecting to the outside in the radial direction.
(Second Comparison Test)
The shell with the hydro form shaping using the pressure shaping device 134 according to the embodiment shown in
As it is apparent from the (table 1), according to the shells with the hydro form shaping of the example A1 and the example A2, the total number (10 pieces) has passed the size examination, however, according to the shells according to the comparative example A3 with the rubber bulge shaping, the total number (10 pieces) has not passed the size examination. However, as to the shells according to the example A2, compared with the shells according to the example A1 and the comparative example A3, since the problem in terms of the quality such as the rust generation is generated if they are left after completing the shaping, the liquid L should be removed from the shell surface by drying, washing, or the like.
(Third Comparison Test)
The shells with the hydro form shaping with the constant K selected in a range of 1.5 to 20 and the bulge pressure P controlled to the calculation value of the formula (1) using the pressure shaping device 134 as the examples B1 to B6, and the shells with the hydro form shaping with the constant K selected in a range of less than 2.0 or more than 20.0 and the bulge pressure P controlled to the calculation value of the formula (1) using the pressure shaping device 134 as the comparative examples B7 to B10, the evaluation results of the size accuracy and the compression strength of the shells 26 are each shown in the following (table 2). As to the evaluation result of the size accuracy, in the case the size error with respect to the design value is less than 2%, the mark “⊚”, in the case the size error with respect to the design value is less than 5%, the mark “◯”, in the case the size error with respect to the design value is 5% or more and less than 10%, the mark “Δ”, and in the case the size error with respect to the design value is more than 10%, the mark “×” are shown respectively. Moreover, as to the evaluation result of the compression strength, in the case the compression strength of 90% or more and 100% or less with respect to the maximum strength in the examples B1 to B6 is shown, the mark “⊚”, in the case the compression strength of 80% or more and 90% or less is shown, the mark “◯”, in the case the compression strength of 60% or more and 80% or less is shown, the mark “Δ”, and in the case the compression strength of 60% or less is shown, the mark “×” are shown respectively.
As it is apparent from the above-mentioned (table 2), the examples B2, B3 and B6 in which the constant K was selected at 5.0 and 8.3 in a range of 2.0 to 10 and the bulge pressure P was controlled to the calculation value of the formula (1), the evaluation of both the size accuracy and the compression strength was “⊚” for the shells 26.
Moreover, according to the shell 26 of the example B1 with the constant K selected at 1.5 in a range of 1.5 to 2.0, and according to the shells 26 of the examples B4 and B5 with he constant K selected at 16.7 and 20.0 in a range of more than 10 and 20 or less, the evaluation of both the size accuracy and the compression strength was “◯”.
On the other hand, according to the shells 26 of the comparative examples B7 to B10 with the constant K selected in a range of more than 20.0 and the bulge pressure P controlled to the calculation value of the formula (1), no one had the evaluation “◯” of both the size accuracy and the compression strength.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-382001 | Nov 2003 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP04/16821 | 11/12/2004 | WO | 5/12/2006 |
