FR2546426A1 - METAL SHEET BEARING AND METHOD OF MANUFACTURING - Google Patents

Abstract

THE INVENTION RELATES TO A METAL SHEET BEARING. ACCORDING TO THE INVENTION, IT INCLUDES A FLEXIBLE METAL SHEET 22 WHICH IS SUPPORTED BY A NUMBER OF SUPPORT PARTS 13, 14, 15 WHICH ARE SPACED FROM ONE ANOTHER AT AN APPROPRIATE DISTANCE IN CIRCUMFERENTIAL DIRECTION FROM A ROTATING SHAFT A APPLY SO THAT THIS SHAFT CAN BE SURROUNDED BY THE SHEET OF METAL, THIS SHEET OF METAL BEING SHAPED BY HEAT TREATMENT SO THAT ITS SUPPORTING SURFACE HAS A DIAMETER SUFFICIENTLY LARGER THAN THAT OF THE ROTARY SHAFT TO MAINTAIN A CLEARANCE THE ROTATING SHAFT AND THE LEAF SUPPORT SURFACE TO THE ROTARY SHAFT ASSEMBLY BY SECURELY ATTACHING AT LEAST ONE END OF THE LEAF TO THE SUPPORT ORGAN. THE INVENTION APPLIES IN PARTICULAR TO FLUID BEARINGS.

Description

The present invention relates to a metal sheet bearing as well

  that to its manufacturing process, and more particularly to a metal sheet bearing where a support surface of a flexible metal sheet of the bearing is formed by circumventing it, along the outer peripheral surface of a bar or a main shaft, by a thermosetting treatment, which bearing surface is then assembled to a desired rotary shaft, it is thus possible to reduce both the starting torque and the rotational torque and more improve

  performance and rotation at fast speed.

  To date, a sheet metal bearing has been known to be a radial pressure bearing of the dynamic pressure type where a single metal sheet or a number of sheets are arranged for

  surround and receive a rotating shaft.

  Such a sheet bearing presents, under

  the inherent flexibility of the metal sheet,

  many advantageous features such as a higher elastic support capacity and a high resistance to thermal deformation, which can not be obtained with

  another type of conventional fluid bearing.

  There are two kinds of sheet metal bearings, one using the tension applied by the sheet or sheets of metal and the other using its stiffness

or its flexural stiffness.

  Among the bearings according to the prior art mentioned above, the tension type sheet bearing consists of a number of support members which are

  arranged axially around a rotating shaft at a dis-

  the sheet of metal stretched around the rotating shaft by means of the support members so that the metal sheet is tensioned under an appropriate tension between its opposing axial ends, to thereby easily ensure a bearing surface of a

  high precision to form a very efficient gas layer.

  By virtue of this construction, the rotational torque that is required for this type of foil bearing is quite low, but yet it is accompanied by a very high starting torque because the metal foil tightly surrounds or greenhouse

Rotating shaft stopped.

  In addition, several types of stiff-leaf flexible bearings such as the multi-leaf type, the hydrocele type, the multi-loop type are used.

and the like.

  All these sheet metal bearings consist of

  of a number of press-formed metal sheets which are assembled and secured to the casing of a bearing to receive and support the shaft due to

  stiffness to flexion It is true that by this construction

  tion, the starting torque is considerably lower than that of the voltage-type bearing above, but there are several disadvantages that can be attributed to independent operation of the respective sheets of the assembly. In other words, is difficult to guarantee a bearing surface having a sufficiently precise clearance necessary to form an effective layer of gas, which results in a high contact pressure between the metal sheet and the shaft requiring a

  high starting torque resulting in a deterioration

  characteristics during rapid rotation.

  The present invention aims to avoid the aforementioned disadvantages that we encountered

  in conventional metal sheet bearings.

  Accordingly, the subject of the present invention is a metal sheet bearing allowing a rotation of the shaft to be received, with a minimum torque also

  well at startup in normal operation.

  Another subject of the present invention is a method of manufacturing a metal sheet bearing by forming its bearing surface of the metal sheet by

  subjecting this sheet to a new heat treatment.

  The sheet bearing according to the invention is -

  constructed by retaining a flexible metal sheet which is tensioned to surround a rotating shaft of any machine, apparatus or the like, by a number of support members which are axially disposed and at a suitable distance from each other on the periphery

external of the rotary shaft.

  The metal sheet is formed by heat treatment so that its bearing surface has a slightly larger internal diameter than the rotary shaft, of a value necessary to produce a predetermined clearance, and furthermore, the sheet of metal thus formed is assembled to the corresponding tree while at least one end

  axial is attached to one of the support members above.

  The sheet bearing according to the invention can

  to be manufactured in the following manner: -

  Instead of a rotary shaft to be received, a main bar or a reference rod having an outer surface of a diameter slightly larger than the shaft, according to a predetermined clearance, is inserted into the area where the metal sheet will surround. the rotary shaft, then a suitable amount of tension force is imparted by some means to the metal sheet so that the metal sheet can tightly surround the main bar and subsequently the metal sheet and the main bar are maintained in the wound state and introduced into a heat treatment furnace, and

  then heated and slowly cooled.

  By the above steps, the metal sheet is formed to have an internal bearing surface that is obtained by exactly contouring the outer surface

from the main bar.

  By the steps mentioned above, the metal sheet is formed by heat treatment so that its bearing surface has an outer diameter slightly larger than that of the rotary shaft, sufficient so that there is the required clearance and in addition the metal sheet is assembled to the rotary shaft so that the bearing surface can face the shaft by fixing to the

  at least one end of the sheet to the support member.

  As a result, the metal sheet will not tighten the rotating shaft even at the rotational stop, and this results not only in a very low starting torque but also in a bearing surface having

  high accuracy compared to the game

  Furthermore, metal sheet bearings according to the invention can be manufactured using one or more ordinary heat treatment furnaces having been used and generally based on

  known heat treatment techniques.

  The invention will be better understood, and other purposes, features, details and advantages thereof

  will become clearer during the description

  explanatory text which will follow with reference to the accompanying schematic drawings given by way of example only, illustrating several embodiments of the invention and in which: FIG. 1 is a perspective view showing how to form a metal sheet bearing according to the invention; Figure 2 is an enlarged sectional view taken along the line 2-2 of Figure 1; Fig. 3 is a perspective view showing an embodiment where a metal sheet is retained by the L-shaped support pieces which are attached to an outer cylinder; and FIG. 4 is an extreme view of the mode of

  production of the sheet bearing according to FIG.

  In Figure 1, one can see how to form a bearing surface on the metal sheet used in

  the sheet bearing according to the invention.

  In the drawing, numeral 10 denotes a member for tensioning a metal sheet into a ready-to-use position, which consists of two opposing retaining discs 11, a first support member 13, a second support member 14 and a

third support member 15.

  In the center of each retaining disk 11 is defined a central opening 12 and the two openings 12 are aligned on the same central axis, when they are assembled. The three support members, from the first to the third members 13, 14 and 15 respectively, are arranged axially parallel to each other and are spaced apart at positions also dividing the support discs 11 into three sections. Each of the support members consists of two guide pins 16 which are placed very close to one another and on the same circular plane of the disk 11 and a support pin 17 which is radially outward and at the same

  distance from the pair of guide pins.

  The three support pins 17 have the same diameter and their centers are on the same circle on

the support disk 11.

  A main bar 20 with an outer diameter smaller than the opening 12, is inserted in the space defined by the two opposite openings 12 above, the outer diameter of the main bar being larger than that of the shaft rotating to be assembled later

  for real use, of diameter giving a pre-game

  determined, however its peripheral configuration will not be restricted to a round cylinder as shown

in Figure 1.

  With regard to the metal sheet 22, a sheet which has been cut from a sheet of stainless steel (10, w thick) is used to have a width slightly shorter than the distance between the two opposite disks of support 11 and at an appropriate length The cut sheet is stretched by passing it through passages defined between the main bar and the support members 13, 14 and 15 in succession, for example, starting from the first support member 13, then by the second support member 14 and then by the third support member 15 to return again to the first support member 13, one after the other, and in addition to a sequence, in more detail, taking a sinuous path by being bent along the radially inner surface of the guide pin 16 of the first support member 13, the outer surface of the main bar 20, the inner surface of the first guide pin 16 of the second organ 14, the outer face of the support pin 17, the inner face of the other guide pin 16 of the second support member 14 and again along the outer surface of the main bar 20 by repeating the same sequence Two longitudinal ends 23 and 24 of the metal foil 22 are fixed to the guide pin 17 by any suitable means such as, for example, by welding or the like, while it is imparted to the sheet of metal 22, a desired tensioning effort by a tensioning means, not shown, to clamp the main bar 20 so that the metal sheet

  22 can be maintained under a pulling force.

  When the metal sheet has been welded to the support pin 17 at both ends 23 and 24, the surplus portions of the metal sheet 22 outside the area

solder are cut.

  Then, the member 10 stretching the metal sheet with the metal sheet thus stretched around the main bar 20 is introduced into a treatment furnace

  thermal for heating for a predetermined time.

  The oven temperature is high and maintained at a value close to the solution treatment temperature, which varies according to the kind of steel to be used, then

  the heated member is slowly cooled.

  It is preferable that the heating step

  mentioned above is carried out under vacuum or in an atmosphere of a neutral or inert gas such as nitrogen

-2546426

gas or the like.

  The sheet of metal 22 thus heat-treated

  It can be released from the applied force and is plastically deformed because it has been heated to a temperature close to the solution treatment temperature of the material, so the metal sheet 22 has its bearing surface 25 which one gets by exactly copying

  the outer surface of the main bar 20.

  After finishing the heat treatment, the main bar 20 is withdrawn through the openings 12 of the retaining discs 11, and a metal sheet bearing is thus obtained which comprises the metal sheet stretching member 10 and the metal sheet 22 having been stretched in organ 10 and that was formed to have

a required area of support 25.

  The sheet metal bearing made in the above-mentioned manner is assembled to a rotating shaft whose diameter is smaller than the main bar 20 in an amount sufficient to form a

required support game.

  In the embodiment explained above, the two ends of the metal sheet were fixed to the support pin of the support member before the heat treatment, but the metal sheet can be heat treated, a other way, while both ends are held by the imparting means the voltage, and then the two ends are attached to

the support pin.

  In this embodiment, the sheet of metal has been explained as a simple cut sheet, but a number of sheets can be used by fixing the two longitudinal ends of each

  sheet to a support pin, respectively.

  Figures 3 and 4 illustrate another embodiment where a sheet of metal is retained in three

  wall positions of an outer cylinder 30 -

  Three slots 31 are formed which pass through the wall of the outer cylinder 30, the slots having equal lengths and each slot being defined to extend axially from one end of the cylinder to the nearest end of the cylinder , and they are circumferentially placed so as to also subdivide the circle of the outer cylinder 30

in three sections.

  Three support members 13, 14 and 15 having the same shape and size are maintained by being

  partially inserted into the respective slots 31.

  Each of the support members 13, 14 and 15 consists of two identical L-shaped pieces and one "A" side of each piece is placed symmetrically in back-to-back relationship, while the inner face of the other side B of the coin contacts the outer face of the cylinder

  external 30 near the edge of the respective slot.

  As can be seen in FIG. 4, a main bar 20 is inserted into the opening of the outer cylinder 30 and three metal sheets are arranged to surround the main bar 20 in a sealed manner. Two opposite ends of each sheet along the circular face of the bar 20 are inserted between the two corresponding sides "A" of the support members 13, 14 and 15 and are welded to the part indicated at 32 on the other side B of each L-shaped member. The heating step to form the required support surface 25 is undertaken in a similar manner

  to what has been explained in the embodiment

above.

  After forming the bearing surface 25, the main bar 20 is removed to form a complete article of a metal sheet bearing as shown

in Figure 3.

  As can be clearly understood from the foregoing explanations, the sheet metal bearing according to the present invention is constructed to have a bearing surface of the metal sheet which has been formed by thermally copying the outer surface of the metal sheet. a main bar having an outer diameter larger than that of the rotating shaft so as to maintain a predetermined clearance, and furthermore both ends of the sheet are attached to the support members and are ready to be attached to a desired rotary shaft .

  As a result, like the incor-

  porée in the bearing according to the invention does not tighten the rotating shaft at rest, not only the starting torque can be very low but it can also

  to obtain a high precision bearing surface.

  Accordingly, the present invention provides a sheet metal bearing of superior performance. Furthermore, metal sheet bearings according to the invention can be manufactured using an ordinary heat treatment furnace without requiring any particular equipment and therefore a sheet metal bearing can be economically manufactured having various advantages that could not be achieved. 'expect

with conventional bearings.

Claims (4)

R E V E N D I C A T I 0 N S   Metal sheet bearing, characterized in that it comprises a flexible sheet of metal (22) supported by a number of support members (13, 14, 15) which are spaced from each other at a distance suitably in the circumferential direction of the rotary shaft to be applied so that said rotating shaft can be surrounded by said metal sheet, said metal sheet being formed by heat treatment so that its bearing surface has a sufficiently larger diameter than the said rotary shaft for maintaining a predetermined clearance between said rotary shaft and said bearing surface of said metal sheet when said sheet is assembled to said rotary shaft by securely fixing at least one end of said sheet to said support member.   Bearing according to claim 1, characterized in that each support member is composed of two L-shaped pieces and is held in a slot (31) formed axially through the wall of an outer cylinder (30), said sheet of metal being arranged by being attached to each L-shaped member to surround   the rotary shaft in said outer cylinder.   3. A method of manufacturing a sheet bearing according to claim 1, characterized in that is inserted, instead of said rotary shaft, a main bar whose outer surface must correspond to the bearing surface of said bearing, and whose diameter is greater than that of the rotary shaft of a sufficient extent to leave a predetermined clearance, in an area where said metal sheet can surround said rotary shaft in the assembled state; providing a pulling force to said means by compressing said main bar by appropriate means; the support member and the metal sheet are maintained in the energized state and heated in a heat treatment furnace; the heated members are cooled to form the bearing surface on the surface of the sheet of metal which is in force contact with said main bar, being exactly contoured as the copy of the outer surface of said main bar. 4. Method according to claim 3, characterized in that the metal sheet is made of stainless steel and the heating is carried out in a vacuum or an inert gas atmosphere at a temperature close to the treatment temperature in solution of said stainless steel.