US2467344A - Bending machine - Google Patents

Description

April 12, 1949. i T. A. TAYLOR 2,467,344

. BENDINCF MACHINE Filed June 13, 1945 3-SheetsSheet 1 April 12, 1949. "r. A. TAYLOR 2,467,344

BENDING MACHINE Filed June l3, 1945 3 Sheets-Sheet 2 7m 7' MEM 7 April 12, 1949.

Filed June 15, 1945 T. A. TAYLOR BENDING MACHINE 3 Sheets-Sheet 3 Patented Apr. 12, 1949 BENDING MACHINE.

Tristram Allan Taylor, Enderby, Leicester, England, assignor to Power Jets (Research and Development) Limited, London, England Application June 13, 1945, Serial No. 599,255 In Great Britain June 17, 1944 7 Claims. 1

This invention relates to a bending machine the purpose of which is to facilitate the operation of bending the vanes of centrifugal impellers or the like, more particularly when such bending is required to be carried out with the work hot. Certain types of centrifugal impeller are made by machining radial vanes integral with a boss, the leading edges of these vanes subsequently being required to be bent in order to afford the necessary shape for aerodynamic or hydraulic reasons. The bending of the vanes is a somewhat delicate operation' and if not carried out under carefully controlled conditions is liable to give rise to failure owing to the formation of cracks or flaws which may be imperceptible under ordinary inspection but which may yet develop in use and bring about failure. It is also desirable to perform such operations as bending without impairing the surface of the vanes and without damaging adjacent areas. For the purposes of production it is desirable that bending should be capable of being done without the exercise of great manipulative skill and also that it should be done quickly; for example in the case of a large impeller which may require hours to be properly heated up for bending it is clearly desirable to be able to bend the whole of one series of vanes in one heat and if the bending is carried out in the open air the temperature of the work may drop considerably if the operation is too prolonged, with the result that, the last of the bending may be effected at too low a temperature with consequent damage to the work. The present invention seeks to provide a machine which will fulfil the various requirements whilst at the same time being relatively simple in nature, economic to make and easy to use.

According to this invention a bending machine for impellers or like objects is constructed and adapted to be heated in respect of at least a part thereof together with said impeller and comprises fluid operated pressure means adapted to bend the vanes of said impeller. The said means may be disposed with suitable location in conjunction with the impeller to be bent, and may be adapted to be registered appropriately with each vane to be bent. To prevent damage to the machine or the impeller, the said machine is preferably operated by compressed air. In one form, the machine comprises a frame adapted to be mounted coaxially with the impeller and to be turned relatively thereto about the impeller axis in conjunction if desired, with means for indexing or registering the frame relative to the impeller; the frame supports a ram arranged for rectilinear movement and suitably guided to that end, and a piston and cylinder adapted, to be connected to a source of compressed air which operates the ram, the latter having attachable to it a die suitably profiled to produce the required bend and incidentally also suitably formed to avert collision with an adjacent vane which may have been previously bent and may therefore tend to cause a foul. In conjunction with the die there is provided a former block called a bend block adapted to the position and held as a pillow behind and beneath the vane to be bent and profiled in the complementary sense to the moving die. Either used separately or made as a part of the bend block a shim of readily deformable sheet metal may be used between the surface of the vane to be bent and the surface of the moving die which must necessarily slide in relation thereto. The following describes for the purpose of example two forms of embodiment of a machine according to the invention with reference to the accompanying drawings in which:

Fig. l is a partial perspective view of an impeller;

Fig. 2 is a view in part section of one form of apparatus according to the invention;

Fig. 3 is a detail sectional view of a stop cock;

Fig. 4 is a section on the line A-A of Fig. 3;

Fig. 5 is a diagrammatic representation of the action of said stop-cock in one position;

Fig. 6 is a similar representation with said stop cock in another position;

Fig. 7 is a partial View of Fig, 2 in the direction of arrow B;

Fig. 3 is a partial View in vertical section of a second form embodiment of the invention.

Referring to the drawings, Fig. l is a perspective View of part of a doublesided centrifugal impeller of which each vane 2 is to be bent over at its leading edge 3 into the position shown at 3A.

Fig. 2 is a partial sectional view of the general arrangement of one form of apparatus according to the invention in which the impeller l is disposed horizontally on a vertical axis 4 with its vanes 2 consequently disposed in vertical planes, each at a different angle to the said axis 4 of said impeller. The diagram shows only one quarter of the impeller l, i. e. the right hand upper quarter, the apparatus being in position to operate eventually on every vane 2 in the upper half of the impeller I,

The said impeller l is supported on a table (not shown) and itself supports a relatively heavily constructed frame 5 which has a central bore 6 acting as a journal on a stubshaft l which pr0- jects upwardly and downwardly coaxially from a circular plate 8 which is adapted to be located with and firmly secured to the hub 9 of the impeller I.

A radial extension ID from the frame supports a vertical air cylinder II Within which there is a piston rod I2 carrying a piston I8 and extending downwards through a heat resisting bush or gland I3 for example of graphite in the frame 5 to project below the radial extension thereof. The piston rod I2 where it extends carries a ram head or platen I4 to which can be fixed the moving die I 5. This die I5 which is not unlike a wedge with a properly contoured surface to produce the required bend has extending from it pins or other projections I6, I! adapted to slide on guide rail 36 attached to the frame 5, so as to ensure rectilinear movement of said die I5. The projection I6 has a cut away portion (Fig. 7) so that it can slide along guide rail 35. The guide rail 36 may be provided with stops (which may be adjustable) to determine the limits of travel of the die I5 and therefore of the piston I8. The said piston I8 is double-acting and preferably furnished with metal piston rings I 9. There are two air connections 23, 2! with readily detachable connectors 20A, 2 IA to air supply unions and the air supply relative to the piston I8 is reversible for example by means of a three-way cock 22 in a supply line 23. A removable part of the machine consists of the bend block 24 which is a metal block so shaped as to be capable of insertion between the impeller vanes 2 and having suitable clamping means for example a C clamp 25 to hold it when inserted. The bend block 24 is profiled to conform to the under side of the vane 2 after bending and is held as a pillow behind and beneath said vane 2. As well as or instead of clamping means the bend block 24 may be arranged to interlock with or be steadied or located by the guide rail 35 for the die I5. For this purpose the bend block 24 is provided with an extension 26 adapted to be rigid with the frame 5. In this way the bend block 24 and die I5 react almost directly one against theother to the effect that any lack of rigidity or any inaccuracy in the construction of the machine is minimized in regard to the accuracy of the bend. Attached to or associated with the bend block '24 is a flap or shim 21 (Fig. 7) of relatively thin and deformable metal which laps over the upper edge 3 of each vane 2 to be bent so as to lie between the die I5 and the surface of the vane 2 which is about to be borne upon by the die I 5 and thus prevents the vane surface from being damaged. All the various parts above described, the sliding parts associated with the piston I8 and ram head I4 as well as any other working parts are of such material that they can be heated along with the impeller I. At present the requisite temperature lies between 400 and 500 C.

The said parts are also adapted to be lubricated by graphite or other heat resisting lubricant.

The three way cock 22 is adapted to pass compressed air from a source of supply (not shown) either to the space in the cylinder above piston I8 so as to force said piston downwards to perform the vane bending operation, or into the space below said piston I8 to move the latter upwards after the bending operation.

The mode of action of the cock 22 is illustrated by Figs. 3-6. In Fig. 3 a frusto-conical valve element 30 is rotatable by means of handle 29 in the body 22 of the cock. The element 30 is provided with an L shaped bore 3| (Fig. 4) of which one end communicates in the position shown in Figs. 3 and 4 with the inlet 23 for supply of compressed air while the other end communicates with a passage 35 in the body 22. The element 30 is also provided over a part of its periphery with an arcuate slot 33 which in the example shown subtends an angle of approximately at the centre of the circle of which it forms part. In the position shown in Figs. 3 and 4, one end of the slot 33 communicates with a passage 32 in the body 22 and the other end of slot 33 communicates with an outlet 34 in said body 22.

As seen in Fig. 2, when the connectors 20A, 20B, and 2IA, 2IB are joined together, passage 35 communicates with the cylinder space above piston I8 and passage 32 with the cylinder space below said piston I8.

Fig. 5 illustrates diagrammatically the operation of the stop cock when the latter is in the position shown in Figs. 3 and 4. Compressed air from a suitable source (not shown) enters inlet 23 and flows through bore 3I to passage 35 and thence through pipe 20 to cylinder II. At the same time exhaust air leaves cylinder II by pipe 2| and flows through passage 32, slot 33 and outlet 34 to atmosphere.

If the handle 29 and thus the element 30 is rotated through 90 to the position shown in Fig. 6, compressed air enters inlet 23 and flows through bore 3I to passage 32 and thence to the space in cylinder II below piston I8 while exhaust air leaves the space above said piston I8 and flows through passage 35, slot 33 and outlet 34 to atmosphere.

The use of the machine is briefly as follows. The impeller i being mounted with its axis 4 vertical on a suitable truck or table for placing in a heating oven has plate 8 with stubshaft 1 secured to it with careful appropriate location. The frame 5 is then mounted on the stubshaft I and secured thereon for example by a nut 29' and washer 30 Which permit rotation of the frame 5 relative to the impeller I. The piston I8 is in its up position and the die I5 in place the precise location of the die I5 in relation to the first vane 2 to be bent having been established and the stops (if any) for the die I5 having been set, the impeller I and the machine are then heated along with the bend block 24 the process of heating up taking maybe three or four hours or longer as necessary. When the appropriate upper temperature has been reached and soaking is complete the apparatus is removed from the oven and the air lines 20, 2I immediately connected to the cylinder 22 and the bend block 24 is put into place behind the first vane 2 with the sheet metal shim 21 overlapping this vane 2. The clamp 25 is secured in position and the air pressure is then turned on with the stop cock in the position of Figs. 3-5 so that the compressed air acts above the piston and the air below the piston I8 is exhausted allowing the latter to descend so that the die I5 bears on the first vane 2 and presses it against the bend block 24 sliding over the shim 21 in the process. As soon as the die I5 has reached its bottom limit of travel the air supply is reversed by rotating handle 29 through 90 to bring the stop cock to the position of Fig. 6. This lifts piston I8 and clears the die I5, the bend block 24 and clamp 25 are removed and the frame 5 is rotated to the next vane 2I, the bend block 24 is again inserted, and the operation is repeated. It is found that the operation is so expeditious and the rate of cooling is such that 'all twenty-nine vanes on one side of a large impeller can be bent in one heat. If the impeller I be double-sided, the frame 5 is now detached from it, the impeller is turned over, the die I5 and bend block 24 are replaced by others of opposite hand and the whole procedure is then repeated including re-heating if necessary.

In certain cases the machine may be arranged to perform the operation more speedily by multiplying the number of dies and bend blocks in use simultaneously or where double-sided impellers are considered the machine may be in effect duplicated on the two sides and operate simultaneously or independently on the two sides. In such case it may be found preferable to mount the impeller during bending on a horizontal axis the rams moving in opposition to each other horizontally. Such an arrangement is shown diagrammatically in Fig. 8.

In said Fig. 8 the mode of operation is similar to that described above but in this case the impeller l is disposed vertically on a horizontal axis 4, and two pistons l8 are provided adapted to move simultaneousl in opposite horizontal directions. Two dies l5 and two bend blocks 24 are used simultaneously the die and one bend block on one side of the impeller I being of opposite hand to the die and bend block on the other side. The inlets 23 for the two threeway cocks 22 are interconnected by a pipe 31 for the supply of compressed air and the bend blocks 24 are clamped into position by means of a bolt 39 and nut 38. The dies I5 are guided in their horizontal movement by means of projections M which slide along slots 40 in the frame 5. The action of the three way cocks 22 and of the remainder of the assembly is substantially as described previously and in this case the vanes 2 can be bent after one heating.

If there be any difficulty in maintaining the appropriate temperature the bend block or die may itself be heated for example by the embodiment therein of electric heater elements and parts of the impeller not being actually worked upon may if required be to some extent lagged against cooling by being enclosed in a loose tent of asbestos cloth or the like which may be supplied with hot air.

The circular plate 8 may be provided with an indexing fixture for example in the form of notches in its periphery, the frame 5 then carryina manually operable latch to engage one of the notches of which there will be as many as there are vanes to be bent. The latch may then be used to lock the frame to the impeller at each vane bending operation.

I claim:

1. A machine for hot bending the vanes of a centrifugal impeller comprising a frame constructed and adapted to be heated together with said impeller, means for mounting said frame on the impeller so as to be rotatable relative to and about the axis of said impeller, a movable profiled die, fluid pressure operated means supported by said frame and adapted to urge said die in one direction against a vane of said impeller and in the opposite direction to release said die from said vane whereby rotation of said frame enables each vane to be successively bent.

2. A machine for hot bending the vanes of a centrifugal impeller comprising a frame constructed and adapted to be heated together with said impeller, means for mounting said frame on the impeller so as to be rotatable relative to and about the axis of said impeller, a movable profiled die, fluid pressure operated means supported by said frame and adapted to urge said die in one direction against a vane of said impeller and in the opposite direction to release said die from said vane, and a profiled block adapted to be held as a pillow behind and beneath the vane to be bent whereby rotation of said frame enables each vane to be successively bent.

3. A machine for hot bending the vanes of a centrifugal impeller comprising a frame constructed and adapted to be heated together with said impeller, means for mounting said frame on the impeller so as to be rotatable relative to and about the axis of said impeller, a movable profiled die, fluid pressure operated means supported by said frame and adapted to urge said die in one direction against a vane of said impeller and in the opposite direction to release said die from said vane, and a detachable profiled block adapted to be held as a pillow behind and beneath the vane to be bent whereby rotation of said frame enables each vane to be successively bent.

4. A machine for hot bending the vanes of a centrifugal impeller comprising a frame constructed and adapted to be heated together with said impeller, means for mounting said frame on the impeller so as to be rotatable relative to and about the axis of said impeller, a movable profiled die, fiuid pressure operated means supported by said frame and adapted to urge said die in one direction against a vane of said impeller and in the opposite direction to release said die from said vane, a detachable profiled block adapted to be held as a pillow behind and beneath the vane to be bent, and a detachable deformable flap adapted to lap over the edge of the vane to be bent and disposed between said die and said vane.

5. A machine according to claim 4 further comprising indexing means.

6. A machine according to claim 4 for a doublesided impeller comprising for each side of said impeller at least one double-acting piston operating under compressed fluid in one direction to urge a profiled die against a vane of said impeller and in the opposite direction to release said die from said vane.

7. A machine for hot bending the vanes of a centrifugal impeller comprising a frame constructed and adapted to be heated together with said impeller, means for mounting said frame on the impeller so as to be rotatable relative to and about the axis of said impeller, a movable profiled die, at least one double acting piston supported by said frame and operating under fluid pressure in one direction to urge said die against a Vane of said impeller and in the opposite direction to release said die from said vane, a detachable profiled block adapted to be held as a pillow behind and beneath the vane to be bent, and a detachable profiled flap adapted to lap over the edge of the vane to be bent and disposed between said die and said vane.

'I'RIS'IRAM ALLAN TAYLOR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 101,394 Stevens Mar. 29, 1870 431,545 Bayley July 8, 1890 1,717,735 Roy June 18, 1929 1,913,591 Graf June 13, 1933 1,962,459 Ostlund June 12, 1934 2,013,705 Warren Sept. 10, 1935 2,092,092 Sinclair et al. Sept. 7, 1937 2,104,468 Osborn ..n Jan. 4, 1938

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