US2240548A - Apparatus for forming curved sheets - Google Patents

Description

May 6, 1941- Y E. B. CAIRNs 2,240,548

APPARATUS FOR FORMING CURVED SHEETS Filed July 27, 1938 Sheets-Sheet 1 ATTORNEYS U] gg IEWI l iii ( I Ha I SPI e May 6, 1941. E. B. CAIRNs l APPARATUS FOR FORMING CURVED SHEETS Filed July 27, 1938 3 Sheets-Sheet 2 BY HMKMAT'n-ORNEYS May 6 19M E. E. cAlRNs 2,240,548

, APPARATUS FOR FORMING CURVED SHEETS Patented May 6, 1941 APPARATUS FOR FORMING CURVED SHEETS Edmund AlB. Cairns, Naugatuck, Conn., assigner, by mesne assignments, to Cairns Corporation, New York, N. Y., a corporation of Delaware Application July 27, 1938, Serial No. 221,473

` In Great Britain August 3, 1937 i Claims.

This invention relates to processes and apparatuses for imparting controlled longitudinal and transverse curvatures to sheets of metal, and relates particularly to metal rolling devices and processes whereby cooperating concave and con- Vex rolls are utilized to impart a transverse curvature to a sheet of metal and a longitudinal curvature is produced by varying the angle, at which the metal is fed into the rolls. The invention further relates to automatically ccntrolled mechanisms for varying the angle at which the metal enters the roll, and includes control elements which may be pre-set to cause a predetermined curvature to be imparted to the sheets of metal.

Devices for bending sheets of metal with compound and intersecting curvatures are already known in the art. For example, my United States Patent No. 1,828,489, patented October`20, 1931, discloses a sheet bending machine consisting of a carriage for drawing a flat sheet of metal between a pair of opposed concave and convex rollers and during the drawing action tilting the rolls to exert longitudinal stresses which will cause the metal to be shaped and drawn into a compound curved sheet. p

My United States Patent No. 1,820,936, patented September 1, 1931, discloses another type of device which includes curved tracks orracks, along which a pair of horizontal complementary concave and convex rollsmay move to curve a sheet of metal both longitudinally and transversely. The curvature of the sheet is controlled bythe curvature of the racks. Therefore, the racks must be replaced when it is desired to produce sheets having dierent curvatures. n

The present invention has as its principal object the provision of devices and processes for imparting longitudinal and transverse curvatures to sheets of metal, whereby identically curved sheets may be produced in successive drawing operations and the curvature of the sheets may be varied as desired.

A further object of the invention is to producer a simplified metal rolling machine which is capable of producing greatly varied curvatures in sheets of material.

A still further object of the invention is to produce a simplied construction which is operable without Vibration or chattering to produce smooth and regularly curved sheets of metal.

The objects of theu invention have been attained by providing a device having a pair of cooperating concave and convex rollers arranged with their axes normal to a Work bench, `which bears and supports the weight of the rollers. The rollers are adapted to be reciprocated longitudinally of the table, and may also be moved transversely of their path to form a longitudinal curvature in a sheet of material which is also carried by the work bench.

rIhe mechanisms for guiding the rolls longitudinally of the work bench and for moving the rolls transversely of the bench are operatively associated through a pre-settable mechanism, whereby the transverse movement cf the `rolls may be varied with respect to the longitudinal movement to produce varying curvatures in the sheets of metal or to produce sheets of metal having gradually changing curves therein.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which:

Figure l is a plan View of a typical form of metal rolling device with the work bench partly broken away;

Figure 2 is a side view of the device disclosed in Figure l;

Figure 3 is a sectional View taken on line --S of Figure 2;

Figure i is a sectional View taken on line i-fi of Figure 2;

Figure 5 is a sectional View of a switch forming a part of the control mechanism for varying the curvature of sheets;

Figure 6 is a top plan view of a modified form of a metal rolling device; and

Figure 'l is a diagrammatic showing oi the electrical circuit for controlling the lateral displacement of the forming rolls.

|The form oi the invention illustrated in Figures 1 and 2 consists of a Work or draw bench lil upon which is supported a guide rail I2. The guide rail l2 is pivotally mounted at one end on a post I4 iixed to the draw bench and carries at the pivoted end a platform it upon which is mounted an electric motor I8. The electric motor i3 drives by means or" suitable reduction gearing 2li a sprocket 22 rotatably mounted on the post I, and a chain 2li for moving the forming mechanism 2S. The guide rail l2, as best shown in Figure 3, is or" generally I-shaped cross section, similar to a railroad rail, providing outwardly opening channels E8 and Lii in which the chain E@ is disposed. The end of the guide rail i2 opposite the post ld is provided with a sprocket Wheel 32 about which the chain 2d passes. Adjacent the sprocket 32 is a bracket 3% carrying an electric motor 38, which is provided with a drive gear 4Q which meshes with an arcuate rack 42 on the draw bench i3. The motor 38 is preferably provided with a reduction gearing system, not shown, which causes the gear l to rotate slowly and move the right-hand end of the guide rail I2 along the rack 42. Y

The forming device 25 may suitably consist of a rectangular frame i4 which carries a concave roll l and a convex roll 48. The rolls 45 and 48 are provided with suitable shafts Eil and 52, respectively, which are journaled in the upper and lower horizontal walls of the frame M. Frictional resistance to rotation of the rolls ll and i8 may be reduced by interposing roller thrust bearings 54 between the ends of the rollers l5 and 113 and the adjacent surfaces of the frame M.

The frame ifi and rollers i5 and 4S are guided along the guide rail I2 by means of rollers 55 and 58 disposed in recesses @t and S2, respectively, inthe lower portion of the frame lill. The rollers 5S and 58 engage the upper lateral edges of the guide rail i2 and prevent a rotation of the frame M relative to the guide rail.

The entire weight of the forming mechanism 26 is supported on the draw bench lil through the medium oi .anti-friction rolls 64, whereby the only stresses applied'to the guide rail are those encountered due to shifting of the forming mechanism 26 relative to the draw bench I5. As the forming mechanism is extremely heavy, there is little tendency for it to vibrate or tilt relative to the draw benchduring a forming opl--V eration.

The device is provided with means for holding a sheet of metal under tension, so that it may be drawn out and curved both longitudinally and transversely by the forming rolls. The sheet holding and tensioning means may consist of a pair or" arcuate jaw members 65 and 53, which are pivotally mounted by mean-s of loops lli on an extension l2 of the pivot post I. The opposite end of a sheet of material may be gripped between an arcuately curved plate I4 pivotally mounted on a post i6 which is iiXed-to the draw bench Ill and a cooperating curved plate 'iii which is bolted to the curved plate 16. t will be understood that the posts i2 and 'l may be braced andere impart a predetermined longitudinal curvature to the sheet of metal so that duplicate sheets of material may be produced, I hav-e provided electrical control means for varying the speed and direction of operation of the motor SS. The motor 33, as well as the motor I8, may be of the three-phase induction type whereby by varying the voltage supplied to the motors their speed of operation may be varied. Adjacent the arcuate rack i2 I have placed a series of switch elements 82 provided with switch actuating arms Sli, which are engaged by a shoe carried on the outer end of the guide rail i2. The shoe 85, during its movement inan arcuate path'with the guide rail, will contact a roller 58 carried on the switch actuating arm 84, as best shown in Figure 5, and will depress a contact arm QD into engagement with another contact arm S2 carried by the switch 82, thereby closing a circuit which, as in a manner hereinafter described, shunts the circuit around a resistance to increase the speed of the motor.

A suitable circuit for controlling the motor 33 is disclosed in Figure 7. This circuit consists of the three-phase lead wires Si@ leading from a source of current supply to the stator of the motor 38. A suitable reversing switch 96 is located in the lines 96 for reversing the direction of rotation 0f the motor. This switch e5 may be located where desired in the path of movement of the shoe 8% in order to reverse the direction of movement ofV the guide rail l2. The rotor Vof the motor 38 is connected through suitable leads 98 to a. double throw switch I, whereby the circuit may be completed either through a manually controlled resistance changing device H32,

or through the automatically. controlled circuit comprising leads Idil'. Each of the leads IM is connected through three identical resistance grids IilG, Iil and H0 to the source of current supply. The grids HIS, H23 and Il consist of a plurality of similar resistances of identical value connected in series through magnetic switches II2. At the beginning of a forming operation, the switches I I2, in the form of the invention illustrated, are closed and the resstances are in to render them rigid enough to withstandfthe stresses to which they are subjected, without bending. One end'of the sheet of metal, designated as Si), is threaded between the rolls l5 and 58, `and its opposite ends then gripped between the arcuate plates G, and lll, '53. The curvature of the gripping plates 55, iand E'IB is substantially the same as the curvature of the rolls "i5 and d8.

If the motor I8, only, is actuated, the forming mechanism 26 is drawn `along the guide rail I2 imparting only a transverse curvature to the sheet of meta-l ci). When, however, the motor 33 is actuated to move the right-hand end of the draw bar I2, for example, in a clockwise direction, the rolls i6 and i8 are likewise moved transversely ci the draw bench it, stretching the sheet of metal Sil longitudinally and changing the angle at which the sheet of metal enters the bight between'the forming rollers. By varying the lateral displacement of the forming mechanism 28, varying longitudinal curvatures are imparted to the sheet. These curvatures can be suitably varied by varying the speed at which the right-hand end of the guide rail l is moved along the arcuate rack 42, and also by varying the extent of displacement of the end of guide rail I2. i

f In t9 control the deviceautomatically to 88 to close the circuit through control switch 82,

' the corresponding resistance in each ofthe grids I, Ilia and Ill is cut out until all the switches I I2 are open as shown in Fig. 7. A master switch I I6 may also be connected in the circuit for controlling operation of the entire'device. The resistances making up the grids are preferably selected to vary in equal stages the change in speed of operation of the motor from the desired minimum speed to the desired maximum speed. It will be seen that a proper spacingV of the switches 82 along the arcuate rack i2 .will'enable the device to form many diiierent longitudinal curvatures to sheets of material, and when once so located will render the duplication of curvatures a very simple matter.

In Figure 6 is illustrated another form of the invention which may consist of a draw bench I'Z having guide rails I22 at its lateral longitudinal edges.V At the left-hand of the draw bench |20 is fixed an electric motor |24 whichA through suitable gearing |26 causes movement of chains |29 about sprockets i3!! and |32 adjacent each of the guide rails |28. One pass of eachV chain |28 is connected to a carriage |34 which is slidable along and guided by the guide rails |22. The carriage i3d is provided with a 4centralr `aperture |36 within which is mounted a metal forming device |3, substantially identical with the metal forming device 2t heretofore described. The carriage |34 also supports a motor M0 which through suitable reduction gearing |i2 Idrives a threaded shaft |44 passing through 'a portion of the metal forming device |38. Operation of motor |153 will cause the metal forming device |33 to move transversely of the draw bench |20. In this construction, the motor |40 is connected through a circuit like that disclosed in Figure 'l to a series of switches |32, which are identical with the switches heretofore described. 'I'he switches 82 are disposed adjacent one guide rail |22 and are engaged by a shoe I 46 to vary the speed of motor |43. The shoe Iif is carried at the end oi the carriage E35.. If desired, one of the switches 32 may be replaced by a reversing switch 9S in order to cause a complete reciprocatory movement of the metal forming device |38.

A sheet of metal may be supported on the draw bench |2l in the manner described in connection with the first described modication of the device, and upon longitudinal and transverse movement of the metal forming device |38 the sheet is shaped into a compound transversely and longitudinally curved body.

While I have described the metal forming devices 26 and |38 as consisting of a pair of complementary concave and convex rollers, it will be apparent that die members consisting of complementary curved iixed members may also be used for shaping the material. rFliese die members may be similar halves of the rollers 46 and 43 disclosed in Figure 3; that is, of such shape as would be produced by severing the rollersvll and iii diametrically alongA their longitudinal axes.

In operation, a sheet of metal is threaded between the rolls of the forming devices 2S or |38 with the forming devices at the right-hand end of the guide rails. rThe ends of the sheets are bent transversely and clamped in the gripping devices E5, 68 and it, le. The motors |8 and 38 in Figures l to 5, or motors lid, lli@ in Figure 6 are started drawing the forming devices along the guide rails. Operation of the lateral traversing motors 3S or it@ will cause displacement of the forming devices and the production of longitudinal and transverse curves in the sheet of meta-l. The longitudinal curvatures imparted to the sheets will, as before explained, be controlled by the transverse displacement of the forming device. During operation, the metal sheet will be stretched and worked to produce a change in shape and rearrangement of the crystalline structure of the metal. The crystalline rearrangement rigidihes and strengthens the sheet so that structures formed from the sheets are far stronger and more rigid than similar structures formed from hat sheets of the same thickness. It will be understood vthat the sheets may be subjected to a plurality of successive shaping passes of the forming devices, and that the final curvature of the sheet may be produced by steps rather than in one shaping pass of the forming device.

It will be understood that any suit-able means may be provided for varying the spacing between the rollers or the die members to accommodate sheets of lmaterial of difieren-t thicknesses, and that such adjusting means may be regulated to produce a narrower space at one end of the rollers than at the other end, thereby working the metal moreat one edge of lthe sheet than the other end, imparting an arcuate bend to the sheet in addition to the longitudinal and transverse curvatures.

In connection with the working of certain types of metals, it may be of advantage to operate under relatively high temperature conditions. This condition might arise, for example, in Working with certain light metals or alloys. In such case the rolls may be conveniently heated internally by hot oil or steam which may be circulated by means of exible connections attached to hollow shafts for the rolls as indicated by reference character 5|. The rolls may be provided with hollow ducts or chambers through which the heating `medium may effectively circulate. If additional heating is necessary, the frame M or the carriage |34 may carry a series of gasjets, fed from a manifold and to which gas or other combustion medium may be supplied with iiexible connections preferably carried overhead to permit easy movement of the carriage. The several jets can be adjusted to heat the sheet uniformly across its face. If necessary, a series of jets can be carried on each side of the movable rolls and on the front and back also. Hoods or muiiles may be provided to obtain more eiective action. Another effective device is the use of electric resistanee coils similarly placed across the face of Y the sheets. The amount of heating can then be closely controlled.

The above described embodiments of the invention should therefore be considered as illustrative only, and not as limiting the scope of the claims.

I claim:

1. A device for imparting a longitudinal and transverse curvature to a sheet of metal comprising means for restraining the ends of the sheet of metal against movement toward each other, a substantially horizontal support, complementary concave and convex forming elements mounted for movement longitudinally and transversely of the support with their axes perpendicular thereto and means for moving the forming elements transversely and longitudinally of the support, said last-named means comprising a guide rail for guiding the forming elements, means connecting one end of the guide rail to the support and means for moving the other end of the guide rail relatively to the support.

2. A device for imparting a longitudinal and transverse curvature to a sheet of metal comprising means for restraining the ends of the` sheet of metal against movement toward each other, a substantially horizontal support, complementary concave and convex forming elements mounted for movement longitudinally and transversely of the support with their axes perpendicular thereto and means for moving the forming elements transversely and longitudinally of the support, said last-named means comprising a guide rail for guiding the forming elements, pivot means connecting one end of the guide rail to the support, a motor mounted on the guide rail adjacent the pivot means and a flexible member connected to the forming elements and actuated by the motor for moving said elements axially of the guide rail.

3. A device for imparting a longitudinal and transverse curvature to a sheet of metal comprising means for restraining the ends of the sheet of metal against movement toward each other, a substantially horizontal support, complementary concave and convex forming elements mounted for movement longitudinally and transversely of the support with their axes perpendicular thereto and means for moving the forming elements transversely and longitudinally of the support, said last-named means comprising guide means for the forming elements pivotally connected at one end to the support, a motor mounted on the free end of the guide means, an arcuate rack fixed with relation to the support adjacent the other end of the guide means and a gear driven by the motor meshing with the rack to move the free end of the guide means transversely of the support.

4. A device for imparting a longitudinal and transverse curvature to a sheet of metal coni-l prising means for restraining the ends of the sheet of metal against movement toward each other, a substantially horizontal support, complementary'concave and convex forming elements mounted for movement longitudinally and ltransversely of the support with their axes perpendicular thereto and means for moving the forming elements transversely and longitudinally of the support, said last-named means comprising a plurality of switch elements, means associated withV the forming elements for actuating said switches, an electric motor for moving the forming elements transversely of the support and an electric circuit for said motor controlled by said switches for Varying the speed of operation of the motor.

' EDMUND B. CAIRNS.

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