US2370215A - Method of and apparatus for forming venetian blind slats - Google Patents

Description

Feb. 21,1

7 A. B. WILSON IETHOD OF AND APPARATUS FOR FORMING VENETIAN BLIND SLATS Filed Feb. 9, 1942 en m es its 2?, 1945 stares PATENT OFFICE THUR-0F APPMATUS FOR FORM- mo VENETIAN' BLIND SLA'ES' I Allen B. Wilson, Evanstcn, Ill, or to Acme Steel (Company, @hiccso, lit, a corporation oi Hlinois Application February 9, 1M2, No. $30,612

ici. 1532) 12 Claims,

curved or other non-planar cross section. The.

present invention is an improvement upon that described and claimed in the copending application of Joseph L. Hunter. Serial No. 279,391, filed June 19, 15, 39,

in order that's. Venetian blind slat may have the required stiffness when it is formed of thin metal, it is necessary that it have a curved or other non-planar crcss section, and strips having this characteristic and alsohaving parallel edges may be used advantageously for other purposes. it has been found that commercial strip steel, as it comes from the mills, is not well adapted for the commercial manufacture of Venetian blind slats because it is not perfectly fiat and has variations in temper and gauge distributed more or less throughout its entire length and area, so that attempts to convert a commercial strip into a form having a curved or other non-planar cross section by any of the usual rolling and bending tions of the strip to be stretched longitudinally to substantially the same extent that the intermedi ate portion was stretched in the first stage of the process. The elongated strip than emerges from the second stage of the process as a straight member having a bowed cross section and parallel longitudinal edges.

In the said application of Joseph L. Hunter, there is illustrated and described a form of apparatus for carrying out the two=stage process above termediate portion is stretched by passing it end-= wise over a crowned roller while under tension sufilcient to sheet the stretching of the desired portion.

The present invention is based upon the discovery that the above-described two-stage method may be practiced without the use or cry supports in advance of and following the forming rolls which impart the transverse curvature to the strip and that this simplification may be accomplished by employing in the first stage the relatively inclined sets of blocks, disclosed in said application of Joseph L. Hunter. and so adiustmg the relative inclination of the successive sets 0! blocks as to cause to be effected in the first stage nallyby a stress exceeding the elastic limit of the metal, the degree of tension exerted upon the metal being such that the irregularities in the portion subjected to the stretching operation are removed so that all parts of this intermediate 4 portion would be under compression if the tension were released. Having thereby established a knowncondition in the metal strip, asdistlngulshed from the uncertain and unknown condition existing in the commercial material at the place of bending, thereby causing the lateral porthat precise relativeelongation of different laterally displaced parts of the strip which will have the efi'ect of causing the strip to emergefrom the I'ormifig rolls of the second stage as a. member-oi bowed cross section and parallel edges which is either straighter .01 any other desired longitudi nal shape. By this improved method the strip passes directly from the first stage to the second stage an toe relativestretching of the intermediate portion and the lateral edge portions is so regulated in the first stage that the strip will coact with the forming rolls and assume a, curved cross section'and a straighttorm. By this improvement both the apparatusand the method are simplified and the apparatus ofthe first stage may be readily adjusted while the stretching and Liorming are in progress in order to cause the final product to have the desired form. Other oblects of the invention relate to various features or construction -and arrangement of the apparatus and to details of the method which will appear morefully hereinafter.

The nature of the invention will be understood from 'the following specification taken with the accompanying drawing .in which one example of thedmprovd method and one form of the improved apparatus are illustrated. In the drawing,

Figure 1 shows a partial side elevation of the improved apparatus of the present invention;

view of a portion of one of the completed slats.

As illustrated in the drawing, the strip metal employed in the practice of the present invention, which metal may preferably be thin steel which is hard and resilient, is wound in a coil supplied from a reel 8 fromwhich it passes around an idler roller and then around a friction drag roller l0 having an outer surface of rubber or the like and provided with an adjusting device i iflwhich may be regulated for varying the resistance to the rotation of the roller for retarding the movement of the metal strip II as it is unwound from the coil. This metal strip is withdrawn from the reel 8 under tension and is moved through confining passages in two sets of die blocks l2 and I3 and, after emerging from the second set of die blocks, the strip passes between forming roll H and It provided with complementary concave and convex peripheral surfaces, respectively, which may conform to the arc of a circle, and which bend the strip transversely as it passes therethrough in a continuous operation. The forming rolls I4 and it maybe relied upon to feed the strip through the apparatus and maintain tension therein, in which case the roll l5 will have a peripheral surface of rubber or the like, or the strip may be drawn through the rolls l4 and II, as well as through the die blocks l2 and It, by power driven drive rollers 29 and 30 which maintain suillcient tension in the strip to bring about the stretching of the metal in the manner hereinafter referred to.

The set of die'blocks l2 comprises an upper block I! and a lower block I! which are provided with complementary concave and convex surfaces, respectively, extending transversely thereof to form between them a confining passage of arcuate cross section concaved downwardly and of substantially the same widthas the strip, the

' height of the passage being only slightly greater than the thickness of the metal strip to be treated so that the upper and lower sides of the strip are engaged by the blocks l2 and I2, respectively,

during the passage .of the strip th'erethrough. The v blocks i2 and l2 are secured together and maintained in the desired spaced relation by side plates l2 which are'secured to the blocks by screw If. The sideplaies W are provided with rearwardly extending arms I! having rotatably mounted be-' tween them a guide roller It which 'is'adapted to contactwiththeundersideofthestrip II asitis withdrawnfrom the reelsothatthestrlpiscaused' tofollowanxedpa'thasitentersoneofthedie block; it, regardless of theangular position of thisbiock.

v The otherset of die blocks lI-comprises an upsecured together arcuate cross section concaved downwardly and and a lower block it" which are and spaced apart by side plates il secured in position by screws It. These die blocks It and It are also provided with opposed concave and convex surfaces, respectively, which form between them a restricted passage of per block, I3

formed by radii having a common center, these surfaces preferably having the same width and curvature and the same spaced relation as the corresponding surfaces formed on the die blocks II. The side plates W are provided with rearwardly extending ears I! which project between similar ears I! formed on the side plates 12. These ears are pivotally connected by pins l1 and are adapted to permit the die blocks I! to be swung angularly with respect to the die blocks It so that the angularity of the restricted passages throiigh the two sets of die blocks may be regulate The die blocks I3 are adapted to be secured upon a fixed support, not illustrated, and the side offset upwardly and rearwardly to provide a support for the rear portion of the die blocks II. For this purpose, the side plates I! are provided with another pair of upwardly extending ears II having a pivotal engagement by means of the pin II with an eye-bolt 2|. This bolt extends upwardly through an elongated slot it formed in the bar 18 and is engaged beneath the bar by a washer 22 and a wing nut 23. On the upper side of the bar, the bolt is engaged by a washer 24 and a wing nut 25. It will be apparent that byadjusting the wing nuts 23 and II the rear end of the set of die blocks 12 may be raised or lowered in order to change the angularity of the passage between the blocks l2 and l2 with respecttto the passage between the blocks It and II". The cylindrical roller It which engages the underside of the commercial strip material being withdrawn from the reel 8 is adapted to maintain the strip in alignment with the passage between the blocks I! and Ill as it enters that passage, regardless of the angular positions of these blocks.

Due to the curvature of the passages between the die blocks, it will be apparent that the intermedlate'portion of the part I I of the strip which is passing through the gap between the two die blocks must travel a longer path than the edge portions which re nearer to the pivot I! whichconnects the two sets of blocks. Inasmuch as all parts of the strip must travel at the same speed,

this difference in the distance throughwhich different parts of the strip must pass, in going from one set or blocks to the other, results in a permanent stretching or elongation of the intermediate portion of the strip. The width of the portion of the strip which is thus stretched and the relative extents of the stretching of dlil'erent portions of the strip which are laterally displaced from each other may be regulated by adlusting the wing nuts 23 and II and thereby effecting a corresponding vadiustment of the longitudinal inclination of the-passage between the die blocks I! with respect to the corresponding passage through the die blocks ll. l'ior example,-by increasing this angle, as a result of lowering the rear end'ofthe die blocks II, the stretching or permanent elongation of the intermediate portion of strip may be increased camera with respect to the edge portions. By suitably adjusting the blocks the permanent stretching which is effected in the blocks l2 and It may be caused to extend throughout a major portion of the width of the strip although varying in magnitude in different laterally displaced parts of the strip. In some cases the commercial strip mate rial may have its center portion elongated as it comes from the supply reel and, in that event, it may he desirable to effect some permanent stretching oi the edge portions of the strip as it passes through the sets of blocks 52 and it. This may be done by raising the blocks 92, as indicated dotmd lines in Fig. 2, thus causing the edge nortions oi the strip to pass through a longer gap than the center portion in traveling from one set of blocks to the other.

After emerging from the die blocks 52, the strip is carried through the forming rollers id and it which are secured on shafts 2? and 2%, respecvely, these shafts being power driven in the ectlons indicated by the arrows. The laterally curved peripheral surfaces l5 and 85 of the i ud, since the resilient metal dency to spring sacs; partially toward was losing thus hent transverse curs-a he peripheral is metal will incl lain p when a number oi then-c are usual manner a Vane-- the rolls 3& and iii moving thestrip and main degree of tension therein,

as well throush the hlcchs cctu driving rolls sa ce opposite sides oi the strip ve cylindrical peripheral suriaces. are preferably iorncecl oi steel after passing around snh= cne hali oi the peripheral surface of reversal and passed around the r portion oi the roll lid "with which it is main in close contact by the pressure roll 32 peripheral portion formed or rubber or e Lie. The rolls 2i? and 38 are of the same arneters and are power driven, being geared tonether so that their peripheral portions travel at same speed. in pacing around the rolls as sl-awn under tension through emerges from the of curved cross section which are relatively iii--v stood that the apparatus and 80 the concave strip is temporarily flattened but promptly resumes its normal transverse curvature due to the resilience of the metal.

If, during the operation of the apparatus, it be found that the portion H is not straight, or doesnot have any other longitudinal shape which is desired, this may be corrected by adjusting the wing nuts 23 and 25 to efiect a corresponding adjustment of the angularity or the die blocks it with respect to the die blocks it, since it has been discovered that by suitably regulating the relative longitudinal stretching of different laterally displaced portions of the strip, as it passes through the die blocks l2 and E3, the strip may be caused to assume any desired longitudinal shape, within reasonable limits, when it emerges from the forming rolls as and it. The concavity of the passages through the die hloclrs l2 and it and the concavity of the passage between the forming rollers it and i5 are both directed downwardly and the relative longitudinal singularity of the passages through the die blocks l2 and i3 is also directed downwardly. The passages through the die blocks are preferably straight longitudinally although they might have other shapes with a similar effect. The major porticn oi the longitudinal stretching, by which the inequalities in the internal stresses in the metal are removed in the final product, may he efiected largely or Wholly by the die blocks but, in general, there will be some longitudinal stretching of the lateral edge portions. of the strip as it passes through the forming rolls by reason of the fact that, due to theincreased concavity of the strip g at the place Where it contacts the forming rolls,

all carts the strip will have been stretched longr dinally to substantially the same degree.

Although one form of the improved apparatus and one example of the improved method have been illustrated and described, will he under e various forms and that the method may lie-p1 enticed in various ways without departing from the scope of the appended claims.

claim:

1. The method of forming metal strip having a predetermined longitudinal cho ce and a non planar cross section, which consists in the strip through a plurality of confining passages cllnecl longitudinally of the strip, then bending the strip transversely to approximate the do sired non-pia. or cross section, maintaining longitudinal tension in the strip while it is passing through said passages and while it is being bent transversely, and adjusting the relative inclination of said passages and thereby regulating the longitudinal shape of the product which follows said transverse bending.

2. The method of forming in a continuous process a straight metal strip having a. curved cross section, which consists in passing the strip under longitudinal tension through successive confining passages of'curved lateral cross section which are relatively inclined longitudinally with respect to each other, then immediately confining the moving strip and bending it transversely while moving it endwise and maintaining said longitudinal tension therein, and adjusting the relative inclination of said passages and thereby causing the strip to emerge from the transverse bending operation as a straight strip having a curved cross section.

3. The combination in apparatus for forming a metal strip having a predetermined longitudinal shape and a non-planar cross section, of a plurality of sets of die blocks each having a longitudinal strip confining passage therethrough which is transversely curved, said passages in said die blocks being-relatively inclined longitudinally, forming rolls having non-planar p eripheral surfaces adapted to receive a metal strip between them, means for pulling a metal strip endwise through the passages of said die blocks and then between said forming rolls, and means for adjusting the relative inclination of said sets of die blocks and thereby causing the metal strip to emerge from said forming rolls with the desired longitudinal shape.

4. The combination in apparatus for forming a metal strip having a predetermined longitudinal shape and a non-planar cross section, of a plurality of sets of die blocks each having a longitudinal strip confining passa e therethrough which is transversely curved, said passages in said die blocks being relatively inclined longitudinally, forming rolls having non-planar peripheral sur-' faces adapted to bend the strip transversely and to pull it through said blocks, and means for adjusting the relative inclination of said blocks and thereby regulating the longitudinal stretching of the metal between successive die blocks and causing the metal strip to emerge from said forming rolls with the desired longitudinal shape.

5. The combination in apparatus for forming a metal strip having a predetermined longitudinal shape and a non-planar cross section, of a plurality of sets of die blocks each having a longitudinal passage therethrough which is transversely curved, said passages in said die blocks being relatively inclined longitudinally and havinga width and height substantially equal to the width and thickness of said strip, forming rolls having non-planar peripheral surfaces adapted to bend the strip transversely and to pull it through said blocks, means for adjusting the relative inclinationoi' said blocks and thereby causing the metal to emerge from said forming rolls withthe desired longitudinal shape, and

means for causing the metal strip to enter the passage of the first die blocks at the same angle with respect to said first die blocks in all relative positions of the sets of die blocks.

6. The combination in apparatus for forming a metal strip having a predetermined longitudinal shape and a non-planar cross section, of a plurality of sets of die blocks each having alongitudinal passage therethrough which is trans versel curved, said passages in said die blocks being relatively inclined longitudinally, and hav- 7 ing a width and height substantially equal to the width and thickness of said strip, iormlng rolls having non-planar peripheralsuriaoes adapted to receive a metal strip between them, means for pulling a metal strip endwise through the passage of said die blocksand then between said forming rolls, means for adjusting therebtive inclination of said sets oi die blocks and thereby causing the metal strip to emerge from said forming rolls with :the desired longitudinal shapasadmeanstorcauslnsthemetslstripto enterthepassageoitheflrstdiebloeksetthe same angle with respect to said iirst die in all relative angular positions of the sets of die blocks.

'7. The combination in apparatus for forming a metal strip having a predetermined longitudinal shape and a non-planar cross section, of a plurality oi sets of die blocks each having a longitudinal passage therethrough which is transversel curved, said passages in said die blocks being relatively inclined longitudinally, forming rolls having non-planar peripheral surfaces adapted to receive a metal strip between them, means for pulling a metal strip endwise through the passages of said die blocks and then between said forming rolls, means for adjusting the rela tive inclination of said sets of die blocks and thereby causing the metal strip to emerge from said forming rolls with the desired longitudinal shape, and a roller carried by the first set of die blocks and movable therewith for supporting the metal strip in advance or said die blocks.

8. The combination in apparatus for forming a metal strip having a predetermined longitudinal shape and a non-planar cross section, or a plurality of sets of die blocks having longitudinal metal strip in advance of that set of die blocks.

9. The combination in apparatus for forming a metal strip having a predetermined longitudinal shape and a non-planar cross section, of a plurality of sets of die blocks having longitudinal confining passages ,therethrough which are of non-planar cross section and which are relatively inclined in adjacent sets of die blocks, means or moving endwise through said passages a long metal strip which is initially substantially flat, means ior supporting one set of die blocks from the adjacent set, means for adjusting said one set of die blocks angularly with respect to said adjacent set through a suilicient range to reverse the relativednclination of said passages, and

means movable with said one set of die blocks for causing said metal strip to enter the Dassm oi said one set of die blocks at the same angle in all relative posltions'of said one set or die blocks. Y

10. The method of forming in a continuous process a straight metal strip having a curved cross section, which consists in passing the strip under longitudinal tension through successive confining passages of curved cross section which as I passes from were! said passages to the" are located in proximity to each other and which are relatively inclined longitudinally, preventing transverse displacement or the strip during its travel through said passages, then immediately confining the moving strip and bending it transversely while moving it endwise and maintaining said longitudinal tension therein, and adjusting the relative inclination of said passages and thereby,- regulating the longitudinal stretching of dilerent laterally displaced portions 0! the strip other and causing tbd strip to emerge from the transverse bending hsvingseurvederossseetion.

operation sea straight strip tion, which consists in moving a substantially flat strip endwise and continuously curving advancing portions of the strip transversely and thereby stressing it within its elastic limit while bending the transversely curved portion of the strip longitudinally during its movement and thereby causing one part of the strip to be elongated with respect to other laterally displaced parts thereof, then bending the strip transversely and thereby stressing it beyond its elastic limit and confining it to a non-planar cross section, and adjusting the degree of said longitudinal bending of the strip and thereby regulating the longitudinal shape of the final product.

12. Themethod of forming in a continuous process a straight metal strip having a curved cross section, comprising a first stage which consists in curving a substantially flat metal strip transversely, and moving it endwise along a transversely curved and longitudinally bent path and thereby effecting the elongation of the intermediate portions of the strip with respect to the lateral edge portions thereof, a second stage which consists in bending the strip transversely and moving it endwise, and thestep of regulating the relative elongation of the intermediate portions and the lateral edge portions of the strip in said first stage and thereby determining the longitudinal shape of the strip emerging from said second stage.

ALLEN B. WILSON.

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