US1946472A - Means for corrugating tubing - Google Patents

Description

Feb. 13, 1934. Y H H BABCOCK 1,946,472

MEANS FOR CORRUGATING TUBING Filed July 30, 1932 4 Sheets-Sheet 1 f/ J2 L! o N513// wW/W/'mz may* l Feb. 13, 1934. H. H. BABcocK MEANS FOR CORRUGATING TUBING.

Filed July 30, 1952 4 Sheets-Sheet 2 H. H. BABcocK 1,946,472

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H. H. BABCOCK MEANS FOR CORRUGATING TUBING Feb. 13, 1934.

Filed July 30, 1932 -4 Sheets-Sheet 4 Patented Feb. 13, 1934 MEANS FOR CORRUGATING TUBING Henry H. Babcock, Oak Park, lll., assigner to The Bishop & Babcock Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application July 30, 1932. Serial No. 626,356

Claims.

This invention relates to corrugated metal tubing, and has to do with means for subjecting tubular metal blanks to axial and radial pressure and thereby contracting the blank axially and 5 extending it radially so as to form corrugations therein.

It is known to produce metal bellows or corrugated tubes by subjecting a tubular metal blank to internal pressure and expanding it radially l0 between spaced and relatively movable dies, while subjecting the blank to endwise pressure so as to contract it axially and move the dies together for shaping the corrugations. Such a method and apparatus for performing the same are disclosed in the patent to Hollerith and Metcalf, No. 349,718, dated September 28, 1886. Various modifications of the method and apparatus of the Hollerith and Metcalf patent have been proposed.

Metal bellows or corrugated tubes of the character referred to are extensively used for the construction of thermostats and various other devices in which the bellows is alternately expanded and contracted axially. It is important in a bellows of this type that the corrugations be truly radial to the bellows structure and be free from any irregularities such as would interfere with proper flexing of the corrugations.

In the production of a bellows in the manner` referred to, the volume of the tubular blank varies materially during the corrugating operation. For example, a cylindrical tubular blank 3 3/64ths inches long and with an interior diameter of .957 inches and an outside diameter of .969 inches has a volume of 35.3 cc., and this same blank, when formed into a bellows having four corrugations each of 1.428 inches outside diameter, and

a length of l--nds inches, has a volume of but 22.9 cc. When the blank is rst subjected to internal and axial pressure, the volume thereof .10 increases from 35.3 cc. to 39.4 cc., and as the corrugating operation proceeds, the volume of the blank decreases to 37.7 cc., then increases to 38.5 cc. an'd thereafter decreases to 34.8 cc., 31.4

cc., and, when the bellows is completed the volume thereof is 22.9 cc. as above noted. The variation in volume of the blank during the corrugating operation is due to the change in form of the blank and not to stretching of the metal thereof, since, in the instance above noted, the metal of the blank is displaced and redistributed but is not stretched to any appreciable extent, if at all. It will be seen, from the instance above referred to, that the volume of the blank being corrugated rst increases, then decreases, and again increases, and thereafter decreases, during the corrugating operation. If the blank is subjected to endwise pressure of considerable value,

at the instant that the volume of the blankincreases, this endwise pressure is apt to cause buckling of the wall of the blank with resulting 60 distortion of the vcorrugations being formed and the production of body wrinkles, since the increase in volume of the blank results in the wall of the blank being completely relieved of internal pressure during the interval required to 65 fill, by liquid, the space provided by the increased volume of the blank. It is during this'interval required to fill the increased volume of the blank, even though short, that the damage is done by the endwise pressure to which the blank is subjected. On the other hand, when the volume of the blank decreases, if the endwise pressure is unrelieved the blank is apt to be stretched to an objectionable extent in order to accommodate the body of liquid retained therein. In all methods and apparatuses for producing metallic bellows by subjecting a tubular metal blank to endwise and radial pressure, with which I am familiar, the endwise pressure and the internal pressure are sustained throughout the operation and no adequate' provision is made for compensating for the above referred to variations in volume of the blank being corrugated. As a result, in metal bellows produced in accordance with present practice, the corrugations of the bellows are frequently more or less undulatory ratherl than being truly radial to the bellows, and present portions which resist expansion and contraction of the bellows to an undesirable extent, such portions being relatively rigid and causing crack- 9o ing of the bellows contiguous thereto. Also, in many instances the corrugations of the bellows are apt to contain wrinkles which materially interfere with proper extension and compression thereof, and are apt to bev thinner than the wall of the original tube due to the stretching action above referred to. In producing metal bellows in accordance with present practice, in which the variations in volumev of the blank during the corrugating operation are not compensated for, it is extremely diicult and, from a practical standpoint, impossible to produce uniformly perfect bellows.

My inventionis directed primarily to means for producing metal bellows from tubular metal blanks in such manner as to compensate for variations in volume of the blank during the corrugating operation, thusV avoiding the objectionsabove noted to the present practice and assuring the production of uniformly perfect bellows in which the corrugations are free from wrinkles or distortions such as would interfere with free expansion and contraction thereof. A further object is to provide means for producing metal bellows by displacing and flowing the metal of the tubular blank, rather than stretching the blank radially, so that the walls of the corrugations of the finished bellows are of the same thickness as that of the original blank or, at any rate, are not stretched or thinned to an objectionable extent. A further object is to provide a means of the character stated particularly adapted for corrugating tubular blanks'of considerable length. In general, the object of the present invention is to provide an improved apparatus of the character referred to, to the end of speed and uniformity for commercial purposes. Further objects and advantages of my invention will appear `from the detail description.

In the drawings:-

Figure 1 is a plan view of invention; 1,

Figure 2 is a section `taken substantially on line 2 2 of Figure 1, partsbeingshown in elevation;

Figure 3 is a sectiontaken;substantially on line 3 3 of Figure 2, with` partsbrok'en away and in section;

Figure 4 is a section taken substantially online 4 4 of Figure 2, the end die'. ringand the yblank being shown fragmentarily .andy inl/section;

Figure 5 is` a section ytaken!substantally on line 5 5 of Figure 4, onan enlarged scale, the end die ring and associated parts being shown fragmentarily;

Figure 6 is a section taken substantially on line 6 6 of Figure 2;

Figure '7 is a view similar vto Figure 2, with the drive gear and associated parts omitted, after initiation of the corrugating opertion;

Figure 8 is a view similar to Figure '7 after completion of the corrugating operation;

Figure 9 is a view similar to Figure 1 illustrating a modied form of apparatus;

Figure 10 is a fragmentary plan View, on an enlarged scale, of one of the` guide bars and associated parts, partly broken away and in section.

I provide a machine for subjecting the tubular blank to radial and axial pressure While compensating for variations in the volume of the blank during the corrugating operation. This machine includes a base frame 1 comprising side bars 2 which connect a xed head 3 at one end of the frame and a bracket 4 at the other end of the frame. An upright 5, rigid with the base frame, is disposed intermediate head 3 and bracket 4. This upright slidably receives a tubular neck 6 of a movable head '7, this head and head 3being disposed in spaced relation for reception therebetween of a tubular metal blank 8 to be corrugated.

The ends of blank 8 abut the inner faces of heads 3 and 7 and may be secured thereto, in any suitable manner, to effect a fluid tight and pressure resistant closure therewith. In the form of spaced relation along the blank 8 andmountedv for relative movement toward'eachother,A Rethe ar'JparatusE-of1 my y ferring more particularlyto Figure 3, each ring 29 comprises two sections 12a and 13a of semicircular shape, these sections being hinged together at 14. Section 12a is provided, at the free end thereof, with an outwardly projecting lug 15 tol which two links 16 are pivotally secured at 17, these links being disposed at opposite sides of the lug. A cam`lever 18 is pivotally mounted at 19 between the links 16 at the other end thereof. When the ring 29 is closed, a lug 20 projecting from the free end of section 13a extends between the links 16 and cooperates with the cam lever 18, when the latter is swung downwardly into operative position, for locking the sections of the ring tightly together.

Rings 9 are constructed similarly to rings 29, in general, and each comprises two sections 12 and 13 lpivoted together and secured closed by cam means lsimilar to the securing means of Fig. 3. Themeans for securing rings 9 to the heads 3 and '7 is thesame in each instance, and a description of the securing means for one of the rings 9 will suffice, Each section of ring 9 is provided with two studs 21 which project from the outer face of the ring, each of these studs having a head 22, the inner face of whichis shaped to provide a camming surface. Head '7 is provided, at the inner face thereof, with openings 23 suitably.

shaped and of proper size and spacing to accommodate the heads of studs 2l, and with arcuate slots 24 extending from the openings or recesses 23. The slots 24 are of a Width to accommodate the Shanks of the studs so that the side portions of the stud head engage behind shoulders 25 at each side of slot 24 and projecting from the side walls of groove 26 which receives the head of the stud. The outer surfaces of shoulders 25 are inclined outwardly and away from recess 23 and provide camming surfaces which cooperate with similarly inclined surfaces on the heads 22 of studs 2l. By inserting the studs 21 into recesses 23 and then turning the ring 9 in a clockwise direction, as Viewed in Figure 4, the ring is secured to head 7 and is forced toward this head so as to clamp flange 10 tightly between the ring and gasket 1l. Conveniently, each section of the ring may be provided, at the periphery thereof, with an opening 27 for reception of a pin of a Spanner wrench or other appropriate tool for turning the ring in the manner described. This provides convenient means for quickly releasing or securing the ends of the blank to the head with facility and expedition.

Each of the rings 9 is provided in its inner face with an annular recess 28 corresponding in size and shape to one-half of the desired corrugation. Each of the rings 29 is provided, at each side thereof, with a recess 30 similar to the recesses 28 of the rings 9.

Section 12a of each of the rings 29 is provided 'c by pins 33, in slotted lugs 34 projecting laterally x from head 3 and upright 5. A similar guide bar 35 is secured at its ends, by means of pins 33, in slotted lugs 34 extending from the other side of-head 3 and upright 5. This bar nts into slotted lugs 36 extendingfrom sections 13a of rings 29,

these lugs 36 being open 'at theirouter sides.

Head 'Imay beprovided' with lugs 'la and 7b,l

as in Fig. 1, which lugs accommodate and cooperate with the guide bars 32, and 35, these lugs being similar to lugsI 31' and36, respectively, of

n having driving connection, through rings 29. Bar 35 is suitably rounded at one end so that by removing the pin 33 at the other end thereof this bar may be swung outwardly into inoperative position so as to clear lugs 36 of sections 13a of rings 29 and permit sections 13a of these rings to be swung downwardly, when the cam locks are released, into inoperative position for removal of the corrugated blank or insertion of a blank to be corrugated. A guide rod 37 is suitably secured at one end to head 7 and is slidable through head 3 which is provided, for this purpose, with an opening snugly receiving the rod. `Rod 37 is disposed adjacent the lower end of sections 12a of rings 29, and section 12a of each of these rings isl provided with an arcuate recess which receives the rod. When sections 13a of the rings 29 are opened, rod` 37 cooperates with guide bar 32 and lug 31 for supporting section 12a of the respective rings 29. Since lthe end rings 9 are clamped to the heads 3 and 7,

these end rings are not provided with guide elements and each of these rings is cut away from its periphery and for a suitable distance circumferentially to provide a notch 38 to accommodate the rod 37 while permitting of the necessary turning movement of rings 9.

Each of the guide bars 32 and 35 is provided with a series of bores extending from the inner side of the bar. These bores accommodate locking balls 39 and expansion coil springs 40 confined between the balls and the inner ends of the bores. Each section of the respective rings 29 is provided with a recess disposed for reception of the projecting portionof the corresponding ball 39. The balls vare spaced along the bars correspondingly to the desired spacing of the ring 29. Assuming that it is desired to space the rings 29 equidistantly from each other and from the rings 9, as shown, balls 39 are spaced accordingly.

When the tubular blank 8 is properly positioned between the heads 3 and 7, neck 6 opens into the blank through head 7. At its outer end, neck 6 opens into a cylinder 45 rigidly secured upon the outer end of the neck in a suitable manner. A piston 46, disposed within cylinder 45 in operative relation thereto, is secured upon the inner end of a piston rod 47 of non-circular cross section, which is slidably mounted through a cover plate 48 secured upon the outer end of the cylinder. Piston rod 47 comprises a screw shaft 49 which has threaded engagement with a nut 50 mounted for rotation in bracket 4 and a plate 51 secured to the inner side of this bracket, the bracket and the plate cooperating to hold the nut against axial movement. A worm gear 52 extends circumferentially of nut 50 and is conveniently formed vintegral therewith. This gear meshes with a worm 53 secured upon a shaft 54 rotatably-mounted in bracket 4, this shaft 54 a suitable coupling 55, to shaft 56 of an electric motor 57 appropriately mounted upon thel base of the machine or in any other convenient location. When motor 57 is in operation, cylinder 45 is moved axially and lengthwise of the frame 1, this movement of the cylinder being guided by side bars 2a.

ofthe base frame.

With the various parts in the relative positions shownvin Figure 2, blank v8 and cylinder 45 are lled with a suitable fluid, preferably a liquid such as oil or'water. tirely satisfactory. Conveniently, a pipe 60 `has Y one end screwed into a bore 61 opening through head 3 into blank 8. This pipe communicates 1 with any suitable source of supply of water under Ordinarily, water is en-` .within the cylinder between the inner end thereof and piston 46, after which the valve 62 is closed. Any suitable or preferred means may be provided for venting air from the blank and the cylinder, if desired. Venting means of this character are well known and need not be illustrated nor described in detail. Also, if desired, pipe 60 may be provided, between valve 62 and head 3, with a loaded relief valve 63 of known type. Though this relief valve may not be essential, as will be hereinafter more fully explained, I prefer to employ a suitable relief valve as a precautionary measure.

As the corrugations are formed in the blank, which is extended outwardly between the die members'or rings, the effective diameter of the blank is correspondingly increased with theresult that the endwise pressure exerted by the blank, due to the internal pressure of the liquid, is also increased so as to present increasing resistance to endwise compression of the blank. For this reason the cylinder 45 is of materially greater diameter than the corrugations to be formed, the diameter of the cylinder being suicient to assure that the pressure exerted thereon will overcome the endwise pressure exerted by the blank and the liquid therein when the pressure in the blankA and in the cylinder is of the same value per unit area. In the machine illustrated the radius of the cylinder is inA excess of the diameter of the corrugations to be produced which, under ordinary conditions, is suflicient. It will be understood, however, that the diameter of the cylinder relative to that of the blank may be varied considerably and as conditions require.

With the parts in position and the system `filled with water', as in Figure 2, the motor is set into operation so as to drivel the piston 46 toward standard 5. This subjects the waterwithin cylinder 45 to pressure, which pressure is transmitted to the inner end of the piston and, through neck 6, to the water within blank 8. The piston and the blank are thus subjected to pressure from the same water column and the pressure per unit area within the blank is the same as the pressure per unit area exerted upon the inner end of cylinder 45. Blank 8 is thus subjected to internal radial pressure which tends to force the blank outwardly between the die members and the blank is simultaneously subjected to endwise pressure by piston 45 acting through neck 6 and head 7. Due to this arrangement, it follows that any radial and outward movement of the blank between the die-members will be accompanied by a simultaneous and corresponding endwise compression of the blank which effectively avoids stretching of the wall of the blank. In this manner, the metal of the blank is displaced and flowedv between the vdie members, avoiding stretching of the metal, the operation being one of displacement and redistribution of the metal of the blank withoutv stretching thereof.

As the operation proceeds, the metal is flowed.

outwardly between the die .members and the blank is compressed or'contracted axially so as to move the die members together and shape the corrugations as they are formed.

liu

During the first part of the operation the blank f eration the volume of the blank is materially increased, and this increase may be as much as per cent. This increase in volume is due to change in shape of the blank and not to any stretching of the metal wall thereof. As the blank increases in volume, water is displaced from cylinder and flows into the blank to fill the same and maintain the pressure therein. This displacementof the water from the cylinder momentarily relieves the pressure exerted upon the inner end of the cylinder, thus avoiding subjecting the blank toeffective endwise pressure momentarily at such time as the volume of the blank is increased with a resulting lowering of the internal pressure in the blank. In this manner, I provide an automatic compensation for the increase in the volume of the blank and eliminate possibility of causing wrinkling thereof or distortion of the corrugations being formed, such as would occur if the blank were subjected to endwise pressure while the internal pressure therein was materially lowered or non-existant. As the operation proceeds, the change in the form of the blank causes reduction in the volume thereof, which is succeeded'by an increase in volume, and thereafter the volume of the blank decreases. Since the unit area pressure is the same within the blank as it is within the cylinder, the water displaced from the blank, when the volume of the latter decreases, can flow therefrom into the cylinder and will cause the latter to advance slightly relative to the piston, While maintaining the pressure within the blank. In this manner the cylinder and the piston cooperate to subject the blank to radial and axial pressure simultaneously while compensating for variations in the volume of the blank during the corrugating operation, this compensating action effectively preventing the formation of body wrinkles or the production of deformations in the corrugations produced. As a result, the corrugations in the completed bellows extend truly radial thereof and the bellows is free of wrinkles or deformations which would impair its efficiency in use. During the successive stages of the corrugating operation the tubular blank is reduced in length or contracted axially and the displaced metal is flowed radially of the blank between the dies, which latter are moved toward each other so as to shape the corrugations as formed, the dies being in contact when the corrugating operation has been completed, as in Figure 8. By removing the pin 33 at one end of bar 35 and swinging this bar into inoperative position, sections 13a of die members 29 may be swung downwardly into open Kposition. After this has been done, the end die members 9 may be turned in a counterclockwise" direction so as to relieve the pressure on flanges 10 at the ends of the bellows, and sections 13 of the die rings 9 are then swung downwardly into open position, after which the bellows may be removed from the dies. To permit of opening of sections 13 of die rings 9, each of the heads 3 and '7 is provided with suitably disposed slots 26a extending from the recesses 23 which receive the heads of studs 21 carried by section 13. Head '7 is then returned to its original position and the die members 29 are moved along bar 32 and rod 37 until they are engaged by the corresponding balls 39, after which a blank is inserted within the dies and secured to the heads 3 and 7 in the manner previously described. Die members 29 are then locked closed, after bar 35 has been secured in operative position, and the operationA above .described is repeated.

In the modified form illustrated in Figure 9, piston 46a is provided with a tubular stem 65 which opens, at its inner end, into the space between the inner end of the cylinder 45a and the piston. Stern is closed at its outer end and is secured against endwise movement in a support 66 rigid with members 2a of the frame. A suitable fluid, preferably a liquid such as water, is supplied to the bore 65a of stem 65 under pressure from a pump 67, by means of a pipe 68 extending from the discharge of the pump, the intake of which is connected by a pipe 69 to a suitable source of supply of water. The pump 67 is a gear pump of known type, though any other suitable or preferred means may be employed for supplying liquid under pressure to the stem 65 of the piston. The operation of this form of the apparatus is similar to that of the form disclosed in Figures 1 to 8, inclusive, with the exception that the piston 46a is xed or stationary, and need not be described in detail.

In both forms of the apparatus the -resistance of the tubular blank to endwise pressure for contracting the same increases as the corrugations are formed and increase in width radially of the blank.4 As a result, as the corrugations decrease in width or thickness axially of the blank the rate at which the blank is contracted axially is automatically reduced. This is advantageous as assuring that the metal in the corrugations being formed will flow radially between the die rings and to the proper extent before the rings are moved together. This eliminates danger of compressing the corrugations too rapidly axially as the metal is being flowed between the die members and eliminates wrinkling or deformation of the corrugations from this cause.

While I have illustrated the apparatus of my invention as disposed horizontally, I contemplate disposing such apparatus vertically if desired. The relief valve 63, while not essential, is preferably provided. This valve should be loaded to open in the event the pressure within the blank should, for anyreason, reach such a high value as to cause objectionable stretching of the metal of the blank. Otherwise, the relief valve is not brought into operation and, under normal conditions, may not be needed.

` What I claim isz- 1. In means for forming corrugated tubular elementsfrom tubular metal blanks, two heads disposed for reception therebetween of a tubular blank to ibezfcorrug'ated, one of the heads having an opening therethrough into the blank and being movable'toward the other head, spaced die members mounted between the heads for relative movement toward each other and disposed to extend vabout the blank in operative relation thereto, and pressure applying means for supplying fluid under pressure through said opening for subjecting the blank lto internal pressure while also subjecting said movable head to pressure and forcing it toward the other head, said pressure applying means comprising two members defining a space adapted for reception of a fluid under pressure, said space communicating with said opening andsaid members having relative movement axially of the blank for compensating for variations in the volume of the blank during corrugating thereof.

2. In means for forming corrugated tubular elements from tubular metal blanks, two heads disposed for reception therebetween of a tubular blank to be corrugated, one of the heads having an opening therethrough into the blank and being movable toward the other head, spaced die members mounted between the heads for relative movement toward each other and disposed to extend circumferentially of the blank in operative relation thereto, a cylinder rigid with the movable head and communicating at its inner end with said opening, said cylinder being of materially greater diameter than the diameter of the corrugations to be produced, and a piston in the cylinder and cooperating therewith to subject the blank to internal pressure and axial pressure simultaneously by uid conned under pressure between said piston and said inner end of the cylinder.

3. In means for forming corrugated tubular elements from tubular metal blanks, two heads disposed for reception therebetween of a tubular blank to be corrugated, one of the heads having an opening therethrough into the blank and being movable toward the other head, spaced die members mounted between the heads for relative movement toward each other and disposed to extend circumferentially of the blank in operative relation thereto, a cylinder rigid with the movable head and communicating at its inner end with said opening, said cylinder being of ma terially greater diameter than the diameter of the corrugations to be produced, a piston operating in the cylinder, and means for forcing the piston toward said end of the cylinder, the piston and the cylinder cooperating to subject the blank to radial pressure and axial pressure simultaneously when the blank and the cylinder are filled with liquid and the piston is forced toward the inner end of the cylinder, said piston and cylinder being capable of relative movement to compensate for variations in the volume of the Ablank during corrugating thereof.

4. In means for forming corrugated tubular elements from tubular metal blanks, a series o! spaced die members movable one toward the other, and means for supporting a tubular blank in operative relation to the die members with the latter extending circumferentially of the blank and for subjecting the blank to simultaneous axial and radial pressure for extending it radially between the die members and contracting the blank axially while forcing the die members toward each other to shape the resulting corrugations formed in the blank, said means comprising two members having, relative movement one toward and away from the other and elements defining a space adapted for reception of uid under pressure and communicating with the blank, said elements being capable of relative movement axially of the blank to compensate for variations in the volume of the blank during corrugating thereof. v

5. In means for forming corrugated tubular elements from tubular metal blanks, two heads disposed for reception therebetween of a tubular blank to be corrugated, die members mounted between the heads in spaced relation and for relative movement and disposed to extend about the blank circumferentially thereof, one of the heads having an opening therethrough into the blank and being mounted for movement toward the other head, a cylinder rigid with the movable head and of materially greater diameter than the corrugations to be produced, said cylinder communicating at its inner end with said opening, a xed piston within the cylinder, the cylinder having endwise movement relative to the piston, and means for supplying liquid under pressure to the cylinder between the inner end thereof and said piston. f

HENRY H. BABCOCK.

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