US3018019A - Coiled flame arrester - Google Patents

Description

Jan. 23, 1962 G. L. GlBBs, JR 3,018,019

coILED FLAME ARRESTER Filed Aug. 7, 1959 /41 U VVE w m u www w H H J /v 1v MIN/1% INVENTOR.

ATTORNEY ilriiteri htates Fatent G 3,018,019 CILED FLAME ARRESTER George L. Gibbs, Ir., Rochester, N.Y., assigner to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Aug. 7, 1959, Ser. No. 832,213 1 Claim. (Cl. 220--3S) The present invention relates to a new and improved coiled flame arrester element and the method for making the same. More speciiically, the present coiled element is made so as to have a chevron shape cross section and further includes uniquely formed tabs which insure equal spacing between the coil convolutions.

While the use of bumps, depressions or indentations on a continuously coiled llame arrester is generally old, these means for separating the coil convolutions have either been diicult to form or when formed, particularly by indentation, permitted the occasional nesting of the indentations within one another and thereby contributed to unequal spacing between the coil convolutions. In the present invention a unique method has been developed VJfor punching out and forming spacing tabs from a continuous strip in such a way that nesting is prevented.

The details as well as other objects and advantages of the present invention will be apparent from a perusal of the detailed description which follows.

In the drawings:

FIGURE 1 is a partially sectioned view of the subject flame arrester coil;

FIGURE 2 is a line diagram diagrammatically showing the apparatus for forming the subject coil;

FIGURE 3 is a view along line 3-3 of FIGURE 2 showing the forming die for punching out the spacing tab members;

FIGURE 4 is a view along line 4 4 of FIGURE 2;

FIGURE 5 is a plan view of the punched strip ybefore it enters the contour rolls;

FIGURE 6 is a view along line 6 6 of FIGURE 2 showing the contour rolls which provide the chevron shape cross section to the strips; and

FIGURE 7 is a view along line 7-7 of FIGURE 2 showing the shape of the strip after it has left the contour rolls.

A portion of a finished flame arresting or quenching coil is shown generally at 1t] in FIGURE 1. In general, the coil is formed of a continuous strip of a suitable heat and corrosion resistant strip metal stock. The flame arrester coil is adapted for use in a flame arrester device. The chevron shape cross section of the coil convolutions is preferred for several reasons. First, by using a chevron shape a greater flame quenching area may be utilized while maintaining a relatively small coil width thickness. This is an important consideration since the width or thickness of the coil plays an important part in reducing r the overall vertical displacement of the power plant with which the ame arrester is adapted to be utilized. Particularly as adapted for use with marine installations, vertical displacement becomes more important since the power plants are disposed below the decks and the less vertical displacement the better. Secondly, the chevron shape cross section causes the exhaust gas to experience a slight change in direction in flowing through the coil convolutions and in so doing to have its speed reduced and thereby exposing it for a longer period to the convolution surfaces resulting in better ilame quenching.

The chevron shape cross section may be otherwise defined. Referring to a longitudinal axis midway of the strip width, each convolution includes a pair of planar surfaces equally inclined from the axis to form a wide V cross section.

Patented Jan. 23, 1952 As already noted, it is old to use spacing elements to separate the coil convolutions in llame arresters. However, the normal practice, as illustrated in the patent to Staak 2,789,238, has been to stamp indentations or bumps periodically along the length of the continuous coil. The problem arises with this type of spacer that in ceiling the strip upon itself periodically one of the indentations or bumps will register with another indentation or bump causing a nesting of the coil at this point and an unequal spacing between coil convolutions. In this way, an unequal distribution of the heated gases will occur reducing the total surface utilized for flame quenching. Coil 1t? is formed so as to prevent adjacent coil convolutions 12 from nesting by the provision of unique spacing tab members 14.

Referring to FIGURE l, it will be seen that spacer tabs 14 are formed yby being punched out of the strip material and rolled back to a limited extent upon themselves. In this way it will Vbe seen that the rolled back portion of the spacing tabs 14- will, when the strip is coiled, abut against a solid portion of the adjacent convolution even when the adjacent spacing tabs are otherwise in overlying or registering relationship. Thus even though adjacent spacing tabs 14 occasionally fall into registry with each other it is impossible for one ofthe tabs to nest within the opening formed by an adjacent tab since the tabs are transversely offset relative to the tab openings. In this way it is assured that all convolutions of coil 1t] will be equally spaced and that the ilow of hot gases through the coil will `be equally distributed to utilize the full coil quenching surface.

The method whereby coil 10 is formed may best ybe understood by referring to the remaining figures of the drawing beginning with FIGURE 2. In FIGURE 2 a reel is shown at 16 on which fiat strip stock 18 is wound. Strip stock 1S is fed from reel 16 to the iirst station which is a punch press Ztl. At the punch press station the spacing elements or tabs 14 are punched out from the strip stock. Referring to FIGURE 3, it will be seen that punch press 2t) includes a die member 22 and a pair of adjacently aligned punch members 24. The punch press may include one set of such die and punches or a plurality of axially spaced dies and punches. The principle of forming the spacing elements is, of course, the same whether one or more sets of punches and dies are utilized. Punches 24 may be mounted on a common member 26 which is adapted to be moved up and down through a suitable punch press actuating mechanism. Each of the punches includes a curved or tapered surface 28 which terminates in a cutting edge Sti such that as the punches are moved into engagement with strip 18 the strip will be pierced so as to form and roll the tabs.

As strip 18 leaves punch press 20 it is in the form shown in FIGURES 4 and 5. The punched strip then passes through a looper indicated generally at 32, which is for the purpose of absorbing uneven motion in the strip.

As the strip leaves looper 32 it s fed into the contour rolls indicated generally at 34. As best seen in FIGURE 6, upper and lower contour rolls 36 and 38 have mating surfaces 4@ and 42 which form the strip into its chevron cross section as it passes therebetween. The lower roll 38 includes a pair of axially spaced annular recesses 44 yformed in the periphery thereof for receiving the spacer tabs 14 without destroying the tab shape during the further shaping of the strip. As it leaves the contour rolls 36 and 38, strip 18 has the shape shown in FIGURE 7.

From the contour rolls strip 18 is wound on a coiler 46.

I claim:

A ame arrester coil comprising a continuously wound metal strip having a plurality of convolutions, said convolutions having a chevron shape cross section, a plurality of circumferentially aligned integral tab members extending along one side of said strip so as to have aligned ends free from the strip, said strip having a plurality of circumferentially aligned openings therein adjacent said tab members, said tabs abutting against and spacing adjacent coil convolutions, said free ends of said tab members Abeing oset axially VJfrom said openings to prevent the free end of any tab member in any convolution from registering with any `opening in an adjacent convolution.

References Cited in the file of this patent UNITED STATES PATENTS 555,297 Anderson Feb. 25, 1896 `947,642 Leave Ian. 25, 1910 1,058,407 Candlish Apr. 8, 1913 4 Patten Dec. 4, Long et al. 1an. 19, Lodge July 29, Simons July 29, Meikle July 3, Bechtel Oct. 3, Chipley Apr. 12, Lisciani Dec. 4, Staak Apr. 16, Neild July 22, Muller Aug. 12,

FOREIGN PATENTS France Sept. 30,

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