US3000073A

US3000073A - Tenter clip

Info

Publication number: US3000073A
Application number: US17984A
Authority: US
Inventors: Matthew M Zuck; John E Waterman
Original assignee: Winsor & Jerauld Manufacturing Co
Current assignee: Winsor & Jerauld Manufacturing Co
Priority date: 1960-03-28
Filing date: 1960-03-28
Publication date: 1961-09-19
Anticipated expiration: 1978-09-19

Description

Sept. 19, 1961 M. M. ZUCK ETAL TENTER CLIP Filed March 28, 1960 INVENTORS MATTHEW M. ZUCK flQHN E. WATERMAN FIG. 3

ATTO R N EYS United States Patent Matthew M. Zuclr, Warwick, and John E. Waterman,

'Chepatchet, RJ., assignors to Winsor & Jerauld Manufacturing Company, a corporation of Maine Filed Mar. 28, 1960, Ser. No. 17,984

- 3 Claims. (Cl. 2662) This invention relates to a clip and more particularly to an improved tenter clip that is particularly adaptable for the lateral stretching of plastic webs by automatic machines.

Tenter clips have long been known and used in the art inconnection with tentering machines which stretch web material as it is fed to the machine. Many shapes of tenter clips have been designed for various purposes and theitem that perhaps has received the most widespread treatment has been the jaw of the tenter clip. The jaws have been shaped in various forms .primarily to. enhance the gripping relation thereof with the web material. The various forms have included knife edges,- corrugated surfaces and other roughened surfaces; With the recent advances that have taken place in the organic plastic web field, it has been found thatthe plastic material will be greatly improved by the physical act of stretching the material. Accordingly, tentering. ma-' chines, which were heretofore used primarily in connection with textiles, have been found especially adaptable for use with organic plastic materials provided certain changes weremade inthe operation of the. machine. The major modification that must be made is the use of an entirely different tenter clip jaw. It will be apparent that when one tries to grip a plastic material, that in the first place the material is not as thick as textile material would be and secondly it is extremely smooth, thus giving a very low coeflicient of friction. Consequently these physical factors give rise to difiiculties with the operation of the tenter clip jaw. It is of course desirable-that the'plastic material be left intact while it is passed through the tentering machine and therefore the tenter clip jaw should not puncture or otherwise mar the material.

It is therefore an object of the present invention to provide a tenter clip which will have a jaw that will hold the plastic film or web material against slippage.

Another object of the invention is an improved tenter clip with a rocking jaw which will insure a large gripping area.

A still further object of the invention is to provide a tenter clip with a large gripping area over which the plastic web material is gripped at hundreds of spaced locations With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawings:

FIGURE 1 is a side elevational view of a tenter clip embodying our invention;

FIGURE 2 is an exploded perspective view of a portion of the jaw;

FIGURE 3 is a fragmentary enlarged view looking at the work engaging portion of the jaw; and

FIGURE 4 is a perspective view of the jaw assembly.

The tenter clip illustrated in the drawings is a link of a tenter machine chain having a base 11 which is adapted to ride upon the usual rails of the tentering machinery. The upper surface of the base 11 forms the lower jaw member of the tenter clip which jaw member actually consists of a hardened facing plate 12 affixed to the base member 11. Rising from the base member 11 is an with concavities 23 and 24 which are sufliciently'deep.

3,000,073 Patented Sept- 2 arched portion 13 which overhangs the lower jaw: portion of the clip. Mounted for swinging movement in the arch portion 13 is an upper jaw member generally desig-' nated 14. The upper jaw 14 has an arm 15 extending; therefrom in a general vertical direction when mounted within the clip and is adapted to engage cams (not shown) located at each end of the tenter machine. Upon such engagement the jaw 14 will pivot in a" counter clockwise direction as seen in FIGURE 1 and will raise above the lower jaw 12 to allow web material to he moved from the clipor to be guided between the jaws of the clip as the case may be. f

The surface engaging portion of the upper jaw 14 isformed by bifurcating the lower portion of the jaw into; two plate portions 16 and 17 (FIG. 1). One or more feeler fingers 18 are mounted upon the plate portion 17 and extend into slots 19 which are formed in the lower jaw 12 for a purpose to be presently described Between the plate portions 16, 17 the surface engaging portionof' the upper jaw is mounted. This surface engaging portion is shown more particularly in FIGURE 2 and coir-i sists of two bars 20 and 21 between which there isheld the work engaging member 22. Thework engaging member 22 is preferably cylindrical and to accommodatethis cylindrical shape, the bars-20 and 21 are formed- I to grasp the cylinder below the median thereof. Bars alignment of the work engaging member 22 with the:

lower jaw 12 is always insured. This comes about. because of the pivoting action of the work engaging. member 22 relative to the upper jaw, this pivoting tak? ing place about'the' pin 26. According to the presentj invent the Work pping surface of the j'a'w'1'4' "a related to the axis of the pivot of jaw 14 a distance greater than the distance between the axis of rotation of jaw 14 and the lower jaw 12. Thus in the closed relation of the jaw 14, the work engaging edge of the work engaging member 22 will engage the lower jaw 12 and limit the clockwise swing of the upper jaw 14. Tension on the material held between the jaws of the tenter clip will therefore only tend to move the upper jaw into tighter engagement with the material positioned on the lower jaw 12.

The surface of the work engaging member 22 has been found to be of critical nature. In order to hold the plastic web material, it is necessary to provide a multiplicity of spaced minute projections which will engage the work at a multiplicity of spaced points along the line of contact of the upper jaw with the web material. Preferably the surface of the work engaging member 22 is a file cut surface and particularly it has been found that a number 4 file cut renders optimum results. It has further been found that by providing this surface on the member 22, that plastic web material will be held against slippage during the travel thereof through the tentering machinery.

In operation, clips manufactured in accordance with the invention are mounted to form a continuous chain along the rails of the tentering machine. As plastic web material enters the tentering machine, the web is caused to pass between the upper and lower jaw members of the tenter clip. This is accomplished by maintaining he pivoting upper jaw member in an open position by the use of cams (not shown) which engage the extending arm 15 of the upper jaw member. As the web enters the space between the upper and lower jaw memhere, the pivoting upper jaw member is released and engages the web by 'force of gravity; The first portion to engage, the web will-be the feeler finger 18 which will hold the upper jaw in open position until the edge of the web has been pulled outwardly a sufficient distance so hat, the: edge will 'pass from under the feeler finger 18 and then the upper jaw will make initial engagement, worl; engaging cylindrical member 22 then making contact with the web material. As the web exerts a pulling force, the frictional force between the web and the contacting surface increases, thus causing a greater holdipgor gripping force thereon. Upon reaching the end of the path of the tentering machine, the pivoting upper jaw member is released and the web leaves the area between the jaw members of the tenter clip.

The great holding power of the tenter clip made in accordance, with the invention is occasioned by the provision of a multiplicity of minute projections, which in effect have quite sharp edges and which are best obtained by using the No. 4 file cut above referred. Positive engagement along a complete line is obtained by virtue of the pivoting action of the surface engaging portion of the upper jaw 14. A further advantage oi the instant invention may be readily ascertained since it will become apparent that when such a fine line of minute projections is provided, these sharp edges or projections will tend to wear after a period of use. Rather than having to change the entire upper jaw, whichis a tedious operation and requires theknoeking u f h p o p n of h pp j o r place t,v have provided avery siml'lll? construction where the Surface engaging memb r 2 may e ota d, a l gh am u t s v i s nte eb' nece saw o lo en. h faste n scr 25 ha ho s... th wo pla e 20 an .1 o ethe nd rota e he y d c m m 22 to. anothe nga Por o wher a e r y new ur ac l be pres ed to h web h t l have th har c er s cs f a w jaw- Th no n y s uper o con act p ded t a o a e of ma n n s p oid c th he ins nt on u on 7 We claim:

1. A tenter clip for a tenter chain comprising a body having a plate portion for supporting a web, a clamp jaw pivotally connected to said body above said plate portion and having a free end depending toward said p e nd d p d t erec r o cla pi g wa b to said Pla e po on h aid fre en of s d i w comprisi a P of damp bar sa d. bars b g ri n d generally p r to he pi ot n ax o s id ja a work' engaging member removably fiast ened between said clamp bars to permit rotation of said work engaging member rela tive to said jaw.

2. A tenter clip as in of said jaw comprises a cylindrical work engaging member that is held between said clamp bars, said clamp bars being mounted on said jaw tor pivotingmovernent relative to said jaw on an axis generally perpendicular to the pivoting axis of said'jaw.

3. A tenter clip comprising a body having a fixed lower jaw member and a relative movable upper jaw member, said upper jaw member being mounted for pivoting movement through an are greater than the distance between the axis of pivoting of the upper jaw member and thelower jaw member, said lower jaw member having a hardened fiat engaging surface, the. pivoting jaw member having a cylindrical surface engage ing member, a pair of clamp bars pivotally mounted on said upper jaw member on an generally perpendicue larto the pivoting axis thereof, said cylindrical surface engaging member being received between said clamp bars for selective rotationabout its own axis.

References Cited in the file of this patent N T S T S PA ENTS claim 1 wherein said'free end