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8 - 9 0 1 2 SPRINGS AND REELS 3 4 5 This invention relates to a spring. This invention 6 also relates to a reel. This invention also relates to 7 methods of producing springs and reels. 8 9 In PCT Patent Application Publication Number 0 WO87/00228 (PCT/AU86/00164) there is disclosed a reel unit 1 having a retractable cover which inter alia may be used to 2 cover vehicles, pools, boats and other things. The whole of 3 the subject matter of WO87/00228 is to be considered to be 4 incorporated into this specification. 5 6 However, that reeling device has been found to be 7 difficult to make and use in practice as the fabric cover 8 has to be retracted into the reel unit through a relatively 9 small aperture. 0 1 In order to bunch the material of the cover, excess 2 torque output from the spring is required to pull the cover 3 through the small aperture particularly at the point where 4 the maximum material coil radius is on the drum and where 5 the spring is at its inherent lowest torque output. 6 7 The fabric cover has to be manually pulled out over 8 the top of the car when fitting it and the minor resistance

j SUBSTITUTE SHIΞT

from the spring gradually tensioning provides a desire ^d effect of resisting wind displacement during fitting of t ^h e cover .

To avoid unnecessary tension to the f abric an ^d unacceptable operation handling tension when the cover is _f u _l ly _. extende _d it is necessary to ensure that limited spr ⁱ ng tension is applied to the cover up to this point.

_N orma _l spring coiling characteristics will not provi ^d e su _i ta _bl e operating performance for this product application.

_τhis pro _bl em is a _l so evident in other reel units that _h ave been considered.

_A ccor _d ing _l y, the present invention provides a spring w _h ich can _b e used in such a reel unit or other reel un ⁱ t wherein the spring has been processed to increase the torqu capacity in t _h e unwound state, to provide a higher torqu output t _h an is available from a normally clock wound sprin configuration.

_i n a specific aspect the present invention provides spira _l coi _l e _d spring wherein part thereof is reverse co ⁱ biased.

The present invention also provides a method of forming a spring comprising spirally coiling a spring stri and imparting to part thereof reverse coil bias .

_Th e present invention also provides a reel uni incorporating such a spring.

The present invention also provides apparatus fo forming suc _h a spring comprising coiling means and means fo imparting reverse coil bias to part of the spring.

The spring of the present invention may be forme ^d b

SUBSTITUTE SHEET

_f ee _d ing a spring strip through rol lers to impart a _p re _d etermine _d amount of reverse coil bias into part of the strip.

The reverse coil bias may be applied to a leading length of the spring.

The reverse coil bias part of the spring and the normal coil bias part of the spring are preferably joined by a portion which is of reducing reverse coil bias along its length.

m a preferred aspect, the present invention provides a reel unit comprising a shaft, a drum mounted on the shaft for rotation thereon and a spiral coiled spring in accordance with this invention connected at an inner end to the shaft and at an outer end to the drum.

Preferably the reverse coil bias part is adjacent said inner end and in this instance the reverse coil bias part will resist the initial clockwork coiling of the spring towards the shaft. This will result in an extended torque arm effect being induced into the spring material adjacent to the shaft and should result in a considerable increase in the initial torque output of the spring. This will gradually reduce as the spring turns transfer from being coiled against a casing inner wall down onto the shaft. The spring strip at the outer end is preferably coiled in an unbiased condition which reduces the torque output of the spring where it is attached to the drum.

In one instance, a length of the spring at least substantially at said inner end has little or no coil bias at all. This should result in an increase in torque arm length in the winding of the spring and a consequential torque arm length in use of the spring and since that increase is in the early stage of the spring where it is most critical it should be generally beneficial.

SUBSTITUTE SH£ET

A method of forming springs and apparatus therefor in accordance with this invention will now be described with the aid of the accompanying drawings in which:-

Fig. 1 is a schematic representation of the apparatus,

Fig. 2 is a side elevation of an inner end of a spring in accordance with this invention, Fig. 3 is a side elevation of an outer end of the spring,

Fig. 4 is a side elevation of clamping means,

Fig. 5 is a top plan view of a specific apparatus,

Fig. 6 is a side elevational view of the apparatus of Fig. 5,

Fig. 7 is an end view of the apparatus of Fig. 5,

Fig. 8 is a side elevational view of part of the apparatus of Fig. 5,

Fig. 9 is a view on line A-A in Fig. 8,

Fig.10 is a cross-sectional view of a reel unit incorporating a spring in accordance with this invention in one condition,

Fig.11 is a cross-sectional view of the reel unit of Fig.10 but in another condition,

Fig.12 is a graph comparing the torque of a spring in accordance with this invention with other springs.

Fig.13 is a perspective view of part of an alternative mode of spring winding, and

Fig.14 is a side elevational view showing the alternative mode of Fig.13 but at a different stage.

Referring to Fig. 1, the apparatus comprises a coil 1 of spring strip 21 which is fed to a mandrel 5 for forming an inner end 7 of the spring to be formed. The mandrel 5 is associated with clamps 2c and 2d which serve to hold the strip 21 for forming the inner end 7. The mandrel 5 may be retracted in the direction of arrow 22 when not required for use.

A mandrel 6 is provided for forming an outer end 8 of the spring to be formed. The mandrel 6 is associated with clamps 2a and 2b which serve to hold the strip 21 for forming the outer end 8. The mandrel 6 may be retracted in the direction of arrow 22 when not required for use.

In a preferred form of the invention, the clamps 2a-d are used all at once, the mandrels 5 and 6 are used at the same time and a strip cropping punch 3 is used to cut the strip so that the mandrel 6 forms the outer end 8 of one spring while the mandrel 5 forms the inner end of a next spring in manufacturing sequence.

The strip 21 is passed through an induction heater 4. Alternative heating means might be used. This heating enables the ends 7 and 8 to be readily formed.

The length of the strip 21 is determined by a setting of a length detector 9.

The strip 21 is passed through a reverse bias inducing unit 11 and the inner end 7 is connected to a mandrel 10 which is driven to coil the strip 21 into the spring to be formed.

The reverse bias inducing unit 11 which is better

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- 6 - _ς 6 8 and 9 comprises a power driven roller

_T he diameter of the roller lib has an effect on th of reverse bias imparted in that the larger th amount o ^ rever ^ ^^ ^ _{reverse bιa} diameter of roller J- ^U . imparted. _z 4-\-.__ -rv-,1 1 or 11a on the arc 3 Further, the V°^ b^s pa ed in that t ^alS ° Z£ ~ tr: s s ^h own ⁱ n ^Fig . ^β a grei tle leading on the roller Ha by the cylind 36 , the greater will be the reverse bias.

in the preferred form of the invention in forming oil ri _h , o ^P f ₇ m length. oni the first 0^ -.^ biased and _ _{. 4} t-h _c e _t t _r r _a annssiitri ⁱ oon from reverse ^bi as τ ^o

=^ _{Q gra} ual by pivoting the frame ^JI coiling is made gradua ^l ny P _pos it cy _l inder 32 to gradually move the roller 8 9 sshhoowwnn iinn pphhaannttoomm aatt lliidd.. 0 When the spring is completely wound onto the mand 1 ₁₀ itly he removed therefrom direct into a c srng 2 3 ddeessiirreedd.. 4 T _h e apparatus shown m •i _t - vFii _a g. 5 ⁵ -7 ^/ i ⁱ ss b ^o asically t ^h e s 5 ₊ >. Tat Fi _g 1 but additionally has a spring ant ⁱ -r 6 as that of ^' _{annealing clamps} is in lieu of 7 _b ack clamp 17, res ⁱ sx ^anu retainers

_Hott er 4 retractable spring coil reta ⁱ ner 38 induction heater * , ^■ *- ^■ = ^»■■ - SUBSTITUTE s;-:

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which can he retracted to transfer a coiled spring, to a

1 casing, a thrust coupling 25, a retracting cyl ⁱ n ^d er 26 for 2

3 retracting the mandrel 10, an hydraulic motor 12 for driving 3

4 the mandrel 10, cylin _d ers 16 for retracting the mandrels 5 4 an _d 6, rotary thrust couplings 14 and racK and pinion ^d r.ves 5 6 13 and 15 for the mandrels 5 and 6. 7

Preference is ma _d e to Fig. 12 wherein line 41 shows 8 the torque characteristics of a conventional hel ⁱ cal coiled -9 0 s _p ring at simulated reducing radius operation and typrcally

I ShhoOwWsS lloOwW ilnniitt-iα-aαli t _.o*_,r_..^_u~e~ a—n-d high end torgue. Line 4,2 sh.o-,ws 1 _j t _h e torque c _h aracteristics of a conventional ^h el ⁱ ca ^l co ^il ed 12 spring at constant ra _d ius operation and typ ⁱ cally shows low 13

14 _i n _i tial torque but low end torque.

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Line 43 shows the torque characteristics of a coil 16 spring of the present invention and shows relatively ^h ig 17 initial torque and relatively low end torque. 18

₂₀ Figs. 10 and 11 show a spring 51 in accor ^d ance wit

21 this invention as appl _* .i _I e_ _Λ d ₊ tno a _ -rreeeel ^l uunni ⁱ t ^t of the type show

22 in WO87/0O228.

24 in Figs.10 and 11 is depicted a shaft 52 which hold the inner end 7 of the spring 51, a drum 53 which i

25 rotata _b ly mounte _d on the shaft 52 and to which the outer en

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27 8 of t _h e spri •„n„g 5c _r 1i -is _c ςs _e eccuurree _d ^u b ^u y_ means of a pin ⁵⁴ .

28 fa _b ric cover 56 is wound on the drum 53.

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_Th e con _d it _i on o _f t _h e spring 51 when the cover ⁱ s ^f ull

30 wound on the drum is shown in full line in Fig. 10 and t ^h

31 theoret _i cal _f orm of t _h e transition from reverse ^bi as t

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33 normal coiling is shown in dash lines.

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_T he cond _i t _i on of the spring 51 when t ^h e cover 56 ⁱ

35 fully drawn off the drum 53 is shown in Fig. 11.

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37 in the alternative mode of spring wind shown ⁱ n Figs

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13 and 14, the shaft end 7' of the spring is given a form similar to the anchor end shown in Fig. 3 but the spring is similarly wound on the mandrel 10 as previously described excepting that the end 7 ' is allowed to be free so that in the winding of the spring the inner coils will be relatively more away from the mandrel 10 and thus there will be an increase in torque arm length in the winding of the spring and a consequential increase in torque arm length in use of the spring and this will occur at a useful stage.

The springs of the present invention should find applications in devices such as reel units where high initial torque and relatively low final torque is required.

The described arrangement has been advanced merely by way of explanation and many modifications may be made thereto without departing from the spirit and scope of the invention which includes every novel feature and combination of novel features herein disclosed.

SUBSTiTUTS S' -r