US3922771A

US3922771A - Method for the manufacture of driving belt packages

Info

Publication number: US3922771A
Application number: US531348A
Authority: US
Inventors: Bernard Josep Beusink; Marinus Hubertus Cuypers; Alexandre Horowitz
Original assignee: Varitrac AG
Current assignee: Varitrac AG; Bosch Transmission Technology BV
Priority date: 1973-12-11
Filing date: 1974-12-10
Publication date: 1975-12-02
Anticipated expiration: 1992-12-02
Also published as: DE2458451B2; NL7316956A; FR2253951A1; FR2253951B1; GB1474818A; DE2458451A1

Abstract

A method is disclosed for obtaining an exact fitting of a plurality of endless metal bands one into the other so as to form a belt package. Each endless belt is obtained as a section from a thin seamless tubing or by welding against each other the ends of a metal strip. Though the closed bands may be shaped with different diameters they will only fit around each other with some play. According to the new method the package is arranged on an expansible template which is then expanded to an extent by which each of the bands is elongated and any play between them is removed and the package is exposed to a tempering treatment preferably when the package is still under tension on the template. The bands are preferably elongated to a degree within the limit of elasticity and belt packages with mutual identical dimensions are obtained by simultaneously treating them side by side in equally dimensioned parts of one template.

Description

United States Patent 1191 Beusink, deceased et al. 1 Dec. 2, 1975 [54] METHOD FOR THE MANUFACTURE OF 2,170,308 8/1939 Purves 140/108 DRIVING BELT PACKAGES [75] Inventors: Bernard Joseph Beusink, deceased, Primary Mehr law of VelhovemDerle, Attorney, Agent, or Firm-Waters, Schwartz & Nissen Netherlands, by Johanna Magaretha Maria Beusink nee Overkamp, T administratrix; Marinus Hubertus [57] ABS RACT Cuypers; Alexandre Horowitz, both A method is disclosed for obtaining an exact fitting of of Eindhoven, Netherlands a plurality of endless metal bands one into the other so as to form a belt package. Each endless belt is ob- [73] Asslgnee vamrac Swltzerland tained as a section from a thin seamless tubing or by [22] Filed: Dec. 10, 1974 welding against each other the ends of a metal strip. Though the closed bands may be shaped with different [211 App! 531348 diameters they will only fit around each other with some play. According to the new method the package [30] Foreign Application Priority Dat is arranged on an expansible template which is then Dec. 11, 1973 Netherlands 7316956 expanded extent by which each 0f the bands is elongated and any play between them is removed and 52 vs. C] 29/445; 29/480 the Package is a tempering treatment Pref- 51 1111.01. B21D 31/04; B21D 53/14 "ably when the Package is Still under 5 Field f Search n 72/183 378 355; 140/108; template. The bands are preferably elongated to a de- 29/445 480 gree within the limit of elasticity and belt packages with mutual identical dimensions are obtained by si- 5 References Cited multaneously treating them side by side in equally di- UNITED STATES PATENTS mensioned parts of one template.

1,625,131 4/1927 14 Claims, 5 Drawing Figures Miller 72/355 U.S. Patent Dec. 2, 1975 METHOD FOR THE MANUFACTURE OF DRIVING BELT PACKAGES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for manufacturing a package of endless metal bands, particularly for use as a driving belt, comprising the steps of arranging a plurality of bands approximately fitting around each other on a template adapted to the inner side of the innermost belt, tensioning the whole by means of the template and preserving the caused deformations by tempering.

2. Description of the Prior Art A methodof the general type indicated hereabove as the field of the invention has been applied in the prior art for the purpose of precurving driving belts in order to reduce bending losses during normal use of the belts on pulleys. In this known art a belt composed of one or more metal bands is curved by guiding it on two pulleys, one of which has a small diameter and the belt is tightly stretched therearound by subjecting one of the pulleys to a spring force tending to separate the pulleys. After the precurving operation the stainless loop is tempered to preserve the precurve quality.

SUMMARY OF THE INVENTION A main object of the present invention is to meet difficulties which are experienced owing to the fact that an exact fitting of the bands into one another is required in order to ensure that the total pull which the package as a whole should absorb is distributed in as much as possible equal parts on the several bands of which the package is composed, while nevertheless each of the bands should be capable of individually following the bending around the pulleys.

It is further an object of the invention to make belt packages perfectly identical to each other which is of particular importance when a plurality of them are utilized in side by side position in a driving belt transmission in order to cause them to participate to an equal extent in the same drive.

on performing the method it is also of importance in order to obtain optimal results that each band to be tensioned has a great uniformity of properties continuously on their whole length. In this connection a further development of the invention is directed to an improved method for obtaining a suitable welded joint by which the ends of a piece of band severed from band material are interconnected so as to form an endless belt.

The invention and a number of advantageously to be applied details are defined in the appending claims and hereinafter clarified with reference to the diagrammatic figures of the drawing.

BRIEF DESCRIPTION OF THE DRAWING.

The drawing illustrates in a schematic way some embodiments of arrangements for the application of the new method to be described at the hand of this drawing.

In the drawing:

FIG. 1 shows an arrangement in which conical means are used as an expansible template for performing the method;

FIG. 2 shows an arrangement in which the belt package is slung over an expansible template formed by two guide rollers of equal diameter which during the treatment are spaced farther from each other by means allowing to impose a well defined elongation of the bands onto a predetermined limit;

FIG. 3 is a plan view of the arrangement of two strip ends which at the location represented in the figure are welded together so as to form a closed band;

FIG. 4 is a cross section on the line IVIV of FIG. 3, in which a detail is shown;

FIG. 5 is a cross section on the line V-V of FIG. 3.

DETAILED DESCRIPTION First follows a theoretical appreciation with refer' ence to FIG. 1 which for this part can serve an an illustration. In this figure two packages are shown, each comprising only three bands, denoted by the reference numerals 1-3. In reality each package may contain more than three, e.g. ten bands.

Though the bands can be obtained as thin sections of seamless tubing of slighly different diameters, they can also be made of a straight strip, in which case they are each bent so as to form a closed endless belt, wherein the ends of the originally straight strips are interconnected.

When by an accurate manufacturing process of the individual endless bands the inside diameter of a band is e.g. at most ahalf per mille A; greater than the outside diameter of its next inner part then, under these circumstances, the object aimed at can be attained by tensioning the belt package within the limit of elasticity of the material.

In order to illustrate this by an example a material for the metal bands may be chosen with a yield tension of 0-,, of kg/mm and a modulus of elasticity E of -2.10 kg/mm (an average for steel). Since the belts as driving belts are liable to bending variations the thickness per band will mostly not be chosen greater than e.g. 1 We, of the diameter of the band when bent in a circular shape and the thickness of the package not greater than e.g. one percent or some percents of that diameter. Now applies:

in which AD is the increment of the diameter D of the bent band under the influence of a tensile stress at in the band. As a consequence of the bending of a band in a circular shape to a diameter D there is already a bending stress o'b available, for which is applicable:

in which 8 is the thickness of one band.

In order to keep within the elastic sphere when the band is stretched the following equation applies for the maximal increment of diameter:

AD a: m D E in which for the maximal tensile stress 0' tmax applies:

o'tmax O' (T Then l 8 E 21 D If the package consists of n bands then (n -l) times the maximally assumed play 1/2000 D should be overcome whereby for the required stretching of the smallest (most inner) band is applicable: "necessary (n l )/2000 D, and this should be smaller than ADmax, whereby for the maximum number of bands to be stretched in the elastic sphere applies:

("nuns mu:

2000 "max s E r| D) if 8 l/2000 D then this gives: max s 12 belts.

If the calculation is made for 8 l/lOOO D then one obtains "max s 11 belts.

If for the belt is selected another metal like beryllium copper for which E can be put down at e.g. l X kg/mm and a band thickness 8 of e.g. l/5OO D is selected, then "max s 21 belts.

A realization of the method within the limit of elasticity is now described with reference to FIG. 1 for a case in which two packages are simultaneously brought into a desired identical form. In each package e.g. ten pieces will be conjoined, but in the figure only three of them are denoted by the reference numerals 1 to 3. Each package is slid on the cylindrical circumference of an annular wedge 4 the outer diameter of which is slightly smaller than the inside diameter of the smallest inner band of each of the packages which are approximately constructed with the same measure. The annular wege 4 which at one location may be transversely cut through in order to allow expansion is, as indicated in the figire, slid on a cone 5 in the direction of the arrow P. The band packages are stretched to an extent such that all bands 1 to 3 of each package are with certainty involved in this extension and as a consequence all bands of each package are smoothly contacting each other under tension on the entire circumference. Thereupon the whole is heated (consequently in the stretched condition of the bands), in principle until all bands have become tensionless and after this tempering treatment the packages are removed from the ring 4. The ring 4 and the cone 5 constitute together an expansible template in this realization.

Both the ring 4 and the cone 5 are made of material which in the heating area undergoes practically no structural changes. Such changes of structure could namely give rise to uncontrollable changes of volume both positive and negative.

On this condition it is possible under circumstances to slide the belt packages on a core made of a material which has a greater coefficient of expansion than the metal belts, so that the expansion of the core plays at least a part in causing the belts to close smoothly and fixedly on each other.

Thanks to the thermal treatment (for which the expression fixing of the deformations may be used) no harmful rest tensions remain.

A second embodiment of the method according to the invention is now described with reference to FIG. 2. Again a belt package is shown comprising only three bands 1 -3, for the sake of clarity they are depicted with a great intermediate space, though in reality the play between them to be removed by the treatment will be only small.

A belt package or a multiple of belt packages in juxtaposition are trained around two

pulleys

6 and 7. The diameter of the pulley 6 is preferably equal to the diameter of the pulley 7, so that in the curved pieces of the belts (in which contact pressure is produced) no relative slip arises.

From an engine block 8 one of the shafts is driven in rotation (the drive is not shown) and a screw spindle 9 driven by the same engine shifts the shaft of the pulley 7 parallely with respect to the shaft of the pulley 6 and uniformly and very slowly so that the extent of elongation of the bands 1 -3 is continuously under control and can be limited to a predetermined value preferably within the limit of elasticity of the bands.

Due to the coupled rotation and continued shifting there is produced a defined stretch in the material of the bands, which is unifonnly distributed on the entire length until all bands completely fit each other and all play between them has been removed.

If necessary for this purpose the limit of elasticity may be passed until the material of all belts have been properly elongated. When as a consequence the bands completely fit each other, the shifting movement is discontinued, while the rotation continues a little longer. The belts are now tend by nature to take the configuration of a circle.

Then the template is released and the packages are removed. The elastic rebound in the belts does not influence the mutual measure tolerances.

Thereupon the properties can be fixed e.g. by thermal treatment in a furnace.

This tempering treatment however is preferably executed simultaneously with the stretching treatment on the pulleys by passing the belt package at the location 10 through a furnace as is indicated by a dash line. The package is thereby locally brought up to a higher temperature. The flow sphere becomes greater as a consequence and the required forces become smaller owing to a decrease of the tension (v at which flowing is produced.

When the above described embodiment is used it becomes even possible to start from bands with mutually identical dimensions for forming a belt package.

As was already indicated it is of importance for the method that bands are used the uniformity of which is not disturbed by the welded joint by which the closed band is made of a strip. For that purpose a welding method has been developed which is now clarified with reference to the FIGS. 3 to 5.

Preferably a welded joint is formed extending obliquely across the width of the band, that is to say according to the sectional line indicated by V-V in FIG. 3. For that purpose each of the strip pieces 11 to be welded is obliquely severed from a supply roll and the two ends are pressed against each other according to the meeting line V-V. Hereupon the strips 12 and. 13 are positioned one covering the line of severance at the upper side and the other one at the underside. Small

additional strips

14 and 15 are provided each along one side edge of the strip 11 inbetween the protruding ends of the

strips

12 and 13.

The whole is clamped in a template. A joint formed by fusion welding, preferably a programmed electronic beam weld ensures that the contacting band ends are welded together by their severed edges, while the

strips

12, 13, 14, are welded along. They serve as influx material. It is therefore of importance that they consist of the same material as the strip 11.

After the weldinng operation the band is ground at the location of the welded joint to the size of the original band, while also the excess material on the side edges is removed.

Nickel steel or also aluminium alloys can e.g. be used, as material for the bands, it is, however, advisable to use materials capable of being hardened like titaniumor beryllium copper alloys with a rather low modulus of elasticity and a high permissible tensile stress.

As a consequence much play can be absorbed within the limits of elasticity when the belt is being stretched and the fixing can be easily performed at temperatures which do not cause risks of disadvantageous changes of the structure of the material, which e.g. could give rise to changes in volume.

In FIG. 1 parts as shown by dotted lines may be added to the arrangement by which a further improvement of the process can be obtained. According to this improvement the packages are fixedly enclosed under pressure at their inner and outer side during the whole tempering treatment or at least during the cooling down period thereof.

For this purpose the

packages

1, 2, 3 are enclosed by the cyclindrical inner wall of an annular wedge 16 of the same type as the annular wedge 4 but in inverse position. For obtaining a complete enclosure under pressure of the package the diameter of the ring 16 is decreased by means of a closed outer annular wedge 17 which is pressed downwardly as indicated by arrows P The annular wedge 16 is supported by a cylindrical ring 18. It has been found by experience that in this way a still greater certainty is obtained for an exact fitting of the bands within each other without any play after treatment.

An explanation may be found therein, that the tight enclosure of the packages on their inner and outer sides procures uniform heating and cooling circumstances for all bands independently from their position in the package and also that influences from differences in thermal expansion coefficients of the cone 5 and of the band material are compensated.

We claim:

1. Method for manufacturing a package of endless metal bands, particularly for use as a driving belt, comprising the steps of arranging a plurality of bands approximately fitting around each other on a template adapted to the inner side of the innermost belt, tensioning the whole by means of the template and preserving the caused deformations by tempering, wherein the template is expanded to an extent at which each of the bands of the package is elongated and any play between the bands is removed.

2. Method as claimed in claim 1, wherein the bands are exposed to the tempering treatment when the packet is still under tension on the template.

3. Method according to claim 2, wherein before exposing the package to a tempering the template is expanded maximally to an extent by which the bands are elongated to a degree within the limit of elasticity.

4. Method according to claim 2, wherein the belt packages are maintained at least during the cooling down period of the tempering step enclosed under pressure on the inner and outer sides between inner template parts and additional outer template parts.

5. Method according to claim 4, wherein one or more band packages on the cylindrical outer face of an expansible conical ring are enclosed on their outer side by the cylindrical inner wall of a compressible outer conical ring the diameter of the latter being decreased by shifting a corresponding but closed ring on its conical outer surface.

6. Method according to claim 1, wherein two or more band packages with approximately identical dimensions are disposed in juxtaposition on parts of a template with mutually identical dimensions and are simultaneously subjected to an equal tensional load and to the tempering treatment.

7. Method according to claim 1, wherein the belt packages are fittingly slid on the cylindrical outer face of an expansible conical ring fitting around a cone on which it is then shifted in the direction of increasing width of the cone and as a consequence expanded and the bands are thereby stretched so that they are completely brought into smooth and fixed contact with each other, whereupon they receive thermal treatment.

8. Method according to claim 1, wherein the belt package is stretched on a template consisting of two pulleys by applying during rotation a continuously increasing, controllable tensile force to one of the pulleys which is slidably supported by which the distance between the shafts of the pulleys is caused to increase to an adjustable extent.

9. Method according to claim 8, wherein the package belt is led through a tempering furnace in its path be tween the pulleys.

10. Method according to claim 8, wherein the pulleys of the template have substantially equal diameters.

11. Method according to claim 1, wherein bands having identical longitudinal dimensions are arranged one within the other in a belt package after which the stretching and tempering treatment is applied to the package.

12. Method according to claim 1, wherein bands are treated which prior to the composition of a package are made from band pieces severed from a band stock, the ends of each band piece being interconnected by a process including the steps of pressing the severed edges of the band piece ends against each other at a meeting line, disposing strips of welding material over the meeting line both on the outer and inner surface of the closed band and further welding strips against the lateral edges of the band, the latter strips likewise overlapping the meeting line, whereupon the whole is clamped in a template and a fusion welded joint is formed, while the strips are welded along and finally the band is ground down to its original thickness and width at the location of the weld.

13. Method according to claim 12, wherein the fusion welded joint is formed as a programmed electronic beam weld.

14. Method according to claim 1, being performed on band material capable of being hardened e.g. titaniumor beryllium alloys, which has a low modulus of elasticity at a high permissible tensile stress.

Claims

9. Method according to claim 8, wherein the package belt is led through a tempering furnace in its path between the pulleys.

14. Method according to claim 1, being performed on band material capable of being hardened e.g. titanium- or beryllium alloys, which has a low modulus of elasticity at a high permissible tensile stress.