Rolling mill

Abstract

A hand powered jewellery rolling mill comprises a support frame and a pair of opposed parallel cylindrical rollers rotatably mounted to the support frame. It further comprises a drive shaft connected

Description

FIELD OF INVENTION The present invention relates to a hand-powered jewellery rolling mill. BACKGROUND Manual rolling mills are used by jewellers and craftspeople in the manufacture of jewellery. Such manual jewellery rolling mills comprise a pair of parallel cylindrical rollers between which precious metals such as silver and gold are passed to reshape material. The rollers may have flat or textured / patterned profiles for sheet material and / or may include recessed grooves (for example having a half-round or v-shaped profiled) for processing wire. Some mills may have a combination of profiles on different portions of the rollers (for example a plain section and a grooved wire section). Some rolling mills may have interchangeable rollers with different profiles. The spacing between the rollers is typically adjustable to allow variation in the resulting thickness of the worked material. At least one of the rollers is turned by the user during use via a crank handle. The crank handle is manually powered by handturning. An example of an improved hand-powered rolling mill is disclosed in the applicant's international patent application WO2022 / 012994 which includes a high ratio gear train (for example greater than 10 to 1) to provide improved usability over traditional designs. These forms of hand-powered rolling mills perform well and are widely used. However, it would be beneficial to provide an alternate or improved hand-powered rolling mill and embodiments of the invention seek to provide such a device which may, for example, have improved usability for the end user. SUMMARY OF INVENTION According to a first aspect of the invention there is provided a hand-powered jewellery rolling mill comprising a support frame and a pairof opposed parallel cylindrical rollers rotatably mounted to the support frame. A drive shaft is connected to at least one of the rollers for rotation thereof. A manually rotatable handle is configured for providing a drive force to the drive shaft. The rolling mill further comprises an input shaft, rotatable by the manually rotatable handle. A gearbox is provided between the input and the drive shaft and comprises a planetary gearset. In embodiments the gearbox may provide a ratio of at least 10 to 1 between the drive shaft and the input. In particular embodiments may provide a 15 to 1 ratio. In embodiments the gearbox may further comprise a simple gear train between the drive shaft and the planetary gearset. The simple gear train may comprise a driving gear on the drive shaft coupled to at least one idler gear. The simple gear train may comprise spur gears. An output from the simple gear train may be coupled to an input of the planetary gearset. The simple gear train may provide a relatively small ratio between the drive shaft and the input of the planetary gearset. For example the gear ratio of the simple gear train may be less than 1 to 5 (and may for example be approximately 1 to 3). The input of the planetary gearset may be coupled to a sun gear. The input may additionally be coupled to a planet carrier. It will be appreciated that planetary gearsets in which the planet carrier and sun gear are coupled (i.e. rotationally fixed relative to one another) provide a direct drive between the sun and planet carrier. In embodiments the gearbox comprises a housing. The housing may comprise a ring gearforthe planetary gearset. In embodiments the ringgear may be integrally formed (for example cast) in an inner surface of the housing. The housing may further comprise a recess coaxial with the ring gear for enclosing a planet carrier of the planetary gearset. The recess may have a different diameter to the ring gear (for example a deduced diameter). The recess may be axially adjacent to the ring gear. The recess may be contiguous with the ring gear. In some embodiments a recess may be provided on each side of the ring gear. In embodiments the drive shaft (and therefore the handle) is provided on a parallel axis to the planetary gearset. The housing may further comprise a driveshaft support portion which projects radially outwardly from the main body of the housing. The driveshaft support portion may include bearings to support the driveshaft, additionally the driveshaft support portion may include parallel bearings to support any idler gears of the simple gear train. The main body of the housing may be coaxial with the planetary gearbox and may, when mounted to the rolling mill be coaxial with the input shaft. In embodiments the housing may comprise first and second housing portions. The housing portions may have complementary profiles which abut to form an enclosure around the gearbox (for example as clamshell halves). A plurality of fasteners may connect the housing portions. Whilst the invention has been described above, it extends to any inventive combination of the features set out above or in the following description or drawings. Unless otherwise stated, each of the integers described may be used in combination with any other integer as would be understood by the person skilled in the art. DESCRIPTION OF THE DRAWINGS Embodiments of the invention may be performed in various ways, and an embodiment thereof will now be described by way of example only, reference being made to the accompanying drawings, in which: Figure 1 shows a schematic three-dimensional view of a hand-powered jewellery rolling mill; Figure 2 shows a schematic view of a gearbox assembly for use with a rolling mill; Figure 3 is an exploded view of the gearbox assembly of Figure 2; and Figure 4 show the assembled gear train of the gearbox assembly of figures 2 and 3. DETAILED DESCRIPTION OF AN EMBODIMENT In the context of embodiments of the invention references may be made to components being horizontal or vertical and it should be appreciated that such references are not intended to be limiting. Such terms are used for ease of reference and are intended to refer to the general directions relative to the apparatus when in use. For example, a "horizontal" direction or plane may, in practice, be defined by being generally parallel to the surface upon which the apparatus is mounted during use. Likewise, a "vertical" direction or plane may be defined by being generally perpendicular to the surface upon which the apparatus is mounted. As such, the relevant axis of the apparatus are not considered fixed in absolute terms (rather only relative to the underlying surface). Any other references to directions such as above / below or upward / downward are likewise intended to be interpreted in a relative, non-limiting, manner. A hand-powered jewellery rolling mill 101 is shown in Figure 1 to help understand the context of the present invention. The rolling mill of figure 1 includes a gearbox in accordance with the Applicant's international patent application WO2022 / 012994. A rolling mill in accordance with the present invention will include a different gearbox configuration as shown in figures 2 to 4. The skilled person will understand that the rolling mill of figure 1 shows the general configuration of the mill and that the gearboxes can readily be interchanged without necessitating other changes to the apparatus. The mill 101 comprises a support frame 105, a pair of opposed parallel cylindrical rollers 110, 112 and a rotatable handle 120 for providing a drive force to the rollers 110,112. The handle 120 a crank arm 121 but other configurations may be possible. In use, a workpiece of precious metal is passed between the rollers 110, 112 by actuating the rollers using the handle 120. The metal is compressed to produce a desired thickness. An adjuster 115 is provided at the upper end of the rolling mill 1 for setting the spacing between the rollers 110,112. The adjustor includes a control dial 116 and a gauge 117. In use, a workpiece may be passed through the rolling mill several times with the spacing of the rollers 110,112 reduced progressively using the adjustor until the final thickness is achieved. The adjustor mechanism is not shown in the figures as it is enclosed by a protective guard, but suitable arrangements would be apparent to those skilled in the art (and the specific details are not essential to the present invention). The frame 105 is formed from a single piece metal casting. The frame 105 comprises two spaced apart parallel upright side members, which extend vertically from a horizontal base portion 106. The base portion 106 is provided with bolt holes 107 at each corner to allow the rolling mill to be secured to a work bench during use. An upper joining member 108 connects the top of the side members, and is generally parallel to the base portion 106. The frame defines a central aperture in which the rollers 110,112 are rotatably mounted. The rollers 110,112 are generally cylindrical and formed of hardened steel. Each roller 110, 112 is mounted on parallel axle extending perpendicular to the side members. The feed direction of the rolling mill 101 is indicated by the arrow F on Figure 1 and is perpendicular to the perpendicular to the axis of the rollers 110, 112 and generally parallel to the base of the frame 105 (i.e. horizontal). The rollers 110,112 both include a first portion having a smooth cylindrical outside portion and a second portion having opposed grooves which define a shaped cross section gap (for example the grooves may each be V-shaped and jointly define a square section). The upper roller 110 is vertically adjustable relative to the lower roller 112 using the mechanism associated with the adjuster 115 such that the desired roller spacing can be set by a user. One side of the rollers 110 and 112 are engaged by a geared coupling 113 (covered by a protective cover in the figures) such that they rotate in unison. As will be known by those skilled in the art, the gears of the geared coupling 113 are configured with a tooth depth selected to ensure that they can intermesh sufficiently at a variety of spacings between the upper and lower roller. In the illustrated embodiment the geared coupling 113 is at an axial end of the rollers but it will be appreciated that in other embodiments the rollers could extend further beyond the coupling such that the coupling is in at a non-end section of the rollers / roller axles. The lower roller 112 typically includes an axle stem (not shown) which extends beyond the frame 105 on the side member 104b opposite to the gear coupling 113. The axle stem includes a coupling feature (not shown) to enable a gearbox assembly to be connected to the axle stem. In accordance with embodiments the rolling mill 1 may be used with the gearbox subassembly 50 as shown in figures 2 to 4. The gearbox subassembly 50 is assembled within a housing 1,2 which is a two-piece, clamshell style, metal casting. As seen in figure 2 the assembled housing comprises a generally cylindrical main body and a radially outwardly projecting driveshaft support portion which supports the drive shaft 5 and the handle 9. The housing comprises a first portion 1 and a second portion 2. The rear side of the first portion 1 of the housing is shaped and proportioned to conform to the external side of one of the side members of the frame 105. The housing is removably attached to the side members 4b via bolts or other fixings to the frame 5. A number of bolts 16 connect the two portions of the housing together in the assembled configuration (as shown in figure 3). The housing 40 encloses the drive train 60 of the gear box which is shown in isolation in Figure 4. The assembly of the drive train may be best seen in the exploded view of Figure 3. The drive train includes a planetary gearset which includes a planet carrier 3, a sun gear 4 and planet gears 8 each mounted to the carrier 3 via spindles 11. The planetary gearset is rotatable mounted in the housing on first and second axially spaced apart bearings 12,14. The planer carrier 3 also includes a planetary input gear 6. The carrier 3, planetary input gear 6 and sun gear 4 are rotationally fixed (by a key arrangement between the shaft of the sun 4 and the corresponding apertures in the gear 6 and carrier 3. The planet gears 8 also mesh with a ring gear formed in the inner face of the housing portion 1. It can also be noted that a portion of the housing adjacent and contiguous with the ring gear has a plain inner circumference and is stepped inwardly relative to the ring gear. This portion of the housing defines a recess for receiving the planet carrier 3 in the assembled gearbox. A corresponding recess is also provided (but not visible in the figure) for the input gear 6 of the planetary gear set in the other housing portion 2 on the opposing side of the ring gear. The input gear 6 of the planetary gearset is engaged and driven by a spur idler gear 7. The idler gear is mounted on a shaft 11 (which is parallel to the axis of the planetary gearset) which is mounted within the housing on a bearing 13. A drive shaft 5 is mounted parallel to the shaft 11 and rotatably supported in the housing on a further bearing 15. The drive shaft 5 includes a stem portion on which is mounted a cast metal handle 9, secured by a keyed arrangement to the drive shaft 5 and retained by a circlip 17. A crank handle 10 may be provided at the opposing end of the handle 9 for grasping by the user. The drive shaft 5 also includes a drive gear which is a spur gear and engages the idler gear 7. The drive gear 5 may for example have 20 teeth, the idler gear 7 may have 27 teeth and the planetary input gear 6 may have 60 teeth. Thus, the drive, idler and input may provide a simple gear train which provides an initial input to the planetary gearset. The simple gear train may therefore have a reduction ration of 1 to 3. The planetary gearset may then provide a further reduction to provide the desired total gearbox ratio - for example 15 to 1. Although the invention has been described above with reference to a preferred embodiment, it will be appreciated that various changes or modification may be made without departing from the scope of the invention as defined in the appended claims. For example, whilst in the illustrated example the gearbox and roller coupling are on opposite sides of the rolling mill it will be appreciated that in some embodiments they could be arranged on a single side of the mill (for example to allow additional rollers to be provided on the opposite side external to the frame).

Claims

1. A hand-powered jewellery rolling mill comprisinga support frame and a pair of opposed parallel cylindrical rollers rotatably mounted to the support frame;a drive shaft connected to at least one of the rollers for rotation thereof;a manually rotatable handle configured for providing a drive force to the drive shaft; andthe rolling mill further comprises an input shaft, rotatable by the manually rotatable handle;a gearbox is provided between the input and the drive shaft and comprises a planetary gearset.

2. The hand-powered jewellery rolling mill of claim 1, wherein the gearbox may provide a ratio of at least 10 to 1 between the drive shaft and the input.

3. The hand-powered jewellery rolling mill of claim 1, wherein the gearbox comprises a 15 to 1 ratio.

4. The hand-powered jewellery rolling mill of any preceding claim, wherein the gearbox further comprises a simple gear train between the drive shaft and the planetary gearset.

5. The hand-powered jewellery rolling mill of claim 4, wherein the simple gear train comprises a driving gear on the drive shaft coupled to at least one idler gear.

6. The hand-powered jewellery rolling mill of claim 4 or 5, wherein the simple gear train has a gear ratio of less than 1 to 5.

7. The hand-powered jewellery rolling mill of any preceding claim, wherein the input of the planetary gearset is coupled to a sun gear and to a planet carrier to provide a direct drive between the sun and planet carrier.

8. The hand-powered jewellery rolling mill of any preceding claim, wherein gearbox comprises a housing, the housing comprising a ring gear for the planetary gearset.

9. The hand-powered jewellery rolling mill of claim 8, wherein the ring gear is integrally formed in an inner surface of the housing.

10. The hand-powered jewellery rolling mill of claim 8 or 9, wherein the housing further comprises a recess coaxial with the ring gear for enclosing a planet carrier of the planetary gearset.

11. The hand-powered jewellery rolling mill of any of claims 8 to 10, wherein the drive shaft is provided on a parallel axis to the planetary gearset, and the housing comprises a driveshaft support portion which projects radially outwardly from the main body of the housing.

12. The hand-powered jewellery rolling mill of claim 11, wherein the driveshaft support portion include bearings to support the driveshaft13. The hand-powered jewellery rolling mill of claim 12, wherein the driveshaft support portion includes parallel bearings to support idler gears of a simple gear train.

14. The hand-powered jewellery rolling mill of any of claims 8 to 13, wherein a main body of the housing is coaxial with the planetary gearbox and, when mounted to the rolling mill, is coaxial with the input shaft.

15. The hand-powered jewellery rolling mill of any of claims 8 to 14, wherein the housing comprises first and second housing portions, the housing portions having complementary profiles which abut to form an enclosure around the gearbox.

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