Patent Description:
Performance bicycle rims need to be light weight, have an inherent stiffness, be durable and well balanced so that these can be used on the road, on race tracks and in off-road applications.

Composite bicycle rims are well known as light weight rims. Unfortunately, the method of manufacture of such rims leads to deficient inter-laminar shear strengths, non-ideal wall thickness leading to rims having less than the desired stiffness and strength and also rims that are comparatively unbalanced.

It should also be noted that such bicycle rims are manufactured by hand in a very time-consuming manner. Typically, it takes between <NUM> to <NUM> hours to produce one rim per hand.

Conventionally known bicycle rims as well as production methods thereof are known from <CIT>, <CIT> and <CIT>.

For this reason, it is an object of the invention to provide an improved method and bicycle rim in which the durability and stiffness of the bicycle rim is increased and the degree of unbalance is reliably reduced. It is yet a further object of the invention to reduce the time of manufacture of such bicycle rims and to provide an at least semi-automated method of manufacture of such bicycle rims.

This object is satisfied by a method having the features of claim <NUM>.

Such a method of assembling a bicycle rim comprises the steps of:.

Said rim according to the invention further has first and second internal spaces that are formed by respective first and second patterns, with the first pattern being formed in one piece and forming said first internal space and being covered with said one or more layers of webs of fiber material and sequentially assembling said second pattern from respective second pattern segments at said covered first pattern from two, three, four, five or more second pattern segments to form said second pattern covered with one or more further layers of webs of fiber material. In this way a high-performance rim having the desired characteristics can be formed.

Additionally, said combined first and second patterns are covered with one or more layers of webs of fiber material. In this way one can ensure a thorough connection between the covered first and second patterns to form a high strength rim having the desired stiffness and inter-laminar shear strength.

By using a removable mold in the form of a pattern of removable material the layers forming the bicycle rim can be ideally pressed together during the formation of the rim, so that rims can be formed with a pre-definable uniform thickness of the sidewalls of the rim. Moreover, through the use of two molds pressing the material of the rim between one another a bond between the layers of webs of fiber material can be enhanced leading to more durable and stable rims. A further benefit obtained by such a method is that the internal surface of internal spaces of the rim can be formed with a reduced desired surface roughness, this leads to a more homogenous rim, to a rim having the desired stiffness and to a rim having an improved inter-laminar shear strength.

Using composite materials, a lightweight rim can be formed for high-performance applications, said rim having the desired characteristics. By way of the method described herein the time of manufacture of the rim can typically be reduced from <NUM> hours to <NUM> to <NUM> minutes depending on the type of resin used to form the composite material and its time of curing. This decrease in time of manufacture is complemented by an increase in the quality of the rim obtained using the presently described method.

It should also be noted that the first temperature range is preferably a temperature range of ± <NUM>° centered about the desired first temperature. The first temperature is preferably selected between <NUM> and <NUM>, especially between <NUM> and <NUM>.

In this connection it should be noted that the webs of fiber material may a layer of fabric made from woven fibers that are made by interlacing two or more tows of fibers at right angles to one another. Additionally or alternatively the web of fiber material may be formed by a tow of fibers. In this connection a tow of fibers is a bunch of fibers like a yarn.

The first temperature may be used for at least one of heating the mold to aid introduction of resin into the mold, heating said mold for curing the material of said rim, and removal of the removable material of the pattern, such as a wax.

In this connection it should be noted that the one or more patterns may be used as part of a mold for a so-called resin transfer molding (RTM) process. In this case, the pattern, i.e. wax mold, may then be covered with roving following which it may be inserted into a further mold for the addition of resin and heat treatment to form the final device of composite material in a manner known per se.

At least one of the one or more patterns may be formed by three, four, five or more pattern segments that are assembled to form the at least one of the one or more patterns. Forming said one or more patterns from a plurality of pattern segments makes the assembly of larger patterns with complex geometries simpler.

Said pattern segments may be covered with one or more layers of webs of fiber material before or after the pattern segments are combined to form said pattern.

At least one of the one or more patterns may comprise one or more first inserts integrally formed therein. The provision of inserts in the pattern means that the patterns can be held in further apparatus and be provided with features providing stability in shape to said patterns of removable material.

At least one of said first inserts may be configured to interact with a support apparatus used to assemble the rim. In this way the pattern can be beneficially held during at least some of the stages of an RTM process.

In this connection it should be noted that at least one of said one or more patterns may be supported at a respective support apparatus. In this way the patterns can all be beneficially held during at least some of the stages of the RTM process.

Said first pattern may further be formed by three, four, five or more pattern segments that are assembled to form the respective pattern of the internal space prior to covering the respective one of the first and second patterns forming the internal space with said one or more layers of webs of fiber material. The use of pattern segments enables the production of complex 3D parts in an expedient and efficient manner.

Said first pattern may also be formed from two, three, four, five or more first pattern segments to form said first pattern. In this way smaller molds for the manufacture of the respective first and second patterns can be used which can simplify the manufacture of the first and second patterns.

The method of assembling the rim may further comprise the step of heating said mold to a second temperature in a second temperature range. It should also be noted that the second temperature range is preferably a temperature range of ± <NUM>° centered about the desired second temperature. The second temperature is preferably selected between <NUM> and <NUM>, preferably between <NUM> and <NUM>.

The second temperature may be used for at least one of heating the mold to heat said mold for curing the material of said rim, and removing said removable material, e.g. melting away said wax.

The method of assembling the rim may further comprise the step of heating said mold to a third temperature in a third temperature range. The third temperature can generally be selected to remove the removable material, e.g. a wax, i.e. to remove said one or more patterns of removable material from said mold. It should also be noted that the third temperature range is preferably a temperature range of ± <NUM>° centered about the desired third temperature. The third temperature is preferably selected between <NUM> and <NUM>, preferably between <NUM> and <NUM>.

The reason for these first, second and/or third temperature ranges existing is that the molds may have a temperature gradient across a length and width of the mold which leads to a higher temperature of the mold at one side of the mold in comparison to the temperature at a further side of the mold.

Said first temperature may be lower than said second temperature. Moreover, said second temperature may be lower than said third temperature. In order to produce the rims a resin used to bond the different one or more layers of webs of fiber material one to another may be subjected to temperature and pressure to ensure that the resin flows into all of the spaces between fibers and bonds these one to another. This flow of the resin can be aided if the temperature of the mold is elevated in comparison to room temperature at standard pressures due to a more runny consistency of the resin. The runnier the consistency of the resin is, reduces the number of air pockets obtained in the rim leading to an increased durability and stiffness of said rim due to the decrease in the number of air pockets.

Following the flow of the resin throughout the mold, the resin is cured in order to obtain the rim, this curing can take place either on the application of the second temperature and/or via the application of UV light. Once the material of the rim has cured and the rim will maintain its final shape, the removable material can be removed from the internal spaces of said rim.

The removal may take place by heating the removable material, e.g. a wax, or a special compound that can be liquified on the application of one or more further chemical substances can be used as the removable material.

A vacuum may be applied to said mold during and/or prior to heating said mold to said first temperature, optionally during and/or prior to heating said mold to said second and third temperatures. The application of a vacuum possibly on heating can assist in the flow of a resin in and around one or more layers of fiber material to ensure that as few as possible air pockets result in the rim. It has namely been found that the presence of too many air pockets can significantly reduce the inter laminar shear strength of the rim. Hence a rim having an as high as possible inter-laminar shear strength is obtainable by such a method which reduces the amount of air pockets present during the manufacture of said rim in and around said layers of webs of fiber material.

Said vacuum may be selected with a pressure in the range of <NUM> to <NUM>-<NUM> bar. Such vacuums are readily obtainable using a roughing pump either on its own or connected in series with a turbomolecular pump. Moreover, such pressure can achieve the desired flow of the resin through and around the layers of webs of fiber material while reducing the number of air-pockets remaining in a rim.

The method of assembling the rim may further comprise the step of introducing a resin into said mold prior to and/or during said step of heating of said mold to said first temperature.

Through the provision of resin from the outside, a web of fiber material which previously is not coated with a resin, i.e. a prepreg, can be used. Thereby the assembly in a mold can be simplified and an average wall thickness of the final rim can be controlled in an improved manner.

Said resin may be heated to below a curing temperature of said resin on the introduction of said resin into said mold. In this way one does not risk the resin curing prior to removing all of any possibly present air gaps.

Said step of the application of heat may comprise heating said mold to said second temperature and/or heating said resin on introduction into said mold to said second temperature in said second temperature range. In this way one can ensure that the material of the rim can cure at the ideal temperature to make it possible to obtain the desired strength and stiffness of the rim in the shortest possible period of time to expedite the manufacture of the rim.

Said resin may be one of a one-component resin, a two-component resin comprising a hardener, and a multi-component resin comprising one or more hardeners.

The resin may comprise a resin on an epoxy basis, a resin on a polyurethane basis, a resin on a cyanate ester basis or another basis suitable for injection or infusion.

Said one or more patterns may comprise at least one of one or more recesses and projections in an outer surface thereof. Such projections can be used to form e.g. apertures or predefined channels at the rim. The recess can be used to form portions having an increased amount of material to increase a stiffness of a portion of the rim, such as for the formation of ribs e.g. in a sidewall of the rim, to strengthen the radial components of the rim. The projections can be arranged at positions of the rim where spokes and/or the valve are arranged. The spokes and thus the projections are generally arranged symmetrically along the circumference of the rim.

Additionally or alternatively the positions at which spokes and a valve are placed at said rim can be reinforced with elevated portions by providing corresponding recesses in the pattern.

Said one or more patterns of removable material may be made of wax. Wax is a comparatively cheap material that can be used in the bulk manufacture of wax patterns in a reliable manner.

Said one or more patterns of removable material are produced in a 3D printing process, an injection molding process and a wax casting process. These are beneficial ways of producing patterns of removable material.

Said wax casting process may comprise the steps of:.

In this way wax patterns can be formed which are generally free off shrinkage effects at an outer surface of the pattern ensuring the manufacture of a rim having the desired wall thickness and wall thickness tolerance.

Said one or more patterns of removable material may have a melting point selected in the temperature range of <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>. Said one or more patterns of removable material remain stable in shape to temperatures selected in the range of <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>. Said one or more patterns of removable material may thus remain stable in shape at temperatures below a melting point of said removable material. This is particularly beneficial to ensure the manufacture of rims having the desired uniform wall thickness.

Said one or more patterns of removable material may remain stable in shape at temperatures below a melting point of said removable material. This means that an outer surface of the one or more patterns does not readily alter its physical state. In this way the one or more patterns can form a part of a mold used in a Resin Transfer Molding Process (RTM process) or a Vacuum Assisted Resin Transfer processes (VARTM process) with which the rim may be formed.

The one or more patterns of removable material that are stable in shape can thus be used to form inner surfaces of enclosed spaces of the rim, with the inner surfaces of the enclosed spaces of the rim having a pre-definable shape and contour.

One or more of the patterns of removable material may be formed by first pattern segments and/or second pattern segments that remain stable in shape at temperatures below a melting point of said removable material. In this way the assembled pattern segments can form patterns that form molds for the one or more internal spaces of the rim.

Said first pattern may be formed by first pattern segments, in particular only formed by first pattern segments and/or wherein said second pattern may be formed by second pattern segments, in particular only formed by second pattern segments.

Said first pattern segments and/or said second pattern segments may be bonded one to another using a pattern material comprising, in particular consisting of said removable material. Using a material comprising said removable material as a bonding agent means that the bonding agent will likewise be removed on removing said pattern. Alternatively the pattern segments can be welded one to another, for example by hot plate welding.

Said first pattern segments and/or said second pattern segments are bonded one to another at respective first and second ends using said pattern material comprising, in particular consisting of said removable material.

First and second ends of said first pattern segments and/or of said second pattern segments may be formed complementary to one another. In this way the first and second ends of respective first and second pattern segments can be bonded one to another in a simple way as these are matching in shape or the like. For this purpose the ends may be chamfered, have features complementary and/or matching in shape and/or the like.

It is particularly preferable to use pattern segments having shapes complementary to one another to assemble the patterns and then to bond these one to another, e.g. by means of a welding technique.

Said first and second pattern segments may have a generally arc-shaped outer shaped viewed in a cross-section thereof. In this way the segments replicate parts forming internal molds for forming the rim, which when assembled form a complete pattern respectively a mold for said rim.

Said one or more patterns have an outer surface, with an average surface roughness Ra below <NUM>, in particular below <NUM> and especially below <NUM>. By providing an internal mold for said rim having such a surface roughness, rims with pre-definable wall thicknesses can be formed.

Two patterns of removable material may be provided, with each pattern of removable material having an outer shape forming a mold for an inner shape of a respective cavity of said rim, with said removable material remaining stable in shape at temperatures below a melting point of said removable material at standard temperatures and pressures, and wherein the same removable material may be used for each of the two patterns of removable material. In this way a mold for a rim may be provided that can be covered with the fiber material prior to insertion into the mold where the rim is subsequently formed.

Said one or more patterns may each have one or more second inserts present therein, with said second inserts being fixedly attached to said rim. The position of the second inserts can correspond to positions in which recesses are present in the pattern to reinforce the portions of the rim where the second inserts are present. The second inserts can also be used to aid in coupling the rim to the further components of a bicycle wheel, such as spokes or a valve of the wheel.

Said second inserts may be provided at positions for spokes of said rim and/or at a position of a valve associated with a wheel formed by said rim. It has hitherto been found that during the production of composite rims, the drilling of the holes for the spokes can lead to a splintering of the material of said rim at the position where it is bored leading to inherent weaknesses in said rim.

In this connection it should be noted that said second inserts may be directly or indirectly attached to said first inserts. In this way the position of the spokes of the bicycle rim can be aligned from the start during the method of assembling the bicycle rim such that a rim with a superior weight distribution can be achieved.

In this connection it should be noted that tows of fibers may be applied at the positions of the inserts to reinforce the position of the inserts in said completed rim, whereas woven fabric can be introduced on areas representing a planar surface of the rim.

Said one or more layers of fiber material are formed by carbon fibers, glass fibers, basalt fibers, wood fibers, hemp fibers, aramid fibers, and polyester fibers, respectively in dry condition or as a prepreg. Such fibers can beneficially be used in the formation of a rim of composite material that is reinforced with fibers. In this connection it should be noted that a prepreg is a layer of fibers which comprise an adhesive.

According to a further aspect the present invention relates to a rim obtained by a method in accordance with the teaching present herein, said rim being formed of composite material, said rim having one or more internal spaces formed by walls, with a wall thickness of said walls of said rim having a predefinable wall thickness with a tolerance of the wall thickness lying in the range of ± <NUM>, in particular of ± <NUM>, especially of ± <NUM>, for a wall thickness selected in the range of <NUM> to <NUM>, in particular for a length of material of said rim cut from said rim in the range of <NUM> to <NUM> and at a width selected in the range of <NUM> to <NUM>.

Said rim has a tolerance of the wall thickness lying in the range of ± <NUM>, especially of ±<NUM>, for a wall thickness selected in the range of <NUM> to <NUM>.

Said rim may have a void content of less than <NUM>%, in particular of less than <NUM>%. A rim having such a void content has a particularly good inter laminar shear strength. Such shear strengths are ideal for high-performance bicycle rims having the desired durability and stiffness.

In this connection it should be noted that a void is a pore present in a composite material that remains unfilled with polymer and fibers. If less than ideal manufacturing standards are used then voids result which cause a degradation of the mechanical properties and lifespan of the composite material. The void content is represented as a ratio where the volume of voids, solid material and bulk volume are taken into account.

Said rim may have a tolerance of the surface profile of ± <NUM>, in particular for a length of material cut from said rim selected in the range of <NUM> to <NUM> and a width selected in the range of <NUM> to <NUM>. In this way a rim having particularly smooth surfaces can be achieved by means of the present teaching.

In this connection it should be noted that the tolerance of the surface profile is a standard measurement technique used to define the surface quality of objects. The more uniform the surface is, the lower its tolerance is. The surface profile is defined by a uniform boundary around a surface within which the elements of the surface must lie. The surface profile is a complex tolerance that simultaneously controls a feature's form, size, orientation, and sometimes location. The surface profile is a three-dimensional tolerance that applies in all directions regardless of the drawing view where the tolerance is specified. It is usually used on parts with complex outer shape and a constant cross-section like extrusions.

To measure the tolerance of a surface profile two planes are placed around the surface whose tolerance profile is to be measured and the tolerance is defined by the spacing between the planes that are placed around the surface.

Said rim may have a tolerance of the surface profile of ± <NUM>, in particular of ± <NUM>, especially of ± <NUM> e.g. at the position of e.g. an insert for a spoke or the like.

Said rim may comprise reinforcing ribs, reinforcing beads, stiffening corrugations and/or reinforcing platforms, i.e. elevated portions, formed at at least an inner surface of a sidewall portion of said rim. Such formations in an otherwise uniform surface add strength to the rim and hence improve the durability and strength of a rim comprising such formations.

Said rim may comprise inserts present at positions of said rim corresponding to positions of spokes and/or of a valve associated with a wheel formed by said rim.

Said rim may comprise apertures inherently present in at least one wall of the rim. By providing a rim having such apertures, weak spots of prior rims can be avoided.

Further embodiments of the invention are described in the following description of the Figures. The invention will be explained in the following in detail by means of embodiments and with reference to the drawing in which is shown:.

In the following the same reference numerals will be used for parts having the same or equivalent function. Any statements made having regard to the direction of a component are made relative to the position shown in the drawing and can naturally vary in the actual position of application.

<FIG> shows a side view of a wheel <NUM> in the form of a bicycle wheel. The wheel <NUM> comprises a rim <NUM> connected to a hub and axle assembly <NUM> via spokes <NUM>. The wheel <NUM> can be connected to e.g. a bicycle (not shown) via the hub and axle assembly <NUM> in a known manner. The axle of the hub and axle assembly <NUM> is thereby fixed relative to the bicycle, whereas the hub of the hub and axle assembly <NUM> can rotate about the axle of the hub and axle assembly <NUM>.

The spokes <NUM> are provided in order to carry the weight of the bicycle as well as its load, e.g. the rider, via the rim <NUM>. The spokes <NUM> and rim <NUM> also absorb any irregularities that may be present on the road or track and thereby aid in ensuring the comfort of the rider. Furthermore, the spokes <NUM> and the rim <NUM> transmit the acceleration and breaking effort of the rider between the road and the hub and axle assembly <NUM> and vice versa. Thus, the rim <NUM> has to be able to cope with the forces transmitted via the spokes <NUM> and in the wheel <NUM> in order to ensure an as efficient as possible ride and comfort using said rim <NUM>.

<FIG> shows a side view of the rim <NUM> of <FIG>. The rim can be a standard sized rim such as a <NUM>", <NUM>", <NUM>", <NUM>" or a <NUM>" rim. It could also be one of a <NUM>" to <NUM>" rim, typically used in children bicycles or BMXs.

<FIG> shows a sectional view along the sectional line A:A of the rim <NUM> of <FIG>. The rim <NUM> comprises two sidewalls <NUM> connected at a bottom end <NUM>, with the two-sidewalls <NUM> forming part of a tire receiving section <NUM> at an end of said sidewalls <NUM> lying radially outward of the bottom end <NUM>, and a hollow section <NUM> directly adjacent to the tire receiving section <NUM>. The tire receiving section <NUM> and the hollow section <NUM> respectively defining internal spaces <NUM>', <NUM>' of said rim <NUM>.

The tire receiving section <NUM> is separated from the hollow section <NUM> via a separating wall <NUM>. The separating wall <NUM> comprises a channel <NUM> which is configured to accommodate part of an inner tube (not shown) of the wheel <NUM>.

An end of the sidewalls <NUM> remote from the bottom end <NUM> comprises projections <NUM> that can be present in order to increase a clamping force on a tire that can be installed in the tire receiving section <NUM>. As indicated in <FIG> such projections are not required at the rim <NUM>.

<FIG> shows a sectional view similar to that of <FIG>, with the rim <NUM> comprising reinforcing ribs <NUM> and an elevated portion <NUM>. The elevated portion forming a reinforcing platform at the bottom end <NUM> of said rim <NUM>, such that the spokes <NUM> can be stably connected to the rim <NUM> at the position of the elevated portion <NUM>. The reinforcing ribs <NUM> are present at an inner surface <NUM> of the rim <NUM>.

<FIG> shows a sectional view similar to that of <FIG>. The rim <NUM> comprises inserts <NUM> present at positions of said rim <NUM> corresponding to positions of the spokes <NUM>. These inserts can be metal inserts <NUM> or the like that can be embedded into the rim <NUM> during the manufacture of the rim <NUM>.

Also visible is an aperture <NUM> via which the spokes can be engaged using a tool in order to balance a wheel <NUM> by tightening or loosening a spoke <NUM> as required.

In this connection it should be noted that the apertures <NUM> could also be formed by inserts <NUM> present in the patterns <NUM>, <NUM> of removable material M at positions which later form the apertures or the position of the spokes in order to fixedly and inherently attach said inserts <NUM> during the manufacture and assembly of said rim.

In this connection it should be noted that inserts <NUM> and apertures <NUM> may also be present at a position of the rim <NUM> where a valve associated with the wheel <NUM> is inserted into the rim <NUM>.

In this connection it should further be noted that the provision of ribs <NUM> and/or elevated portions <NUM> and/or inserts <NUM> and/or apertures <NUM> within the internal spaces <NUM>', <NUM>' of the rim <NUM> has hitherto not been possible using prior art techniques of forming rims of composite materials. This is because the prior art methods had no control over the formation of the inner space <NUM>', <NUM>' of said rims <NUM> therefore not making it possible to foresee such structures in the rims <NUM>.

The rim <NUM> as will be explained in the following is formed by the composite material. A wall thickness of the walls <NUM>, <NUM> of said rim <NUM> have a pre-definable wall thickness with a tolerance of the wall thickness lying in the range of ± <NUM> for a wall thickness selected in the range of <NUM> to <NUM>.

In order to test the tolerance of the wall thickness a strip of material of a part of the rim <NUM> is cut from the rim, for example a strip having a length of <NUM> and a width of <NUM>, or a strip having a length of <NUM> and a width of <NUM> and a variation of the thickness of each strip is measured at <NUM> intervals along both the length and the width of the strip of material using e.g. a pair of Vernier calipers or the like. The measured thicknesses are then added and divided by the amount of measurements to obtain an average thickness. This average thickness is then compared to the pre-defined thickness of said part of said rim <NUM>.

Indeed for very high-performance rims <NUM> manufactured using the method described herein, the rims <NUM> may have a tolerance of the wall thickness lying in the range of ± <NUM>, especially of ±<NUM>, for a wall thickness selected in the range of <NUM> to <NUM>.

The rim <NUM> may have an increased inter laminar shear strength due to a comparatively low void content of less than <NUM>%.

<FIG> shows a sectional view similar to that of <FIG> of a mold <NUM> in which internal spaces <NUM>', <NUM>' of said rim <NUM> are filed with a pattern <NUM>, <NUM> of removable material M. The mold <NUM> comprises an internal cavity <NUM>' into which the patterns <NUM>, <NUM>, and the layers of webs of fiber material <NUM>, <NUM>, <NUM> are placed on assembly of the rim. On assembly of the rim, the top and bottom halves <NUM>, <NUM> of the mold <NUM> are closed. In order to form the composite material of the rim <NUM>, resin R is introduced into the mold <NUM> via a resin port <NUM> and a corresponding passage <NUM>' from a non-shown reservoir.

Thus, the patterns of removable material M can be used as a mold in resin transfer molding (RTM) processes to form composite bicycle rims.

The removeable material M forming the first pattern <NUM> is covered completely with layer of webs of fiber material <NUM>. Three sides of the second pattern <NUM> formed by removable material M are covered with layers of webs of fiber material <NUM>. Once the covered second pattern <NUM> is brought into contact with the covered first pattern <NUM>, a third layer of webs of fiber material <NUM> cover both parts of both the first and second patterns <NUM>, <NUM>. Said one or more layers of fiber material <NUM>, <NUM>, <NUM> can be formed from carbon fibers, glass fibers, wood fibers, hemp fibers, aramid fibers, polyester fibers, a prepreg.

In this connection it should be noted that it is preferred to use pure fibers that are not in prepreg form, as such fibers are still comparatively flexible and have not reached the final thickness obtained on the addition of the resin R. In this way the covered patterns <NUM>, <NUM> can be placed into the mold <NUM> in a simpler manner. Leading to a reduction in the time required to assemble the rim <NUM>. Moreover, layers of webs of fiber material <NUM>, <NUM>, <NUM> to which a resin R is added can be produced having a superior inter-laminar shear force in comparison to layers of pre-pregs.

In order to aid the flow of resin R into a space filled with the layer of webs of fiber material <NUM>, <NUM>, <NUM> formed between an inner surface <NUM>" of the mold <NUM> and an outer surface 48ʺʺ of the pattern <NUM>, respectively of an outer surface 50ʺʺ of the pattern <NUM>, a vacuum and/or heat can be applied. This leads to a more runny consistency of the resin R so that the resin R can be distributed better in the mold <NUM>. Such a runny resin R can be used to reduce the amount of air pockets in said rim <NUM>. Further air pockets can be extracted using said vacuum. The vacuum can be set to a pressure in the range of <NUM> to <NUM>-<NUM> bar.

The vacuum can be applied by sucking air from the internal cavity <NUM>' using a vacuum pump <NUM>. The vacuum pump <NUM> is connected to the internal cavity <NUM>' via a vacuum port <NUM> and a channel <NUM>'.

The heat can be applied via a heating and/or cooling device <NUM>. This can be configured to heat and/or cool the mold <NUM> directly and/or the reservoir of the resin R in order to heat the resin R to a first temperature in a first temperature range.

In this connection it should be noted that the resin R can be cured through the application of heat and/or UV light.

If the resin R is cured through the application of heat the mold <NUM> is heated further to a second temperature in a second temperature range via the heating and/or cooling device <NUM>. In this connection it should be noted that the mold <NUM> and/or the resin R is/are heated to a temperature below a curing temperature of said resin R on the introduction of said resin R into said mold <NUM> to ensure that the rim <NUM> does not prematurely cure during the introduction of the resin R into the mold <NUM>.

Once the material of the rim <NUM> has cured the removable material M, which is typically a wax, but can also be other kinds of materials, is removed through the application of heat. For this purpose the mold <NUM> is heated further to a third temperature in a third temperature range.

Thus, said first temperature is lower than said second temperature and the second temperature is lower than said third temperature.

In this connection it should be noted that when the mold is heated to one of the first, second and third temperatures, the heating steps may be carried out gradually in a stepwise manner. For example, the temperature can be increased in steps of <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>° C over a period of <NUM>, <NUM>, <NUM>, etc., such that the material present in the mold can gradually adapt to the temperature of the mold.

Particularly during RTM processes, it should be noted that the composite of fiber and resin is typically heated in steps to below the glass transition temperature of the resin in order to prevent the device to be formed from becoming soft and thereby obtaining a device with a deformed outer and/or inner surface.

In this connection it should be noted that the mold used in the RTM process and the wax mold may each preferably be formed from a thermally conductive and non-magnetic material, such as aluminum or an aluminum alloy.

The resin R is one of a one-component resin, a two-component resin comprising a hardener, and a multi-component resin comprising one or several hardener. Moreover, the resin can comprise a resin on an epoxy basis, a resin on a polyurethane basis, a resin R on a cyanate ester basis or another basis suitable for injection or infusion. Such resin can be beneficially used in the formation of composite devices.

Said one or more patterns <NUM>, <NUM> of removable material M can be produced in a 3D printing process, an injection molding process and a wax casting process. By way of example a wax casting process will now be described in connection with <FIG>.

<FIG> show respective sectional views through wax molds <NUM> having inner spaces <NUM>' for forming the first and second patterns <NUM>, <NUM> of removable material M of said rim <NUM>.

<FIG> shows a sectional view through the mold <NUM> comprising mold segments with inner spaces <NUM>' for first and second pattern segments <NUM>', <NUM>' of removable material R. It has namely been found that due to the complex shape of the rim <NUM> as it is shown e.g. in <FIG> with the separating wall <NUM> having the channel <NUM> projecting into the inner cavity <NUM>' of the hollow section <NUM>, it is necessary to assemble at least the second pattern <NUM> of removable material <NUM>' from individual segments. Moreover, this assembly from segments has also been found to make the wax mold <NUM> in which the wax patterns <NUM>, <NUM> can be made simpler. It should be noted that for simpler rims <NUM> having only one cavity it may not be necessary to form patterns <NUM>, <NUM> from pattern segments <NUM>', <NUM>' but that only one pattern <NUM> is required which can be formed in one piece.

Each internal space <NUM>', <NUM>' is formed by the first and second patterns <NUM>, <NUM>, with each first and second pattern <NUM>, <NUM> being formed by three, four, five or more pattern segments <NUM>', <NUM>' that are assembled to form the pattern <NUM>, <NUM> of the respective internal space <NUM>', <NUM>'. For this purpose, first and second ends <NUM>", <NUM>"', <NUM>", <NUM>‴ of the pattern segments <NUM>', <NUM>', comprise complementary shaped tongue and groove like features as indicated in <FIG>. Also other shapes complementary in shape can be provided at the respective ends <NUM>", <NUM>" of the pattern segments <NUM>', <NUM>'. The complementary shaped first and second ends <NUM>", <NUM>‴, <NUM>", <NUM>‴ enable the combining of the individual segments to a wheel shaped pattern <NUM>, <NUM>.

An inner surface <NUM>" of the respective molds <NUM> is shaped such that it has the inner shape of the respective rim <NUM> to be formed by the pattern <NUM>, <NUM> or pattern segments <NUM>', <NUM>' formed in the respective wax mold <NUM>, i.e. the wax mold <NUM> has an inner space <NUM>' having a shape corresponding to an outer shape of said pattern <NUM>, <NUM> or pattern segments <NUM>', <NUM>'.

The wax, i.e. the removable material M, is introduced into said inner space <NUM>' of the mold <NUM> in liquid form from a reservoir <NUM> via a supply line <NUM>'. Between <NUM> and <NUM>% of said inner space <NUM>' of the wax mold <NUM> is filled with liquid removable material M.

Following this a gas G is introduced into said liquid removable material M present in said wax mold <NUM> to pressurize said removable material M present in said wax mold <NUM>. The wax M is pressurized with a pressure difference between an outside of said formed wax pattern <NUM>, <NUM> and a hollow space within said wax pattern <NUM>, <NUM> selected in the range of <NUM> to <NUM> bar in comparison to the wax M which is not pressurized.

The wax mold <NUM> is then moved to completely coat an inner surface <NUM>" of said wax mold <NUM> with said liquid removable material M during a cooling of said mold <NUM>. This can take place by cooling the mold <NUM> while simultaneously rotating the mold <NUM> about at least one axis and thereby exploiting the centrifugal force to coat the inner surface <NUM>" of said wax mold, while forming a hollow pattern <NUM>, <NUM>. By pressurizing an interior of the wax pattern, the wax of the pattern can be urged into contact with the inner surface <NUM>" of the wax mold <NUM> to form the outer surface <NUM>"", 50ʺʺ of the pattern <NUM>, <NUM> or pattern segments <NUM>', <NUM>' of wax can be achieved free of defects whose outer surface <NUM>"", 50ʺʺ is free of shrinkage effects. Such patterns <NUM>, <NUM> form ideal parts of the mold <NUM> for forming the inner spaces <NUM>', <NUM>" of the rim <NUM>. The removable material M is solidified in said wax mold <NUM> prior to the removal of the first and/or second pattern <NUM>, <NUM> respectively the first and second pattern segments <NUM>', <NUM>'.

Also other methods of making a wax pattern <NUM>, <NUM> or wax pattern segments <NUM>', <NUM>' which avoid shrinkage effects at an outer surface <NUM>"", 50ʺʺ of the wax pattern <NUM>, <NUM> or wax pattern segments <NUM>', <NUM>' can be employed to form the wax pattern.

The one or more patterns <NUM>, <NUM> or wax pattern segments <NUM>', <NUM>' of removable material M are selected such that they remain stable in shape at temperatures below a melting point of said removable material M, but with said temperature corresponding to a curing temperature of the resin R or said Temperature at which the one or more patterns <NUM>, <NUM> or wax pattern segments <NUM>', <NUM>' of removable material M remain stable in shape is selected higher than a curing temperature of the resin R. The wax can beneficially be selected as one of the following waxes.

The one or more patterns <NUM>, <NUM> or wax pattern segments <NUM>', <NUM>' of removable material M may have a melting point selected in the temperature range of <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>. Moreover, the one or more patterns <NUM>, <NUM> or wax pattern segments <NUM>', <NUM>' of removable material M remain stable in shape to temperatures selected in the range of <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>.

Typically the wax may be selected to be a wax molten at a higher temperature in a range from <NUM> to <NUM>, in particular <NUM> to <NUM> and to be solid at a lower temperature in a range from <NUM> to <NUM>, in particular <NUM> to <NUM>. The temperature difference between the higher temperature and the lower temperature is preferably selected to be less than <NUM>, preferably less than <NUM>, in particular less than <NUM> and especially less than <NUM>.

The wax may have a viscosity of greater than <NUM> mPas for a temperature of less than <NUM> and a viscosity of less than <NUM> mPas for a temperature greater than <NUM>. Such waxes have found to be particularly stable in shape up to their melting point and the transition between the liquid state and the solid state takes place over comparatively small temperature ranges making said waxes more cost effective in their use.

On forming the wax pattern <NUM>, <NUM> the wax mold may be heated to a temperature below a solidification temperature of the wax, in particular to a temperature selected in the range of <NUM> to <NUM>, in particular <NUM> to <NUM>, below the solidification temperature of the wax. In this way the wax can be solidified in a more controlled manner and the shrinkage effects at the surface of the wax pattern <NUM>, <NUM> can be reduced as the wax does not automatically solidify on contact with the surface of the mold cavity.

The mold cavity may be evacuated to a pressure selected in the range of <NUM> to <NUM> bar, in particular to a pressure selected in the range of <NUM> to <NUM> bar.

To form the first and second patterns optionally having inserts <NUM>, <NUM>' placed at one or more predefined positions a vacuum may be applied at said wax mold using a vacuum pump. Once the desired vacuum of e.g. <NUM> bar is achieved in the wax mold, a valve may be closed to maintain the pressure within the cavity. Thereafter a liquid form of the removable material M may be introduced into the wax mold. For example, <NUM>% of the volume of the mold <NUM> may be filled with liquid material M, e.g. wax W. Thereby the residual air in the mold is compressed through the addition of the wax W in such a way that the pressure in the wax mold may now be in the range of <NUM> to <NUM> bar depending on the initial vacuum pressure and the amount of wax added.

The wax mold may then be rotated about an axis of rotation, e.g. the axis of the rim while the wax mold is cooled, due to the pressurized gas in the wax mold and the rotation of the mold, the initially liquid wax covers the complete surface of the mold such that a wax pattern can be formed having the outer shape resembling that of the inner shape of the mold used in the RTM process, with the wax pattern having a hollow interior.

If a pattern having a particularly complex outer shape is to be formed, additional gas may be added to the wax mold prior to, during and/or after the addition of the liquid removable material M. Additionally or alternatively more than <NUM>% of the volume of the cavity of the wax mold can be filled with the removable material M. This additional pressure in the mold can guide the liquid removable material into the complex negative geometries of the mold to ensure that a pattern having an outer surface <NUM>"", 50ʺʺ substantially free of defects can be formed.

<FIG> shows a side view of an assembly of second pattern segments <NUM>' of removable material at a support apparatus <NUM>. The support apparatus <NUM> is configured to support the patterns <NUM>, <NUM> and their respective segments <NUM>', <NUM>' during the assembly of the components of the rim <NUM> prior to and/or during the introduction of the components of the rim <NUM> into the mold <NUM> in which the composite material forming the rim <NUM> is cured.

For this purpose, the individual pattern segments <NUM>' are connected at their ends <NUM>". Once the pattern segments <NUM>' have been combined to the first pattern <NUM>, all of the sides of this are completely covered with one or more layers of webs of fiber material <NUM>.

Once the first pattern is completely covered with the one or more layers of webs of material <NUM>, the second pattern segments <NUM>' are assembled at the covered first pattern <NUM> as shown in <FIG>. During the assembly of the second pattern segments <NUM>" to form the second pattern <NUM>, three of four sides of the second pattern segments <NUM>" are covered with one or more layers of webs of fiber material <NUM> to from the inner space <NUM>' of the tire receiving section <NUM>.

The covered and combined first and second patterns <NUM>, <NUM> are subsequently covered with one or more further layers of webs of fiber material <NUM>. Following this the covered patterns <NUM>, <NUM> are introduced into the mold <NUM> as shown in <FIG> for the curing of the rim <NUM> to form the final rim <NUM>.

<FIG> shows a sectional view through a mold <NUM> for the first patterns <NUM> similar to that of <FIG>. The difference being that the mold comprises projections <NUM> present which are distributed about the inner surface <NUM>" of the mold <NUM> in order to form e.g. the ribs <NUM> and/or the elevated portion <NUM> at the inner surface <NUM>' of the sidewalls <NUM> of said rim <NUM>. In this connection it should be noted that each inner surface <NUM>' of the sidewall <NUM> can comprise a plurality of evenly spaced apart ribs, for example between <NUM> and <NUM> such ribs <NUM> can be provided, whereas the elevated portion <NUM> can be either continuous and extend around the whole length of the bottom end of the rim <NUM> or several elevated portions <NUM> can be provided at regions where the spokes <NUM> are connected to the rim <NUM>.

<FIG> shows a partial side view of the second pattern <NUM> used to form the rim of <FIG> at a position where the spokes <NUM> are introduced into said rim <NUM>. The apertures <NUM>, <NUM> (see <FIG>) of the rim are formed via projections <NUM> of said second pattern <NUM>. The projections <NUM> are present in a respective recess <NUM> of said pattern <NUM>.

In this connection it should be noted that similar recesses <NUM> and projections can be present in the first pattern <NUM>.

In this connection it should be further noted that each of the patterns <NUM>, <NUM> may only comprise either recesses <NUM> or projections <NUM>.

<FIG> shows a sectional view similar to that of <FIG> formed using the second pattern <NUM> according to <FIG>. The rim <NUM> comprises apertures <NUM>, <NUM> integrally formed during the manufacture of said rim <NUM>. The apertures <NUM> is inherently present at the bottom end <NUM> formed by the sidewalls <NUM>, whereas the aperture <NUM> is present in the separating wall <NUM>.

It should also be noted that simper forms of rims <NUM> can be formed using the method described in the foregoing namely rims <NUM> only having one internal space <NUM>'. Such an internal space <NUM>' could be formed e.g. in a manner similar to the internal space <NUM>' of the tire receiving section <NUM>, with the spokes then being connected to the rim <NUM> directly in the channel <NUM> formed in the separating wall <NUM>. In this case said channel <NUM> may be formed deeper and/or comprise recesses at positions where the spokes <NUM> are attached to the rim <NUM>. If such a comparatively simple structure is selected the wax pattern <NUM> used can be produced as one without the need of combining several wax patterns <NUM>, significantly reducing the cost of manufacture of such a rim.

Thus in the RTM process described in the foregoing at least one layer of roving is provided as a first layer of fiber material <NUM> optionally also a second layer of fiber material <NUM> is provided as further roving and/or a third layer of fiber material <NUM> is provided as further roving. The one or more patterns covered with the roving are then placed into the mold. The mold is then evacuated to create a vacuum in the mold. The resin R is then injected into the mold at a temperature above room temperature but below the ideal hardening temperature of the resin R possibly under pressure. The resin R at elevated temperature and which is possible pressurized is more flowable than unpressurized resin R at room temperature and hence can flow more easily through the roving and the cavity in the mold in order to ensure, if possible, that no air pockets are formed in the composite material of the final device.

The resin R is then permitted to solidify, i.e. harden, at a temperature selected below the melting temperature of the wax pattern, preferably while gradually increasing the temperature of the mold between the boundaries of the second temperature range from the lower temperature to the higher temperature, e.g. from <NUM> to <NUM>. If required, openings and/or apertures can be applied at the hardened composite device. Following which the temperature of the mold is gradually increased from e.g. <NUM> to <NUM> during the third heating step in order to melt out the wax patterns.

As is known to the person skilled in the art of RTM processes, the glass transition temperature of the resin can be increased temporally in the mold during the stepwise gradual increase in temperature to above the melting point of the wax to form the device. The liquid wax can then be removed via the openings and/or apertures present at the rim, e.g. at the position of the spokes.

<FIG> show an alternative assembly of the bicycle rim <NUM> to the one discussed in connection with <FIG> and <FIG>. In this mold <NUM> a first pattern <NUM> formed from a single piece and having an insert <NUM>' present therein is used. This first pattern <NUM> forms the outer hollow space of the rim <NUM> in contrast to the first pattern <NUM> shown in <FIG> and <FIG> which forms the inner of the two hollow spaces of the rim <NUM> shown there.

<FIG> shows a top sectional view of the mold of <FIG>, with the first pattern <NUM> installed therein. The insert <NUM>' completely surrounds the outer surface 48ʺʺ of the pattern <NUM>. The pattern <NUM> can be gripped via this insert <NUM>' without the removable material M of the pattern being damaged during the handling of the first pattern <NUM>. Thereby the outer surface 48ʺʺ of the pattern <NUM> can be protected against damages.

<FIG> shows a view similar to that of <FIG> for a different type of pattern <NUM>. The insert <NUM>' of the pattern <NUM> comprises two stubs <NUM>" via which the first pattern can be held in an aligned manner during the further handling of the pattern <NUM>. For example, as shown in <FIG>, the insert <NUM>' can be held in an aligned manner at the support apparatus <NUM>. The alignment being carried out relative to the two stubs <NUM>".

<FIG> shows a sectional view of the first and second patterns <NUM>, <NUM> similar to <FIG> prior to the application of a third layer of roving of fiber material <NUM>. In this connection it should be noted that the second pattern <NUM> may not have to be completely coated with the second roving of fiber material <NUM>, but may be free of fiber material at the point of connection with the first pattern <NUM>, since this comprises roving of first material <NUM> at this point of connection.

<FIG> shows a schematic sectional view of the assembly of second pattern segments <NUM>' at the first pattern <NUM> covered with roving of fiber material <NUM> and <NUM>. Like in the example shown in <FIG> and <FIG> the individual segments <NUM>' are assembled to the completed pattern <NUM>.

<FIG> shows a schematic sectional view of the first and second patterns <NUM>, <NUM> of <FIG> in the mold <NUM> formed from top and bottom halves <NUM>, <NUM>. The rim <NUM> has been formed as part of the steps conducted during the RTM process, with the final temperature step not yet having been carried out in which the removable material M is removed from the internal spaces of the rim <NUM>.

Claim 1:
Method of assembling a bicycle rim (<NUM>), the method comprising the steps of:
providing one or more patterns (<NUM>, <NUM>) of removable material (M), said one or more patterns (<NUM>, <NUM>) together having an outer shape resembling an inner shape of at least part of said rim (<NUM>);
covering at least some of the outer sides of said one or more patterns (<NUM>, <NUM>) of removable material (M) with one or more layers of webs of fiber material (<NUM>, <NUM>, <NUM>); said one or more layers of webs of fiber material (<NUM>, <NUM>, <NUM>) forming said rim (<NUM>);
placing said covered one or more patterns (<NUM>, <NUM>) of removable material (M) into a mold (<NUM>), said mold (<NUM>) having an internal cavity (<NUM>') the internal cavity (<NUM>') corresponding to an outer shape of said rim (<NUM>);
heating said mold (<NUM>) to a first temperature in a first temperature range, wherein said bicycle rim (<NUM>) has first and second internal spaces (<NUM>', <NUM>') that are formed by respective first and second patterns (<NUM>, <NUM>), with the first pattern (<NUM>, <NUM>) forming said first internal space (<NUM>') and being covered with said one or more layers of webs of fiber material (<NUM>) and
characterised by sequentially assembling said second pattern (<NUM>, <NUM>) from respective second pattern segments (<NUM>', <NUM>') at said covered first pattern (<NUM>, <NUM>) from two, three, four, five or more second pattern segments (<NUM>', <NUM>') to form said second pattern (<NUM>, <NUM>) covered with one or more further layers of webs of fiber material (<NUM>, <NUM>), and
wherein said combined first and second patterns (<NUM>, <NUM>) are covered with one or more further layers of webs of fiber material (<NUM>).