Method for manufacturing frames made of composite materials, particularly for bicycles and the like

Abstract

A method (100) for manufacturing frames made of composite materials, particularly for bicycles and the like, comprising the following steps: – providing (101) a mandrel (10) forming a central cavity (12) adapted to accommodate a central spacer element (13) which protrudes at its ends from the mandrel (10); – assembling and expanding (102) the mandrel (10); – providing and treating (103) a fiber fabric with a thermosetting bonding material; – placing (104) the mandrel (10) in a machine for wrapping material in fabric form; – wrapping (105) the treated fiber fabric (16) onto the mandrel (10) to form at least one first layer; – heating (106) the layer wrapped on the mandrel (10) for the activation of the thermosetting bonding material; – repeating (107) the two previous steps to obtain a multilayer tubular structure (16); – removing and extracting (108) the mandrel (10) from the wrapping machine and from the multilayer tubular structure (16), respectively; – cutting (109) the multilayer tubular structure (16) to form individual tubular elements (17) which form a frame (1) of a bicycle or the like; – connecting (110) the tubular elements (17) and any additional preforms made of a composite material comprising the fiber fabric and deriving from other production processes; – placing and preparing (111) in a mold (19) the tubular elements (17), the optional additional preforms and inserts and mechanical parts; – closing (112) the mold (19) hermetically; – pressurizing (113) the mold (19) to produce a vacuum in the mold (19); – injecting (114) a thermosetting resin into the mold (19); – polymerizing (115) the thermosetting resin; – opening (116) the mold (19); – extracting (117) the frame (1) constituted by the tubular elements (17), the optional additional preforms, the inserts and the mechanical parts.

Description

[0001] METHOD FOR MANUFACTURING FRAMES MADE OF COMPOSITE MATERIALS, PARTICULARLY FOR BICYCLES AND THE LIKE

[0002] The present invention relates to a method for manufacturing frames made of composite materials, particularly for bicycles and the like, to a frame that can be provided by means of the method, and to a bicycle that can be assembled with the frame.

[0003] It is known to use carbon fiber composite materials or the like for the provision of frames for bicycles and the like.

[0004] The provision methods are very varied; in fact, they can range from entirely manual to automated procedures that still involve the execution of manual operations.

[0005] The uncertainty of methods of the known type leads to the presence of defects and nonconformities of the frames, which may have different mechanical characteristics from frame to frame.

[0006] The aim of the present invention is to provide a method for manufacturing frames made of composite materials that offers a sequence of standardized steps such as to eliminate the presence of unpredictable defects.

[0007] Within this aim, an object of the present invention is to provide a method for manufacturing frames made of composite materials that is highly reliable, relatively simple to provide and at competitive costs.

[0008] This aim, as well as this and other objects that will become more apparent hereinafter, are achieved by a method for manufacturing frames made of composite materials, particularly for bicycles and the like, characterized in that it comprises the following steps:

[0009] - providing a mandrel constituted by a plurality of parts shaped to be associated with each other in a radially narrow configuration and movable from said configuration to assume a radially enlarged configuration so as to form a central cavity adapted to accommodate a central spacer element which protrudes at its ends from said mandrel; - assembling and expanding said mandrel;

[0010] - providing and treating a fiber fabric with a thermosetting bonding material;

[0011] - placing said mandrel in a machine for wrapping material in fabric form;

[0012] - wrapping said treated fiber fabric onto said mandrel to form at least one first layer;

[0013] - heating said at least one first layer wrapped on said mandrel for the activation of said thermosetting bonding material;

[0014] - repeating said two previous steps to obtain a multilayer tubular structure;

[0015] - removing and extracting said mandrel from said wrapping machine and from said multilayer tubular structure, respectively;

[0016] - cutting said multilayer tubular structure to form individual tubular elements which form a frame of a bicycle or the like;

[0017] - connecting said tubular elements and any additional preforms made of a composite material comprising said fiber fabric and deriving from other production processes;

[0018] - placing and preparing in a mold said tubular elements, said optional additional preforms and inserts and mechanical parts;

[0019] - closing said mold hermetically;

[0020] - pressurizing said mold to produce a vacuum in said mold;

[0021] - injecting a thermosetting resin into said mold;

[0022] - polymerizing said thermosetting resin;

[0023] - opening said mold;

[0024] - extracting said frame constituted by said tubular elements, said optional additional preforms, said inserts and said mechanical parts.

[0025] Further characteristics and advantages of the invention will become more apparent from the description of a preferred but not exclusive embodiment of a method for manufacturing frames made of composite materials, illustrated by way of non-limiting example in the accompanying drawings, wherein:

[0026] Figure 1 is a block diagram of the steps of the method according to the invention;

[0027] Figure 2 is a perspective view of a mandrel according to the present invention in its radially narrow configuration;

[0028] Figure 3 is a front view of the mandrel shown in Figure 2;

[0029] Figure 4 is a view of the mandrel shown in the preceding figures in its radially enlarged configuration;

[0030] Figure 5 is a schematic view of a bicycle frame according to the invention constituted by a plurality of individual tubular elements;

[0031] Figure 6 is an example view of connecting cores used to connect the tubular elements shown in Figure 5;

[0032] Figure 7 is an exploded perspective view of a mold used for the provision of a bicycle frame according to the invention;

[0033] Figure 8 is a perspective view of a bicycle frame according to the present invention.

[0034] With reference to the figures, and particularly with reference to the block diagram of Figure 1, the method for manufacturing frames made of composite materials, particularly for bicycles and the like, generally designated by the reference numeral 100, comprises first and foremost a step of providing 101 a mandrel 10 constituted by a plurality of parts 11 which are shaped to be associated with each other in a radially narrow configuration, shown in Figures 2 and 3 and are movable from said configuration to assume a radially enlarged configuration, shown in Figure 4, so as to form a central cavity 12 adapted to accommodate a central spacer element 13 which protrudes at its ends from the mandrel 10.

[0035] In greater detail, after the provision step 101 there is the step of assembly and expansion 102 of the mandrel 10, in which its parts 11 are assembled and moved apart for their transition from the radially narrow configuration to the radially enlarged configuration to form the central cavity 12.

[0036] In greater detail, the parts 11 comprise a plurality of engagement teeth 14 and engagement seats 15 shaped to allow assembly of the mandrel 10 and their mutual movement between said radially narrow configuration and said radially enlarged configuration.

[0037] Once the parts 11 are spaced, one proceeds with the insertion of the central spacer element 13 into the central cavity 12 so as to stably reach the radially enlarged configuration without the risk of the parts 11 collapsing into each other during subsequent steps.

[0038] Conveniently, the central spacer element 13 and the central cavity 12 have prismatic and mutually conjugate geometries.

[0039] Once the mandrel 10 has been obtained, the method moves on to the step of providing and treating 103 a fiber fabric, for example made of carbon fiber, with a thermosetting bonding material.

[0040] In the proposed embodiment, the thermosetting bonding material is supplied in powder form and applied to the fiber fabric by means of an applicator device which is external to the wrapping machine.

[0041] Once the fiber fabric has been treated, one proceeds with the step 104 of placing the mandrel in a fabric material wrapping machine and a step 105 of wrapping the fiber fabric on the mandrel 10 is performed for form at least one first layer.

[0042] A heating step 106 is then performed to activate the thermosetting bonding material.

[0043] In the proposed embodiment, the heating step 108 just described is performed by using infrared lamps.

[0044] Depending on the specifications to be obtained, an iteration 107 of the previous two steps is performed to obtain a multilayer tubular structure 16. Advantageously, during the above iteration the fiber fabric is wound onto the mandrel 10 in such a way that the fibers of each layer are crossed over those of the layer below.

[0045] Once these steps have been performed, a step 108 of removal and extraction of the mandrel 10 from said wrapping machine and from the multilayer tubular structure 16 is carried out.

[0046] In such step, the central spacer element 13 is extracted in this manner, so that the mandrel 10 collapses onto itself within the multilayer tubular structure 16 so as to make the parts 11 collapse and separate them from said multilayer tubular structure 16.

[0047] Next, a step takes place for cutting 109 the multilayer tubular structure 16 to form individual tubular elements 17 that will form the frame 1 of a bicycle or similar that is to be provided, as shown in Figure 5.

[0048] In the proposed embodiment, the cutting step 109 is performed manually by following cutting lines formed by the geometric shape of the mandrel 10.

[0049] In fact, the latter has well-defined edges and shapes that allow the fabric material to assume precise and well-delineated shapes that facilitate performing of the cutting operations by the operator.

[0050] At this point, a step 110 is carried out by means of removable connection cores 18, for example made of silicone, for connecting the tubular elements 17 and any additional preforms made of a composite material comprising the fiber fabric and derived from other production processes, illustrated by way of example in Figure 6.

[0051] Once what will be the frame 1 has been assembled, one proceeds with the step of placing and preparing 111 the frame 1 in a mold 19 with the addition of inserts and mechanical parts, such as for example the pedal bottom bracket.

[0052] Here, the connecting portions between the tubular elements 19, any additional preforms and inserts and mechanical parts are wrapped with sheets of fiber fabric, followed by a step 112 of closing the mold 19 in such a way that it is hermetic.

[0053] Advantageously, a step 113 of pressurization of the mold 19 is performed to form a vacuum inside it for a time, for example, of 30 seconds.

[0054] Next, a step 114 of injecting a thermosetting resin into the mold 19 is performed, followed by a step 115 for polymerizing the thermosetting resin.

[0055] Advantageously, the injection step 114 is performed by pushing the thermosetting resin into the mold 19 through an inlet nozzle 20 and simultaneously drawing the resin from the mold 19 through an output nozzle 21.

[0056] Conveniently, the nozzles 20 21 are placed in two opposite portions of the mold 19, for example at the head tube and at the saddle sleeve of the frame 1.

[0057] At this point a step 116 is performed for opening the mold 19 and with the step 117 of extraction of the frame 1 from the mold 19.

[0058] In the latter step, extraction of the removable connecting cores 20 from the frame 1 is also performed.

[0059] The resulting frame 1 is constituted by the tubular elements 17, any additional preforms, inserts and mechanical parts and can be used for the provision of high-performance bicycles.

[0060] In practice it has been found that the manufacturing method according to the present invention achieves the intended aim.

[0061] The manufacturing method thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

[0062] All the details may furthermore be replaced with other technically equivalent elements.

[0063] In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions may be any according to the requirements and the state of the art. The disclosures in Italian Patent Application No. 102024000016351 from which this application claims priority are incorporated herein by reference.

[0064] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

CLAIMS1. A method (100) for manufacturing frames made of composite materials, particularly for bicycles and the like, characterized in that it comprises the following steps:- providing (101) a mandrel (10) constituted by a plurality of parts (11) shaped to be associated with each other in a radially narrow configuration and movable from said configuration to assume a radially enlarged configuration so as to form a central cavity (12) adapted to accommodate a central spacer element (13) which protrudes at its ends from said mandrel (10);- assembling and expanding (102) said mandrel (10);- providing and treating (103) a fiber fabric with a thermosetting bonding material;- placing (104) said mandrel (10) in a machine for wrapping material in fabric form;- wrapping (105) said treated fiber fabric (16) onto said mandrel (10) to form at least one first layer;- heating (106) said at least one first layer wrapped on said mandrel (10) for the activation of said thermosetting bonding material;- repeating (107) said two previous steps to obtain a multilayer tubular structure (16);- removing and extracting (108) said mandrel (10) from said wrapping machine and from said multilayer tubular structure (16), respectively;- cutting (109) said multilayer tubular structure (16) to form individual tubular elements (17) which form a frame (1) of a bicycle or the like;- connecting (110) said tubular elements (17) and any additional preforms made of a composite material comprising said fiber fabric and deriving from other production processes;- placing and preparing (111) in a mold (19) said tubular elements (17), said optional additional preforms and inserts and mechanical parts;- closing (112) said mold (19) hermetically;- pressurizing (113) said mold (19) to produce a vacuum in said mold (19);- injecting (114) a thermosetting resin into said mold (19);- polymerizing (115) said thermosetting resin;- opening (116) said mold (19);- extracting (117) said frame (1) constituted by said tubular elements (17), said optional additional preforms, said inserts and said mechanical parts.

2. The method (100) according to claim 1, characterized in that said assembly and expansion step (102) comprises expanding said parts (11) for their transition from said radially narrow configuration to said radially enlarged configuration for the definition of said central cavity (12) and the insertion of said central spacer element (13) into said central cavity (12); said parts (11) comprising a plurality of engagement teeth (14) and engagement seats (15) shaped to enable the assembly of said mandrel (10) and their mutual movement between said radially narrow configuration and said radially enlarged configuration.

3. The method (100) according to claim 1, characterized in that said central spacer element (13) and said central cavity (12) have prism-like and mutually conjugate geometries.

4. The method (100) according to claim 1, characterized in that said fiber fabric is a carbon fiber fabric.

5. The method (100) according to one or more of the preceding claims, characterized in that said thermosetting bonding material is supplied in powder form and applied to said fiber fabric by means of an applicator device which is external to said wrapping machine.

6. The method (100) according to one or more of the precedingclaims, characterized in that said step (106) of heating said at least one first layer wrapped onto said mandrel (10) is performed by using infrared lamps.

7. The method (100) according to one or more of the preceding claims, characterized in that during said iteration (107) said fiber fabric is wrapped onto said mandrel (10) in such a way that the fibers of each layer are crossed with respect to those of the underlying layer.

8. The method (100) according to one or more of the preceding claims, characterized in that said step (108) of removing and extracting said mandrel (10) comprises extracting said central spacer element (13) and moving said parts (11) from said radially enlarged configuration to said radially narrower configuration in such a manner as to make said parts (11) collapse and separate them from said multilayer tubular structure (16).

9. The method (100) according to one or more of the preceding claims, characterized in that said step (109) of cutting said multilayer tubular structure (16) is performed manually by following cutting lines defined by the geometric shape of said mandrel (10).

10. The method (100) according to one or more of the preceding claims, characterized in that said connection step (110) is performed by means of removable connecting cores (18).

11. The method (100) according to claim 10, characterized in that said removable connecting cores (18) are made of silicone.

12. The method (100) according to one or more of the preceding claims, characterized in that the positioning and preparation step (111) comprises wrapping the connecting portions between said tubular elements (17), said possible further preforms and inserts and mechanical parts with sheets of said fiber fabric.

13. The method (100) according to one or more of the preceding claims, characterized in that said step (113) of pressurizing said mold (19) is performed for 30 seconds.

14. The method (100) according to one or more of the precedingclaims, characterized in that said injection step (114) is performed by pushing said thermosetting resin into said mold (19) through an inlet nozzle (20) and by simultaneously drawing said resin from said mold (19) through an output nozzle (21); said nozzles (20, 21) being positioned in two opposite portions of said mold (19).

15. The method (100) according to one or more of the preceding claims, characterized in that said step (117) of extracting said frame (1) also comprises extracting said connecting cores (18) from said frame (1).

16. A bicycle frame (1), characterized in that it is provided by means of a method (100) according to one or more of the preceding claims.

17. A bicycle, characterized in that it comprises a frame (1) according to claim 16.

Images