JPH04504386A - How to join composite materials - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] How to join composite materials Technical field The present invention involves melting, fusing, bonding, or welding materials at the interface between parts to be joined. A method for joining plastic materials by using induction heating to .

Thermoplastics (e.g. polyetheretherketone (PEEK), Plastics such as polyethersulfone (PES) and polyamideimide carbon fiber reinforced composite materials in particular, without compromising the strength of the constituent materials. It is necessary to be able to join without adding parasitic weight.

For this purpose, induction melting of plastics, including carbon fiber reinforced plastic materials, is Many attempts have been made to do so, but so far success has been limited.

As used herein, the term "thermoplastic" refers to and thereafter exhibit thermosetting properties, such thermosetting thermoplastic materials shall be construed as including. An example of such a material is rTor1on's registration. It is a polyamideimide known as a registered trademark.

Soybean quantity The well-known prior art involves bonding the constituent materials at the interface where the materials are to be joined by melting and fusing. An induction-heated metal surface plate placed against the surface of the surface has been used. preheated The surface plate is removed from the surface and the two surfaces are pressed together to form a joint. do. In general, achieving uniform heating with this heating method is difficult due to the construction materials being very This is difficult to achieve unless the thin The strength of the bond is low.

Another method of induction heating plastic materials involves a wire being used to melt the plastic material. embedded near the area where it should be.

Although a suitable bond may be formed in this manner, the wire adds parasitic weight, e.g. Protruding between component materials may cause corrosion or impair the safety of the component materials. may affect the electrical shielding of the materials of construction, and may affect other materials of construction. By changing the physical properties such as the coefficient of thermal expansion of the joint compared to the material of The use of wire is very disadvantageous, as it can cause problems.

The object of the present invention is to use carbon fibers as a heat source to be heated by induction.

The use of carbon fiber as an induction heating source has proven non-trivial. Consecutive Carbon fiber tows can be stacked as a single unidirectional layer or unidirectional fibers. The use of two or more adjacent layers of fibers stacked in parallel requires proper bonding. A layer of carbon fiber fabric woven from continuous carbon fiber tows would not be fabricated. Attempts have been made to use this, but this too has not resulted in a satisfactory bond. . The failure to create a satisfactory bond is probably due to the contact surface melting the plastic material. This is because sufficient uniform heating cannot be achieved.

21st Gallery Doljo After extensive experimentation, it was possible to circulate the eddy currents generated in the structure. It is concluded that an electrically lossy (10533F) J structure configured in According to the present invention and therefore the present joining method, at least some of the carbon fibers are Such multiple Contacting layer containing oriented discontinuous carbon fibers in the presence of thermoplastic material and thereby electrically induce eddy currents in said layer to generate heat. heating the plastic material and heating the thermoplastic material; By such a step causing melting at the contact surface and bonding between said two parts. characterized.

As claimed, the present invention provides carbon fiber and thermoplastic materials. plastic materials, especially by induction heating of composites, e.g. fiber bundles thereof. Thus, a method for joining reinforced plastic materials is provided.

The term "fiber bundle" as used herein refers to tow, sliver, or tow of fibers. It should be construed as including spun yarn.

In a preferred embodiment, the fiber bundles of carbon fibers are discontinuous fibers, preferably twisted yarns. Consists of. Ideally, carbon fiber bundles are mixed with thermoplastic fibers. Consisting of bonded discontinuous carbon fibers.

Preferably, the mixture of carbon fibers and thermoplastic fibers includes carbon fibers and thermoplastic fibers. Stretch-breaking of plastic fiber tow This is achieved by

Induction processing of multidirectional discontinuous carbon fibers using electric induction coils is a method of the present invention. An acceptable bond can be achieved by heating.

"oa-curse" The invention will now be further described by way of example with reference to the accompanying drawings.

FIG. 1 shows the process of joining two laminated composite plastic materials according to the method of the present invention. a schematic diagram showing one implementation of an apparatus used for Figures 2 to 4 show the results of bonding strength tests of laminates bonded using the apparatus shown in Figure 1. graph, FIG. 5 shows a method for bonding other plastic materials together according to the method of the invention. 2 is a schematic diagram illustrating how the apparatus of FIG. 1 may be used; FIG.

for Referring to FIG. ．． It consists of a multilayer core material 12 sandwiched by 14. Each heartwood is referred to here as “Material X”. Consisting of multiple layers of continuous carbon fiber reinforced PEEK shown as . Fibers in each layer of heartwood The fibers are (but need not be) parallel to each other, but the layers are such that all fibers in the heartwood are flat. They can be stacked in rows or with the fibers in the core oriented in multiple directions. can.

The coating 13.14 is made of fiber threads that are a blend of carbon and PEEK fibers, Several such laminates have been constructed. This thread is He1tra Lim1 ted, a. Manufactured by Courtaulds Ltd. and its UK Registered Trademark. It will be sold under the title "rFi1mix". rFilmix" yarn has different structures, e.g. i.e. woven, braided, knitted fabrics or tied multi-directional mats. Processed into various materials. rFilmix, 1 material approximately 55% carbon by volume carbon fibers, and as an essential feature, the carbon fibers are multidirectional and discontinuous. It was. Furthermore, the PEEK fibers are closely connected to the carbon fibers in the rF i 1mi XJ yarn. mixed with.

Furthermore, the film 13.14 was not created with rFi 1m1x, but was randomly placed. carbon fiber mat or fabric made of carbon fiber mat or carbon fiber fabric or layers of material A laminate sample was constructed. These examples include smooth carbon fibers and random carbon fibers. The raw mat is placed between one layer of PEEK resin before providing a suitable coating for the core material 12. Sandwiched. This was to supply enough resin to wet the carbon fibers. a If the laminate is made of PEEK or polyethersulfone (PES), to provide a resin-rich surface. various laminates Listed in Table 1.

, table-”- LI　U,D,　F-No textile L2 U, opening, F-fabric PE5 L3 U, D, F-fabric PEEK L4 M, D, Material X None L5 M, D, F-woven fabric none L6'U, D, Material X None L7 U, D, C-woven fabric none L8 [1,0,C-mat none L9 U, D, F-U, D, None υ, D, - Unidirectional carbon fiber in the core material M, D, - Multidirectional carbon fiber in the core material F-fabric - rFi1mixj woven fabric made from yarn F-blade - rFi1m Blades F-U, D, made from ``ix'' yarns - rFi1 arranged in one direction miXJ yarn C-fabric-5 harness satin carbon fabric C-matte-random carbon Knitted carbon/PEEK rF i 1m1x without fiber mat core material, Two more layers, including 2 layers of 1 yarn (Lll) or 6 layers of woven carbon/PEEK A laminate was also produced.

Laminates L1 to L12 were manufactured as follows.

Two sheets of stainless steel are coated with various layers, each pre-coated with a mold release agent. They were stacked and tucked between the sheets. This layer is then placed on a preheated surface plate. It was compressed to a thickness of about 1 mII+ for 10 minutes in between. The surface plate is then quickly cooled, and A cured laminate was produced from a stainless steel sheet.

A sample of 100 mm x 25 mm and 1 mm thick was prepared, in each case the unidirectional fibers in the core were The laminates L1 to L3 and L6 to Llo are arranged parallel to the long axis direction of the sample. I took it out and it was 7. The samples taken from L4 and 1 and 5 are One layer was oriented parallel to the long axis of the sample. Cut out from Lll The sample was oriented so that the main fiber direction was parallel to the long sleeve of the sample. Attached. The sample taken from L12 has warp or weft fibers in the long sleeve of the sample. oriented parallel to.

A pair of identical samples taken as described above were then processed according to the method of the invention as shown in FIG. were joined together by forming a single lap joint as shown in FIG. This layering Before making the joint, the surfaces that form the interface between the two parts to be joined are coated with fat. Degreasing was performed using a solvent such as propan-2-ol. overlapping joint contact points The weight was 12.5mat. The overlapping samples of materials 10 and 11 were welded using an induction welder. 15 was used for joining. The particular machine used was a flat coil (pancake S t, ane 1 c o 100 with induction coil 16 of coil) It was a 0 Watt, 2.5 MHz device. The induction coil 16 is wound in a common plane. and formed a substantial square measuring 25mm x 25mm in plan view. . The alternating magnetic field created by the induction coil 16 is applied to the carbon fibers inside the coating 13.14. Eddy currents were induced in the fiber reinforcement. Two power settings, i.e. 70 percent and 80 percent in laminates LL, L2. and L3, and each Two different welding times were applied at power settings. Remove from laminate L4 100 percent power was applied for 240 seconds to weld the sample. . Samples of laminate L5 were welded with a 30 second exposure at 80 percent power. Ta. Laminate L7. L8. and samples from L9 have approximately 80 percent power Heated by applying for 60 seconds. Bonding laminates with different fiber arrangements In order to investigate the possibility of 1. and L12 at 75, 60, respectively at 80 percent power. Reach and bonded for 45 seconds. High silicate glass (e.g. rPyrex®) ) (surface plate 17) and phenolic resin/glass composites, such as P A non-metallic surface plate such as axolin (surface plate 18) is used during welding and induction. After the magnetic field ends, the entire bond contact area remains 0. 66MPa (90psi) Unity pressure was applied.

The welded joint thus formed was processed in accordance with ASTM D-2919 (01002). I tested it. Table 2 shows four laminates L4. L5. This for L7° and L8 The test results are shown below.

ni-4 Laminate heating power welding time apparent shear strength average value % seconds MPa (P s　i　　) L4 100 240 11.29 (1637) L5 80 30 35.9 5 (5213) L7 80 60 29.86 (4330) L8 80 6 0 10.07 (1460) The contact shown as the apparent shear strength in Table 2. The bond strength of a joint is obtained by dividing the load at the failure point by the nominal overlap area of the joint. It was done. Laminates Ll, L2. and L3 with different time and power conditions. The results of the bond strength obtained are shown in FIGS. 2 to 4.

Laminate L6 samples were tested by increasing the welding time to 360 seconds and increasing the power by 100%. Even when the temperature is increased to won. This has rFilmix' threads oriented in one direction in the film. The same was true for the sample taken from laminate L9. These samples, Tests for L6 and L9 weld samples containing unidirectional fibers as the main stream. This indicates that it is difficult to do so.

This result shows that if multidirectional conductive fibers are present at the interface to be joined, the induced Weld carbon fiber reinforced PEEK composite material using heat and around 50MPa We show that it is possible to obtain a bond strength of This uses epoxy adhesive This is comparable to the bond strength of approximately 15-25 MPa obtained when joining parts together by Ru. An important feature of the invention is that the laminate with unidirectional fibers is heated using induction heating. It is difficult, if not impossible, to join them together. actual However, it was not possible to successfully bond such laminates together.

Referring to FIG. 5, a further embodiment of the invention is illustrated. This implementation is , in that samples 10 and 11 are somewhat different and a coupling insert 20 is used. This differs from the embodiment described above with reference to FIG. In other respects, the device Similar to the device described above with respect to FIG. In particular, samples 10 and 11 were It is not necessary to consist of a laminate having such a coating, and a single constituent layer 12A may be used. It is shown like this.

In this latter embodiment, the constituent materials to be bonded are plastics, ceramics, etc. or a non-conductive material such as glass, and the coupling insert 20 is made of The plastic material contains one or more layers of multidirectional discontinuous carbon fibers. Connecting insert A preferred material for 20 is a yarn commercially available under the aforementioned trademark lrFi1mix. on another structure, i.e. woven, braided, stockinette fabric or multi-directional mat It is processed.

If desired, this rFilmix material may be further coated with thermoplastic. It is possible to apply coatings or coatings.

However, the essential feature of the coupling insert 20 is that it is placed in the magnetic field of the electric induction coil. The multidirectional discontinuous carbon fibers, which act as receptors and heating elements when twisted, act as bonding differentials. It is included in the inclusion 20.

The joining insert 20 can be inserted between any component materials to be joined. It is conceivable that it can be produced as such a long item that is cut into lengths. Ru.

In a sample with unidirectional fibers at the interface and core, the fibers are shifted and the constituent materials are deposited. It was found that there was a tendency for the bond to rise and not form a good bond.

The essential feature of the invention is that layers of multi-directionally oriented discontinuous carbon fibers are bonded together. It is used on or near the surface of plastic materials.

Why multidirectional discontinuous fiber bundles of carbon fibers work well, and unidirectional fibers do not. Although it is not completely understood why unidirectional fibers are used or not, unidirectional fibers are eddy currents on its surface without producing any beneficial heating effects. multidirectional fibers create a more even heating effect across the surface considered to be a thing.

Generally, the resistivity along the length of the fiber bundle of discontinuous fibers is higher than that of continuous fibers. Because of their large size, fiber bundles of discontinuous carbon fibers are less “lossy” than layers formed of continuous fibers. ” forms a layer.

Furthermore, the hairiness of the fiber bundle (due to broken ends protruding from the fiber bundle) is Providing resistive conductive paths that can better circulate eddy currents between various adjacent layers There is a possibility of making a contribution by providing. f! Crab, discontinuous carbon fibers are woven or When stacked in a fabric or non-woven fabric, the area where the warp and weft intersect is This creates a conductive path (or capacitive coupling) around which eddy currents flow. It will be done.

The example based on FIG. 1 has a coating formed of a material such as "Filmix" material. Although a laminate was used, the laminate of the component parts to be joined is not the same as the part to be joined. If one or more layers of multidirectional discontinuous carbon fibers are included near the contact surface between the It will be understood that there is no need to supply the same at any time. Fewer parts on the contact surface If both contain carbon fiber of the required type, a joining insert 20 may be used. There is no need to use it.

Furthermore, the blended carbon fibers and thermoplastic fibers are The fiber-to-fiber and yarn-to-yarn contact is, for example, a thermoplastic film or sheet. Between carbon fiber cloths woven only from discontinuous carbon fibers containing a thin layer of in contact with the carbon cloth The inventor believes that this produces the best results because it is closer than contact.

Furthermore, using twisted tow of discontinuous carbon fibers to make yarns to orient the fibers in a preferred direction to improve yarn-to-yarn contact, and It can also improve the formation of eddy current circulation in the plane of each layer, so The inventor considers this to be advantageous.

□　Welding time (seconds)　-111 - Welding time (seconds) - 1　Welding time (seconds)　−1→− international search report -11-l^-Gosa Pass-PCτ7GBcro10oo34 International Investigation Report

Claims (14)

[Claims] 1. bringing the two members (10, 11) to be joined into contact; arranging an electrical induction coil (16) in close proximity and near said contact surface of said member; In a method of joining plastic materials by electric induction heating of the edges, Multidirectional discontinuous carbon in the presence of thermoplastic material near the contact surface providing a layer (13, 14; 20) comprising fibers, at least some of said carbon fibers; The fibers are oriented to provide a conductive path that is resistant to the flow of eddy currents, and These electrically induce eddy currents in the layer to process the thermoplastic material. heating and melting the thermoplastic material at the contact surface and the two of plastic materials characterized by such a step that causes a bond between the parts Joining method. 2. Claim further characterized in that the carbon fibers are fiber bundles of discontinuous fibers. The method described in Scope 1. 3. Claim characterized in that the carbon fibers consist of fiber bundles of stable fibers. The method according to scope 2. 4. The carbon fiber is a stretch-broken fiber. 3. The method according to claim 2, characterized in that: 5. The carbon fibers may have discontinuous fibers inside the fiber bundle or fiber bundles in various directions. Consisting of fiber bundles of discontinuous fibers woven to create loops of fibers protruding from the The method according to claim 1, characterized in that: 6. The claimed thermoplastic material is fibrous. The method described in Scope 1. 7. The carbon fiber and thermoplastic fiber are made from a fiber bundle of mixed fibers. 7. The method according to claim 6, characterized in that: 8. The fiber bundle of the mixed fibers is produced by cutting the fibers. 8. The method according to claim 7, characterized in that: 9. The carbon fibers are formed by twisting tows of discontinuous carbon fibers. 3. A method according to claim 2, characterized in that the method consists of a thread that has been woven into a thread. 10. Claim 2, characterized in that the fiber bundles are woven to form a fabric. Method described. 11. A resistive conductive path is formed between the layers to allow the eddy current to flow through each layer. The carbon fibers are arranged in each layer, with the carbon fibers positioned relative to the carbon fibers in adjacent layers at a Claims characterized in that said fiber bundles are stacked as adjacent layers. The method described in 2. 12. Claims characterized in that the fiber bundles are woven to form plaids. The method described in 2. 13. As claimed, the fiber bundle is stacked as a non-woven fabric. The method described in scope 2. 14. said layer is arranged at an interface forming a contact surface between said parts to be joined; The method according to claim 1, characterized in that it constitutes an independent coupling insert. Law.