Preparation tool for composite material double-dumbbell test piece

Abstract

The utility model discloses a preparation tool for a composite material double-dumbbell test piece. The preparation tool comprises a laminated board unit and a processing unit, wherein the laminated board unit is used for forming two surfaces of the composite material double-dumbbell test piece in the thickness direction; the processing unit is used for forming two surfaces of the composite material double-dumbbell test piece in the width direction; the laminated board unit comprises an upper die, a lower die and a side stop block which define a cavity for forming two surfaces of a test piece in the thickness direction; the forming surfaces of the upper die and the lower die are matched with two surfaces of a test piece in the thickness direction; the side stop block is provided with a side stop block reference edge, and the side stop block reference edge is used for the test piece to form a positioning reference edge in the laminated board unit; the machining unit comprises a positioning block, and the positioning block is provided with a positioning edge matched with the positioning reference edge of the test piece. The device has the characteristics of high test piece processing efficiency, small damage to the test piece, high accuracy and reproduction rate of the performance of the test piece, and the like.

Description

Technical Field

[0001] The utility model belongs to the technical field of composite material test piece manufacturing, and specifically relates to a preparation tool for a composite material double dumbbell test piece. Background Art

[0002] Continuous fiber reinforced resin matrix composite materials are widely used in the aerospace field due to their high specific strength, specific modulus, good fatigue resistance and designability. The application parts have gradually developed from the initial non-load-bearing to secondary load-bearing and complex main load-bearing structures, and the dosage has also increased from less than 10% to more than 30% now. With the change of application parts, the selection criteria of static covering fatigue are no longer accepted in aircraft structural design, especially helicopter rotor blades are mainly subjected to high-cycle low-stress fatigue, so more attention is paid to fatigue and durability issues in material selection. Due to the anisotropy and ply diversity of composite materials, the tension-tension fatigue performance of unidirectional plates is the most basic.

[0003] Currently, in the fatigue tensile performance test of unidirectional plates, the test pieces are usually processed into a double dumbbell configuration by milling, grinding, etc., and fiber damage and stress concentration will occur in the grinding process, which will greatly reduce the fatigue strength and fatigue life of the test pieces. In addition, the four surfaces of the working section need to be ground to a certain arc, resulting in very low processing efficiency of the test pieces and poor process repeatability. Utility Model Content

[0004] In order to solve the deficiencies in the prior art, the utility model provides a preparation tool for a composite material double dumbbell test piece, which has the characteristics of high test piece processing efficiency, little damage to the test piece, and high accuracy and reproducibility of test piece performance.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is:

[0006] In a first aspect, a preparation tool for a composite double dumbbell test piece is provided, comprising: a laminate unit for molding two surfaces in a thickness direction of the composite double dumbbell test piece and a processing unit for molding two surfaces in a width direction of the composite double dumbbell test piece; the laminate unit comprises: an upper mold, a lower mold and a plurality of side blocks, the upper mold, the lower mold and the plurality of side blocks enclose a cavity for molding two surfaces in a thickness direction of the composite double dumbbell test piece; wherein the molding surfaces of the upper mold and the lower mold match the two surfaces in the thickness direction of the composite double dumbbell test piece; the side block is provided with a side block reference edge, the side block reference edge is used for the composite double dumbbell test piece to form a positioning reference edge in the laminate unit; the processing unit comprises a plurality of positioning blocks, the positioning blocks have positioning edges that match the positioning reference edges of the composite double dumbbell test piece.

[0007] Furthermore, the upper die, the lower die and the side block are made of metal, plastic, hard rubber or ceramic.

[0008] Furthermore, each of the side blocks is provided with a plurality of glue flow grooves.

[0009] Furthermore, each of the side blocks is provided with at least one cylindrical pin for positioning.

[0010] Furthermore, the side block includes: side block one, side block two, side block three and side block four, and the side block one, side block two, side block three and side block four are located between the upper mold and the lower mold and enclose a rectangular space.

[0011] Furthermore, the processing unit comprises: a processing unit 1 and a processing unit 2, wherein the processing unit 2 has a convex surface matching the surface of the composite material double dumbbell test piece in the width direction.

[0012] In a second aspect, a method for preparing a composite double dumbbell test piece is provided, using the preparation tooling for the composite double dumbbell test piece described in the first aspect, the method comprising: preparing prepreg for making the composite double dumbbell test piece; assembling the laminate unit in the preparation tooling for the composite double dumbbell test piece; laying the prepreg, closing the mold, curing, and demolding in the preparation tooling for the composite double dumbbell test piece to obtain a semi-finished product of the composite double dumbbell test piece; and processing and polishing the two surfaces of the semi-finished composite double dumbbell test piece in the width direction of the composite double dumbbell test piece using the processing unit in the preparation tooling for the composite double dumbbell test piece to obtain a finished product of the composite double dumbbell test piece.

[0013] Furthermore, the prepreg is a resin-based carbon fiber prepreg, wherein the resin content is 20-60% and the fiber surface density is 50-600g / m 2 Resin-based carbon fiber prepregs include: epoxy resin-based, bismaleimide resin-based, phenolic resin-based, and cyanate-based carbon fiber prepregs.

[0014] Furthermore, laying prepreg in the preparation tool of the composite double dumbbell test piece includes: laying the cut prepreg in the laminate unit according to a specified order, using the side block reference edge as the laying reference for the adjacent two sides of the prepreg, and pre-compacting once each set number of layers of prepreg.

[0015] Furthermore, the processing unit in the preparation tooling of the composite material double dumbbell test piece is used to process and polish the two surfaces of the semi-finished product of the composite material double dumbbell test piece in the width direction, including: fixing the semi-finished product of the composite material double dumbbell test piece on the auxiliary tooling of the grinder, wherein the positioning reference edge of the semi-finished product is fitted with the side positioning strip of the auxiliary tooling, and cutting is performed along the fiber direction perpendicular to the semi-finished product to complete the processing of the length of the composite material double dumbbell test piece; rotating the auxiliary tooling 90 degrees clockwise, and cutting again along the fiber direction of the semi-finished product to complete the processing of the width of the composite material double dumbbell test piece. Processing unit 1 is a process of placing the semi-finished product sideways in sequence on processing unit 1, with the end face and surface of the semi-finished product respectively fitting the positioning edge 1 and the positioning edge 2 of processing unit 1, and fixing the semi-finished product; fixing processing unit 1 on a high-precision grinding machine platform, and grinding according to the set procedure; placing the semi-finished product on processing unit 2, with the concave surface of the semi-finished product in the width direction fitting the convex surface of processing unit 2, and at the same time, with the end face and surface of the semi-finished product respectively fitting the positioning edge 3 and the positioning edge 4 of processing unit 2, and fixing the semi-finished product; fixing processing unit 2 on a high-precision grinding machine platform, and grinding according to the set procedure.

[0016] Compared with the prior art, the utility model has the following beneficial effects: the utility model manufactures a composite material double dumbbell test piece by means of a laminate unit for molding two surfaces in the thickness direction of the composite material double dumbbell test piece and a processing unit for molding two surfaces in the width direction of the composite material double dumbbell test piece, the laminate unit is surrounded by an upper mold, a lower mold and a plurality of side blocks to form a cavity for molding two surfaces in the thickness direction of the composite material double dumbbell test piece; wherein the molding surfaces of the upper mold and the lower mold match the two surfaces in the thickness direction of the composite material double dumbbell test piece; a side block reference edge is provided on the side block, and the side block reference edge is used for forming a positioning reference edge of the composite material double dumbbell test piece in the laminate unit; the processing unit includes a positioning block, and the positioning block has a positioning edge that matches the positioning reference edge of the composite material double dumbbell test piece; the utility model has the characteristics of high test piece processing efficiency, little damage to the test piece, and high accuracy and reproducibility of test piece performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an exploded view of a laminate unit in a tooling for preparing a composite material double dumbbell test piece provided by an embodiment of the utility model;

[0018] Figure 2 yes Figure 1 A schematic diagram of the structure of the middle side stopper;

[0019] Figure 3 yes Figure 1 Schematic diagram of the combined cross section;

[0020] Figure 4 It is a schematic diagram of the planar structure of a processing unit 1 in a preparation tool for a composite material double dumbbell test piece provided by an embodiment of the utility model;

[0021] Figure 5 yes Figure 4 Bottom view of

[0022] Figure 6 It is a schematic diagram of the planar structure of a processing unit 2 in a preparation tool for a composite material double dumbbell test piece provided by an embodiment of the utility model;

[0023] Figure 7 yes Figure 6 Bottom view of

[0024] Figure 8 It is a schematic diagram of a composite material double dumbbell test piece manufactured using a composite material double dumbbell test piece preparation tool provided by an embodiment of the utility model;

[0025] In the figure: 01, upper die; 02, lower die; 03, side block one; 04, side block two; 05, side block three; 06, side block four; 07, cylindrical pin one; 08, cylindrical pin two; 09, glue flow groove; 10, side block reference edge; 11, cavity; 12, positioning edge one; 13, positioning edge two; 14, positioning edge three; 15, positioning edge four; 16, convex surface. DETAILED DESCRIPTION

[0026] The utility model is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the utility model, and cannot be used to limit the protection scope of the utility model.

[0027] Embodiment 1:

[0028] like Figures 1 to 8 As shown, a preparation tool for a composite material double dumbbell test piece includes: a laminate unit for molding two surfaces of the composite material double dumbbell test piece in the thickness direction and a processing unit for molding two surfaces of the composite material double dumbbell test piece in the width direction.

[0029] The laminate unit includes: an upper mold 01, a lower mold 02 and a plurality of side blocks, wherein the upper mold 01, the lower mold 02 and the plurality of side blocks form a cavity 11 for molding two surfaces in the thickness direction of the composite material double dumbbell test piece; wherein the molding surfaces of the upper mold 01 and the lower mold 02 match the two surfaces in the thickness direction of the composite material double dumbbell test piece; a side block reference edge 10 is provided on the side block, and the side block reference edge 10 is used to form a positioning reference edge for the composite material double dumbbell test piece in the laminate unit.

[0030] The side blocks include side block 1 03, side block 2 04, side block 3 05 and side block 4 06. Side block 1 03, side block 2 04, side block 3 05 and side block 4 06 are located between the upper mold 01 and the lower mold 02 and enclose a rectangular space.

[0031] The processing unit comprises a plurality of positioning blocks, wherein the positioning blocks have positioning edges which match the positioning reference edges of the composite material double dumbbell test piece.

[0032] The sample preparation process of the utility model includes two major processes: preparation of a hyperbolic laminate, which includes ply design, material laying, and laminate curing. Double dumbbell-shaped test piece processing, wherein the hyperbolic configuration of the composite material double dumbbell test piece in the thickness direction is ensured by the laminate unit in the preparation tooling of the composite material double dumbbell test piece, and one-time molding does not require processing, and the curvature of the two surfaces in the width direction is ensured by the processing process (with the help of the processing unit).

[0033] The forming methods of composite hyperbolic laminates include but are not limited to molding, autoclave, vacuum bag pressing, etc.

[0034] The utility model uses the laminate unit in the preparation tooling of the composite material double dumbbell test piece, and combines the ply design to prepare the concave arc surface that meets the two surfaces of the double dumbbell test piece in the thickness direction. At the same time, the laminate unit can reduce the fiber directional deviation caused by paving, resin flow, etc. during the preparation process. The materials of the upper mold 01, the lower mold 02 and the side block in the laminate unit can be metal, plastic, hard rubber, ceramic, etc. The tooling is a machined product with high flatness, verticality, straightness, etc., which is conducive to improving the dimensional accuracy of the final test piece.

[0035] The size of the composite material laminated plate prepared by the utility model is larger than the size of the actually required spline, which is convenient for positioning, edge removal and processing loss during the processing.

[0036] During the molding process of the composite laminate, a positioning reference edge is prepared. When the test piece is cut, it is placed close to the positioning edge of the processing unit to complete the positioning of the laminate.

[0037] There are many processing methods for processing composite double dumbbell test pieces, including but not limited to engraving machine milling, CNC milling, grinding wheel cutting, etc.

[0038] The utility model can grind concave arc surfaces of multiple pieces or multiple groups of test pieces at the same time, and can ensure that the processing accuracy of the test pieces is high and the stability between batches is good.

[0039] The specific process of making a composite material double dumbbell test piece using the preparation tool for a composite material double dumbbell test piece of the utility model is as follows.

[0040] Step 1: The material used is epoxy resin / T800-6K carbon fiber prepreg, with a resin content of 35% and a fiber surface density of 145g / m 2 .

[0041] Step 2: Cutting: Cut the prepreg from step 1 according to the laminate size and layer loss design, and mark the sheet number on the prepreg.

[0042] Step 3, mold assembly: fix side block 1 03, side block 2 04, side block 3 05 and side block 4 06 around the lower mold 02 with screws, wherein each side block has two glue flow grooves 09 for excess resin to flow out to ensure uniform thickness of the laminate after curing.

[0043] Step 4, laying: Lay the prepreg cut in step 2 on the laminate unit in the specified order, with the side block reference edge 10 of the side block as the laying reference for the adjacent two sides of the prepreg, and pre-compact every eight layers of prepreg.

[0044] Step 5, mold closing: After completing the paving according to step 4, move the upper mold 01 through the cylindrical pin (such as Figure 1 The cylindrical pin 1 (07) and the cylindrical pin 2 (08) are positioned and covered on the lower mold 02 to form a closed cavity 11.

[0045] Step 6, curing: the molded part after the mold closing in step 5 is placed in a hot press and cured according to the curing parameters of the material.

[0046] Step 7, demoulding: demoulding the laminate that has been cured in step 6.

[0047] Step 8, cutting: Fix the laminate in step 7 on the auxiliary fixture of the high-precision grinder, where the positioning reference edge of the laminate is tightly fitted with the side positioning strip of the auxiliary fixture, and use a diamond cutting saw blade to cut along the direction perpendicular to the laminate fiber to complete the processing of the length of the test piece. Rotate the auxiliary fixture 90 degrees clockwise, and use a diamond saw blade to cut along the direction of the laminate fiber to complete the processing of the width of the test piece.

[0048] Step 9, grinding on one side: Place the test piece in step 8 on the processing unit 1 (such as Figure 4 As shown in the figure, the end face and the surface of the test piece are closely attached to the positioning edge 12 and the positioning edge 2 13 on one side of the processing unit, and the test piece is fixed with a U-shaped clamp. The processing unit 1 is fixed on the high-precision grinder platform and polished according to the set program.

[0049] Step 10, grinding the other side: Place the test pieces that have been polished in step 9 on the processing unit 2 (such as Figure 6As shown in the figure, the concave surface of the test piece in the width direction fits with the convex surface 16 of the processing unit 2, and the end face and surface of the test piece are respectively closely fitted with the positioning edge 3 14 and the positioning edge 4 15 on the side of the processing unit 2, and the test piece is fixed with a U-shaped clamp. The processing tool is fixed on the high-precision grinder platform and polished according to the set program.

[0050] Step 11, inspection: inspect the appearance quality, size and arc centering of the test piece polished in step 10. If the inspection is qualified, the fatigue tensile test piece is processed.

[0051] The utility model has a simple tooling structure and is easy to process. It can ensure that the thickness uniformity of the laminate and the fiber angle deviation meet the test requirements without buckling. The two curved surfaces in the thickness direction of the fatigue test piece are formed at one time without secondary processing, which reduces the damage to the fiber during the grinding process and greatly improves production efficiency. It can grind multiple test pieces at the same time and position them accurately, which reduces the requirements for the skill level of the operator and facilitates operation by inexperienced personnel. The accuracy and reproducibility of the performance test results of the prepared composite double dumbbell test piece during the fatigue tensile test have been greatly improved.

[0052] Embodiment 2:

[0053] Based on the preparation tooling of a composite material double dumbbell test piece described in Example 1, this embodiment provides a method for preparing a composite material double dumbbell test piece, using the preparation tooling of the composite material double dumbbell test piece described in Example 1, the method comprising:

[0054] Prepare prepreg for making composite double dumbbell test piece, the prepreg is epoxy resin / T800-6K carbon fiber prepreg, the resin content is 35%, the fiber surface density is 145g / m 2 ;

[0055] Assembling laminate units in the preparation tooling for composite double dumbbell test pieces;

[0056] Laying prepreg, closing molds, curing, and demoulding in a preparation tool for a composite material double dumbbell test piece to obtain a semi-finished product of the composite material double dumbbell test piece (i.e., a laminate formed by laminate units);

[0057] The two surfaces in the width direction of the semi-finished product of the composite material double dumbbell test piece are processed and polished by the processing unit in the preparation tool of the composite material double dumbbell test piece to obtain the finished product of the composite material double dumbbell test piece.

[0058] The method of laying prepreg in a preparation tool for a composite double dumbbell test piece includes laying the cut prepreg in a laminate unit in a prescribed order, using the side block reference edge 10 as a laying reference for two adjacent sides of the prepreg, and pre-compacting once each time a set number of prepreg layers are laid.

[0059] The two surfaces of the semi-finished product of the composite material double dumbbell test piece in the width direction are processed and polished by using the processing unit in the preparation tool of the composite material double dumbbell test piece, including:

[0060] Fix the semi-finished product of the composite material double dumbbell test piece on the auxiliary tooling of the grinder, wherein the positioning reference edge of the semi-finished product is fitted with the side positioning strip of the auxiliary tooling, and cut along the fiber direction perpendicular to the semi-finished product to complete the processing of the length of the composite material double dumbbell test piece; rotate the auxiliary tooling 90 degrees clockwise, and cut again along the fiber direction of the semi-finished product to complete the processing of the width of the composite material double dumbbell test piece;

[0061] The semi-finished product is placed sideways on the processing unit one in sequence, and the end face and surface of the semi-finished product are respectively attached to the positioning edge 12 and the positioning edge 2 13 of the processing unit one, and the semi-finished product is fixed; the processing unit one is fixed on the high-precision grinding machine platform, and is ground according to the set program;

[0062] Place the semi-finished product on processing unit two, with the concave surface of the semi-finished product in the width direction fitting with the convex surface 16 of processing unit two, and the end face and surface of the semi-finished product fitting with positioning edge three 14 and positioning edge four 15 of processing unit two respectively, and fix the semi-finished product; fix processing unit two on the high-precision grinder platform, and grind according to the set procedure.

[0063] Embodiment 3

[0064] The difference between this embodiment and the first embodiment is that:

[0065] The material used is phenolic resin / T800-12K carbon fiber prepreg, with a resin content of 40% and a fiber surface density of 130g / m 2 .

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A preparation tool for a composite material double dumbbell test piece, characterized in that: include: A laminate unit for forming two surfaces in the thickness direction of a composite double dumbbell test piece and a processing unit for forming two surfaces in the width direction of a composite double dumbbell test piece; The laminate unit comprises: An upper mold (01), a lower mold (02) and a plurality of side blocks, wherein the upper mold (01), the lower mold (02) and the plurality of side blocks enclose a mold cavity (11) for molding two surfaces of a composite material double dumbbell test piece in a thickness direction; wherein the molding surfaces of the upper mold (01) and the lower mold (02) match the two surfaces of the composite material double dumbbell test piece in a thickness direction; and the side blocks are provided with side block reference edges (10), and the side block reference edges (10) are used for forming a positioning reference edge of the composite material double dumbbell test piece in the laminate unit; The processing unit comprises a plurality of positioning blocks, each of which has a positioning edge matching a positioning reference edge of a composite material double dumbbell test piece.

2. The preparation tool for the composite material double dumbbell test piece according to claim 1, characterized in that: The upper mold (01), the lower mold (02) and the side block are made of metal, plastic, hard rubber or ceramic.

3. The preparation tool for the composite material double dumbbell test piece according to claim 1, characterized in that: Each of the side blocks is provided with a plurality of glue flow grooves (09).

4. The preparation tool for composite material double dumbbell test piece according to claim 1, characterized in that: Each of the side blocks is provided with at least one cylindrical pin for positioning.

5. The preparation tool for composite material double dumbbell test piece according to claim 1, characterized in that: The side block comprises: side block one (03), side block two (04), side block three (05) and side block four (06); the side block one (03), side block two (04), side block three (05) and side block four (06) are located between the upper mold (01) and the lower mold (02) and enclose a rectangular space.

6. The preparation tool for composite material double dumbbell test piece according to claim 1, characterized in that: The processing unit comprises: a processing unit 1 and a processing unit 2, wherein the processing unit 2 has a convex surface (16) that matches the surface of the composite material double dumbbell test piece in the width direction.

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