JP4290990B2 - Needling machine with device for measuring the penetration - Google Patents

Abstract

The invention concerns a needle-punching machine for a textile structure consisting of a plurality of superposed layers (12) comprising a vertically mobile needle-punching table (10), a needle-punching head including s specific number of barbed needles (18) and arranged in line with said needle-punching table, and means for driving the needle-punching head to impart thereto a reciprocating vertical movement defining a maximum needle penetration low point, wherein are provided measuring means (36), arranged at said needle-punching head to measure the position of an upper surface of the textile structure at the maximum needle penetration low point. Said measuring means are preferably arranged in a median plane of the needle-punching head perpendicular to a forward moving direction of the textile structure.

Description

FIELD OF THE INVENTION The present invention manufactures protective components used at high temperatures, used in structural parts of rocket engines, or used in very high performance brake discs for aircraft and land vehicles. It relates to the manufacture of a needled fiber structure used in the manufacturing process.

Prior art Brake discs must be able to withstand braking that generates particularly high shear forces. In an aircraft, such a phenomenon is remarkable because a large stress is applied to the brake disc.

  In order to withstand the shear forces that would delaminate the brake disc, the brake disc must be manufactured to be minimally non-structural. A non-uniform brake disc will also have a localized area that is significantly more likely to tear due to non-uniform stress characteristics.

Traditionally, brake discs are manufactured from a reinforced fibrous structure composed of a plurality of superimposed layers that are needled by a set of barbed needles that penetrate in the Z direction, i.e., across the layers. The fiber structure is carbonized after being cut to an appropriate size, then densified with a matrix-forming material and finally subjected to an optional heat treatment. The layers are overlaid on the support. In general, when the layers are overlaid, the support is lowered and the individual layers are needled. The mechanical properties of the final product thus obtained are highly dependent on the actual needling density used for the fiber reinforced structure. “Actual” needling density is a function of the number of needle stabs per cubic centimeter (cm ³ ) viewed in the basic volume of the fiber structure, and the needling density per unit area, the needles in the Z direction It includes the degree of penetration, the degree of the downward displacement process, and the functional characteristics of the needle.

  According to today's needling methods, some of them give excellent results, especially by adjusting the degree of the downward process, but it is difficult to obtain a completely uniform as desired. It has been proposed in US Pat. No. 4790052 to increase the distance between the needle and the layer support by a distance equal to the thickness of the layer to be needled for each superimposed layer. Similarly, in European Patent No. 0736115, a displacement process is adopted for the layer support by adopting a displacement process that reduces the degree according to a predetermined relationship by adopting a displacement process for the layer support. I am trying to make the thickness constant.

  The disadvantage of such a method is that the degree of the downward displacement process relative to the layer support is theoretically preliminarily calculated theoretically, in particular as a function of the number of layers constituting the resulting fiber structure, and the actual needle of the needle This means that no consideration is given to the entrance. Unfortunately, it is important to know the above parameters in order to ensure a uniform needling density, which is a prerequisite for obtaining a final fiber structure with good uniformity. Furthermore, when the fiber structure is thick, the error margin related to the recognition of the penetration is increased accordingly.

  European Patent Application No. 0 695 823 measures the position of the upper surface of the fiber structure during the needling operation and improves the needle penetration recognition by means of a feeler roller located next to the working area of the needle. .

  However, such a solution is also unsatisfactory because the fiber structure is compressed to the extent that it is not detected by the measurement due to the needling force. The inconvenience that the deformation of the fiber structure cannot be taken into account means that accurate recognition of the actual needle penetration cannot be obtained.

OBJECT AND DEFINITION OF THE INVENTION Therefore, the present invention provides an actual needle needle in the fiber structure for each needling in order to take into account deformation of the fiber structure while needing each layer forming the fiber structure. A needling machine and a related method are proposed in which the above inconvenience is reduced by enabling the penetration depth to be measured.

The above object is a machine for needling a fiber structure composed of a plurality of superposed layers, and a needling table movable in the vertical direction, and vertically disposed above the needling table. A needling head having a predetermined number of barbed needles, and means for driving the needling head to reciprocate the needling head in a vertical direction so as to define a maximum needle entry low point in the fiber structure. This is achieved by a machine further comprising measuring means arranged on the needling head for measuring the position of the upper surface of the fiber structure at the maximum needle penetration low point.
By disposing the measuring means on the needle board, the actual needle penetration depth can be determined in consideration of the degree to which the fiber structure is compressed by the effect of the needling force.

It is preferable that the measuring means is disposed on the center surface of the needling head perpendicular to the advancing direction of the fiber structure.
In a preferred embodiment, the means for measuring the position of the upper surface of the fiber structure includes an optical assembly that performs non-contact measurement. The measurement means preferably has a broad beam type laser emitter / receiver.
In an alternative embodiment, the measuring means has a mechanical feeler for measuring by contact.

In order to measure the maximum needle penetration low point, preferably an inductive or optical sensor is provided, as a function of the position of the upper surface of the fiber structure measured by the measuring means at the maximum needle penetration low point. It is therefore advantageous to provide processor means for controlling the displacement of the needling table in the vertical direction.
The present invention also provides a method of using the above machine to produce a fiber structure and a fiber structure obtained by the method. The position of the upper surface of the fiber structure is preferably measured by averaging instantaneous measurements made in real time over the entire length of the fiber structure.
The characteristics and advantages of the present invention will be more clearly understood from the following description with reference to the drawings and in a non-limiting manner.

Detailed Description of the Preferred Embodiments Two embodiments of a machine for needling flat fiber structures are shown in FIGS. Of course, regardless of whether the sheet or fabric is twisted in an annular and spiral manner so that the sheets overlap, or whether the sheets are wound on a mandrel so that they overlap, the present invention provides a flat structure. It is not limited only to manufacture of a body, and it is also the scope of application of the present invention to manufacture a structure by winding a fiber sheet.

  As is conventional, the machine has a length and width that depend on the final structure to be manufactured, and “needling” to support layers or sheets 12 that are fed one after the other so as to overlap in successive layers. It has a table 10. The needling table is arranged vertically below the needling head 14 having a predetermined number of conventional barbed needles 18 provided on the needle board 16, and the needling head is driven by one or more motors. One or more crank assemblies 20 can be driven to reciprocate in the vertical direction. A stripper 22 fixed to the frame 24 of the machine is provided above the needling table, and this stripper 22 prevents the fiber structure from being attached when the needle is raised. Of course, both the needling table and the stripper are perforated with corresponding holes 26, 28, respectively, for passing the needle. The needling table is moved in the vertical direction by driving by a device 30 constituted by, for example, a motor-driven worm screw. Two series of drive rollers 32, 34 (also known as inlet press and outlet press) arranged on the upstream side and downstream side feed the fibrous structure horizontally toward the needling head.

  The present invention provides a means disposed on the needling head 14 for measuring the position of the upper surface of the fiber structure to determine the actual penetration depth of the barbed needle in the fiber structure at the maximum needle penetration point. 36 is provided. Since the barbed needle travel is constant with respect to the frame to which these barbed needles are connected and the needling table is located at a known distance from the frame, the barbed needle enters the fabric material. The depth to be directly related to the thickness of the material present between the needling table and the measured top surface.

  For this reason, the measuring means 36 is fixed to the frame 24, and the needling board 16 (and the stripper 22) are respectively perforated with orifices 38, 40 which allow the measuring means and the upper surface of the fiber structure to cooperate. The

  In the illustrated example, this cooperation is either without contact (by remotely measuring the position of the top surface of the fiber structure) or with contact (lowering the mechanical feeler onto the top surface of the fiber structure). Can be done).

  FIG. 1 shows a preferred embodiment of the invention in which the non-contact type measuring means is constituted by an optical measuring assembly such as a laser emitter / receiver 42. The emitter sends a laser beam through the needle board and stripper toward the top surface of the fiber structure, and the top surface of the fiber structure then reflects the laser beam to the receiver. Since the distance between the emitter and the needling table is known by the previous measurement, the distance between the emitter and the top surface of the fiber structure is determined by analyzing the round trip path of the laser beam, and Thereby, the thickness of the fiber structure supported by the needling table is obtained sufficiently accurately. Furthermore, in order to avoid problems with noticeable defects in the fiber structure, the laser assembly is preferably of the broad beam type (since this type of laser has an integrated effect by measurement over the full width of the beam). ). Of course, it is preferred that there be no infrared, but an optical measurement assembly that operates in the infrared may be used.

  FIG. 2 shows an alternative embodiment in which the measuring means is constituted by a mechanical feeler formed by an inner piston 44 fixed to the frame 24, on which an outer sleeve 46 is placed. Is slidably mounted and the sleeve has a slightly rounded end that directly contacts the fibrous structure (after passing through the needle board and stripper). The sleeve is slid by controlling and injecting fluid, preferably compressed air, into the piston from a control module 48 secured to the frame 24. The pressure of the fluid is adjusted based on the properties (hardness, repulsion reaction) of the fiber structure to be needled and adjusted so that the sleeve does not spring on the fiber structure. The sleeve also has a reflective collar 50 at its apex for cooperating with an optical measurement assembly such as a laser or infrared emitter / receiver 52 secured to the frame. The emitter directs the beam to the reflective color on the sleeve, which is then reflected by the reflective color to the receiver. Since the distance between the emitter and receiver when the end of the feeler contacts the needling table is known by prior measurements, the emitter and receiver when the end of the feeler contacts the upper surface of the fiber structure Is determined (by analyzing the reciprocal path of the beam) to determine the thickness of the fiber structure supported by the needling table with sufficient accuracy.

  In both embodiments described above, the measuring means 36 (of course may be considerably away from the center plane of the needling head 14), the center plane of the needling head 14 perpendicular to the direction in which the fiber structure advances. It is preferable to arrange | position. If the fibrous structure is in the form of two adjacent plates that advance parallel to each other under the needling head, two measuring means may be provided. In the structure shown in FIG. 3, the needling head has two independent needle boards arranged side by side, in which case the measuring means are arranged approximately at the center of each board. For ease of understanding, FIG. 3 shows the machine of the above alternative embodiment in two separate positions, one position (the left half of FIG. 3) corresponds to a stationary position with the needling head raised. The other position (right side portion) corresponds to the position of the needling head at which the needling head is at the maximum needle penetration low point.

  The maximum needle penetration low point is measured in real time by, for example, an inductive or optical sensor 54 fixed to the frame, which is used for example to control the reciprocating motion of the needling head in the vertical direction. It cooperates with a specific cam profile 56 on the assembly 20. This cam profile preferably determines a time period (not just a single momentary measurement time) during the needle board descending stroke, close to the low point, during which the measuring means 36 Operates to obtain a plurality of measured values, and from these measured values, a processing module 58 connected to both the sensor 54 and the measuring means 36 determines a first average value of the thickness of the needled layer. . These measurements are repeated subsequent to each step of advancing the fiber structure horizontally, and the set of values obtained at the end of a given pass is used to determine the actual average penetration of the barbed needle The device 30 that is used and connected to the processor means 58 to drive the needling table based on this automatically moves the needling table vertically so that it accepts the next pass, where the needling table The degree of the downward process is controlled so that the barbed needle penetrates the fiber structure by a predetermined distance.

  Thus, the needling method performed on the machine of the present invention can be summarized as follows. First, a thick second layer is superposed on a thick first layer disposed on a needling table, and the two superposed layers are provided under a predetermined condition. They are joined together by a piercing needle. The needling table is then moved relative to the needling head by a displacement step determined by a function of the position of the upper surface of the two superimposed layers measured by suitable measuring means at the maximum needle penetration point. I'm damned. Finally, a thick third layer is superimposed on the two thick layers, and the thick third layer is bonded to the two thick layers under the same predetermined conditions. Is done. And the process mentioned above is repeated also with respect to the following layer until a fiber structure is formed in desired thickness.

  The machine-implemented method described above consists in first placing one or two superposed layers on the needling table 10, and then these layers are made up of fiber structures by advance rollers 32, 34. While being moved in the horizontal direction over the entire length of the body, they are joined together by needling using the needle board 16. The needling table is then lowered by a determined size displacement process so that the third layer can be superimposed and then needled to the other two layers, etc. until the desired thickness is achieved.

  In the present invention, the determined degree of the displacement process is neither fixed nor subjected to a predetermined descent relationship, and the maximum needle needle is obtained so that a desired actual density needling is obtained in the fiber structure. Determined from the actual needle penetration in the previous layer of the fiber structure measured at the entry point, where the density is constant or may vary depending on the thickness of the fiber structure . Accordingly, a predetermined degree downward process of the needling table is performed, and the position of the upper surface of the fiber structure is measured at the center of the needle so that the needle can be inserted into the fiber structure by the determined distance.

1 is a schematic view of a first embodiment of a machine of the present invention for needling a fiber structure. FIG. FIG. 3 is a schematic view of a second embodiment of the machine of the present invention for needling a fiber structure. FIG. 3 is a side view of the machine of FIG. 2 with the right-hand portion shown at the maximum penetration position of the barbed needle.

Claims (10)

  A machine for needling a fiber structure composed of a plurality of superposed layers (12), a needling table (10) movable in the vertical direction, and vertically disposed above the needling table A needling head (14) having a predetermined number of barbed needles (18) and the needling head vertically to drive the needling head to define a maximum needle penetration point in the fiber structure. Means for reciprocating in the direction, further comprising measuring means (36) arranged on the needling head for measuring the position of the upper surface of the fiber structure at the maximum needle penetration low point. Machine characterized. The machine according to claim 1, characterized in that the measuring means is arranged on the center plane of the needling head perpendicular to the advance direction of the fiber structure. Machine according to claim 1 or 2, characterized in that said means for measuring the position of the upper surface of said fibrous structure has an optical assembly for performing noncontact measurement (42).   The machine according to claim 1 or 2, wherein the optical assembly comprises a laser emitter / receiver.   5. The machine according to claim 4, wherein the laser emitter / receiver is of a broad beam type. Machine according to claim 1 or 2, characterized in that said means for measuring the position of the upper surface of said fibrous structure has a mechanical feeler (44-52) for performing measurement by contact.   The machine according to any one of the preceding claims, further comprising an inductive or optical sensor (54), preferably for determining the maximum needle penetration low point. Further comprising a processor means (58) for controlling the displacement in the vertical direction before Symbol needling table with a function of the position of the upper surface of the fibrous structure to be measured by said measuring means have contact to the maximum needle penetration low point The machine according to claim 7, wherein: A method for producing a fibrous structure comprising a plurality of layers (12) superposed, comprising: a) a thick second layer on a thick first layer disposed on a needling table (10) And b) connecting the two layers having the superimposed thicknesses to each other under a predetermined condition using the barbed needle (16) of the needling head (14). , c) a position of the upper surface of the superimposed two layers, needle via the degree of displacement step is determined with a function of position in had us the maximum needle penetration low point is measured in the needling head Displacing the ring table relative to the needling head; d) superimposing a new thick layer on the thick previous layer; e) having the thickness on the thick previous layer. new A step of binding under conditions in which the predetermined and for the layer with a f) subsequent thickness, the step c) and the step d) and the above step e), the displacement in step c) is configured that way a position of the upper surface of the fiber structure to have you maximize needle penetration low point is determined with a function of position measured in the needling head, the method comprising the step of repeating.   10. The method according to claim 9, wherein the position of the upper surface of the fiber structure is measured by averaging instantaneous measurements obtained in real time over the entire length of the fiber structure.

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