Patent Description:
Composite materials have a large range of applications, especially in high-tech industries where their combination of strength and low mass make them particularly useful. In the aerospace industry, composite materials are considered for a number of different uses, including the manufacture of fan, turbine, and compressor blades. In such blades, the composite material is built up layers until the desired volume of material is reached. Whilst parts made using composite materials in this way are generally strong, the bonding between layers is not as strong as the bonding within a layer. To improve the strength of the bond between layers, it is known to place pins through the layers of the composite component, as for example described in <CIT>. In order to place the pins through the layers of composite material, it is advisable to first create pinning holes in the composite material in which to place the pins. Needle drive assemblies are known for creating arrays of such pinning holes, as to create each pinning hole individually one at a time is very time consuming. In a known example of such a device, a plurality of needles are fed into the composite material, pushing aside the fibres and the resin of the composite material to form a pinning hole into which pins, or rodstock, can be inserted. The pins or rodstock is then tamped down, thus pinning the composite layers together.

The alignment between the composite material and the plurality of needles is crucial in ensuring the holes created in the composite material are of the correct depth.

The needles use to create the pinning holes will often have a shaped tip in order to aid their passage through the fibres of the composite material layers. As they are used, this shaping gets worn down, and the needles become less effective, meaning they have to be replaced. Replacing the needles of a needle drive assembly needs to be done frequently, and requires much of the assembly to be dismantled, adding to the time it takes to produce the finished composite component.

Unites States patent application <CIT> discloses an insertion apparatus and a method of providing through-thickness reinforcement in a laminated material. A guide foot is moved to a datum location relative the laminated material, at which the guide foot abuts a reinforcement zone on a surface of the laminated material. An insertion operation is conducted by inserting an insertion element through the guide foot into the laminated material along an insertion direction when the guide foot is in the datum location. The insertion element has a needle for forming a hole in the laminated material, a reinforcement rod to be received in the laminated material or a tamping pin for tamping a reinforcement rod received in the laminated material.

There is a need for an improved needle system and needle drive assembly which loses less time due to needle replacement, and can provide better depth control for the pinning holes it creates.

The present disclosure concerns a needle apparatus, a needle drive device and a method for creating pinning holes in composite material as set out in the appended claims.

According to a first aspect there is provided a needle apparatus for making a pinning hole in a composite material as set out in claim <NUM>.

Such a needle apparatus provides a means for accurately controlling the position of the needle, allowing for greater control over the depth of pinning hole it can be used to make in a material.

According to a second aspect, there is provided a needle drive device for making pinning holes in composite material as set out in claim <NUM>.

Such a needle drive device allows for the precise control of an array of needles, allowing for pinning holes of different depths to be created in a material in a single operation, or for calibration purposes such as determining if a needle or needles need replacing due to excess wear on the needle tip.

Each motor housing may be removed from the motor mount individually. Such a feature allows for quicker and easier replacement of a motor.

Each linear actuator can be removed from the linear actuator mount individually. Such a feature allows for quicker and easier replacement of a linear actuator.

The combination of each linear actuator and motor housing being individually removable means that an individual needle apparatus can be removed from the needle drive device without needing to remove other or neighbouring needle apparatus.

According to a third aspect, there is provided a method of making a plurality of pinning holes of non-uniform depth simultaneously in a composite material, the method comprising providing a needle drive device of the second aspect, using said needle drive device to simultaneously create a plurality of holes of non-uniform depth in the composite material.

The method can comprise actuating the holder to place the needles such that an end of each needle is proximate to the composite material, rotating each needle using the motor the needle is fixed to, and displacing each motor along its axis of rotation using the linear actuator fixed to the motor such that each needle is pushed into the composite material by a depth controlled by the linear actuator to create a plurality of holes of non-uniform depth in the composite material.

This method allows for a plurality of pinning holes of different depths to be created in a fast and efficient manner.

The method can comprise actuating the linear actuators to adjust a position of an end of each needle closest to the composite material, rotating each needle using the motor the needle is fixed to, and actuating the holder such that each needle is pushed into the composite material by a depth controlled by the holder.

Such a method allows for the depth profile of the needles to be observed and checked against the depth profile of the composite component prior to insertion of the needles into the composite component.

Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying drawings.

With reference to <FIG>, a schematic of a known needle drive assembly <NUM> is shown ready to make pinning holes in a piece of composite material <NUM>, which are used for inserting pins, or rodstock, through the layers of composite so as to pin the layers of the composite together. The known needle drive assembly comprises a number of known needle systems <NUM> - in this case seven known needle systems are shown, but the number may be fewer, such as one or two needle systems, or far greater - for example twelve, twenty-four, thirty-six, forty-eight, or sixty-four needle system, depending on the application, or the size of the composite component being worked on.

Each needle system <NUM> includes a needle <NUM> and a motor <NUM> (see <FIG>) within a known motor housing <NUM>, the motor being able to rotate the needle around longitudinal axis. The needles <NUM> can be made of steel, e.g. stainless steel, which, whilst being stiff enough to form a pinning hole in the composite material, is also flexible enough to be bent prior to insertion through the composite material to allow attachment to a motor. These properties are desirable where needle packing density exceeds motor packing density, and therefore requires the needles to be splayed out between the end proximate the composite component and the opposite end being driven by the motor. In the Figures, the needles <NUM> are shown as having at least one bend so that, whilst the tips of the needles can be densely packed in parallel alignment at the point where they contact the composite material <NUM> (i.e. to the left of <FIG>), they can be further spaced apart at a point further way from the composite material (i.e. to the right of <FIG>) in order to provide space to locate the motors <NUM>. The known motor housings <NUM> are generally mounted on a known motor mount <NUM>, which holds the known motor housings in place and attaches them to the holder <NUM>. The known motor mount <NUM> is shown schematically on a straight mount, but it will be understood that the mount may in fact be curved, so as to allow each of the known motor housings to be mounted perpendicular to the surface.

In order to prevent longitudinal reaction forces generated by the composite material <NUM> from being exerted on the motor <NUM> as a needle is pressed into the composite material, each needle passes through a needle collar housing <NUM>. Within the needle collar housing each needle has a collar <NUM> (see <FIG>) fixed to it, the collar being held in place by a first bush <NUM> and second bush <NUM>. The collar <NUM> and bushes <NUM>, <NUM> prevent the needle from moving longitudinally away from or towards the motor, but allow the needle to rotate freely around its longitudinal axis. The needle collar housing is fixed to the holder <NUM>, so as to move with the holder <NUM>.

In order to arrange the tips of the needles <NUM> prior to insertion into the composite material <NUM>, each needle <NUM> travels through a sleeve (not shown). The sleeves, and therefore the needles, pass through a series of needle guides <NUM>. The needle guides <NUM> are generally pieces of material with an array of holes in, through which the sleeves are passed. The needles <NUM> can then be inserted through the sleeves. The sleeves, being supported by needle guides <NUM>, help guide the needles between the motor <NUM> and the composite material <NUM>.

It should also be noted that whilst <FIG> is shown with an array of needle systems in a single plane for clarity (i.e. a <NUM> × <NUM> array), it is possible for the needle systems to be arranged in multiple planes. For example, the needle systems may be arranged in a grid pattern, so as to create an array of needle systems, for example a <NUM> × <NUM> array (<NUM> needle systems), a <NUM> × <NUM> array (<NUM> needle systems), an <NUM> × <NUM> array (<NUM> needle systems), or an <NUM> × <NUM> array (<NUM> needle systems). An example of a needle guide <NUM> for a <NUM> × <NUM> array is shown in plan view in <FIG>. The needle guide has an array of guidance holes <NUM> through which the needles <NUM> can pass.

As with the exemplary single plane system shown in the drawings, assemblies with multiple planes of needle systems have at least part of the needles angled towards each other as they exit the motor housings so that the needles to converge together prior to reaching a foot <NUM>. This is because, if the needles only extended in parallel away from the foot and did not include any bend section(s), there would not be enough room for all of the motor housings required to move the needles. The skilled person will be familiar with such arrangements of needle systems.

At the end of the known needle drive assembly <NUM> closest to the composite material, there is the foot <NUM> (see <FIG>). The foot functions much like the needle guides <NUM> in that the foot <NUM> comprises a piece of material with an array of holes in through which the sleeves pass, and then the needles <NUM> can be inserted. However, the array of holes in the foot matches the desired arrangement of the pinning holes to be made in the composite material, as this is the final guide the needles will pass through before they start to pierce the composite material <NUM>.

<FIG> shows a sectional schematic of a known needle system <NUM>, showing in more detail the needle <NUM>, collar <NUM> and motor <NUM>. The distance between the collar <NUM> and the known motor housing <NUM> has been shortened for clarity, as indicated by the zig-zag section. The motor <NUM> is situated within the known motor housing <NUM> which is fixed to the motor mount <NUM> (see <FIG>), and therefore fixes the motor <NUM> in place with respect to the motor mount <NUM>. The motor <NUM> rotates a drive key <NUM>, which in turn rotates the needle <NUM>. Further along the needle, towards the tip, is fixed a collar <NUM>, which is positioned between a first bush <NUM> and a second bush <NUM>. The collar <NUM> and bushes <NUM>, <NUM> prevent the needle from moving longitudinally away from or towards the motor, but allow the needle to rotate freely around its longitudinal axis. This prevents longitudinal reaction force generated by the composite material <NUM> as the needle is pressed into it from being exerted on the motor <NUM>, which is not optimised for having translational forces applied to it. By preventing the motor <NUM> from having longitudinal forces exerted upon it, the collar <NUM> first bush <NUM>, and second bush <NUM> allow the motor to rotate the needle <NUM> unhindered, and extend the lifespan of the motor.

During operation, the needles <NUM> are positioned through the sleeves so as to emerge from the foot <NUM> by a controlled distance. The composite material <NUM> is fixed in place relative to the needle drive assembly <NUM>, and the motors <NUM> are set to start rotating the needles <NUM>. Once the needles are rotating, the holder <NUM> is actuated so as to move the known needle drive assembly <NUM> towards the composite material <NUM>. In doing so, the now rotating needles <NUM> will make contact with the composite material, and be pushed into it by the actuation of the holder. Once the needles <NUM> have reached the required depth within the composite material <NUM>, the actuation of the holder <NUM> will be stopped, and then reversed, so as to draw the known needle drive assembly <NUM> away from the composite component <NUM>, and take the needles <NUM> out of the pinning holes they have created in the composite component <NUM>.

As the needle is separately fixed to both the motor <NUM> in the known motor housing <NUM>, and to the collar <NUM> in the needle collar housing <NUM>, if a needle needs replacing, it must be disconnected from both its collar and motor before it can be removed from the known needle drive assembly. This is a time consuming process.

<FIG> shows a sectional schematic of a needle apparatus according to the present disclosure. The needle apparatus <NUM> has differences to the known needle system <NUM> of <FIG>. Firstly, a linear actuator <NUM> has been added which in this example is connected to the motor <NUM> via a motor housing <NUM> by an actuator connector <NUM>. The linear actuator <NUM> is capable of moving the motor housing <NUM>, and therefore the motor <NUM>, collar <NUM>, bushes <NUM>, <NUM>, drive key <NUM> and needle <NUM> within the motor housing, along the rotational axis of the motor <NUM>. Alternatively the linear actuator <NUM> could be directly connected to the motor <NUM> so as to move the motor housing <NUM> and other components within the motor housing via movement of the motor <NUM>.

Secondly, the collar <NUM>, first bush <NUM> and second bush <NUM> have been incorporated into an extension of the motor housing <NUM>. This provides an important advantage over the known needle system <NUM>, as it means that in order to replace a needle, only a single needle apparatus unit needs to be removed from the needle drive device <NUM> (see <FIG>). This saves time when replacing needles, which is important when needles frequently need to be replaced. Having the collar incorporated into an extension of the motor housing also means that the collar moves in step with the motor and drive key, meaning no additional stress is put on the needle when the linear actuator moves the motor or motor housing.

<FIG> shows an alternative sectional schematic of a needle apparatus according to the present disclosure. In this example, a keyway <NUM> has been added to the needle apparatus. The keyway is advantageous when using the needle apparatus as part of a needle drive device (see <FIG>), as it can be fitted into a corresponding groove in a motor mount <NUM> (for motor mount see <FIG>. Corresponding groove not shown) so as to allow the motor housing <NUM> to be moved linearly through the motor mount <NUM> by the linear actuator <NUM>, but preventing the motor housing <NUM> from rotating within the motor mount <NUM>. The design of a keyway <NUM> for performing such a restraining function will be familiar to the person skilled in the art.

<FIG> shows a needle drive device <NUM> according to the present disclosure. The needle drive device includes a number of needle apparatus <NUM> as described with reference to <FIG>. This new needle drive device <NUM> has a linear actuator mount <NUM>, upon which are positioned the linear actuators <NUM> of the needle apparatus <NUM> such that each motor <NUM> or motor housing <NUM> of the needle apparatus <NUM> is connected to a linear actuator <NUM>. The linear actuator mount <NUM> is connected to a holder <NUM> so that when the holder moves, the linear actuator mount <NUM>, and therefore all the linear actuators <NUM> attached to the linear actuator mount <NUM>, move with it. Each linear actuator <NUM> can be fixed to the linear actuator mount <NUM> using known types of fixing, such as screws, or nuts and bolts. Each linear actuator can be fixed to the linear actuator mount <NUM> so as to be detachable and removable from the linear actuator mount individually, without the need to detach or remove other linear actuators from the linear actuator mount. This can be achieved by having the linear actuators inserted into the linear actuator mount along the path of the needle, with the fixings accessible from the top of the linear actuator mount (i.e. to the right of the linear actuator mount, according to the orientation shown in <FIG>).

Each motor housing <NUM> can also be individually inserted into and removed from the motor mount <NUM> without needing to detach other motor housings <NUM> from the motor mount <NUM>. Therefore an entire needle apparatus <NUM> can be inserted into, and removed from, the needle drive device <NUM> without the need to remove any neighbouring linear actuators <NUM> or motor housings <NUM> or their respective mounts <NUM>, <NUM>. This can be achieved by, for example, configuring the apertures in the linear actuator mount <NUM> to allow the motor housings <NUM> to pass through them along the axis of the needle, so that when a linear actuator is removed, the connected motor housing of the needle apparatus <NUM> can be also passed through the linear actuator mount.

With the addition of the linear actuators <NUM>, the position of the needle <NUM> in each needle apparatus <NUM> can be accurately set at a different distance from the surface of the composite material <NUM>, as shown in <FIG>. Using the linear actuators, the motor housings <NUM> and therefore the needle tips have been repositioned relative to one another such that the tips of the needles are at different distances from the foot <NUM> of the needle drive device <NUM>. In use, when the holder <NUM> is actuated towards the composite material <NUM>, the needles <NUM> will penetrate the composite material <NUM> to different depths to create holes of different depths within the composite material. Alternatively, the needle tips can be arranged to all lie at a single distance from the foot of the needle drive device, the holder <NUM> can be actuated to bring the needles into position relative to the composite material <NUM>, and then the linear actuators <NUM> can be used to drive the needles <NUM> into the composite material, with the depth each needle is driven into the composite material being controllable by the linear actuator connected to the needle. This method is useful where the composite material has a varying thickness profile across the region where the needle drive device will be creating pinning holes, an example of which is shown in <FIG>. Again, this means the depth of each hole can be individually controlled. An alternative method to produce the same result would be to first use the linear actuators to arrange the tips of the needles according to the depths of pinning hole each needle is intended to produce. The needles can then be spun up using the motors, before the holder is advanced towards the composite material. The depth of the pinning hole created by each needle will be determined by how far towards the composite material the needle tip was moved by the linear actuator prior to the movement of the holder. In this way, the depth profile of the needles can be observed and checked against the depth profile of the composite component prior to insertion of the needles into the composite component. Once the desired pinning hole depths have been achieved, the movement of the holder can be reversed and the needles removed from the composite component, ready for e.g. rodstocks to be inserted into the pinning holes.

Claim 1:
A needle apparatus (<NUM>) for making a pinning hole in a composite material (<NUM>), the needle apparatus comprising:
a needle (<NUM>) having a longitudinal axis;
a collar (<NUM>) fixed about the needle; and
a motor (<NUM>) having an axis of rotation, and being fixed to the needle such that the needle can be rotated by the motor, the motor and the collar being situated within a motor housing (<NUM>), the motor housing having a first bush (<NUM>), and a second bush (<NUM>), wherein the collar is positioned between the first bush and second bush so as to prevent the needle from moving away from or towards the motor, but allow the needle to rotate freely around its longitudinal axis;
wherein the needle apparatus further comprises a linear actuator (<NUM>) connected to the motor (<NUM>) such that the motor can be moved along the axis of rotation of the motor by the linear actuator.