Patent Description:
There are challenges in manufacturing large composite parts. These will be explained in the context of wind turbine blades, as an example, which can be many tens of metres long.

Conventionally, wind turbine blades comprise an outer shell composed of two shell-halves that are joined together, one shell-half defining one surface of the blade, and the other shell-half defining a surface on the opposite side of the blade (in some contexts, each shell-half may alternatively be referred to as a "shell", and this terminology will generally be used in the rest of this document). The two shell-halves may also be referred as the upper shell and lower shell (depending on the orientation in which the blade is fabricated), or the leeward shell and windward shell, or the pressure side (PS) shell and the suction side (SS) shell, based on the aerodynamic shape of the blade. The shell defines a relatively thin surface or skin of the blade. The interior of the blade is generally hollow, except for one or more longitudinal internal structural components that provide the blade with stiffness.

To manufacture a blade, a shell mold is provided for each of the upper shell and lower shell. Each mold defines the shape of the exterior aerodynamic surface of the respective shell portion. Dry fiber materials are laid up in each mold; each mold is bagged; and liquid resin is infused into the fiber. The resin is cured to form each solid shell. Longitudinal internal structural components of one or more spar structures and/or web assembly or web assemblies are bonded into the lower shell. Adhesive is applied to the leading edge (LE) and trailing edge (TE) of the lower shell, as well as to the tops of the internal structural components. Referring to <FIG>, the upper shell mold <NUM> containing the upper shell (not shown) is then lifted and rotated into position above the lower shell mold <NUM> containing the lower shell. The upper shell mold <NUM> is lowered into position on the lower shell mold <NUM>. Clamps (not shown) around the edges of the molds align the mold flanges (and the shells within the molds) and apply a clamping force. The adhesive is cured to an appropriate level such that the two shells are bonded together to form the blade. The clamps are released, the upper mold is removed and the blade is lifted from the lower mold, so that the blade can be taken to a finishing area.

A conventional clamp for the mold will be described with reference to <FIG>. <FIG> show a support <NUM> which, in use, is bolted to a first mold part (not shown), such as a mold <NUM> for the upper shell. A fastening pin <NUM> is fixed to the support <NUM>. A clamp body <NUM> is bolted to a second mold part (not shown), such as a mold for the lower shell <NUM>. Starting with the clamp in an open state, shown in <FIG>, as the mold is closed, the fastening pin <NUM> enters an insertion slot <NUM> provided in opposing walls of the clamp body <NUM>. Hooks <NUM> are mounted on guide pins <NUM> that run in guide slots <NUM> in walls of the clamp body <NUM>. To close the clamp, a hydraulic cylinder <NUM> operates to pull the hooks <NUM>, whose movement is controlled by the guide slots <NUM>, such that the hooks <NUM> firstly pivot over to close the insertion slots <NUM> and then pull down to engage the fastening pin <NUM> to apply a clamping force to close the mold. The closed state of the clamp is shown in <FIG>. The clamp can be opened and the mold released by reversing the operation of the hydraulic cylinder.

To avoid ingress of objects into the clamp and to ensure operator safety, particularly in the vicinity of the hooks <NUM>, a cover <NUM> can be provided for the clamp, as illustrated in <FIG>. The cover <NUM> is fixed over the clamp body and is made of thin sheet metal. To permit movement of the hooks to the open state of the clamp, the upper portion of the cover <NUM> is hinged to the main portion of the cover <NUM> by a hinge <NUM>. The open state of the clamp is shown in <FIG>. When opening the clamp, as the hooks move up and then outward, they push upper portion of the cover <NUM> out of the way. A spring mechanism (not shown) biases the upper portion of the cover <NUM> back to the closed position, so that when the clamp is closed, the upper portion of the cover <NUM> naturally returns to the position shown in <FIG> covering the clamping mechanism.

A clamp similar to the conventional clamp described above is disclosed in <CIT>.

There are a number of problems with this conventional clamp. The moving part of the cover <NUM> is thin and easily damaged, particularly when in the clamp is in the open state and projecting, so may get caught or impacted. The cover, hinge, and spring bias mechanism require extra parts to be manufactured and assembled, which is time consuming and costly. Furthermore, it is difficult to adjust the alignment of the two parts of the clamp laterally (in a direction along the edge of the mold parts, such as in the spanwise direction for a turbine blade mold). Also, mis-alignment of the hydraulic cylinder in the clamp can cause wear on the cylinder seals which leads to seal bypass, so the cylinder needs to be replaced, resulting in costly production downtime for the mold.

The present invention aims to alleviate, at least partially, some or any of the above problems.

<CIT> is considered to represent the closest prior art, and its disclosure forms the basis of the pre-characterizing portion of claim <NUM>.

<CIT> discloses a clamp with first and second portions and an actuator in the second portion, a catch plate in the second portion and an insertion slot in the first portion. A hook plate is attached to the catch plate and the hook plate is contacted by an engagement part.

According to one aspect of the invention there is provided a clamping device as defined in claim <NUM>.

Another aspect of the invention provides mold comprising at least one clamping device according to the preceding aspect of the invention, and said two mold parts.

Further optional aspects of the invention are defined in the dependent claims.

Embodiments of the invention will now be described, by way of non-limiting example, with reference to the accompanying drawings. The invention may further comprise, in any combination, any features of the embodiments which will now be described.

In the drawings, like parts are indicated with like reference numerals, and, for conciseness, description thereof will not be repeated.

An example of a clamping device according to an embodiment of the invention is illustrated in <FIG>.

The clamping device comprises a first portion <NUM> fixed in use to a first mold part (such as an upper mold), and a second portion <NUM> fixed in use to a second mold part (such as a lower mold). The first portion <NUM> comprises a catch plate <NUM> attached to a support <NUM> fixable to the first mold part. The second portion <NUM> comprises: a clamp body <NUM> fixable to the second mold part; an engaging part <NUM>; an insertion slot <NUM>; and an actuator <NUM>.

<FIG> shows the engaging part <NUM> in an open position in which the catch plate <NUM> is inserted into the insertion slot <NUM> along an insertion path, which in this illustration is a vertical path. The catch plate <NUM> is also removeable from the insertion slot in this condition. The insertion slot <NUM> is defined by slots in two opposing parts within the clamp body <NUM>, but this is merely one possible arrangement. In alternative embodiments, the slots can be provided in the walls of the clamp body <NUM>, and may be different in number than two. The slots have a flared opening to guide the catch plate <NUM> on insertion, and then a straight sided portion to constrain the catch plate <NUM> to align the mold parts. The alignment in the chordwise direction of a wind turbine blade can be adjusted by means of the slotted bolt holes by which the support <NUM> is attached to the first mold part.

Operating the actuator <NUM> moves the engaging part <NUM> between the open position of <FIG> to a closed position shown in <FIG> and <FIG> in which the engaging part <NUM> rotates over to retain the catch plate in the insertion slot and contacts the catch plate <NUM> to urge the catch plate along the insertion path with a clamping force for closing the mold parts. The clamping force of each clamp is typically <NUM> to <NUM> tonnes force (<NUM> to <NUM> kgf). The motion of the engaging part <NUM> is governed by co-operation between guide pins <NUM> and guide slots <NUM>. The engaging part <NUM> acts as a cover for the end of the clamp body <NUM>.

As can be seen, in the preferred embodiment, the engaging part <NUM> comprises a plate (also known as a gripper plate or engagement plate), and the under-surface of the plate contacts the upper edge of the catch plate <NUM>. When clamping, the engaging part <NUM> stops moving when the catch plate <NUM> is pressed against the bottom of the insertion slot <NUM>, in a state shown in <FIG> and <FIG>. If adjustment of the depth of closure is required (in the illustrated orientation it is in the vertical direction, or a height adjustment), an adjustment screw <NUM> can be turned (<FIG>) such that the movement stops when engagement part <NUM> presses on the catch plate <NUM> such that the head of the screw <NUM> is pressed against the back wall of the clamp body <NUM>.

When the clamp is not in use (with the first portion <NUM> removed), the actuator can move the engaging part <NUM> down to a fully closed position as shown in <FIG>.

The catch plate <NUM> is provided with at least one slotted hole <NUM> through which it is bolted to the support <NUM> (<FIG>). The slotted hole(s) <NUM> enable the position of the catch-plate to be adjusted laterally (in a direction along the edge of the mold parts, such as in the spanwise direction for a turbine blade mold). The catch plate <NUM> can also be replaced if damaged or worn, and this further provides a chordwise alignment feature.

Referring to <FIG>, the actuator <NUM> comprises two parts <NUM>, <NUM> that are moveable relative to each other to close and open the clamp, and to provide the clamping force. The first part <NUM> is coupled to the engaging part <NUM> by a spherical bearing <NUM> (such as a spherical plain bearing). The second part <NUM> is coupled to the clamp body <NUM> by a spherical bearing <NUM> (such as a spherical plain bearing). In this embodiment, the outer rings of the respective spherical bearings <NUM>, <NUM> are attached to the actuator first part <NUM> and the actuator second part <NUM>. A pin fixed to the engaging part <NUM> fits through the inner ring of the spherical bearing <NUM> (the upper spherical bearing in <FIG>); this pin can be one of the guide pins <NUM>. A pin fixed to the clamp body <NUM> fits through the inner ring of the other spherical bearing <NUM> (the lower spherical bearing in <FIG>). The spherical bearings <NUM>, <NUM> permit rotation in the plane of <FIG>, but also permit twisting and rotation not in that plane, for example by a few degrees, such as <NUM> degrees. Conventionally a clevis fastener and pin, or eye and pin were used as the couplings, and did not have this degree of freedom. If the actuator is not installed perfectly straight in the conventional arrangement, it is subject to undesirable lateral loads.

The actuator <NUM> can be any suitable form of linear actuator, such as hydraulic, screw, telescopic, electrical, and so forth. The preferred embodiment shown in <FIG> is a hydraulic actuator with the first part <NUM> comprising cylinder rod, and the second part <NUM> comprising a cylinder body. Lateral loading of a hydraulic actuator wears the seals and leads to seal bypass. Spherical bearings avoid lateral load being applied, and so prolong the service life of the hydraulic actuator.

The clamping device of an embodiment of the invention can be used with a mold apparatus, such as for large composite moldings, for example as one or more of the clamping devices on a wind turbine blade mold illustrated in <FIG>. <FIG> is an end on view at an intermediate cross-section of a portion of a wind turbine blade mold apparatus including a clamping device according to an embodiment of the invention. The first portion <NUM> of the clamping device is fixed to an arm <NUM> joined to the framework of the first mold part <NUM> (upper mold), and the second portion <NUM> of the clamping device is fixed to an arm <NUM> joined to the framework of the second mold part <NUM> (lower mold). Further clamping devices (not shown) are provided on the opposite edge of the mold apparatus, and each edge can have many spaced-apart clamping devices, for example at least ten. The clamping devices apply a constant clamping force during the bonding operation, while the adhesive between the upper shell and lower shell cures to a desired extent.

Although the above description has specifically mentioned manufacturing a wind turbine blade, the invention can also be applied in other embodiments to assembling blade structures such as for wind assisted propulsion of sea transportation vessels. One or more of these blades can typically be vertically mounted on top of the vessel, and is rotatable about the vertical axis. The vessel can be, for example, a cargo container, oil/gas tanker, or grain tanker. The aerodynamic blade or blades utilises wind assistance to augment the conventional propulsion of the vessel, thereby reducing fuel costs and emissions. In this context, a blade may also be called a wing or a sail, but the term 'blade' is used herein to encompass these alternative terms. Thus, every aspect of the present description can be read as disclosing such methods, apparatus and blades by replacing the term "wind turbine" by "shipping vessel".

Claim 1:
A clamping device for releasably clamping together two mold parts (<NUM>, <NUM>), wherein the clamping device comprises a first portion (<NUM>) for fixing to a first mold part (<NUM>) and a second portion (<NUM>) for fixing to a second mold part (<NUM>), wherein:
the first portion (<NUM>) comprises a catch plate (<NUM>) attached to a support (<NUM>) fixable to the first mold part (<NUM>);
the second portion (<NUM>) comprises: a clamp body (<NUM>) fixable to the second mold part (<NUM>); an engaging part (<NUM>); and an insertion slot (<NUM>);
wherein the catch plate (<NUM>) is insertable into the insertion slot (<NUM>) along an insertion path; and
characterized in that:
the second portion (<NUM>) further comprises an actuator (<NUM>);
wherein the actuator (<NUM>) is arranged to move the engaging part (<NUM>) between a first position in which the insertion slot (<NUM>) is open for insertion of the catch plate (<NUM>) into the insertion slot (<NUM>) along the insertion path, and a second position in which the engaging part (<NUM>) contacts the catch plate (<NUM>) to urge the catch plate (<NUM>) along the insertion path with a clamping force for closing the mold parts (<NUM>, <NUM>) and to retain the catch plate (<NUM>) in the insertion slot (<NUM>).