Patent Description:
It is well known in the art to provide prefabricated housings where a plurality of prefabricated modules are manufactured in a factory and then shipped to a building site where they are assembled to form a housing. Examples of modules are wall frames, floors and roof trusses. The modules are typically produced in high speed production lines.

Depending on the design and size of the individual module, the input raw material in the form of wood studs of a certain cross sectional dimension is provided on pallets to the production line. The palletized studs are provided pre-cut in a desired length. Since a production plant should allow a certain degree of flexibility, a plurality of pallets with different dimensions must be readily accessible. This applies both in cross section and length. This requires a lot of stock articles, available storage place and also a logistic system which allows easy transportation to and from the production line. This increases the production costs and hence the price on the end product. There is hence a need for a more cost efficient solution which reduces costs for storage and transport of raw material to the production line.

Further, since wood is a natural product, there is a variance in the curvature as seen along the longitudinal extension caused by the milled wood absorbing moisture from the air during storing. The absorption causes warping and shrinking of the wood whereby a piece of wood, such as a stud, that once has been milled to a correct cross sectional dimension and to a linear extension may change its geometry. This is known as crowning. A crown will be the edge of the wood that warps upward in the center when holding it on edge. Highly exaggerated, the crowning may be seen as the wood having a single curved longitudinal extension. When installing the studs it is of importance that the studs crown all face the same direction. Otherwise, in e.g. a finished wall, some studs that have warped toward the outside and some toward the inside will make it difficult to properly attach the finishes and produce a very unattractive finish as well as causing nail pops in the finish. In case of floor joists, ceiling joists, and roof rafters, the orientation is of even more importance because of structural aspects. Over time gravity can cause the lumber to warp or sag in a downward direction. If all of the natural crown are installed up then that effect will take a very long time to notice. If on the other hand, the joists were installed with the crown down, a floor, ceiling and roof would probably, if not immediately, very soon look like a bowl. Also if the crowns are not all the same then the floor, ceiling and roof will have noticeable rolls in them.

It is further a well-known fact that the more uniform raw material, the easier handling, and this is especially the case when it comes to highly automatized handling systems and high-speed production lines.

<CIT> discloses examples of a lumber retrieval system and one example of a lumber retrieval method with selective crown orientation. <CIT> discloses a system configured to orient a plurality of studs into one and the same curvature based orientation, the system comprising: a sensor arrangement configured to measure the curvature of the stud as seen along its longitudinal extension and as seen in a major plane of the lower conveyor; and a turning arrangement configured to turn a stud <NUM> degrees around its longitudinal extension, wherein the turning arrangement comprises at least one pivotable arm configured to be movable from a resting position in which it has no contact with the stud into a turning position in which it engages and lifts a first longitudinal edge portion of the stud to such extent that the stud is turned <NUM> degrees around its longitudinal extension.

<CIT> discloses a grading and trimming method for a sawmill.

<CIT> discloses a high speed board feeder.

One object of the present invention is to provide a handling system that allows an automatized determination and correction of the orientation of studs.

Another object is to provide a handling system that allows determination and correction of the orientation of studs in a high-speed production line.

Yet another object is to provide a system that allows un-cut studs having mutually different lengths to be provided as raw material.

These and other objects are solved by a system according to claim <NUM>, which system is configured to orient a plurality of studs into one and the same curvature based orientation.

The system may be seen as a screening system that sorts and orients arbitrary arranged crowned studs into one and the same orientation. In the context of the invention, the term "one and the same curvature based orientation" should be understood as that all studs are oriented side by side with a convex longitudinal edge of a first stud facing a concave longitudinal edge of a subsequent stud. Thereby, all studs will be arranged with their crowning extending in the same orientation. Roughly speaking it may be seen as spooning. In its most simple form, the sensor arrangement may be configured to measure and provide a signal that may be used to determine if there is a need for turning the stud or not. A turning should be initiated if it is determined that the curvature of the measured stud is incorrect. Otherwise the stud should be allowed to pass. The conveyor may be a single conveyor or two or more, preferably three parallel sub-conveyors. The conveyor or sub-conveyors may be a belt conveyor or a chain conveyor. The invention should not be limited to the type of conveyor or the number of conveyors used.

The sensor arrangement may comprise at least one sensor being any of a photocell, a laser sensor, a radar sensor, a pressure sensor or an image sensor. The sensor arrangement may comprise a combination of two or more sensor types.

The sensor arrangement may be an array of a plurality of sensors. In the context of the invention, the term "array" should be understood as a group of sensors which are arranged in a determined pattern. The array may by way of example be a straight linear pattern with the sensors being arranged one after the other along a straight line. Alternative the array may be a pattern comprising several adjacent straight lines in which lines sensors are arranged one after the other. No matter pattern of the array, it is preferred that the individual sensors are arranged on a distance from each other and distributed in a direction transverse the feeding direction of the conveyor. In case of a straight linear pattern, it is preferred that at least three sensors are provided. Thereby, in the event not all three indicates a positive signal, i.e. a detection of a stud portion, this may be used as an indication of an incorrect orientation which may be corrected by turning the stud <NUM> degrees. Further, an array comprising several lines of sensors may be used to determine not only an incorrect orientation, but also to determine if the curvature is too curved. If too curved, it may be used as a signal of that the stud should be removed from the conveyor. It is to be understood that the similar effect may be provided for by using a single image sensor, where the curvature is determined by image analysis.

The system may comprise a positioning arrangement which forces the stud to be oriented substantially perpendicular to the feeding direction of the conveyor before the stud reaches the sensor arrangement. In case the conveyor comprises two or more parallel sub-conveyors, the positioning arrangement may comprise a reciprocating projection which is arranged in a fixed position adjacent each sub-conveyor. As the stud reaches the positioning arrangement, each projection may be set to a position in which it projects transverse the path of the conveyor. As the stud reaches and abuts the respective projection, any angular misalignment will be corrected by the speed of the leading end of the stud temporarily slowing down by that specific projection.

The system may further comprise a control unit, the control unit being configured to receive a signal from the sensor arrangement; determine whether or not the stud has an acceptable curvature as seen along its longitudinal extension and as seen in the major plane of the conveyor; and instruct the turning arrangement to turn the stud if it is determined that the stud has a non-acceptable curvature. By way of example, in the case of a straight-linear pattern with three sensors, if all three sensors indicate a detection of a stud portion, this is indicative of a correct curvature. Contrary, if not all three sensors indicate a detection of a stud portion, this is indicative of a non-acceptable curvature. In case the sensor arrangement is an image sensor, the signal from that image sensor may be handled by image analysis.

The turning arrangement comprises at least one pivotable arm configured to be movable from a resting position in which it has no contact with the stud into a turning position in which it engages and lifts a first longitudinal edge portion of the stud to such extent that the stud is turned <NUM> degrees around its longitudinal extension. The turning arrangement is arranged in a position downstream the sensor arrangement. The pivotable arm may be pivotable around a support positioned below the conveyor. In case of the conveyor comprises a plurality of sub-conveyors, a pivotable arm may be arranged below each sub-conveyor.

The system may further comprise a cutting arrangement configured to cut at least one of the two free ends of the stud. The cutting arrangement is preferably arranged downstream the turning arrangement. It is further preferred that both free ends of the stud are cut. One end may be cut to provide a clean cut, whereas the other end may be used to cut the stud to a pre-set length. Thus, the cutting arrangement may comprise two cutting blades, one at each end of the stud. Before cutting the free ends, the stud may be pushed in the longitudinal direction towards an anvil.

According to another aspect, the invention refers to a method with the features of claim <NUM>, of orienting a plurality of studs into one and the same curvature based orientation.

The system and its function discussed above is directly applicable also to the method, and to avoid undue repetition, reference is made to that discussion.

The act of determining whether or not the stud has an acceptable curvature may comprise receiving, by a control unit, a signal from the sensor arrangement; determining whether or not the stud has an acceptable curvature as seen along its longitudinal extension and as seen in the major plane of the conveyor; and instructing the turning arrangement to turn the stud <NUM> degrees around its longitudinal extension if it is determined that the stud has a non-acceptable curvature.

According to yet another aspect, the invention refers to the use according to claim <NUM> of a system according to any of claims <NUM>-<NUM> in an establishment for prefabricated house manufacturing. The system and its advantages has been described in detail above and to avoid undue repetition, reference is made to the sections above which are equally applicable.

Further objects and advantages of the present invention will be obvious to a person skilled in the art reading the detailed description given below describing different embodiments.

The invention will be described in detail with reference to the schematic drawings.

Now turning to <FIG>, a side view of the system <NUM> is disclosed. The system <NUM> comprises a first section <NUM> forming a handling and turning arrangement <NUM> and an optional second section <NUM> forming a cutting arrangement <NUM>. The second section <NUM> is arranged downstream the first section <NUM> and the two sections are arranged in communication with each other via a lower conveyor <NUM> that extends between the two sections. The lower conveyor <NUM> has a feeding direction as illustrated by arrow A.

Turning to <FIG> and <FIG>, the first section <NUM> comprises a frame <NUM> supported by legs <NUM>. The frame <NUM> supports an upper conveyor <NUM> that comprises four parallel sub-conveyors <NUM> in the form of chain-conveyors. Each sub-conveyor <NUM> is supported by a first and a second driving wheel 110a, 110b. The first driving wheels 110a are supported and/or driven by a common motor driven shaft <NUM>. All sub-conveyors <NUM> may thereby operate at the same speed. The upper conveyor <NUM> is preferably continuously driven.

The invention should not be limited to the type of conveyor or the number of sub-conveyors used. The sub-conveyors <NUM> have a feeding direction as illustrated by arrow B in <FIG>. The feeding direction of the upper conveyor <NUM> is accordingly opposite the feeding direction of the lower conveyor <NUM>.

The upper surface <NUM> of the upper conveyor <NUM> is configured to receive a package of studs <NUM> (schematically disclosed) arranged edgeways side by side in an abutting relation with their longitudinal extensions extending transverse the feeding direction of the upper conveyor <NUM>. The package of studs <NUM> represents a single layer of studs that may be picked by a robot gripper (not disclosed), such as a vacuum plate from a pallet of studs (not disclosed).

A separating arrangement <NUM> is arranged adjacent the downstream end of the upper conveyor <NUM>. The separating arrangement <NUM> comprises a set of sensors <NUM> configured to detect if a stud (200A, 200B) is approaching. The sensors <NUM> may by the way of example be photo sensors or laser sensors. The separating arrangement <NUM> further comprises a reciprocating projection <NUM> which is arranged in a fixed position adjacent each sub-conveyor <NUM>. The reciprocation may be provided by using non disclosed pistons or using a cam shaft. Further, the separating arrangement <NUM> comprises a plurality of wheels <NUM> which are arranged on the same shaft 110a that drives the upper conveyor <NUM>. Each wheel <NUM> has a larger diameter than the driving wheel 111a of the upper conveyor <NUM>. Thereby, the peripheral velocity of the wheels <NUM> will be higher than the driving wheels 111a of the upper conveyor <NUM>. Additionally, the separating arrangement <NUM> comprises a plurality of lifting blocks <NUM> which are movable in the vertical direction by non-disclosed pistons.

As the leading stud 200A of the package of studs <NUM> reaches the separating arrangement <NUM>, the sensors <NUM> will detect the same and provide a signal to a non-disclosed control unit. The control unit is configured to set the projections <NUM> to a position in which they project in the vertical direction transverse the path of the upper conveyor <NUM>. Thus, the package of studs <NUM> is prevented from falling from the upper conveyor <NUM> although the upper conveyor <NUM> as such has a continuous operation. Simultaneously, the control unit is configured to set the lifting blocks <NUM> into a vertically lifted position whereby at least the first stud 200A in the package of studs <NUM> is raised to a clearance position above the upper conveyor <NUM>. The leading stud 200A will thereby come in contact with the wheels <NUM>. Since the wheels <NUM> have a higher peripheral velocity than the driving wheels 111a of the upper conveyor <NUM>, the leading stud 200A will be accelerated and hence be separated from the remaining studs in the package of studs <NUM>. At the same time the projection <NUM> is returned to its lowered position. Accordingly, one stud 200B at the time will be allowed to leave the upper conveyor <NUM> and fall own onto the lower conveyor <NUM>. The lifting blocks <NUM> are then lowered whereby the package of studs <NUM> comes in contact with the upper conveyor <NUM> anew and is moved forward. This process is repeated as long as there are any studs remaining in the package <NUM>. As a result of the separating arrangement <NUM>, the studs 200B will be arranged on the lower conveyor <NUM> with a longitudinal mutual distance to each other.

The system <NUM> further comprises a guide arrangement <NUM> that is arranged downstream the upper conveyor <NUM> in a position between the upper and the lower conveyors <NUM>, <NUM>. The guide arrangement <NUM> comprises a first set of guiding arms <NUM>, with one guiding arm adjacent each sub-conveyor <NUM> of the upper conveyor <NUM>. Each guiding arm <NUM> is pivotable attached to the frame <NUM> adjacent the lower conveyor <NUM> and forms an angle thereto. In the disclosed embodiment, a substantially vertically acting piston <NUM> operates the guiding arms <NUM> to be adjustable in a direction towards the upper conveyor <NUM>. Further, each guiding arm <NUM> in the first set is provided with a conveyor belt <NUM> having a feeding direction (arrow C) towards the lower conveyor <NUM>.

The guide arrangement <NUM> further comprises a second set of guiding arms <NUM> which are pivotably attached to the frame <NUM> adjacent the upper conveyor <NUM> and forms and angle thereto. In the disclosed embodiment, a substantially horizontally acting piston <NUM> operates the guiding arms <NUM> to be movable in a direction towards the guiding arms <NUM> of the first set.

The purpose of the guide arrangement <NUM> is to guide the stud 200A which leaves the upper conveyor <NUM> so that it falls to the lower conveyor <NUM> in a controlled manner held between the first and second sets of guiding arms <NUM>,<NUM> without rolling over.

As a result of the angles of the first and second sets of guiding arms <NUM>, <NUM> the stud 200B has changed orientation when entering the lower conveyor <NUM> so that instead of being standing edgeways it is lying down. The separated studs 200B are schematically illustrated on the lower conveyor <NUM>.

The lower conveyor <NUM> comprises in the disclosed embodiment three parallel sub-conveyors <NUM>. Each sub-conveyor <NUM> is supported by a first and a second driving wheel 141a, 141b. In the disclosed embodiment the second driving wheels 141b are motor driven. The lower conveyor <NUM> is preferably continuously driven. The sub-conveyors are disclosed as chain-conveyors. The invention should not be limited to the type of conveyor or the number of sub-conveyors used.

An optional positioning arrangement <NUM>, see <FIG> and <FIG> may be arranged adjacent the upstream end of the lower conveyor <NUM>. The positioning arrangement <NUM> comprises a rotatable projection <NUM> which is arranged adjacent each sub-conveyor <NUM>. As the stud 200B approaches the positioning arrangement <NUM>, each projection <NUM> is configured to be set to a position in which it projects transverse the path of the lower conveyor <NUM>, see dashed lines. Thereby, as the leading edge of a stud 200B reaches and abuts the a first of the three projections <NUM> any misalignment of the stud 200B will be corrected by the leading end of the stud 200B being temporarily stopped. Since the stud 200B as a whole is fed by a plurality of sub-conveyors <NUM>, the stud 200A will automatically align by turning into a direction perpendicularly to the feeding direction of the lower conveyor <NUM>.

A sensor arrangement <NUM> is arranged downstream the positioning arrangement <NUM>, see <FIG> and <FIG>. The sensor arrangement <NUM> is configured to measure the curvature of the stud 200B as seen along its longitudinal extension and as seen in a major plane of the lower conveyor <NUM>.

The sensor arrangement <NUM> comprises in the disclosed embodiment, see <FIG>, an array of three sensors 161a-161c. One sensor is arranged adjacent each sub-conveyor <NUM>. The sensors 161a-161c are directed upwards to thereby be able to detect a stud 200B that passes over the sensor arrangement. The individual sensors 161a-161c are arranged on a distance from each other and distributed along a virtual line L that extends transverse, i.e. perpendicular to the feeding direction of the lower conveyor <NUM>. The sensors 161a-161c are arranged to communicate with a control unit to be discussed below. A stud 200B passing the array of sensors 161a-161c is schematically illustrated. In <FIG>, each sensor 161a-161c indicates a positive signal, i.e. detection of a stud portion. This is an indication of that the stud 200B has an acceptable orientation and hence a correct curvature. In <FIG>, only one of the sensors161a-161c, the sensor 161b in the middle, indicates a positive signal, i.e. a detection of a stud portion. This may be used as an indication of an incorrect orientation which may be corrected by turning the stud 200B <NUM> degrees. The signals from the sensors 161a-161c are transmitted to the control unit which processes the information and further controls the operation of a turning arrangement to be discussed below.

Now turning to <FIG>. As given above, the sensor arrangement <NUM> may be an array of a plurality of sensors. The sensor arrangement <NUM> may comprise at least one sensor being any of a photocell, a laser sensor, a radar sensor, a pressure sensor or an image sensor. The sensor arrangement <NUM> may comprise a combination of two or more sensor types. In the context of the invention, the term "array" should be understood as a group of sensors which are arranged in determined pattern. The array may by way of example be a straight linear pattern with the sensors 161a-161c being arranged one after the other along a straight line L, see <FIG>. In another embodiment, the array may be a pattern comprising several adjacent straight lines in which lines sensors 161a-161c are arranged one after the other, see <FIG>. No matter pattern of the array, it is preferred that the individual sensors 161a-161c are arranged on a distance from each other and distributed in a direction transverse the feeding direction of the lower conveyor <NUM>. In case of a straight linear pattern, it is preferred that at least three sensors 161a-161c are provided. Thereby, in the event not all three sensors 161a-161c indicates a positive signal, i.e. a detection of a stud portion, this may be used as an indication of an incorrect orientation which may be corrected by turning the stud 200B <NUM> degrees. Further, an array comprising several lines of sensors 161a-161c may be used to determine not only an incorrect orientation, but also to determine if the curvature is too curved. If too curved, it may be used as a signal of that the stud should be removed from the conveyor.

<FIG> illustrates another example in which the sensor arrangement <NUM> uses a single image sensor <NUM> and where the curvature is determined by image analysis. In such embodiment, the image sensor <NUM>, such as camera may be arranged above the lower conveyor <NUM> to be able to monitor studs 200A passing on the lower conveyor <NUM>. The image sensor has a working area schematically illustrated by dash-dotted lines. The image captured by the image sensor <NUM> is compared, by using the control unit, with pre-determined geometrical boundaries, illustrated by dashed lines, representing an acceptable orientation. If the orientation of the stud 200B is determined by the control unit to be non-acceptable, the stud 200B should be turned <NUM> degrees. This is made by the control unit communicating with and instructing the turning arrangement to be discussed below to turn the stud 200B.

Now turning to <FIG> anew and also <FIG>, the system comprises a turning arrangement <NUM> which is arranged downstream the sensor arrangement <NUM>. The turning arrangement <NUM> comprises in the disclosed embodiment three pivotable arms <NUM> (only one arm being disclosed in <FIG>), where each arm <NUM> is pivotably attached to the frame <NUM> in a position below an adjacent sub-conveyor <NUM>. The pivotable arm <NUM> has a curved extension with a finger <NUM> in its free end. Each pivotable arm <NUM> is configured to be movable from a resting position, see <FIG> in which the arm <NUM> has no contact with the stud 200B, into an engagement position, see <FIG> where it engages a first edge portion <NUM> of the stud 200B, and then to a turning position, see <FIG> in which it lifts and flips the stud 200B to such extent that the stud 200B is turned <NUM> degrees around its longitudinal extension. The turning arrangement <NUM> is configured to be operated based on instructions from the control unit related to the sensor arrangement <NUM>. Accordingly, the turning arrangement <NUM> is configured to be operated only in the event the stud 200A approaching the turning arrangement <NUM> has been determined by using the sensor arrangement <NUM> to have a non-acceptable curvature. Otherwise the stud 200A should be allowed to pass. Accordingly, as a result of the system comprising a sensor arrangement <NUM>, a control unit and a turning arrangement <NUM>, all studs passing the turning arrangement <NUM> on the lower conveyor <NUM> will be oriented into one and the same orientation. Thus, the system may be seen as a screening system that sorts and orients arbitrary arranged single-curved studs into one and the same orientation where all studs are oriented side by side with a convex longitudinal edge of a first stud facing a concave longitudinal edge of a subsequent stud.

The system further comprises a cutting arrangement <NUM>, see <FIG>. The cutting arrangement <NUM> is arranged downstream the lower conveyor <NUM> and is configured to cut at least one of the two free ends of the stud 200B. It is preferred that both free ends of the stud 200B are cut. One end may be cut to provide a clean cut, whereas the other end may be used to cut the stud 200B to a pre-set length.

In the disclosed embodiment, the cutting arrangement <NUM> comprises two cutting machines <NUM>. The cutting machines <NUM> may by way of example be circular saws having disc saw blades (not disclosed) encapsulated in protective housings <NUM>. The cutting machines <NUM> are arranged in parallel with the longitudinal extension of the lower conveyor <NUM>, i.e. one at each end of the stud 200B. Before cutting the free ends, the stud 200B may be pushed in its longitudinal direction towards a non-disclosed anvil. It is preferred that at least one of the cutting machines <NUM> is movable in a direction transverse the feeding direction of the lower conveyor <NUM> to thereby set the system to cut studs to a pre-set length. In the disclosed embodiment this is made by one of the cutting machines <NUM> being movable along rails 183a, 183b extending transverse the lower conveyor <NUM>. The movement of the cutting machines <NUM> in view of each other may be made based on information communicated directly to the control unit from a CAD model representing a building module, such as a frame wall in which the stud later is to be used.

Now turning to <FIG> a method of orienting a plurality of studs 200A into one and the same curvature based orientation will be disclosed. The method comprises the following acts:
Arranging a package of studs <NUM> on an upper conveyor <NUM>.

Separating, by using a separating arrangement <NUM>, the plurality of studs 200A, 200B arranged in the package of studs <NUM>, thereby allowing one stud 200A, 200B at a time to be fed to a lower conveyor <NUM> with a mutual distance to each other.

Positioning <NUM> the stud 200A on the lower conveyor with a longitudinal extension of the stud 200A oriented in a direction transverse a feeding direction of the lower conveyor.

Measuring <NUM>, by using a sensor arrangement <NUM>, the curvature of the stud 200A as seen along its longitudinal extension and as seen in a major plane of the conveyor.

Determining <NUM>, based on input from said measuring, whether or not the stud 200A has an acceptable curvature as seen along its longitudinal extension and as seen in a major plane of the conveyor. The act of determining whether or not the stud 200A has an acceptable curvature may comprise receiving, by a control unit, a signal from the sensor arrangement <NUM>; determining whether or not the stud 200A has an acceptable curvature as seen along its longitudinal extension and as seen in the major plane of the conveyor; and instructing the turning arrangement <NUM> to turn the stud 200A <NUM> degrees around its longitudinal extension if it is determined that the stud 200A has a non-acceptable curvature.

Turning <NUM> the stud 200A <NUM> degrees around its longitudinal extension if it is determined that the stud 200A has a non-acceptable curvature. The act of turning the stud 200A may comprise moving at least one pivotable arm <NUM> from a resting position in which it has no contact with the stud 200A into a turning position in which it engages and lifts a first longitudinal edge portion of the stud 200A to such extent that the stud 200A is turned <NUM> degrees around its longitudinal extension.

Many modifications of the system are possible without departing from the inventive concept as defined in the appended claims.

Claim 1:
System configured to orient a plurality of studs into one and the same curvature based orientation, the system comprising:
an upper conveyor (<NUM>) having a feeding direction and comprising an upper surface (<NUM>) configured to receive a package of studs (<NUM>);
a separating arrangement (<NUM>) configured to allow one stud (200A, 200B) at a time to be fed from the package of studs (<NUM>) with a mutual distance to each other to a lower conveyor (<NUM>);
the lower conveyor (<NUM>) having a feeding direction (A) opposite the feeding direction of the upper conveyor (<NUM>) and being arranged to receive the stud (200A, 200B) being oriented with its longitudinal extension in a direction transverse to the feeding direction;
a sensor arrangement (<NUM>) configured to measure the curvature of the stud (200A, 200B) as seen along its longitudinal extension and as seen in a major plane of the lower conveyor (<NUM>);and
a turning arrangement (<NUM>) configured to turn the stud (200A, 200B) <NUM> degrees around its longitudinal extension, wherein
the turning arrangement (<NUM>) comprises at least one pivotable arm (<NUM>) configured to be movable from a resting position in which it has no contact with the stud (200A, 200B) into a turning position in which it engages and lifts a first longitudinal edge portion of the stud (200A, 200B) to such extent that the stud (200A, 200B) is turned <NUM> degrees around its longitudinal extension.