Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J15/00—Gripping heads and other end effectors
  • B25J15/06—Gripping heads and other end effectors with vacuum or magnetic holding means
  • B25J15/0616—Gripping heads and other end effectors with vacuum or magnetic holding means with vacuum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J11/00—Manipulators not otherwise provided for
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J9/00—Programme-controlled manipulators
  • B25J9/0093—Programme-controlled manipulators co-operating with conveyor means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J9/00—Programme-controlled manipulators
  • B25J9/02—Programme-controlled manipulators characterised by movement of the arms, e.g. cartesian coordinate type
  • B25J9/04—Programme-controlled manipulators characterised by movement of the arms, e.g. cartesian coordinate type by rotating at least one arm, excluding the head movement itself, e.g. cylindrical coordinate type or polar coordinate type
  • B25J9/041—Cylindrical coordinate type
  • B25J9/042—Cylindrical coordinate type comprising an articulated arm
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27D—WORKING VENEER OR PLYWOOD
  • B27D1/00—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G17/00—Apparatus for or methods of weighing material of special form or property
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
  • G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/46—Wood

Definitions

• the present invention relates to the field of grading elongated wooden objects.
• planks In the timber industry there is a need for grading of elongated wooden objects, in particular planks. This is in particular desirable for wooden planks that are to be integrated in a wooden structure, e.g. laminated wooden structure, e.g. a roof beam, a laminated wooden board, cross-laminated timber panels, etc.
• a wooden structure e.g. laminated wooden structure, e.g. a roof beam, a laminated wooden board, cross-laminated timber panels, etc.
• Grading of elongated wooden objects often involves a range of different measurements, which may include measurement of one or more dimensions of the wooden object, measurement of the weight of the wooden object, measurement of the moisture content, measurement of the temperature, measurement of the presence of defects, etc.
• a particular assessment that is nowadays frequently performed in the timber industry relates to the need to have a grading of the strength of the elongated wooden object, in particular if the elongated wooden object is considered as structural timber, so to be integrated in a load bearing structure like a roof beam, a column, a floor, a wall, etc.
• an apparatus For strength grading, an apparatus is available like the Brookhuis TimberGrader as illustrated in EP1724578.
• the measurement is based on an impulse generator which is adapted to generate a single calibrated impulse corresponding to a hammer blow and transfer thereof to a longitudinal end face of the wooden object.
• a sensor e.g. a microphone, an optical (e.g. laser) device, or an accelerometer, measures the reflection of the impulse transmitted to the wooden and the signal from the sensor is processed to determine one or more parameters related to the strength of the wooden object.
• this apparatus determines the natural frequency of the wooden object in the longitudinal direction thereof.
• EP2369340 discloses an installation for grading wooden objects, like planks or logs, wherein the elongated wooden objects are transported in succession on a transverse conveyor, wherein the object is conveyed horizontally and transverse to its length.
• the strength grading apparatus is arranged, here including an impulse generator and sensor generally operating on the same principle as described above.
• a further example of an installation for grading wooden objects comprising a transverse conveyor for the wooden objects and a strength grading apparatus generally operating on the same principle as described above is disclosed as embodiment in US2015/0247825.
• the strength grading apparatus disclosed in EP1724578, EP2369340, or US2015/0247825 can be considered as an example of timber grading based on the measurement of the natural frequency in longitudinal vibration. Based on the natural frequency, a length measurement, and a density of the wooden object, a modulus of elasticity is calculated.
• the present invention aims to provide measures to allow for enhanced grading, e.g. in view of efficiency, required investment, and/or footprint of the equipment.
• the invention contributes to a wider adaptation of grading in the timber industry, in particular the grading involving an assessment of the wooden objects related to the strength.
• the invention provides, according to a first aspect thereof, a method for automated grading of elongated wooden objects, each wooden object having a longitudinal end face, wherein the method is performed by a system comprising:
• a strength grading measuring apparatus that is configured to perform a measurement on the wooden object at a measuring position thereof, which apparatus comprises an impulse generator which is adapted to generate a single calibrated impulse corresponding to a hammer blow and transfer thereof to a longitudinal end face of the wooden object, as well as a sensor that measures the reflection of the impulse transmitted to the wooden object, wherein the apparatus further comprises a signal processing device that uses the signal of the sensor to determine one or more parameters related to the strength of the wooden object,
• a weighing device embodied to determine the weight of the wooden object, wherein the signal processing device is configured to use the weight of the wooden object in a determination of the density of the wooden object, the density being included in the determination of a strength grade attributed to the wooden object,
• a computer controlled robot having a movable arm, e.g. an articulated arm, and a gripper attached to the arm, wherein the gripper is configured to grip the wooden object, wherein the robot has an operative reach that includes the measuring position allowing the robot to transfer the wooden object to and/or from the measuring position, wherein the method includes an automated routine that comprises:
• the signal processing device attributes a strength grade to the wooden object.
• the robot is, preferably, a general purpose industrial robot, e.g. having at least four degrees of freedom for the gripper, e.g. five or six degrees of freedom, e.g. allowing to program the robot to apply the gripper at various positions along the length of the wooden object, e.g. the gripping position of the gripper relative to the wooden object being based on the actual length of the wooden element to be gripped, e.g. in view of gripping the wooden object with the center of gravity thereof in a vertical plane through the robot arm.
• a general purpose industrial robot e.g. having at least four degrees of freedom for the gripper, e.g. five or six degrees of freedom, e.g. allowing to program the robot to apply the gripper at various positions along the length of the wooden object, e.g. the gripping position of the gripper relative to the wooden object being based on the actual length of the wooden element to be gripped, e.g. in view of gripping the wooden object with the center of gravity thereof in a vertical
• the robot has a base, e.g. to be mounted stationary or drivable on a floor, and a slewable member, slewable - over 360 degrees if desired - about a vertical axis relative to the base, on which slewable member a first arm section is articulated about a horizontal axis, with a second arm section being articulated about a further horizontal axis relative to the first arm section.
• the gripper may be arranged at the end of the second arm section, e.g. via a wrist providing bend, swivel, and/or roll motion functionality about one or more further pivot axes as is known in the art.
• the inventive system is very efficient as the robot can be programmed to handle the gripped wooden object in various manners in coordination with operation of the strength grading measuring apparatus.
• the coordination can be effected in various manners, e.g. a direct communication between the controller of the robot and the measuring apparatus, and any other equipment of the automated system.
• the robot is operated, e.g. programmed, to stack the wooden objects that have been graded in one or more stacks, e.g. on cart(s) that allow to transport a stack to another location in a timber processing plant.
• the robot is operated, e.g. programmed, to stack a wooden object that has been graded onto a selected stack of a group of multiple stacks, e.g. the stack being selected automatically from the group on the basis of the grade attributed to the wooden object.
• the robot is operated, e.g. programmed, to perform one or more additional actions in addition to a removal of the wooden object from the measuring position, and - possibly - a later stacking of the wooden object.
• the robot is used for application of a mark to the wooden object, e.g. a mark corresponding to the grade that has been determined for the respective wooden object.
• the robot arm is provided with a marking device that is configured to apply a mark to the wooden object, e.g. a paint application device, e.g. a coloured dot corresponding to a certain grade.
• a marking device mounted on the robot is configured and operated to apply the mark on the wooden object, whilst the wooden object is held by the gripper of the robot.
• the system comprises a marking device that is not arranged on the robot itself, yet arranged within the operative reach of the robot such that a wooden object held by the gripper of the robot is brought in proximity of the marking device and the marking device is operated to apply the mark to the wooden object.
• the mark contains a so-called CE-mark.
• the mark is printed by the marking device directly on the wooden object or embossed in the wooden object.
• the weighing device is arranged at the measurement position and configured to weigh the wooden object whilst at the measurement position, e.g. whilst not being gripped/retained by the gripper of the robot.
• the weighing device is integrated in the robot, e.g. allowing for weighing of the wooden object as the object is pick-up by means of the gripper at a pick-up position.
• the weighing device is arranged between the robot arm and the gripper.
• the robot including the gripper of the robot, is configured and operated, e.g. programmed, to hold the wooden object during the measurement by the strength grading measuring apparatus.
• the robot is first operated to grip the wooden object at a pick-up position that is remote from the measuring position and to then transfer the wooden object to the measuring position where the measurement is performed whilst the wooden object is still held by the robot.
• the robot is then operated to remove the wooden object from the measurement position, e.g. to deposit the graded wooden object onto a stack, e.g. onto a selected one of multiple stacks, e.g. stacks each to be made up of wooden objects of a specific grade.
• the robot could pick-up the wooden object, for example, from a linear conveyor or from a stack, e.g. a stack on a transport vehicle, e.g. a cart.
• the gripper is elastic, e.g. embodied as an elastic material suction cup, or is supported in elastic manner relative to the robot arm.
• the gripper is temporarily made elastic or supported elastic, so that a measurement based on the impulse applied to the wooden object, to an axial end face thereof, is not interfered by the grip of the robot, e.g. the impulse not being lost or unduly impaired by the wooden object being held by the robot during the measurement.
• the gripper is made to be elastic in longitudinal direction of the wooden object.
• the gripper includes a vacuum gripper as is often used in the timber industry.
• the vacuum gripper is, preferably, embodied to be elastic, e.g. so as to not interfere with the measurement based on the impulse applied to the wooden object when the object is being held by the vacuum gripper of the robot.
• the vacuum gripper is elastically mobile in a longitudinal direction of the retained wooden object relative to the robot arm.
• the vacuum gripper comprises multiple elastic material suction cups.
• the vacuum gripper comprises an elongated main gripper frame connected, e.g. via a wrist, to the robot arm, wherein the main gripper frame is provided with multiple suction cups of elastic material along the length of the main gripper frame.
• the gripper includes lateral support members, e.g. pins or the like, engaging the vertical sides of the wooden object, whereas the vacuum gripper engages the top side of the wooden object.
• the gripper could also include one or more support members, e.g. elastic support members or support members that are elastically arranged on the robot arm, that engage underneath the wooden object.
• the one or more support members could be embodied to weigh the wooden object carried thereon.
• the robot is embodied to weigh the wooden object that is picked up from the conveyor by means of the gripper.
• the system comprises a linear conveyor, e.g. a roller conveyor, having a receiving end and an terminal end, the linear conveyor being configured and operated for conveyance of the elongated wooden object from a receiving end of the linear conveyor towards the terminal end of the linear conveyor.
• the linear conveyor is configured and operated to convey the wooden objects to the measuring position, with the strength grading measuring apparatus being arranged in proximity of the linear conveyor, for example at the terminal end thereof.
• the robot is then operated, e.g. programmed, to remove the wooden objects from the measuring position, e.g. in view of (selective) stacking of the wooden object after grading.
• the weighing device comprises one or more support members, preferably elastic support members, that are configured and operated to lift the wooden object relative to the linear conveyor, so that the wooden object becomes separated from the linear conveyor and is supported on said one or more (elastic) support members, e.g. prior to a measurement by means of the strength grading measuring apparatus.
• the wooden object is lifted by two spaced apart vertically mobile support members that raise the wooden object above the linear conveyor, e.g. roller conveyor, e.g. at the measuring position.
• These support members can be elastic and/or arranged in elastic manner so that any measurement based on an impulse applied to the wooden object is not disturbed by the support members.
• the robot gripper engages the wooden object whilst the object is still lifted above the linear conveyor by means of the one or more support members of the weighing device.
• the weighing device is embodied by one or more support members thereof being movable upwards between rollers of a roller conveyor as linear conveyor at the measurement location, so that the wooden object is lifted off the rollers. It is then envisaged that the measurement based on an impulse applied to the wooden object is performed with the object being lifted.
• a moisture measurement apparatus is arranged along the linear conveyor.
• the moisture measurement apparatus is configured and operated to determine the moisture content of the wooden object.
• one or more sensors adapted to sense one or more physical dimensions of the wooden object are arranged along the linear conveyor and/or with the operative reach of the robot. For example, a measurement is performed of the length, and/or the width, and/or the thickness of the wooden object, e.g. whilst the wooden object is arranged on, or travels over, the linear conveyor or whilst the wooden object is held by the gripper of the robot.
• an optical laser triangulation device is provided and operated to measure the length, and/or the width, and/or the thickness of the wooden object.
• the robot picks up a wooden object, e.g.
• a measurement device configured and operated to measure the length, and/or the width, and/or the thickness of the wooden object, e.g. prior to the wooden object being brought into the measuring position by the robot or after the removal of the wooden object from the measuring position by the robot.
• the robot is embodied, e.g. provided with one or more sensors, to determine one or more physical dimensions of the wooden object when arranged on a linear conveyor, for example, a measurement is performed of the length, and/or the width, and/or the thickness of the wooden object.
• one or more sensors adapted to sense the horizontal position of the wooden object on the linear conveyor are arranged along the linear conveyor, e.g. at the measuring position when the linear conveyor is configured to convey the wooden object to the measuring position.
• a stop assembly is arranged at the terminal end of the linear conveyor, which stop assembly is configured to stop an advancing wooden object, e.g. whilst avoiding a recoil of the advancing object.
• a wooden object detector is arranged that is configured to sense the arrival of a wooden object at the measuring location and is configured to control the linear conveyor so that the object is slowed down, e.g. ahead of the object reaching the abovementioned stop assembly.
• one or more rollers of a roller conveyor design of the linear conveyor are retarded upon such detection and to slow down the wooden object.
• a temperature sensor is arranged along the linear conveyor, when present, conveying the wooden object and is configured to sense the temperature of the wooden object, e.g. a contactless temperature measurement.
• a temperature sensor is arranged within the operative reach of the robot, wherein the wooden object held by the gripper of the robot is brought in proximity of the temperature sensor to measure the temperature.
• the robot is provided, e.g. on the arm thereof, with one or more of a temperature sensors for sensing the temperature of the wooden object and/or with a moisture measurement apparatus for sensing the moisture content of the wooden object.
• a saw device is arranged along the linear conveyor to make a saw cut that provides the end face upon which an impulse is applied by the strength grading measuring apparatus.
• a saw device is arranged within the operative reach of the robot, wherein the wooden object held by the gripper of the robot is brought with an longitudinal end thereof in proximity of the saw device, the saw device making the saw cut that provides the end face upon which an impulse is applied by the strength grading measuring apparatus.
• one or more of the weighing device, temperature sensor, sensor(s) adapted to sense one or more physical dimensions of the wooden object, and/or moisture measurement apparatus are (when present and appropriate) linked to the signal processing device, that uses these one or more additional inputs in order to determine one or more parameters related to the strength of the wooden object, e.g. natural frequency, density, etc.
• the system comprises a main controller that stores for each wooden object the one or more parameters as determined by any one or more of the strength grading apparatus, weighing device, temperature sensor, sensor(s) adapted to sense one or more physical dimensions of the wooden object, and/or moisture measurement apparatus. For instance, these wooden object related data are made available to further processing steps involving the respective wooden object.
• the system further includes one or more planing and/or profiling machines that are configured and operated to plane and/or profile the wooden object, for example, a linear conveyor being arranged to adjoin the output end of the one or more planing and/or profiling machines.
• the system further includes an X-ray device that is configured and operated to X-ray the wooden object, e.g. in view of imaging the internal
• composition/structure of the object and/or detection of metallic parts in the wooden object.
• the system comprises:
• a linear conveyor e.g. a roller conveyor, having a receiving end and an terminal end
• the strength grading measuring apparatus is arranged at the terminal end of the linear conveyor
• the linear conveyor is configured and operated for conveyance of an elongated wooden object from the receiving end of the linear conveyor, where the object is received on the linear conveyor, to the measuring position in proximity of the terminal end of the linear conveyor. It is envisaged that the measurement is performed on the wooden object when at the measuring position in order determine a strength grading.
• the computer controlled robot is then configured and operated so that the gripper grips the wooden object that is located on the measuring position for removal of the gripped wooden object by means of the robot once the strength grading measuring apparatus has performed the associated measurement.
• the robot can then stack the wooden objects removed from the measuring position in or more stacks, e.g. each stack corresponding to a certain grade.
• weighing of the wooden object can be done using a weighing device arranged at the terminal end of the linear conveyor, or by means of a weighing device included in the robot so that weighing, and thus determination of the grade, is done after the strength measurement, e.g. whilst the wooden object is transferred by the robot to the stack that is selected on the basis of the attributed grade.
• the first aspect of the invention also relates to a system for automated grading of elongated wooden objects, each wooden object having a longitudinal end face, wherein the system comprises:
• a strength grading measuring apparatus that is configured to perform a measurement on the wooden object at a measuring position thereof, which apparatus comprises an impulse generator which is adapted to generate a single calibrated impulse corresponding to a hammer blow and transfer thereof to a longitudinal end face of the wooden object, as well as a sensor that measures the reflection of the impulse transmitted to the wooden object, wherein the apparatus further comprises a signal processing device that uses the signal of the sensor to determine one or more parameters related to the strength of the wooden object,
• a weighing device embodied to determine the weight of the wooden object, wherein the signal processing device is configured to use the weight of the wooden object in a determination of the density of the wooden object, the density being included in the determination of a strength grade attributed to the wooden object,
• a computer controlled robot having a movable arm, e.g. an articulated arm, and a gripper attached to the arm, wherein the gripper is configured to grip the wooden object, wherein the robot has an operative reach that includes the measuring position allowing the robot to transfer the wooden object to and/or from the measuring position,
• system is configured to perform an automated routine that comprises:
• the signal processing device attributes a strength grade to the wooden object.
• the system may comprises one of more optional or advantageous features as discussed herein, e.g. in relation to the method of the first aspect of the invention.
• a second aspect of the invention relates a system for automated grading of elongated wooden objects, wherein the system comprises:
• a computer controlled robot having an movable arm, e.g. an articulated arm, and a gripper attached to the arm, wherein the gripper is configured to grip the wooden object, e.g. a vacuum gripper, wherein the robot has an operative reach so that the gripper can grip a wooden object that is located on a pick-up position for removal of the gripped wooden object by means of the robot from the pick-up position,
• a strength grading measuring apparatus that is arranged on the robot arm and that is configured to perform a measurement on the wooden object after having been pick-up by means of the gripper.
• a conveyor for, e.g. a roller conveyor, the conveyor being configured for conveyance of an elongated wooden object from a receiving end of the conveyor, where the object is received on the linear conveyor, to the pick-up position.
• the robot is configured, e.g.
• the robot is configured to stack the wooden objects in one or more stacks, e.g. each stack corresponding to a certain grade.
• the robot may be programmed to stack a wooden object onto a selected stack of a group of multiple stacks, e.g. the stack being selected from the group on the basis of the grade attributed to the object.
• the robot is configured, e.g.
• the robot could be used to apply a mark to the wooden object, e.g. a mark corresponding to the grade that has been determined for the respective wooden object.
• the robot arm is provided with a marking device configured to apply a mark to the wooden object, e.g. a paint application device, e.g. some coloured dot corresponding to a certain grade.
• the second aspect of the invention of the present invention also relates to a robot for use in a system for automated grading of elongated wooden objects, wherein the computer controlled robot has a movable arm, e.g.
• the gripper is configured to grip the wooden object, e.g. a vacuum gripper, wherein the robot has an operative reach so that the gripper can grip a wooden object that is located on a pick-up position for removal of the gripped wooden object by means of the robot from the pick-up position,
• a strength grading measuring apparatus is arranged on the robot arm that is configured to perform a measurement on the wooden object after having been pick-up by means of the gripper.
• the robot and/or strength grading measuring apparatus and/or conveyor of the second aspect of the invention may comprise one or more details as discussed herein with reference to the first aspect of the invention.
• the second aspect of the invention also relates to a method for automated grading of wooden objects wherein use is made of the system of the second aspect.
• the present invention also relates to a system for automated grading of elongated wooden objects, wherein the system comprises:
• a computer controlled robot having an movable arm, e.g. an articulated arm, and a gripper attached to the arm, wherein the gripper is configured to grip the wooden object, e.g. a vacuum gripper, wherein the robot has an operative reach so that the gripper can grip a wooden object that is located on a pick-up position for removal of the gripped wooden object by means of the robot from the pick-up position,
• system comprises one or more of:
• a strength grading measuring apparatus that is arranged on the robot arm and that is configured to perform a measurement on the wooden object after having been pick-up by means of the gripper
• a moisture content measuring device that is arranged on the robot arm, e.g. that is configured to perform a measurement on the wooden object after having been pick-up by means of the gripper,
• a marking device configured to apply a mark to the wooden object, e.g. a paint application device, e.g. some coloured dot corresponding to a certain grade, - one or more sensor configured to determine physical dimensions of the wooden object, e.g. arranged along the linear conveyor, for example a measurement is performed of the length, and/or the width, and/or the thickness of the wooden object.
• a linear conveyor e.g. a roller conveyor, the conveyor being configured for conveyance of an elongated wooden object from a receiving end of the linear conveyor, where the object is received on the linear conveyor, to the pick-up position, where the wooden object can be picked-up by the robot.
• the robot may also have one or more of the features described herein.
• the present invention also relates to a method and system for automated grading of elongated wooden objects wherein a strength grading measuring apparatus transfers a single calibrated impulse to a longitudinal end face of the object.
• a sensor measures the reflection of the impulse and a signal processing device determines one or more parameters related to the strength of the wooden object.
• a weighing device determines the weight of the object and the signal processing device uses the weight in a determination of the density which is included in the determination of a strength grade attributed to the object.
• a computer controlled robot has a movable arm and a gripper attached to the arm to grip the wooden object. The robot has an operative reach that includes the measuring position allowing the robot to transfer the wooden object to and/or from the measuring position.
• the method includes an automated routine that comprises operating the gripper to grip a wooden object, operating the robot so as to transfer the gripped wooden object to and/or from the measuring position, weighing the wooden object, and operating the strength grading measuring apparatus, wherein the signal processing device attributes a strength grade to the wooden object.
• the invention also pertains to a method for automated or semi-automated grading of wooden objects, wherein use is made of a system and/or a robot as described herein.
• the robot is configured and operated to transfer the wooden object from the pick-up position to the measuring position where a human operator holds a hand held strength grading measuring apparatus.
• the operator then operates the hand-held apparatus and then signals the robot, e.g. via a command button on the hand-held apparatus, that the wooden object can be removed from the measuring position, e.g. to be stacked as described herein.
• FIG. 1 schematically shows an example of a system according to the first aspect of the invention
• FIG. 2 schematically shows another example of a system according to the first aspect of the invention
• FIG. 3 schematically shows an example of a system according to the second aspect of the invention.
• Figure 1 shows an example of a system for automated grading of elongated wooden objects 5.
• Each wooden object has longitudinal end faces at the axial ends thereof.
• the system comprises a strength grading measuring apparatus 20 that is configured to perform a measurement on the wooden object 5 at a measuring position A thereof, here shown by a dashed line.
• the apparatus 20 is mounted here in a fixed position, e.g. on a support frame above the floor.
• the apparatus 20 for example a Brookhuis TimberGrader, comprises an impulse generator 21 which is adapted to generate a single calibrated impulse corresponding to a hammer blow and transfer thereof to a longitudinal end face of the wooden object, as well as a sensor 22 that measures the reflection of the impulse transmitted to the wooden object.
• an impulse generator 21 which is adapted to generate a single calibrated impulse corresponding to a hammer blow and transfer thereof to a longitudinal end face of the wooden object, as well as a sensor 22 that measures the reflection of the impulse transmitted to the wooden object.
• the apparatus 20 further comprises a signal processing device 25, e.g. a programmable computer, that uses the signal of the sensor 22 to determine one or more parameters related to the strength of the wooden object 5.
• a signal processing device 25 e.g. a programmable computer, that uses the signal of the sensor 22 to determine one or more parameters related to the strength of the wooden object 5.
• the system further comprises a computer controlled robot 40 having a movable arm, e.g. an articulated arm, and a gripper 45 attached to the arm.
• the gripper 45 is configured to grip the wooden object.
• the robot 40 has an operative reach that includes the measuring position A allowing the robot to transfer the wooden object to and/or from the measuring position.
• a weighing device 30 is integrated in the robot 40.
• the weighing device 30 is arranged between the robot arm and the gripper 45.
• the weighing device 30 embodied to determine the weight of the wooden object 5 and is linked to the signal processing device 25.
• the signal processing device 25 is configured to use the weight of the wooden object in a determination of the density of the wooden object, e.g. with the volume of the object 5 being known through measurements of length, width, and thickness of the object.
• the density is included in the determination of a strength grade attributed to the wooden object, as is known in the art of wood strength grading.
• system shown in figure 1 is configured and operated, e.g. programmed, to perform an automated routine that comprises:
• the signal processing device 25 attributes a strength grade to the wooden object 5.
• the robot 40 is an industrial robot having at least four degrees of freedom for the gripper, e.g. allowing to program the robot 40 to apply the gripper 45 at various positions along the length of the wooden object 5., e.g. to position the centre of gravity of the wooden object 5 in a vertical plane through the arm of the robot.
• the robot 40 has a base 41 that is here placed on the floor of a timber processing plant.
• the robot 40 has a slewable member 41 a, slewable about a vertical axis relative to the base 41 , on which slewable member 41a a first arm section 42 is articulated about a horizontal axis, with a second arm section 43 being articulated about a further horizontal axis relative to the first arm section.
• the gripper 45 is arranged at the end of the second arm section 43, here via a wrist 44 providing one or more of bend, swivel, and/or roll motion functionality about one or more further pivot axes.
• the robot 40 including the gripper 45 of the robot, is configured and programmed to hold the wooden object 5 during the measurement by the strength grading measuring apparatus 20 at the measurement position A.
• the object 5 is solely held by the gripper 45 as is preferred.
• the robot 40 is programmed to grip the wooden object 5 at a pick-up position that is remote from the measuring position A and to then transfer the wooden object 5 to the measuring position where the measurement is performed by apparatus 20 whilst the wooden object is still held by the robot 40.
• the robot 40 grips a wooden object 5 from a stack 50 of wooden objects, or from a conveyor, e.g. a linear roller conveyor.
• the robot 40 is programmed to then remove the wooden object from the measurement position A, in this example programmed to deposit the graded wooden object onto another stack 51 , e.g. onto a selected one of multiple stacks, e.g. stacks each to be made up of wooden objects of a specific grade.
• the gripper 45 is elastic.
• the gripper is a vacuum gripper which comprises multiple elastic material suction cups 46, a vacuum line 48 and vacuum pump 49.
• the vacuum gripper 45 comprises an elongated main gripper frame 47 connected, e.g. via a wrist, to the robot arm, wherein the main gripper frame is provided with multiple suction cups 46 of elastic material along the length of the main gripper frame.
• the elastic design of the vacuum gripper avoids interfere of the gripper 45 with the measurement based on the impulse applied by apparatus 25 to the wooden object when the wooden object 5 is being held by the vacuum gripper of the robot.
• the robot 40 is programmed to stack the wooden objects that have been graded in one or more stacks 51.
• the robot is programmed to stack a wooden object that has been graded onto a selected stack of a group of multiple stacks, e.g. the stack being selected automatically from the group on the basis of the grade attributed to the wooden object.
• the robot 40 can be programmed to perform one or more additional actions in addition to a removal of the wooden object from the measuring position A, and - possibly - a later stacking of the wooden object.
• the system comprises a marking device 80 that is not arranged on the robot itself. Instead the device 80 is arranged within the operative reach of the robot, such that a wooden object 5 held by the gripper 45 of the robot is brought in proximity of the marking device 80 and the marking device is operated to apply the mark to the wooden object, e.g. a CE-mark.
• the system comprises, aside from the robot 40 with a gripper 45 and the measurement apparatus 20 with signal processing device 25, a linear conveyor 110, here a roller conveyor.
• the conveyor 110 has a receiving end 111 and an terminal end 112.
• the linear conveyor is configured for conveyance of an elongated wooden object 5 from a receiving end of the linear conveyor, where the object is received on the linear conveyor, to a measuring position A in proximity of the terminal end of the linear conveyor.
• the strength grading measuring apparatus 20 is arranged at the terminal end 112 of the linear conveyor 110 and is configured and operated to perform a measurement on the wooden object 5 when at said measuring position in order determine a strength grading.
• Figure 2 illustrates an embodiment, wherein the weighing device is arranged at the measuring position relative to the linear conveyor 110 and configured to weigh the wooden object whilst at the measurement position, e.g. whilst not being gripped/retained by the gripper of the robot 40.
• the weighing device 30 comprises one or more support members 31 , preferably elastic support members, that are configured and operated to lift the wooden object relative to the linear conveyor 110 , so that the wooden object 5 becomes separated from the linear conveyor and is supported on said one or more support members, e.g. prior to a
• the computer controlled robot 40 has an operative reach so that the gripper 45 can grip a wooden object that is located on the measuring position A for removal of the gripped wooden object by means of the robot 40 once the strength grading measuring apparatus 20 has performed the associated measurement.
• the wooden object is supported on the elastic support members 31 during the measurement and then the gripper 45 grips the wooden object 5 for its removal, e.g. to be marked and then stacked using the robot 40.
• the robot 40 then places the wooden object 5 on a selected one of the multiple stacks 50, 51 on the basis of the grading of the object 5.
• all objects 5 are stacked on one and the same stack, with the mark on each object 5 providing information on the grade of the individual wooden object 5.
• the system may be arranged with a cell that is shielded from human access.
• reference numeral 60 denotes a saw device adapted to make a saw cut that will form the end face to which an impulse is applied by apparatus 20 in view of the strength grading. It is noted that, in an embodiment, a saw device may also be provided for in combination with the system of figure 1 , wherein the robot 40 holds the wooden object 5 whilst the saw device 60 makes a longitudinal end cut.
• reference numeral 65 denotes an inline wood moisture content measurement device.
• reference numerals 66, 67 denote one or more sensors that measure one or more physical dimensions, e.g. length, width, and or thickness.
• reference numeral 70 denotes a stop assembly for stopping the object 5.
• reference numeral 68 denotes a temperature sensor that sense the temperature of the object 5.
• components 65, 66, 67, 68 can be varied.
• the robot 40 may have a camera, e.g. to have a camera-based or camera assisted handling of the wooden object.
• Figure 3 illustrates a system for automated grading of elongated wooden objects, wherein the system comprises:
• a computer controlled robot40 having a movable arm 41 , e.g. an articulated arm, and a gripper 45, wherein the robot has an operative reach so that the gripper can grip a wooden object that is located on a pick-up position for removal of the gripped wooden object by means of the robot from the pick-up position,
• a strength grading measuring apparatus 20 that is arranged on the robot arm and that is configured to perform a measurement on the wooden object 5 after having been pick-up, e.g. from a conveyor 110 or from a stack, by means of the gripper 45.
• the wooden object 5 is held substantially horizontal by the robot 40 during the measurement.
• the gripper 45 can be a vacuum gripper as explained herein.
• the gripper 45 could also include lateral support members, e.g. pins or the like, engaging the vertical sides of the wooden object 5.
• the gripper 45 could also include one or more support members, e.g. elastic support members, that engage underneath the wooden object 5.
• the one or more support members could be embodied to weigh the object 5 carried thereon.

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• 2020
  • 2020-01-27 WO PCT/NL2020/050040 patent/WO2020153848A1/en unknown
  • 2020-01-27 EP EP20704619.4A patent/EP3914894A1/de active Pending

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