SI22020A - Procedure and device for testing timber structural elements - Google Patents

Abstract

The invention concerns a procedure and device (9) for testing timber structural elements (20), especially finger-jointed ties within massive structural timber. A timber structural element (20) is loaded by a defined tensile force below its characteristic strength and at the same time, a measurement of parameters of tensile properties and/or oscillation properties or just of oscillation properties of a timber structural element (20) is carried out within the range of tensile load by using a measuring device (40). The measuring device (40) is foreseen between two devices (33) for application of tensile force to the timber structural element (20).

Description

PROCEDURE AND DEVICE FOR TESTING WOOD BUILDING ELEMENTS

The invention relates to a process for testing non-bursting wooden building elements, especially wedged mats in structural wood, as well as a device for testing the strength of wooden building elements, especially wooden building elements in the form of poles, with arrangements for applying a certain tensile force to the wooden building element.

The invention is directed in particular to the testing of non-broken glued wooden ties, preferably to one-piece wedge-shaped solid wood, which is produced in series.

The increasing use of timber in the construction industry is closely linked to the development and expansion of wedge-rusted, one-piece or multi-section pole. One-piece mast is a so-called structural solid wood, for example, multi-mast is a laminated board of boards or duolam or triolam.

By visual or wasteful machine sorting process, it is possible to select quantitative portions of different strength classes from a certain amount of untreated timber. The proportion of high strength by cutting out local defects, such as cramps, cracks or curves, from individual wooden parts can increase significantly. The defective and defective pieces of wood, which are assigned to a certain strength class, are then folded together into wedges using a wedge-shaped crochet ties. This wooden building element then achieves the same strength class as the wooden parts used for it. This makes it possible to provide building elements with a length of 50 m or more, thus significantly larger than the lengths of generally available untreated timber would allow.

Correctly wedged wedges do not in any way impair the strength of the wooden construction element. However, implementation according to the regulations requires high mechanical engineering costs, careful operation and wasteful process control. Mounting establishments wishing to install wedge-shaped croissant ties must obtain a certificate from an independent inspection institution and then obtain a permit for bonding. In addition, they must undertake to carry out their own internal controls carefully and to be subject to additional verification by an external control body that carries out certification of.

For their own internal control, two additional wedges are to be made for each variety class and working layer, which, after the adhesive bond has hardened on the bending test table, must be loaded to a breaking point. The breaking force shall be measured and documented and a statement of basic compliance with the required production parameters shall be allowed. External controls additionally take random samples from the production plant unannounced during extended periods of time. Of the 20 samples taken, only one sample may exceed the characteristic strength values (5% fractile). The downside of this test procedure is the destructive test of the jammed croissant connection. wooden construction element as well as a large time shift of the test from production.

Complexly speaking, these test measures have in all cases led to some high production security and thus to some high acceptability or acceptance and the expansion of the use of one-piece wedged solid wood and plywood. However, individual claims are raised, although they rarely occur, this acceptance is questioned over and over. In extreme cases, the strength of a single jammed bond can depend on the strength of the entire structure.

To achieve even greater production security, the so-called "Proof Loading Procedure" is used. Each building element is tested on a special test rig, which is typically integrated into the production process. The building element is clamped at both ends and loaded with a predetermined tensile load, which is determined depending on the dimensions of the building element and the strength class. Construction elements with a significant defect are eliminated, eliminated and subsequently repaired. The downside of this process is that the error sites that barely pass the test load are not recognized. The test load on these defects can lead to damages that adversely affect the strength of the wooden building components.

Increasing the test load leads to greater safety, but it can also cause further damage and increase scum.

Patent AT 1699/2003 discloses a process for ensuring the quality of long timber, whereby long timber is loaded with a defined tensile load. At the time of tensile loading, the elongation of the entire building element is measured. In this way, some increased security can be ensured in the detection of defects, while the problem of damage to wooden construction elements persists. In addition, localization of any fault location is only possible in the case of long-timber failure.

The object of the present invention is to present a process and a device for testing wooden building elements, which can be used to obtain a statement of strength without breaking a wooden building element.

According to the invention, this task is accomplished by the method of claim 1 as well as the device of claim 17. Preferred embodiments and further embodiments of the invention are described in the sub-claims.

The method according to the invention provides that the wooden building element is loaded by sections with a defined tensile force below its characteristic strength, and at the same time measurements are made with respect to sound emission and / or the oscillatory and tensile characteristics of the wooden building element in the tensile load area. At the same time, non-destructive measurement of the test parameters of a loaded section makes it possible to obtain a statement of its strength. In this case, it is preferable that the applied test load, that is, the tensile force, may be significantly lower than the breaking load of any of the errors detected. Minimum defects in the observed section of a wooden construction element, such as a partially defective wedge-shaped croissant or some other defect site, under the load at the tips of the croissants or in the defect area, produce emissions in the ultrasonic range that can be captured by suitable sensing. Errors can also be recognized by the nonlinearity o in the local expansion field. Local oscillatory characteristics can be measured both with the inlet of some tensile force and without tensile force and contribute to the accuracy of the statement.

In order to carry out the process, it is envisaged that the wooden construction element is clamped in the clamping device and the clamping devices are separated from each other apart, in particular the hydraulic drive of the clamping devices is provided. This makes it possible to perform a timed measurement and test of a wooden building element.

Alternatively, the wooden construction element can be loaded with two opposite driving forces, for example through pairs of discs or pairs of track chains driven by antisense drive torques.

Instead of a timed measurement, of the test, the wooden construction element is transported clamped between two conveyors with different driving torques, whereby any measuring device or. measuring devices during transport devices mimic the parameters in question.

Preferably, local expansion measurements are performed at the measuring point in order to identify nonlinearities in the local expansion field. Measurement of this elongation may be performed without contact with any laser extensiometer or with a touching incision and measurement based on a measuring elongation strip.

It is also envisaged to record acoustic emission at the measurement site, capturing acoustic emissions in the ultrasonic field generated under load in the area of fault sites or connection points. Assembling the measuring device or. sensors on a wooden building element are preferably carried out without a coupling auxiliary, such as e.g. what a gel.

Alternatively or additionally, it is provided that the oscillating excitation of the wooden building element is carried out and the oscillatory characteristics of the wooden building element are measured with a sensor. Since the fault locations represent a local rigidity disturbance within the wooden building element, these disturbances can be characterized by transmission parameters, for example, for ultrasonic waves. In order to measure the transmission parameters, energy-rich, low-frequency ultrasonic waves or pulses are fed to a wooden building element, and the wavelengths of these waves are measured and evaluated with appropriate sensing. The transmission characteristics shall be measured with or without the applied tensile forces.

It is envisaged that less than 70% of the characteristic strength of a wooden building element is brought in as a tensile force such that the wooden construction part or. some connecting point of the two wooden elements does not damage the unrecognizable or suffers initial damage due to the reduced load level and by introducing a non-destructive testing and measurement procedure. Therefore, it is possible to test the wooden building element with a lower, but still permissible, strength without breaking the material, only the bonds and defect sites with some very small, no more permissible strength are destroyed in such a process. In any case, these wooden building blocks must be eliminated or subsequently improved. Due to the lower tensile force applied to the test of a wooden building element, the machine's consumption of the test fixture is reduced so that the fixtures can be made easier and more cost-effective. The potential damage that may result from the mechanical application of the tensile force to the surface of the building element, ie in the area of the force supply, is reduced because the tensile forces are dimensioned significantly lower than in traditional test procedures. The required compressive force for the test fixture or the reels is lower than for traditional methods, so that the material of the test fixture in the test fixture has a reduced impact on the material.

Preferably, a measurement is made at some junction point of two wooden building elements on which they are glued to one another.

Particularly in the case of a timed procedure, it is provided that the test sites of the wooden building element are marked, that the wooden construction element is transported through the testing device and that the test site is identified by a sensor. The measuring devices are positioned depending on the sensor data in the area of the test site. This makes it possible to test the purpose-selected locations of the wooden building element, such as the connecting points, with the test site being able to determine the exact measurement device.

Areas of error identified areas of the wooden building element can be marked and subsequently eliminated because the local tensile loading of the sections is followed by the local decomposition of the measurement results. The measurement results can be reliably attributed to the concrete section of the wooden building element so that the combination of some smaller test load, additional measurements of non-destructively obtained parameters and local decomposition can significantly increase the accuracy of the error location and location of these errors.

In addition to the marking and elimination of identifiable errors, it is possible to determine the strength or strength of the process. the strength class of the wooden building element and that the wooden building element can be classified in a particular strength class and characterized accordingly.

Device according to the invention for testing the strength of wood

- 8 construction elements, in particular wooden construction elements in the form of poles, with arrangements for supplying a tensile force to a wooden construction element, provide that at least one measuring device is provided for recording the parameters of the sound emission and the oscillatory or elongation characteristics of the building element, the acoustic emissions, oscillatory or tensile characteristics of the wooden construction element shall be recorded during the tensile force feed preparation. Measuring preparation or. measuring devices are designed as an extensiometer or oscillation sensor, in particular an ultrasonic sensor, the extensiometers can be mounted as laser extensiometers or on the basis of stretching measuring tapes.

For the purpose of determining the oscillatory characteristics, it is envisaged to include some oscillating exciter or pulse exciter of the measuring device through which the oscillation or impulse is led to a wooden building element. Based on impulse response or. Transmission characteristics of the wooden building element can be identified by defect locations and the strength of the wooden building element can be determined.

The devices for applying tensile forces to the wooden construction element are formed as two movable clamping devices against each other, which can be secured separately on the wooden construction element. At least one hydraulic cylinder is intended for these clamping arrangements for spacing clamping devices in order to be able to apply a tensile force to the wooden construction element. Alternatively, the tensile force feed devices are configured as opposing disc pairs or track pairs.

A measuring analyzer is added to the measuring device so that it can be decided immediately after the test whether defects occur, if any, in which strength class the wooden building element is placed and if or where the defects should be eliminated.

Particularly for a timed test of a wooden building element, it is contemplated that a transport device for supplying and draining the tested wooden building elements is provided, which transports the tested wooden building elements with respect to the clamping device or the disc vapor or caterpillar vapor. After positioning the tested segments of wooden building elements, the clamping device is planted on the wooden building element and a certain tensile force is applied. The test site is then investigated using a measuring device.

If specific sites of a wooden building element are to be purposefully tested, for example, some connecting point of two wooden parts, it is preferable if a sensor is provided to record the marking on the wooden building element or to record the test site coupled with the control that manages the devices for the supply of a certain tensile force, and preferably also manages the preparations for the transport of wooden building elements. The wooden construction element is then transported by the transport device until the sensor records the marking or test site. The sensor is preferably an optical recognition system that recognizes a connecting point or color marking in the passage. Based on the sensor data, the transport device is then stopped. The tensile forces are brought in and the test site is measured.

To the preparation for testing wooden building elements, some unloading preparation for wooden building elements of unsatisfactory strength was added. The preparation can be integrated into the production process of any existing as well as new plant for the production of wooden building elements, especially one-piece wedge-shaped structural solid wood.

The following is a more detailed explanation of an embodiment of the invention by means of the accompanying drawings. They show:

Figure 1- Schematic illustration of a manufacturing facility with an integrated test facility; and Figure 2 is a schematic illustration of a clocked test device.

Figure 1 shows a manufacturing device for wooden structural parts in the form of poles 20. In the raw wood depot 1, the said untreated timber is loaded and fed to the first test site 2, marked at the defect points and the untreated timber classified in a certain strength class. In the then connected sorting point 3, the inferior material is ejected, for example if it does not reach the required strength class or if the material is too dry or wet. Further processed materials are sorted by quality and brought to intermediate storage facilities 4. From these intermediate storage facilities, they are fed to a saw mill 5 in which defects are cut. These fault locations are thrown away and discharged to the waste station

13.

After the saw blade station 5, the wooden parts are fed into a jamming device 6, in which the wooden rod-shaped parts are glued to each other in a wedge-shaped antler. The jamming device 6 is a format saw 7 connected in series, which cuts the wooden construction element to the desired length. The format saw 7 is connected to the so-called solidification warehouse 8, which is designed as a continuous or continuous transitional warehouse. The wooden construction elements are retained for a certain minimum time in the curing warehouse 8 so that the adhesive in the wedge caulk can harden the construction element followed by the curing warehouse 8 after

Testing the strength of the wood in a meaningful manner at the attachment to and reaching the final hardening strength of the stuck wedges, but before finishing. To test the strength of the connection site as well as the entire wooden element or the wooden building element is brought in from the curing warehouse 8 to the test fixture 9 in which all the wooden building elements are tested. Those wooden building blocks that achieve the required strength value are brought into the unloading preparation 10 for finishing in finishing form 11, from which the wooden building elements are brought for further processing 12.

If the test on test fixture 9 shows that the wooden building element or part of the wooden building element does not meet the desired strength requirements, it shall be eliminated. With the help of the saw blade 14, the defect points are recovered and taken to the waste collector 13. The concrete strength classes corresponding to the wooden construction elements or wooden parts are then re-introduced into the appropriate intermediate storage 4 and re-processed in the jamming device 6.

As the defects found on the wooden building elements are not further evident by the break, marking of the places with defects is foreseen, for example in the form of color marking. Alternatively to the firing of defective sites, it is envisaged that the wooden building blocks may be classified in the lower strength class after the test. This is possible after the test of the wooden building element shows some lower strength than that which would be found to belong to the original strength class, but this strength satisfies the requirements of an even lower strength class. For example, an MS7 structural element is formed from a wooden building element of MS13.

The entire function path can be derived and controlled by automatic control.

In order to accelerate the manufacturing process described above and to save the curing warehouse 8 and the space required, the curing of the adhesive of the jammed croissant can be significantly accelerated by means of a fast energy supply with high frequency waves or microwaves. Using this technology, the so-called hardening tunnel is installed directly behind the jamming device 6. A test device 9 can then be connected directly to this hardening tunnel before shortening the wooden construction elements with the format saw 7.

An example of test device 9 is shown in Figure 2, in which it is a clocked test device for wooden structural members 20 in the form of poles. The wooden building element 20 moves forward in a longitudinal direction via conveyor devices 30, for example conveyors or conveyor belts, as shown by the arrows in the conveyor 30 and in the wooden construction element 20. The wooden construction element 20 is provided with contacts 21 in the form wedges are secured through two clamping devices 30. If it is now necessary to test the strength of the wooden building element or junction 21, the wooden building element 20 in the clamping device 33 is clamped, the clamping jaws 34 being guided. via the hydraulic cylinder 35 in the direction of the wooden building element 20. After the two clamping devices 33 are fixedly positioned on the wooden building element 20, one further hydraulic cylinder 31 is actuated, which opens the clamping device 33 disposed apart on the longitudinal guide 32. In this way, a tensile force is applied to the wooden building element 20. During the feeding of this tensile force, the binding site 21 is measured by means of a measuring device 40. The measuring device 40 may record the sound-transmission characteristics of the wooden building element 20 or the sound emission. Audio-transmission characteristics are found to be a oscillatory response to the introduction of pulses or low-frequency ultrasonic waves of high energy content. Such impulses or ultrasonic waves are introduced by means of the excitation head not shown here.

Alternatively, the locations of defects or disturbances within the wooden building element 20 can be measured without touch or by touch using an extensiometer. Touchless measurement is performed using a laser extensiometer, touch measurement using cutting in the technique of stretching measuring tapes. In this case, when applying a tensile force significantly below the assumed strength class, eg less than 70% of the characteristic strength, the nonlinear elongation within the tested sector of the wooden building element is measured. 20. If there are any errors or disturbances in the wooden building element, non - linear extensions may occur in the tensile action. forces recorded by the measuring device 40.

Audible emissions, oscillatory responses or non-linear extensions may be transmitted as sensor data of an analyzer (evaluation unit) 41 to determine if and to what extent the fault sites are present or if the strength class of the wooden building element 20 must be otherwise classified .

As a rule, only the special segments of the wooden building element 20, such as e.g. jammed croissants or selected places in the woodwork. In order to obtain an accurate positioning of the test site between the clamping devices 33, a sensor 42 is provided which, by means of image evaluation, recognizes the wedge-shaped hinged ties 21 or the color marking 50 applied to the wooden building element 20. The positioning of the investigated segment between the clamping devices 33 is then carried out by controlling the transport device 30 depending on the sensor signal of the sensor 42.

Alternatively to the design of the clamping devices 33 with the clamping jaws 34 and the hydraulic cylinder 35, it is provided that the wooden building element 20 is transported discontinuously through two mutually tensioned stable pairs of wheels or tracks and after positioning the measuring segment of the wooden building element between pairs of wheels or a pair of track chains, by introducing some opposite driving torque through both pairs of reels or track pairs, introduces a defined tensile load on the wooden building element. In this way, the sectors of the wooden building element are measured one by one. Measuring apparatus 40 or measuring devices shall be positioned in a meaningful way between pairs of reels or pairs of tracks. The wooden building element 20 can be clocked one by one between pairs of reels or tracks of tracks, which are added to each other in an opposite manner to the wooden building element 20 so that the entire wooden building element 20 is controlled by sector. Alternatively, only special segments of the wooden building element 20, for example, tie-downs 21, are controlled.

The test device 20 may be integrated into the production process of any existing or new plant for one-piece wedged solid wood or for multi-piece wedged solid wood. Jam wedges can be tightened immediately after the press of the jam bar 6 with an increased energy supply and then fed directly to the test fixture 9.

Instead of a clocked test, a continuous test of the wooden building element 20 can be performed, with two transport devices with different drive speeds provided in the transport direction one after the other, with the transport device at the rear having a higher transport speed than the transport device in front. This applies a tensile force to that segment of the wooden construction element that lies between the two transport devices. Appropriate measuring devices, oscillator or pulse encoder are installed between the transport devices and affect the wooden construction element 20 or. are assigned to a wooden building element

20.

Claims (27)

Patent claims A method for the non-destructive testing of wooden building elements, in particular wedge-shaped croissant ties in structural solid wood, characterized in that the wooden building element is subjected to a defined tensile force below the characteristic strength and at the same time measurements of sound emissions and / or oscillation parameters are made. or tensile characteristics in the area of tensile loading or the oscillatory characteristics of a wooden building element. Method according to claim 1, characterized in that the wooden construction part is clamped in the clamping device and the clamping devices move away from each other. Method according to claim 2, characterized in that the clamping devices are separated apart by hydraulic pressure. A method according to claim 1, characterized in that the wooden construction element is loaded with two opposing running torques for supplying tensile force. Method according to one of the preceding claims, characterized in that the measurement is clocked. Method according to claim 1, characterized in that the wooden construction element is transported in the engaged state between two transport devices at different speeds and at least one measuring device during the transport preparations records the parameters. Method according to one of the preceding claims, characterized in that a local expansion measurement is performed at the measuring point. Method according to claim 7, characterized in that the expansion measurement is performed with a laser extensiometer or with a device with an expansion measuring tape. Method according to one of the preceding claims, characterized in that acoustic emission is measured at the measuring point. Method according to one of the preceding claims, characterized in that the oscillating excitation of the wooden building element is carried out and the oscillatory characteristics are measured with the sensor. A method according to claim 9, characterized in that the wooden building element is excited by ultrasound or a single pulse. Method according to one of the preceding claims, characterized in that less than 70% of the characteristic strength is applied as a tensile force. Method according to one of the preceding claims, characterized in that the measurement is carried out at the junction point of two wooden building elements. Method according to one of the preceding claims, characterized in that the controlled sites of the wooden building element are marked, that the wooden construction part is transported through the test device and through one sensor, which detects the test site and positions the measuring devices depending on the sensor data. in the area of the test site. Method according to one of the preceding claims, characterized in that the identified error sites are marked and these error sites are eliminated. Method according to one of Claims 1 to 14, characterized in that the strength of the wooden building element is determined and the wooden building element is classified in a particular strength class and marked accordingly. 17. Apparatus for checking the strength of wooden building elements, in particular wooden building elements in the form of poles, with arrangements for applying a certain tensile force to a wooden building element, characterized in that at least one measuring device (40) is provided for recording parameters regarding sound emissions as well as the oscillatory or tensile characteristics of the wooden building element (20) during preparation (33). Apparatus according to claim 17, characterized in that the measuring device (40) is formed as an extensiometer or a swing sensor. Apparatus according to claim 17, characterized in that the extensiometer is designed as a laser extensiometer or on the basis of stretchable measuring tapes. Apparatus according to one of Claims 17 to 19, characterized in that a measuring oscillator (40) is provided with a single oscillator or pulse exciter to excite the wooden building element (20). Apparatus according to one of Claims 17 to 20, characterized in that the tensile force feeders (33) are formed on two wooden movable clamping devices which are fixedly fixed on the wooden construction element (20). . Apparatus according to claim 21, characterized in that a hydraulic cylinder (31) is assigned to the clamping devices (33) to move the clamping devices (33). Apparatus according to one of Claims 17 to 20, characterized in that the traction feed devices are formed as discs or track chains. Apparatus according to one of claims 17 to 23, characterized in that an analyzer (41) is added for measuring results of the measuring device (40). Apparatus according to one of Claims 17 to 24, characterized by a transport device (30) for the conveyance and removal of the tested wooden building elements (20). Apparatus according to one of Claims 17 to 25, characterized in that a sensor (42) is provided for recording markings on a wooden building element (20) or a test site coupled to a control device which controls the feeders (33). tensile force supply. Apparatus according to one of claims 17 to 26, characterized in that the unloading device (14) of the device (9) for wooden building elements (20) of insufficient strength is further included.