RU2369832C1 - Method of integrated assessment of lumber width and non-straightness of its edges - Google Patents

Abstract

FIELD: woodworking industry.

SUBSTANCE: invention relates to wood working industry and can be used for the integrated assessment of the lumber width and non-straightness of its edges (bouge). The essence of the invention: method is implemented with the help of a closed dimension chain including measuring the board width in the control points by a vernier caliper and the non-straightness of its edges by a depth gage. The straightline bases are made at a certain distance from each other by plane-parallel bars which are laid and fixed at the rigid basement parallel to the stretched strings. The lumber piece being tested is laid along one of the bars with its concave edge resting on the bar. The deflection from the base is measured by contact basing of the depth gage jaw on the straightline bars and of the main scale tip - on the control points of the surface being tested. The bouges are evaluated by the comparison of the measured edge deflections from the respective straightline bases to the distances from them to the base points on the edges.

EFFECT: improvement of the measurement accuracy and reliability, simplification and facilitation of the measurement procedure, providing for the integrated assessment and suitability of the method for wide use.

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Description

The invention relates to the woodworking industry and can be used to assess the width and deviations from the straightness of the longitudinal edges of lumber (PM) up to 6 meters or more.

There is a standard method for measuring the width and deviations from the straightness of lumber (GOST 10294-90) using a caliper, a special calibration ruler 2200 mm long and probes: the ruler is alternately superimposed on the face and on the longitudinal edge of the boards, deviations are measured with a probe.

The disadvantages of the method are the complexity and duration of measuring deviations from the straightness of the lumber using probes and a heavy ruler, the limited length of the measurement, the high cost of the calibration ruler and its periodic verification, the lack of estimates of measurement errors.

There is also a method of creating a straight-line base using a tightly stretched string, widely used in construction, carpentry and installation.

The disadvantages of this method are the visual assessment of deviations from straightness, low stringency, making it difficult to base the measuring tool on it and the lack of estimates of measurement errors.

There is also a general method for detecting measurement errors by creating closed measurement circuits, requiring refinement in each case.

The task of the invention is to remedy these shortcomings.

The solution to the problem is achieved by creating a closed dimensional chain of two rectilinear bases in the form of plane-parallel rails laid along tightly stretched strings at a certain distance from the timber being checked, measuring its width with a caliper and the deviations of its edges from the bases using a depth gauge (drawing).

A plane-parallel rail 2 is applied and fixed to the rectilinear base — the string 1, stretched on a landing site (drawing), and fixed (solid or composite); the test sample 3 is laid on it. From the outer edge of the rail 2, a second straight base is pulled at a certain distance B, the string 5, and rail 4 is laid along it (parallel to rail 2) and also fixed.

A closed dimensional chain is formed by: the distance B between the base edges of the rails, the distance y _ni from the bottom edge of the board to the edge of the first rack 2; the distance y _bi from the top edge of the board to the edge of the second rail 5 and the width of the board b _i in i section.

where B is the distance between the base edges of the rails, mm;

y _нi is the distance from the lower edge of the board to the edge of the first rail, mm;

b _i - board width in i section, mm;

y _вi is the distance from the top edge of the board to the edge of the second rail, mm.

In this case, the arrows of the deflection a _нi and a _Bj will be calculated by the formulas

where a _ni is the arrow of deflection at the lower edge in the i section, mm;

_Bi = y a -y _{BL Bi;}

where a _bi is the arrow of deflection at the upper edge in the i section, mm;

In _pH - the width of the lower rail (the distance of the reference points of the lower edge of the board from the rectilinear base), mm;

y _B1 is the distance to the reference points of the upper edge.

The estimated width of the board, mm, is calculated by the formula

Total error Δb _i four dimensions (B, y _n, y _Bi, b _i) in each control section is calculated by comparing the calculated width of the plank b _pi, the measured B:

where Δb _i - total error of four dimensions (B, y _n, y _Bi, b _i) in each control section, mm.

по всем контрольным точкам, можно определить среднюю квадратическую ошибку трех измерений СКО₃:Summing the squared deviations

for all control points, it is possible to determine the root-mean-square error of three measurements of RMSE ₃ :

where RMS ₃ is the mean square error of three dimensions,

n is the number of control sections.

And comparing the average values of the calculated b _p and the measured width b _i , we can estimate the value of the systematic (for all four measurements) error Δ _{s with} :

where Δз _с is the value of the systematic (for all four measurements) errors, mm.

Technical result

1. Reliable basing of the rod and depth gauge pads is ensured, which increases the reliability and accuracy of measurements.

2. The measurement procedure is simplified and accelerated.

3. A comprehensive assessment of the deflection arrows of both longitudinal edges, the width of the board and the measurement errors both at each control point and on average for all measurements is provided.

4. The suitability of the method for mass measurements is ensured both for operational control in production and for scientific research.

Claims (1)

A method for comprehensively evaluating the width of lumber and deviations from the straightness of its longitudinal edges, including creating a closed dimensional chain by measuring the width of the board and deviations of its edges from the straight base at the control points of the surface being tested, characterized in that the straight line is created using two rows of plane-parallel rails laid at a certain distance parallel to each other along tightly stretched strings and fixed on a rigid base, and the checked lumber is located between them with a support on one of the rails of the concave edge; deviations of the tested surfaces from straight-line bases are measured by contacting the depth gauge pads on plane-parallel rails, and the rod measuring tip on the control points of the tested surfaces; deflection estimated by comparing the measured deviations edges by respective rectilinear bases from their distance from reference points on the edges, the difference between the calculated and the measured width of the board to evaluate the total error of all four measurements (V, y _HI, y _Bi b _i), in each control section, and the average over all sections,
where B is the distance between the base edges of the rails, mm;
y _нi is the distance from the lower edge of the board to the edge of the first rail, mm;
b _i - board width in i section, mm;
y _вi is the distance from the top edge of the board to the edge of the second rail, mm.