RU2315970C1 - Method and device to determine strength of article produced of deformable material - Google Patents

Abstract

FIELD: control equipment.

SUBSTANCE: method involves lifting load for predetermined height; providing free load falling on rod; driving rod in material for predetermined depth by applying serial impacts thereto; measuring depth of rod immersion in material with the use of indicator at each load falling stage and rotating indenter in depression before each impact application. Device comprises free-falling load and rod. Indenter is secured to rod installed in body so that the rod may slide with respect to the body. Mechanical pointer indicator is connected to the body so that measuring pin thereof rests upon holder secured to the rod. Handle is connected to the rod.

EFFECT: increased article strength measurement accuracy.

3 cl, 2 dwg

Description

FIELD OF THE INVENTION

The invention relates to instrumentation, in particular to devices for determining the strength characteristics of building materials by non-destructive method, and is intended for use in construction, the production of building materials, as well as in research work.

State of the art

A known method for determining the strength of non-metallic materials, including the operation of crushing presses of samples of cubic or prismatic forms. The temporary stress σ _in , corresponding to the greatest force during compression of the sample, is determined by the formula

where P _max is the maximum compression force of the sample; A is the cross-sectional area of the sample (Resistance of materials. Laboratory workshop. A.S. Volmir, Yu.P. Grigoriev, etc. M .: Drofa, 2004. 352 p.).

The disadvantage of this test method is the destruction of the test samples and, therefore, the high cost of testing.

Closest to the proposed method is a method for dynamically determining the strength of soil and products made of building materials, including the operation of lifting the shock to a predetermined height, the operation of the free fall of the load, the operation of immersing the rod into the material with successive strokes to a given depth (Earthmoving Machines. A .N. Zelenin et al. M .: Engineering, 1975. 422 p.).

The considered method has an imperfect system for measuring rod movements during shock immersion and an imperfect design in which the diameter of the rod and the length of the immersed part of the rod are fixed, which lead to the fact that when testing durable products (roads, compacted bases), dozens are required to be performed hits of falling cargo on the rod. In addition, the accuracy of determining the strength of products is significantly affected by the friction of the side surface of the immersed part of the rod on the ground.

Disclosure of invention

The objective of the invention is to increase the accuracy of determining the strength of products by eliminating friction on the side surface of the rod, as well as expanding the functionality of the device by supplying the rod with replaceable indenters.

The problem is solved in that in the method for determining the strength of products from deformable building materials, including the operation of lifting the load to a predetermined height, the operation of the free fall of the load on the rod, the operation of immersing the rod in the material by successive strokes to a given depth, the operation of measuring the value of immersion of the rod in the material, according to the claimed invention, the operation of measuring the value of the immersion of the rod in the material is performed according to the indicator for each impact of the falling load and, additionally, before each subsequent stroke, the operation of turning the indenter in the hole is taken.

The technical result, namely improving the accuracy of determining the strength of products, is achieved by the fact that before each subsequent impact on the rod, the indenter is rotated in the well of the test material, thereby eliminating the friction forces of the side surface of the immersed part of the rod on the material.

The problem is also solved by the fact that in the device for determining the strength of products from deformable building materials containing a falling load and a rod, according to the claimed invention, an indenter is fixed on a rod installed in the housing with relative movement, a mechanical dial indicator, a measuring leg are fixed on the housing which abuts against a bracket fixed to the rod, while a handle is attached to the rod.

Comparison of the invention with the prototype found in the first of them a number of distinctive features, which determines the compliance of the invention with the criterion of "novelty."

Brief Description of the Drawings

The essence of the method and device is illustrated by drawings, which depict:

figure 1 - a device for determining the strength of products, a longitudinal section;

figure 2 is a device for determining the strength of products, front view.

The implementation of the invention

The inventive method for determining the strength of products from deformable building materials can be carried out using the inventive device.

A device for determining the strength of products contains a load 1 that is installed with the possibility of movement relative to the rod 2 between the stops 3, 4. The rod 2 is installed in the housing 5 with the possibility of relative vertical movement and rotation. At the end of the rod 2, a holder 6 is fixed, in which an indenter 7 is installed, made in the form of a cylindrical rod. A clamp 8 is fixed on the housing 5, in which a mechanical dial indicator 9 is fixed, the measuring leg of which abuts against the bracket 10 mounted on the rod 2. A handle 11 is attached to the holder 6 with the possibility of vertical movement and rotation relative to the housing 5 together with the rod 2.

The essence of the method for determining the strength of products is as follows. To measure the strength of the test product, the operation of lifting the load to a given height is performed, the operation of the free fall of the load on the rod, the indicator determines the value of the immersion of the rod in the material at each impact.

To obtain accurate statistics, the immersion operation of the rod is repeated as many times as necessary. Moreover, before each subsequent impact, the rod with the indenter in the formed material hole is rotated to eliminate friction forces on the lateral surface of the cylindrical indenter 7.

The found value of the immersion of the rod in the material assesses the strength of the products.

The average normal voltage under the plane of the indenter 7 is determined by the formula:

where d is the diameter of the indenter;

m ₁ , m ₂ - respectively, the mass of the falling load 1 and the rod 2;

H - drop height 1;

z _k is the indenter penetration into the material in one stroke.

A device that implements the method operates as follows. Consider the operation of the device on the example of determining the strength of raw bricks, pressed from clay powder. The device is mounted on the product so that the indenter 7 rests freely on the surface of the test product. Indicator 9 is configured to receive the movement of the rod upon impact of the order of several millimeters. Raise the load 1 to the height specified by the upper stop 4 on the rod 2. Release the load 1 to make a free fall and strike on the lower stop 3 of the rod 2, as a result of which the indenter 7 is buried by the value of z _k in the test product.

The value of the immersion of the rod is determined by indicator 9. The system for measuring the value of immersion of the rod is made in such a way that when it hits the rod, the indicator mechanism operates in the mode of free tracking of deformation, without responding to the impact of the falling load. To obtain a statistical result, make several consecutive strokes in one hole of the product. Moreover, before each subsequent impact, the rod 2 with the indenter 7 is turned by a handle 11 at a certain angle.

By replacing the indenter 7 and changing the mass of the load 1 extend the range of measurement of the strength of the products.

The use of the invention allows to significantly improve the accuracy of measurements. The design of the device is easy to manufacture and use. In addition, the device is equipped with a set of interchangeable indenters to expand its functionality.

Claims (2)

1. The method of determining the strength of products from deformable building materials, including the operation of lifting the load to a predetermined height, the operation of the free fall of the load on the rod, the operation of immersing the rod in the material by successive strokes to the specified depth, the operation of measuring the value of the immersion of the rod in the material, characterized in that the operation measuring the immersion of the rod in the material is carried out according to the indicator for each impact of the falling load and additionally perform the operation before each subsequent impact. ota indenter into the hole. 2. A device for determining the strength of products from deformable building materials, containing a falling load and a rod, characterized in that an indenter is fixed on a rod mounted in the housing with the possibility of relative movement, a mechanical dial indicator is fixed on the housing, the measuring leg of which rests on the fixed the rod bracket, while the handle is attached to the rod.

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