RU2115351C1 - Vibration-proof mitten - Google Patents

Abstract

FIELD: light and wood-working industry, in particular, protective overalls for workers operating with gasoline-engine saw. SUBSTANCE: vibration-proof mitten has enclosure defined by palm part and rear part, thumb finger stall, inner liner and vibration-proof insert manufactured from polyurethane foam. Insert is shaped in accordance with palm part of enclosure and finger stall and made as integral construction and is provided with spherical gas cells of different diameter isolated one from another and nonuniformly distributed across insert thickness. Thickness of insert is 0.025-0,050 of palm part length. Outer surface of insert is provided with open gas cells. EFFECT: increased efficiency in protecting operator's hand from vibration at wide frequency range and high loads. 4 dwg

Description

 The invention relates to personal protective equipment for hands from vibration generated by vibro hazardous equipment and hand tools, and can mainly be used in the forestry and woodworking industries when the operator is working with gasoline-powered saws.

 A gasoline-powered saw is a powerful source of dynamic loads, which, depending on the operating mode, are fully or partially perceived by the operator. In this regard, one of the most important tasks when creating a vibration-proof gauntlet is to minimize the level of vibration in the palm of the hand, which perceives the main influx of vibrational energy when the operator is working with the saw.

 The complexity of solving this problem lies in the fact that, depending on the operating mode (idling on the bucking, bucking, felling), the operator’s hands are affected by vibration loads in a wide frequency range of 30-1000 Hz.

 In the countries of Scandinavia (Finland, Sweden, Norway), where the forestry and woodworking industries are most developed, protective gloves are widely used by operators when working with gasoline-powered saws.

 Known protective gloves are made of durable and soft calf skin and have a shape that prevents the formation of wrinkles (wrinkles) on the palm surface, are designed to protect against injury and are convenient when grabbing a chainsaw. The saw guard is located on the back of the left gauntlet. As follows from the design description of the mitten, they are not intended to protect the operator’s hands from vibration, but protect them only from mechanical damage.

 Known vibration protective gloves related to personal protective equipment against vibration caused by vibration-hazardous tools, in particular chipping hammers (see application of the USSR auth. St. 901646, class A 41 D 13/08, 1982). In this design, the gloves are vibration-proof liner made in the form of a series of parallel horizontal tubes filled with air.

 The main disadvantages of this design of the mitten are: the complexity of the design of the inflatable vibration-proof liner from mechanical damage, the limited range of application of the mitten at the operating vibration frequencies.

 MV anti-vibration gloves (GOST 12.4.010-75, TO 78-349-75), widely used in industry for protecting the operator’s hands when working with pneumatic chisels, rammers, jack hammers, drills and other types of hand tools, are also interesting (see book "Personal protective equipment for workers in production", "Directory-directory" -M .: Profizdat, 1988, p. 97.).

 They are made from cotton fabrics. The incense part of the mittens is reinforced with a textin pad and a foam cushioning pad. The use of foam rubber as a vibration-proof insert allows to significantly simplify the design of mittens and make them more reliable in operation. Foam is a polyurethane foam with open, interconnected gas cells (pores).

 Vibration damping is carried out in the insert itself due to internal friction in the polymer base (matrix) of the visco-resistant material of the foam insert. Since the bulk of the liner is occupied by interconnected gas cells (pores), the polymer base itself (its mass) is not enough to effectively damp the vibration. As noted in the book by M. Brainina, L. P. Klimova and others. “Personal protective equipment for hands” (M.: Profizdat, 1990, p. 22), anti-vibration gloves produced by the industry (GOST 12.4.010-75, TO 78-349-75) with foam padding are ineffective. Effective damping of vibration by such mittens is carried out only at a strictly defined resonant frequency of the liner, determined by the physical and mechanical characteristics of the foam matrix.

 Also known vibration-proof mitten [1], adopted by the authors for the prototype.

 It contains a housing, a vibration-proof liner, napalka on the thumb and forefinger, an inner gasket.

 The vibroprotective liner is made of polyurethane foam 0.05-0.1 thick from the width of the palm part of the mitten body and has spherical gas cells of different diameters, isolated from each other, spaced apart from one another, the total volume of which is 0.4-0.6 of the total the volume of the liner, while the vibration-proof liner is made in the form of patterns of the palm of the body and napalka on the thumb and forefinger in the form of an integral structure.

 The vibration damping is carried out in the liner itself due to internal friction in the polymer base (matrix) of the visco-resistant material of the liner and due to the work of deformation of the shells of the internal gas cells under the influence of vibration load. Thus, in this design of the mitt, two mechanisms of dispersion of vibrational energy supplied to the control handles of the saw are combined. Gas cells isolated from each other that are unevenly distributed over the thickness of the liner have different diameters that determine their different corresponding resonant frequencies. As a result of this, an effective reduction in the level of vibration in the mitt is provided over a wide frequency range.

The main disadvantage of this design of the gauntlet is that its effectiveness substantially depends on the internal structure of the liner material, namely the ratio of the total volume of gas cells V _g to the total volume of the liner V _in , in accordance with the invention, the total volume of gas cells in the liner of this gauge must be strictly 0.4-0.6 of the total volume of the liner.

When the total volume of gas V _g cells less than 0.4 V from the total volume of the liner _{in the} slump properties of the vibration-absorbing gloves since small amount of gas cells leads to a reduction in the diffusion of the vibrational energy through the work of deformation of the shells from the effects of vibration loads. In this case, vibration absorption is carried out only due to internal friction in the polymer base (matrix) of the visco-resistant material of the liner. With a total volume of gas cells of more than 0.6 of the total volume of the liner of the handle, the viscoelastic properties of the polymer base (matrix) of the handle significantly deteriorate. The decrease in the viscous properties of the matrix of the polymer material of the handle is associated with a general decrease in its mass at V _g 0.6 V _in , resulting in a decrease in the amount of dispersion of vibrational energy due to internal friction in the matrix of the polymer material of the liner.

 It is extremely difficult to achieve a strict ratio of the volume of gas cells and the matrix of the polyurethane foam insert in practice. Each time when pouring vibration-insulating liners, it is required to produce an advanced sample and examine it for gas filling. This significantly complicates the technology of manufacturing the gloves, which is unacceptable in the conditions of their mass production.

 In addition, this well-known mitten does not provide effective damping of the vibration in a wide frequency range at high loads.

 The objective of the invention is the creation of a vibration-proof gauntlet that provides the most effective protection for the operator’s hands from vibration in a wide frequency range (30-1000 Hz) at high loads (pressing force on the control handle of tools up to 150 m).

 This problem has been solved due to the fact that in the vibration-proof mitten, which includes the case in the form of the back and palm parts, the thumbs, the inner lining and the vibration-proof polyurethane foam insert located between the case and the inner lining on the palm side, made in the form of the palm pattern parts of the body and the thumb finger in the form of an integral structure and having gas cells of a spherical shape of different diameters unevenly distributed across the thickness from each other, ene thickness of 0,025-0,050 on the length of the palm portion of the housing and has on the outer surfaces of the open gas cells.

 In FIG. 1 shows a general view of the mitten; in FIG. 2 is a section AA in FIG. one; in FIG. 3 - general view of the liner; in FIG. 4 - section AA in FIG. 3.

 The vibration-protective mitten includes a housing 1 in the form of the back and palm parts, a vibration-proof liner 2 made of polyurethane foam, napalok 3 on the thumb and the inner lining 4.

 The liner 2 is located between the housing 1 and the inner lining 4 on the palm side, made in the form of a pattern of the palm of the housing 1 and napal 3 on the thumb in the form of a solid structure and has unevenly distributed across the thickness, isolated from each other gas cells 5 of spherical shape different diameters. The liner is made of thickness = 0.025 - 0.050 of the length of the palm of the body and has open gas cells 6 on the outer surfaces.

 When sawing, the main flow of vibrational energy comes from the saw apparatus of the chainsaw and is transmitted through the support frame to the control handles.

 The work of the gauntlet is as follows.

 During operation, the operator in the gloves takes on the handle of the chainsaw with a certain force (up to 150N) to hold and control the chainsaw, as a result of which the deformation of the sleeve insert occurs.

 The vibration damping is carried out in the liner itself due to internal friction in the polymer base (matrix) of the visco-resistant material of the liner and due to the work of deformation of the shells of the internal gas cells under the influence of vibration load. Gas cells isolated from each other that are unevenly distributed over the thickness of the liner have different diameters that determine their different corresponding resonant frequencies. As a result of this, an effective reduction in the level of vibration in the mitt is provided over a wide frequency range. Thus, as in the prototype, in the proposed design of the gauntlet, these two types of mechanisms for dispersing vibrational energy are preserved, but two more mechanisms for combating vibration are added.

 In the presence of open gas cells on the outer (to the control handle of the vibration tool) and inner (to the palm of the operator) surfaces of the liner from the influence of vibration of the tool N-waves are formed, well known in the theory of aeroelasticity (see, for example, the book by G. Fershing "Fundamentals of Aeroelasticity - M .: Engineering. 1984).

 Based on numerous experimental data (sawing on a stand in idle mode, bucking and felling with measuring vibration levels on the palms of the operator’s hands), it was found that with a liner thickness equal to 0.025-0.05 of the length of the palm of the N-wave case on the outside and the inner surfaces of the liner are in antiphase and mutually absorb each other. Exit the thickness of the liner beyond the stated ratios leads to a phase shift of N-waves on the surfaces of the liner and it becomes a good conductor of vibrational energy from the control handle of the vibration tool.

 The presence of open gas cells on the surfaces of the liner additionally provides vibration isolation between the operator’s hand and the vibration tool control handle.

Thus, in the proposed design of the mitten, four mechanisms of dispersion of vibrational energy are combined:
- due to internal friction in the polymer base of the liner;
- due to the adiabatic compressibility of the inner gas cells of the liner;
- due to the anti-resonance effect of vibrational movements of the inner and outer surfaces of the liner (N-wave);
- due to vibration isolation of the liner from the control handle of the vibration tool.

 At present, bench and field tests of the proposed vibration-proof mittings have been carried out. Three times vibration damping (up to 10 dB) was achieved on mittens in octave bands of working frequencies 31; 5; 63; 125; 250; 500; 1000 Hz.

Claims (1)

 A vibration-proof mitten, which includes a body in the form of the back and palms, finger thumbs, an inner lining, and a vibration-proof polyurethane foam liner located between the body and the inner lining on the palm side, made in the form of a pattern of the palm of the body and a thumb finger in the form integral design and having non-uniformly distributed over the thickness, isolated from each other gas cells of spherical shape of different diameters, characterized in that the liner is made with a thickness of 0.025 - 0.050 t volar length of the housing and has on the outer surfaces of the open gas cells.

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