US3793953A

US3793953A - Blasting mat

Info

Publication number: US3793953A
Application number: US00256264A
Authority: US
Inventors: D Lewis
Original assignee: SUDBURY BLASTING MATS Ltd
Current assignee: SUDBURY BLASTING MATS Ltd
Priority date: 1971-08-31
Filing date: 1972-05-24
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26
Also published as: CA933413A

Abstract

A blasting mat formed of a plurality of plates of resilient material arranged on edge in side-by-side relationship in contiguous rows with the rows interconnected and with the plates in each row spaced apart; flexible means is threaded through the spaced plates and the spaced plates are secured on the flexible means so that there is sufficient movement of the plate edges when the mat is flexed to reduce the spaces between the plates at the area of flexure of the mat.

Description

United States Patent 1191 Lewis Feb. 26, 1974 [54] BLASTING MAT FOREIGN PATENTS OR APPLICATIONS Inventorl Douglas Lewis, Sudbury, Ontario, 57,918 4 1937 Norway .7 102 22 Canada 120,935 2/1948 Sweden 102/22 73 Assi nee: Sudbur Blastin Mats Limited 1 g ontarii, Canada Primary ExaminerVerlin R. Pendegrass Attorney, Agent, or FirmCushman, Darby & [22] Filed: May 24, 1972 Cushman [21] Appl. No.: 256,264

[57] ABSTRACT [30] Foreign Application Priority Data A blasting mat formed of a plurality of plates of resil Aug. 31, 1971 Canada 121814 ient material arranged edge in side'by'side relation ship in contiguous rows with the rows interconnected [52 US. Cl. 102/22 and with the Plate5 in eeeh few SPeeed apart; flexible 51 Im. 01. F42d 5/00 means is threaded through the Spaced Plates and the [58] Field of Search 102/22 Spaced Plates are Secured the flexible means so that there is sufficient movement of the plate edges when [56] References Cited the mat is flexed to reduce the spaces between the plates at the area of flexure of the mat.

8 Claims, 6 Drawing Figures PATENTEUFEB26 I974 BLASTING MAT This invention relates to blasting mats for use in covering a site at which an explosive charge has been laid and to a method of constructing a blasting mat.

BACKGROUND OF THE INVENTION Blasting mats have developed over the years from crude constructions using wooden blocks or heavy girders to mats employing portions of old automobile tires or resilient tubes which are laced together to provide an interleaved reinforced resilient structure.

Blasting mats utilizing portions of automobile tires are commonly constructed by first cutting the automobile tire into segments and then interleaving the segments and with some form of wire rope or binding passed through the interleaved sections in a torturous path to tie the sections together. The wire rope usually is threaded through holes in the side wall portions of the tire segments, and to provide a sufficient depth of material, a number of layers must be used. This results in a mat which tends to be more or less air-tight and while it will act to contain rock or other material dislodged by an explosion, pressure exerted against the mat by the explosive blast has been found to cause premature destruction of the mat in that portions of the mat are blown out and cables in the mat are broken.

A number of attempts have been made to solve the above-noted problem of blast destruction of a mat and in some instances, a mat has been formed of resilient tubes bound loosely together to provide an air passage between the tubes. While a mat constructed in this fashion will permit the passage of blast air through the mat, it has been found the loose construction of the mat will at the same time permit passage of small particles of rock or other materials through the same air passages and thereby result in danger to persons or equipment in the immediate blast area.

Mats of the type described and others using various forms of resilient material usually are so arranged that the explosive force and material dislodged by the explosion will be directed against the thinnest dimension of the material segments. It has been found that such mats are readily damaged by the explosive blast and by debris being blown through the thin dimension of the material and, as a result, such mats usually will only withstand one or two heavy blasting effects before they become damaged and will require repair or replacement.

A further disadvantage in prior art blasting mats stems from the use of cables that are extended throughout the mat in a continuous torturous length. In such mats, a cable broken at any point in its length usually results in the necessity to restring the entire mat before it may once again be used.

SUMMARY OF THE INVENTION The present invention is designed to overcome the above and other disadvantages inherent in prior art blasting mats and to provide a mat constructed of a plurality of interleaved rectangular plates of resilient material arranged on edge in side-by-side spaced relationship in contiguous rows and strung together to secure the spaced plates in position in the mat while at the same time allowing movement of the edges of the plates when the mat is flexed to reduce the spacing between the plates.

BRIEF DESCRIPTION OF THE DRAWINGS connection of the cable ends;

FIG. 3 is a perspective plan view of a typical plate for use in a mat;

FIG. 4 is a perspective plan view showing a typical spacer as used in a mat;

FIG. 5 is a broken away perspective view showing the mat in the flexed position;

FIG. 6 is a diagrammatic view illustrating the action of the mat during blasting operations.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference now to the drawings, and particularly to FIGS 3 and 4, the mat includes a plurality of rectangular plates of resilient material one of which is designated generally at 1, and a plurality of spacers, one of which is designated generally at 2. The plates 1 and 2 preferably are of the same resilient material which may be segments of surplus conveyor belting of reinforced resilient material. In the alternative, reinforced rubber or neoprene of suitable strength and thickness may be used. While the size of the plates 1 and spacers 2 may be of any convenient size, it has been found that plates of 30 inches X 7 inches, or in other words, of substantially greater length than width, and in an edge thickness of approximately /2 inch, or again, of substantially greater width than edge thickness, are suitable. The spacers 2 of the same material preferably are constructed in a dimension of 7 inches X 7 inches. The plates 1 are provided with suitable openings 3 adjacent each end of the plate, while a suitable opening 4 is located in the centre of the spacer 2. Again, while the spacing of the openings 33 in the plate 1 is not critical, it has been found preferably to space the openings 22 inches apart in the preferred embodiment.

The plates 1 and spacers 2 are assembled to form a mat as best illustrated in FIGS. 1 and 2 in the drawings. The plates 1 are arranged on edge, in side-by-side relationship in a plurality of contiguous rows, designated generally at R in FIG. 2 in the drawings. The meeting ends of the plates 1 in the contiguous rows are interleaved as indicated at 5 in the drawings to space the plates 1 apart in each row as indicated at S and the spacers 2 are positioned between the plates 1 at the non-meeting ends to maintain the spacing S of the plates.

The interleaved plates 1 with spacers 2 are threaded onto suitable resilient cable or chain means 7 extending through the openings 3 and 4 in the interleaved plates and spacers. A metal end plate 6 is provided at each end of a completed mat and the cables or chains 7 are locked in position with suitable clamps C which bear against the metal plates 6 at each end of the mat. The ends of the cables 7 are then joined together as indicated at 8 and connected to a suitable clevis or other connecting means 9.

A blasting mat in accordance with the preferred embodiment described and illustrated is assembled by stringing sufficient plates 1 and spacers 2 on cable means 7 to form a mat of the length and width desired. For example, ifa mat 10 feet X 20 feet were to be constructed utilizing plates of a dimension of 30 inches X 7 inches and spacers of a dimension of 7 inches X 7 inches and of belting of approximately /2 inch thickness, the stringing of the spacers and plates on the table means would result in air openings or spaces between the plates of approximately inches inch. It has been found in a mat of this size, spaces or air openings of this approximate dimension are sufficient to permit blast air to escape when the mat is in use and to thereby avoid premature destruction of the mat by the air blast.

The plates and spacers are secured in position by stringing end plates 6 at the ends of the completed mat and with the cable means 7 locked by the application of clamps on the outside of the metal plate 6. It is important to note the clamps C are secured on the cables 7 to bear against the end plates 6 and to secure the assembled plates and spacers under sufficient tension to hold the mat in assembled form and at the same time, to allow flexing of the mat as illustrated in FIGS. 5 and 6 of the drawings. It should also be noted the plates and spacers are sufficiently loose to permit the edges of the plates 1 to move together, as seen at 12 in FIG. 5, when the mat is flexed to thereby reduce the spacing between the plates when the mat is flexed and to prevent the passage of loose particles of rock or other material dislodged by the explosion.

ln operation, the mat is assembled as illustrated and described and, after an explosive charge has been laid, the mat is lifted and placed in position over the charge. When the explosive charge is released, there will be an initial blast of air which will be permitted to escape through the spaces in the mat and, at the same time, will raise the mat as indicated in FIGS. 5 and 6 to place the mat under flexion. This will close off the spaces between the plates 1 of the mat so that the rock or other material dislodged by the blast and which follows the blast of air will be contained by the mat and will not be permitted to pass through the mat.

I claim:

1. A blasting mat comprisng a plurality of rectangular plates of resilient material arranged on edge in side-byside relationship in contiguous rows with the rows interconnected and with the plates in each row spaced apart; flexible means threaded through the spaced plates in each row and means for securing the spaced plates on the flexible means whereby there is allowed sufficient movement of the plate edges as the mat is flexed to reduce the spaces between the plates at the area of flexure of the mat.

2. The blasting mat as claimed in claim 1 wherein the meeting ends of the plates in each row are interleaved so as to space the plates apart in each row and there is provided spacers to space apart the nonmeeting ends of the plates.

3. The blasting mat as claimed in claim 2 wherein the plates are formed of reinforced resilient material.

4. The blasting mat of claim 3 wherein the plates are formed from conveyor belting.

5. The blasting mat as claimed in claim 1 and rigid metallic plates threaded on the flexible means to bear against opposite ends of the mat and clamping means engageable on the flexible means to secure the rigid metallic member and the plates and spacers together on the flexible means.

6. The blasting mat of claim 1 wherein the plates are formed of substantially greater length than width and of substantially greater width than thickness, and wherein the spacers are formed in the same thickness as the plates.

7. The method of constructing a blasting mat comprising forming a plurality of rectangular plates of reinforced resilient material, such segments having substantially greater width than thickness, forming openings through the thickness of the plates, threading the plates onto flexible means in spaced side-by-side relationship in a plurality of contiguous rows with the meeting ends of the plates in each row interleaved to space the plates apart in each row, securing the ends of the flexible means at the ends of the mat and compressing the resilient plates on the flexible means under sufficient tension to form a mat with spaces between the plates for the passage of blast air and to allow movement of the plate edges as the mat is flexed to reduce the spaces between the plates at the area of flexure of the mat to retain material dislodged by the blast under the mat.

8. A blasting mat comprising:

at least four longitudinally extending, rope-like, elongated flexible members spaced laterally from one another;

a plurality of generally rectangular plates of reinforced rubbery material such as that commonly used in the manufacture of conveyor belting, means defining an opening through the thickness of each plate near each end thereof;

a plurality of spacer plates comparing in thickness to said rectangular plates, but being shorter in length and each having means defining an opening through the thickness thereof;

the rectangular plates and spacer plates being strung on said elongated flexible members via said openings so that the plates stand on edge, longitudinally adjacent, transversally extending in rows, with some rows containing at least two of said rectangular plates and alternating others of said rows containing at least one of said rectangular plates and at least one of said spacer plates, with the spacer plates being at least one lateral extreme of each row wherein they are provided; all of the plates in each row being transversally spaced from one another to provide gaps extending upwardly through the mats between transversally adjacent plates in the same row and adjacent plates in longitudinally adjoining rows;

stop means provided between the plates and the elongated flexible means at the two opposite ends of the mat to retain the mat together, but with sufficient excess of length of said elongated flexible members that when and where the mat bulges generally convesly upwardly during a blast, said gaps between the plates are temporarily substantially reduced in cross-sectional area on the underside of the mat to trap fragments propelled by the blast from escaping through those gaps.

Claims

1. A blasting mat comprisng a plurality of rectangular plates of resilient material arranged on edge in side-by-side relationship in contiguous rows with the rows interconnected and with the plates in each row spaced apart; flexible means threaded through the spaced plates in each row and means for securing the spaced plates on the flexible means whereby there is allowed sufficient movement of the plate edges as the mat is flexed to reduce the spaces between the plates at the area of flexure of the mat.

8. A blasting mat comprising: at least four longitudinally extending, rope-like, elongated flexible members spaced laterally from one another; a plurality of generally rectangular plates of reinforced rubbery material such as that commonly used in the manufacture of conveyor belting, means defining an opening through the thickness of each plate near each end thereof; a plurality of spacer plates comparing in thickness to said rectangular plates, but being shorter in length and each having means defining an opening through the thickness thereof; the rectangular plates and spacer plates being strung on said elongated flexible members via said openings so that the plates stand on edge, longitudinally adjacent, transversally extending in rows, with some rows containing at least two of said rectangular plates and alternating others of said rows containing at least one of said rectangular plates and at least one of said spacer plates, with the spacer plates being at least one lateral extreme of each row wherein they are provided; all of the plates in each row being transversally spaced from one another to provide gaps extending upwardly through the mats between transversally adjacent plates in the same row and adjacent plates in longitudinally adjoining rows; stop means provided between the plates and the elongated flexible means at the two opposite ends of the mat to retain the mat together, but with sufficient excess of length of said elongated flexible members that when and where the mat bulges generally convesly upwardly during a blast, said gaps between the plates are temporarily substantially reduced in cross-sectional area on the underside of the mat to trap fragments propelled by the blast from escaping through those gaps.