US3325220A - Cutting auger - Google Patents

Description

June 13, 1967 P. GUILLON ETAL 3,325,220

CUTTING AUGER Filed Nov. 29, 1966 4 Sheets-Sheet l Pia-1. Fig-Z INVENTORS Pierre Guillon 8 Alfred Valentin BY Kai; LA- f-cam ATTORNEY June 13, 1967 P. GUILLON ETAL 3,325,220

CUTTING AUGER Filed Nov. 29, 1966 4 Sheets-Sheet 2 INVENTORS Plerre-Guillon & Alfred Valcmfin BY \62L 0 RTOCKS ATTORNEY June 13, 1967 P. GUILLON ETAL 3,325,220

CUTTING AUGER Filed Nov. 29, 1966 4 Sheets-Sheet 3 INVENTORS Pierre Guillon 8 Alfred Valentin ATTORNEY n 3, 1967 P. GUILLON ETAL CUTTING AUGER 4 Sheets-Sheet 4.

Filed Nov. 29, 1966 Pie-.6.

Pic-L5 INVENTORS Pierre Guillon 8:

Alfred Valentin BY \eh LQ-FLocKS ATTORNEY United States Patent C) 3,325,220 CUTTING AUGER Pierre Guillon, Paris, and Alfred Valentin, Clermont, France, assignors to Charbonnages de France, Paris, France, a public institution of France Filed Nov. 29, 1966, Ser. No. 604,519 Claims priority, application France, July 23, 1963, 942,414 Claims. (Cl. 299--90) This application is a continuation-in-part of application Ser. No. 384,097, filed July 21, 1964, and now abandoned.

Studies carried out by the applicants have made it possible to understand more fully the very special evolution of the forces developed by an ore-cutting pick in the case where a cut is being deepened. It has been found that in this case, the forces are the same as if a groove of the same total depth as that obtained by the deepening cut were carried out in a single pass from the free surface of the rock. This fact is still valid in the case where two adjacent cuts are separated by a step or ridge of uncut rock.

The studies referred to were directed (a) to the maximum lateral spacing of the picks so that no ridge is left between their tracks; (b) to the number of picks to be utilized in order to produce furrows; (c) to the minimum width to be given to the said furrows.

It will be observed that on cutting machines, the adjacent picks follow each other at a relatively large distance, which leads to the conclusion that in practice, the stresses developed in the rock by one of the picks have no influence on the conditions of working of the following picks.

It is known that the ridge becomes sufficiently fragile for it to be broken up by the passage of the pick making the next adjacent cut when the ratio of its height to its width is greater than 1.5 in the case of hard rock and in the vicinity of 1 for soft rock.

For example, with picks which have a cutting head of 16 mm. in width, the ridge is fragile if, for a height of 10 mm., its width varies from 10 to 6 mm. (or the distance between centers of the picks varies from 26 to 22 mm.) depending on the nature of the rock.

Now, we have found that 1) the pass depth has an influence on the minimum width to be given to the furrow.

Thus, for a pass of 7.5 mm. in depth, the furrow must have a minimum width of 35 to 40 mm. in order that picks of 16 mm. do not work in repeated depth-cutting. (2) A minimum of three picks is necessary to make a furrow without falling into the case of repeated depth-cutting.

The invention is based on the above findings, and consists of a new type of cutting auger comprising a plurality of sets of picks, the distribution of said picks in a set being such that the tracks left by the picks in the rock are sufficiently close to provide in their vicinity a substantially plane surface.

The new auger according to the invention is a result of the combination of the following characteristics: it comprises sets of at least three picks; the extremities of the picks of the same set are spaced apart radially from each other by a distance substantially equal to the width of the said picks; the different sets of picks are spaced apart .radially from each other, a hollow space being formed between the supports of two successive sets of picks, considered in the radial direction, the width of the hollow being less than, or, at the most, equal to its depth.

In accordance with further characteristic features, the lateral picks are set back with respect to the central pick by an amount which increases with their retard in the direction of rotation, with respect to the said central pick; two picks at an equal distance from the axis of rotation are located in two adjacent radial planes and their extremities are located substantially in the same plane perpendicular to the axis; the sets of picks are carried by spaced supports on an elongated arm, substantially symmetrical with respect to the axis of rotation of the auger, with supports on both sides of the axis, the shape of the supports permitting them to pass in the track of the set of tools of which they carry a part; two symmetrical supports forming a group, have the same length considered in the direction of the axis of the auger, the whole of the picks of the set being divided up between these two supports; alternatively, the length of the supports increases as the distance from the axis increases; the inclination of the picks toward the rear, considered in the direction of rotation, increases as the picks are located closer to the axis of rotation.

Other particular features and advantages of the invention will be brought out from the following description with reference to the accompanying drawings in which:

FIG. 1 is a side view of a construction of anger accord ing to the invention;

FIG. 2 is an end view of the auger of FIG. 1;

FIG. 3 is a distribution diagram of the picks of one set;

FIG. 4 is the diagram of the tracks cut by two adjacent sets of picks;

FIG. 5 is a side view of an improved construction of the auger according to the invention; and

FIG. 6 is an end view of the anger of FIG. 5.

In the description which follows, the term cut is used to represent the track left by a pick in the solid mass to be cut, and furrow represents the track left by a set of picks. The same indices have been given to the cuts and to the picks which have cut them.

The order in which the picks of one set attack the min eral is indicated by the successive numerals 1, 2, 3, 4 given to the indices which designate the picks.

FIG. 1 shows diagrammatically a construction of the auger in accordance with the invention.

The auger is composed of one double arm 1, substantially symmetrical with respect to its axis of rotation XX. It comprises the external groups or pairs of supports A1 and A2, symmetrically arranged with respect to the axis X'X. These supports have a thickness less than the width of the furrow cut in the solid mass 0 by all the picks which they respectively carry. These supports have substantially the same length along the axis XX with respect to the arm which carries them. This length is such that the distance H which separates the plane P (or P containing the extremities of the picks carried by these supports and the arm is 1.5 times greater than or at least equal ot the distance R which separates two adjacent sets of picks, in the case vof soft to medium hardness material, and may be as much as 2 times that distance for hard material.

The sets of four picks each (two central picks and two lateral picks) are distributed as follows:

(1) The central picks of each set are carried by the supports of the same arm, namely the picks 1A and 2A by the support A1, the picks 11B and 213 by the support B1, and the picks 1C and 2C by the support C1.

(2) The side picks of each set are carried by the symmetrical supports of the other arm, namely, the picks 3A and 4A by the support A2, the picks 3B and 48 by the support B2 and the picks 3C and 4C by the support C2.

The extremities of all the central picks are located in a single plane P1, the extremities of all the lateral or end picks are located in a single plane P2, set back with respect to the plane P1 by a distance x which is a function of the advance provided for the auger.

The group of picks carried by the outer supports A1 (and A2) cuts the annular furrow GA, the set of picks carried by the central supports cuts the annular furrow GB, the set of picks carried by the inner supports cuts the annular furrow GC. The adjacent furrows GA and GB leave uncut the annular ridge of mineral AA; the adjacent furrows GB and GC leave intact the annular ridge of uncut mineral BB; the furrow GC leaves uncut the central cylindrical ridge CC which is removed by the breaker tool 11.

As will be seen from the remainder of the description which follows, the ridges are broken at their bases, following the line of fracture represented by a double continuous line.

FIG. 2 shows diagrammatically the distribution of the picks on the arms, the arrow F indicating the direction of rotation of the arm.

It will be observed that the picks such as 1A and 2A, 3A and 4A, located at nearly equal distances from the axis X'X are situated in adjacent radial planes, that the picks such as 3A and 4A are set back with respect to the picks such as 1A and 2A, by an amount which increases with their retard, considered in the direction of rotation, with respect to these latter.

The pick 3A is located behind the end pick 3A of the outer set so as to replace the latter in the event of it breaking under the load which is applied to it. Its extremity is located on the circle described by the extremity of the picks 3A.

The radial arrangement of the picks of one set is in accordance with discoveries made by the inventors. FIG. 3 provides an illustration of this. There has been shown in full lines the position of the central picks of the outer set at the beginning of a revolution, without advance of the arm, and in broken lines the position of the lateral picks of this same set after one-half revolution of the arm. In accordance with the conditions for repeated depth-cutting, there are provided:

(1) a distance q between the centers of the extremities of the picks approximately the same as the width e of the said picks;

(2) a number of picks for a width E of the furrow GA which is a function of the forward movement of the auger and of the width 2 of the said picks.

This arrangement of the picks and the sets of picks resolves the problem of destruction of the ridges, which is an essential condition for the reduction of the force to be applied in cutting the mineral.

FIG. 4 illustrates the application of the phenomenon of breaking of the ridges.

The cuts made by the picks 1A, 2A, 3A and 4A of a single set leave existing at the bottom of the corresponding groove GA small ridges having a width r=(qc) and a height h. When the ratio h/r is equal to 1.5 or at least equal to 1, these ridges become broken up in the course of a given pass by the force applied by the side faces of the picks in the vicinity of their heads, i.e., their working extremities.

The ridge AA which is left between the furrows GA and GB having a width R and a height H, becomes fragile when the ratio H/R is greater than 1.5 or at least equal to 1 if the rock is soft. Otherwise stated, for soft rock, the ridge AA is fragile and will shear at its base if it has a height equal to its width; for hard rock, the ridge is fragile and will shear at its base if it has a height greater than its widht, up to a ratio of twice the width being required in some hard rock. For rock of intermediate hardness, the ratio H/R may be approximately 1.5. Shearing of the ridge is caused by lateral force applied to its side face as by a pick support or by a side surface of the pick. These side forces are caused by lateral movements of small amplitude resulting from the inherent vibrations present in the machine as it works.

As the picks cut a helix in the solid mass to be cut, it can be seen that the rake angle of the picks will be smaller as and when the picks become closer to the axis X'X. In order to prevent the undercutting of the picks forming the central and inner sets, the cutting angle of the said picks is reduced by an amount depending on their distance from the axis, that is to say, the picks are more inclined toward the rear, considered in the direction of rotation, as they are located closer to the axis X'X. Otherwise stated, the 1 'cks closer to axis X'X are less inclined toward the direction of rotation.

In order to obtain a better evacuation of the products cut by the picks carried by the inner or central supports, the alternative form of construction which has been shown in FIGS. 5 and 6 may be used.

With the same radial arrangement of the picks and of the sets of picks, the supports (A1, B1, etc.) which are farther from the axis X'X are longer in the direction of the axis X'X. Two supports symmetrical with respect to X'X, such as A1 and A2, B1 and B2, C1 and C2, have substantially the same length.

The description and the examples given above have only been given by way of explanation and without any implied limitation, and the scope of the invention will not be departed from by making modifications, concerning for example the number of picks of one set, the relative positions of the picks and the sets, the lengths of the supports or the shape of the arm. Thus, although the distances Q (the distances between axes of two consecutive supports) have been shown on the drawings as being substantially equal to each other, and although the same distance H, the same distance R, and the same distance B have been substantially provided in all cases, it will be understood that these distances may be separately modified provided that the conditions of ratio constituting the important characteristics of the invention are respected.

What is claimed is:

1. A cutting auger comprising a rotatable member having an axis, at least two groups of spaced supports on said member, the supports of each group being equally spaced from said axis and one group being closer to said axis than the other group,

sets of picks of substantially equal width on each group of supports, each set comprising at least three picks of substantially equal width, the extremities of said picks of each set being spaced apart radially from each other by a distance substantially equal to the width of a pick,

the distance between the supports of one group and the supports of the adjacent group being no greater than the distance from the member to the pick extremities.

2;. The cutting auger of claim 1, the said distance between said supports being less than the distance from said member to the pick extremities.

3. A cutting auger according to claim 1, wherein each set of at least three picks comprises at least two lateral picks and at least one central pick, the extremities of said lateral picks being set back with respect to the extremities of said central pick.

4-. The cutting auger of claim 3, the extremities of said lateral picks being progressively more set back as the circumferential distance of said lateral picks from said central picks in the direction of rotation increases.

5. A cutting auger according to claim 1, comprising in each set of at least three picks, two picks at an equal distance from said axis of rotation and with their extremities between the supports of one group and the supports of the adjacent group is substantially equal to the Width of a set of picks.

References Cited UNITED STATES PATENTS 1,854,911 4/1932 Scott 175404 2,587,065 2/1952 Robbins 29990 2,711,888 6/1955 Robbins et al 29980 10 2,955,810 10/1960 MOW-hotter et al 29990 ERNEST R. PURSER, Primary Examiner.

Claims (1)

1. A CUTTING AUGER COMPRISING A ROTATABLE MEMBER HAVING AN AXIS, AT LEAST TWO GROUPS OF SPACED SUPPORTS ON SAID MEMBER, THE SUPPORTS OF EACH GROUP BEING EQUALLY SPACED FROM SAID AXIS AND ONE GROUP BEING CLOSER TO SAID AXIS THAN THE OTHER GROUP, SETS OF PICKS OF SUBSTANTIALLY EQUAL WIDTH ON EACH GROUP OF SUPPORTS, EACH SET COMPRISING AT LEAST THREE PICKS OF SUBSTANTIALLY EQUAL WIDTH, THE EXTREMITIES OF SAID PICKS OF EACH SET BEING SPACED APART RADIALLY FROM EACH OTHER BY A DISTANCE SUBSTANTIALLY EQUAL TO THE WIDTH OF A PICK, THE DISTANCE BETWEEN THE SUPPORTS OF ONE GROUP AND THE SUPPORTS OF THE ADJACENT GROUP BEING NO GREATER THAN THE DISTANCE FROM THE MEMBER TO THE PICK EXTREMITIES.

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