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Publication numberUS3143022 A
Publication typeGrant
Publication dateAug 4, 1964
Filing dateMay 1, 1961
Priority dateMay 1, 1961
Publication numberUS 3143022 A, US 3143022A, US-A-3143022, US3143022 A, US3143022A
InventorsEgil A Andersen
Original AssigneeUs Envelope Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Rotary window cutter for envelope machines or the like
US 3143022 A
Abstract  available in
Images(4)
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Claims  available in
Description  (OCR text may contain errors)

g- 4, 1954 EMA. ANDERSEN 3,143,022

ROTARY WINDOW CUTTER FOR ENVELOPE MACHINES OR THE LIKE Filed May 1 1961 4 Sheets-Sheet 1 INVEN TOR. Egi/ A. Andersen AGE/VT Aug. 4, 1964 E. ANDERSEN Q 3,143,022

ROTARY WINDOW CUTTER FORENVELOPE'MACHINES OR THE LIKE Filed May 1, 1961 4 Sheets-Sheet 2 s g N r u "3 I a i I t v Q I 'l' w Q l s, hl ll' .1 K) O) N l n 3 \ZP/ I Y a arm a a mvsuron Egi/ A. Andersen F H AGE/VT 1964 E. A. ANDERSEN 3,143,022

ROTARY wmoow CUTTER FOR ENVELOPE MACHINES OR THE LIKE Filed May 1, 1961 j 4 Sheets-Sheet s INVENTOR. E g/'/ A. Andersen gremaimw AGENT Aug. 4, 1964 ROTARY WINDOW CUTTER FOR ENVELOPE MACHINES 0R LIKE Filed May 1, 1961 "'ilg iii'lll Fig. 4

INVENTOR. Egi/ A. Andersen v BY 9% 9m E. A. ANDERSEIN 3,143,022

4 Sheets-Sheet 4 United States Patent 3,143,022 RUTARY WHNDQW CUTTER FGR ENVELGPE MACEEJES 0R TIE LIKE Egil A. Andersen, Auburn, Mass, assignor to United States Envelope Company, Springfield, Mass., a corporation of Maine Filed May 1, 1961, Ser. No. 106,917 5 Claims. (Cl. 83-341) This invention relates generally to rotary window cutting mechanism, and more specifically to die mechanisms designed for cutting openings in blanks or webs of paper or similar material, which openings are to have at least one edge substantially perpendicular to the direction of feed.

The present invention is particularly applicable for use on envelope machinery used in the manufacture of win dow envelopes, and is equally applicable whether the cutting operation is to be performed upon previously cut envelope blanks or upon continuous webs which are subsequently to be made into envelope blanks. It is to be understood, however, that the invention is not restricted to operation upon envelope blanks or upon webs which are destined to form envelope blanks, but that it is also adapted for other uses as well.

This invention is particularly adapted for use in conjunction with machinery disclosed in Heywood Patent No. 2,953,071, entitled Manufacture of Window Envelopes. In such machinery, the flat, unfolded blanks are advanced into the window patch applicator mechanism at rates of the order of 900 to 1200 per minute, several times faster than the rate of blank advance in conventional envelope making equipment. Equipment which performs the necessary operations at similar speeds for plain envelopes without windows is now already in use, such as that disclosed in Heywood Patent No. 2,696,255 and Heywood Patent No. 2,772,611.

The present invention provides a shear cutting mechanism and method for cutting windows from these extremely fast moving blanks or Webs mentioned above. The invention is in the nature of a pair of cooperating male and female die elements of a size and shape which conform to that of the desired window, mounted on rotary carrier members.

Rotary shear cutting is, in itself, old. To effect a cutting action between the male and femal dies, it is necessary that the cutting edges overlap around the entire periphery of the dies, and hence for the cutting edges of one or both of the dies to project beyond the circular pitch line between the rolls. By the teachings of Swift, Patent No. 1,202,122 and Novick, Patent No. 2,677,422, it is desirable that the dies be designed in such a manner that the leading cutting edge of the female die extend beyond the pitch line, while the leading cutting edge of the male die coincides with or falls short of the pitch line. In similar respect, it is desirable that the trailing cutting edge of the male die extend beyond the pitch line and the trailing cutting edge of the female die coincide with or fall short of the pitch line. In other words, the leading cutting edge of the female die should be of a greater radial extent in relation to the pitch circle than corresponding parts of the male die and the trailing cutting edge of the male die should be of a greater radial extent in relation to the pitch circle than corresponding parts of the female die. This concept of die design was actually the first major advancement in rotary shear cutting, because of the fact that the mating portions of the leading and trailing cutting edges separate quickly as the dies are rotated. This is because of the fact that the leading cutting edge of the female die will travel faster than the leading cutting edge of the male die, and there- 3,143,022 Patented Aug. 4, 1964 fore, the cutting edges separate immediately after contact. The opposite relationship is true of the trailing cutting edges of the dies, i.e., the trailing cutting edge of the male die will travel faster than the trailing cutting edge of the female die, allowing these cutting edges to separate immediately after contact. Also, Novick, in U. S. Patent #2,677,422 teaches that it is necessary for the cutting edges of the dies to be undercut to avoid interference of the mating cutting edges.

The present invention utilizes the teachings of the aforementioned patents, but in addition, involves an entirely now concept in the design of rotary shear dies.

For purposes of this disclosure, the cutting edges of the male and female dies are referred to in three different parts, although the entire periphery of the cutting edges is substantially continuous, for all practical purposes. The only deviation from the continuity of the cutting edges is the fact that the female die is preferably in two parts, for purposes hereinafter described.

The leading cutting edges and the trailing cutting edges, which have been frequently referred to hereinbefore actually need no description because these terms are commonly used in this art. The leading cutting edges are the first to make contact and normally extend axially of the carrier members. The trailing cutting edges are last to make contact, and also normally extend axially of the carrier members. The cutting edges connecting the ends of these leading and trailing cutting edges will be hereinafter referred to as the intermediate cutting edges. The intermediate cutting edges are usually semicircular, formed on the arcuate surface of the die. However, these intermediate cutting edges are not limited to a semicircular design.

The dies according to the present invention are designed in such a manner that the initial contact of the leading cutting edges of the dies is along a relatively short segment in relation to the entire length of the leading cutting edges, and progressively contact laterally until the cutting action is complete along the leading cutting edge, and the intermediate cutting edges of the dies begin to contact. By the curved nature of the intermediate cutting edges, i.e., extending partially around the circumference of the die, the cutting edges will progressively contact until the trailing cutting edges of the dies begin to contact. Also, the present invention provides that the trailing cutting edges of the dies progressively contact, beginning at the end of the intermediate cutting edges and progressively contact, i.e., contact points converge, until the entire length of the trailing cutting edges have contacted.

The above operation can be accomplished by making the leading cutting edge of the female die convex in relation to a tangential plane at the location of the leading cutting edge, and the trailing edge of the femal die concave in relation to a tangential plane at the location of the trailing cutting edge. Dies so constructed would initiate the cut at the approximate center of the leading cutting edges and end the cut at the approximate center of the trailing cutting edges. It is to be understood that these cutting edges do not have to be convex and concave in a strict sense of the word. All that is necessary is a high point on the leading cutting edge which gradually slopes down to the intermediate cutting edges, and a low point on the trailing cutting edge which slopes up to the intermediate cutting edges. The point mentioned above is not limited to a point in the strict sense of the word. The point may be a very short segment of the cutting edges. Also, the degree of convexity and concavity need only be slight, say in the order of 2 inch, measured as 'a differential from the ends of the leading or trailing cutting edges, whichever the case may be.

It seems reasonable to assume that the advantage of a progressively cutting the flats of the window arises from the fact that there is no surge of power requirement at the leading and trailing cutting edges of the dies. Instead of cutting the entire flats each instantaneously, the flats are smoothly and progressively cut.

Other provisions of the present invention will appear hereinafter.

In the drawings:

FIGURE 1 is a fragmentary, side elevation view, diagrammatically showing a portion of an illustrative machine which is designed to act upon separate envelope blanks or webs and which embodies features of the invention.

FIGURE 2 is a fragmentary elevation view on a larger scale, looking in the direction of stock feed into the cutter, and showing the design and relative location of the dies and die-carrying rolls.

FIGURE 3 is a fragmentary sectional view taken along line 33 of FIGURE 2.

FIGURE 4 is a fragmentary sectional view taken along radial plane 44 of FIGURE 3 showing the complete length of the leading cutting edge of the female die in a somewhat distorted shape to amplify the novel die construction.

FIGURE 5 is a fragmentary sectional view taken along radial plane 55 of FIGURE 3 showing the complete length of the trailing cutting edge of the female die in a somewhat distorted shape to amplify the novel die construction.

Envelope blanks are usually fed into a window cutting machine successively in spaced relationship. The blanks used on high speed machines are usually out directly from a web and fed into the envelope machine to be clipped, scored, gummed, folded, and have the window opening cut and the transparent patch applied. The window cutting operation is usually one of the first operations to be performed. It is to be understood that, while the present invention is primarily concerned with cutting windows from blanks, it may also easily be used for cutting windows from a traveling web.

Referring to FIGURE 1, only as much of a typical machine employing the present invention is shown as to give an idea of its position relative to surrounding stations. A continuously moving high speed succession of envelope blanks E (shown in broken lines) passes from the right to the left between the various opposed rolls which are illustrated in the figure. The blanks may be fed from a stack, or from a blank forming mechanism of the type which is disclosed, for example, in Heywood Patent No. 2,696,255. One of the main features of this patent involves the cutting, from a continuous web, of diamond or rhomboid-shaped blanks which are then fed at an angle to the direction of web feed for subsequent window cutting, scoring, and corner clipping. Whereas the instant invention has been designed for use in connection with the mechanism of the above mentioned patent, and the mechanism described in Heywood Patent No. 2,953,071, which describes a method and apparatus for the application of window patches, it is by no means limited thereby.

The envelope blanks as shown in FIGURE 1 pass into the window cutter from the proceeding station, which in this case, is a scoring station. Solid roll 8 and a pair of spaced upper scoring rolls 9 cooperate to provide suitable score lines for the side flaps of the envelope blanks in a conventional manner.

From the side flap scoring rolls, the envelope blanks pass between a pair of window cutting rolls designated generally at 10 and 11 which form the present invention and will be described hereinafter. The blanks E pass into the window cutting members, in timed relation, depending on the speed and circular pitch diameter of the window cutting members 10 and 11. The accurate timing of the entry of blanks E into the members 10 and 11 may be accomplished in any manner known in the art, and does not form a part of this invention. From the window cutting station, the blanks pass on to the next station, rolls 12 and 13, for the next operation, which also does not form a part of this invention.

As shown in FIGURE 2, female dies 14 and 15 are mounted on shaft 16, and male die 17 is mounted on shaft 18. The shafts 16 and 18 are positioned such that dies 14, 15, and 17 cooperate and overlap in all cutting positions. Shaft 16 is suitably journaled in bearings 19 and 20, and shaft 18 is suitably journaled in bearings 21 and 22, and in turn, the bearings are supported by fran1ework 23. Meshing gears 24 and 25 are driven by an outside power source and are fixed to shafts 16 and 18 respectively. Gears 24 and 25 are of the same size, hence shafts 16 and 18 rotate at the same speed.

The female dies carried by shaft 16 are preferably in two pieces, 14 and 15, for purposes that will be described hereinafter. Male die 17 engages the female dies 14 and 15 as the shafts are rotated approximately from the position shown in the figure. Advancing wheels 26, 27, 28 and 22 serve to engage the successive blanks in their bite and progressively feed the blanks through the cutters. It may be desirable to cover one pair of wheels, say 26 and 27, with rubber or like material to decrease slippage and effectively engage the blanks as they pass through the cutters. The plane of the blanks passing through the wheels 26, 27, 28 and 29 is necessarily tangent to the pitch circles of the dies 14, 15, and 17.

As taught in the prior art and shown in FIGURE 3, the dies 14, 15 and 17 are designed such that the leading cutting edge of the female die extends further radially than corresponding parts of the male die, and the trailing cutting edge of the male die extends further radially than corresponding parts of the female die. In FIGURE 3 the leading cutting edge of the male die lies on the pitch circle P, and the trailing cutting edge of the male die extends beyond the pitch circle P. The transition in radial extension of the cutting edges is absorbed in the intermediate or end cutting edges 36. On the female die, the intermediate cutting edges 35 extend beyond the pitch circle. At the junction of the intermediate cutting edge 35 and the leading cutting edge 31, the leading cutting edge slopes outwardly to a maximum radial extent at 60. At the junction of the intermediate cutting edge and the trailing cutting edge, the trailing cutting edge slopes inwardly to a minimum radial extent at 61. Every point on the leading cutting edge 31 of female die 15 is of a greater radial extent than a corresponding point on the leading cutting edge 32 of male die 17 and every point on the trailing cutting edge 34 of male die 17 is of a greater radial extent than a corresponding point on the trailing cutting edge 33 of female die 14.

Also, to reduce the chances of interference between the cutting edges and the adjacent portions of the dies, the cutting edges are undercut. The undercut of the cutting edges is best seen in FIGURE 3, the degree of undercut being measured by the angle a. Angle a should be at least 18", measured from radial lines b. This phenomenon is also described in Novick 2,677,422.

The novel features of the present invention are best shown in FIGURES 4 and 5, which are somewhat distorted to amplify the novel features of this invention. FIGURE 4 shows a longitudinal view of the leading cutting edge of the female die 15. It can readily be seen that the center of the leading cutting edge, generally designated as 31, is higher than the end cutting edges. This is preferably accomplished by making the cutting edge 31 convex or high at a point, and providing a constant slope down to the ends thereof.

Overlapping of the cutting edges is a necessity in shear cutting. It is readily seen in FIGURE 3 that the leading cutting edges 31 of die 15 extend beyond this pitch line at all points. Also, the leading cutting edge of the male die 17 is coincident with the pitch line, and, in this case, there would be an overlapping of the cutting edges by the amount of the die 15 which protrudes beyond the pitch line. Hence, when the male and female dies begin to engage, initial contact is made at a point, or very short segment of cutting edge 31. The cutting of the blank or web progresses from this point of initial contact each way, toward the end cutting edges 35, until the out along the leading cutting edges 31 of the dies is complete, and cutting along the end cutting edges 35, is begun. By the geometry of these end cutting edges 35 and 36, the cutting edges of the mating dies engage at point contact until the engagement at the end cutting edges 35 and 36 is complete, and the engagement of the trailing cutting edges begins.

In FIGURE 5, a longitudinal view similar to that shown in FIGURE 4 is shown of the trailing cutting edge 33 of female die 14. With the trailing cutting edge 34 of the male die 17 extending beyond the pitch line, a greater amount than a corresponding part of the trailing cutting edge 33 of female die 17, the engagement of the dies will continue from the end cutting edges 35 and 36 progressively toward the center of the trailing cutting edge 33 until the engagement of the cutting edges of the dies is completed at this point.

Also in FIGURES 2 and 3, a somewhat detailed view is shown of the dies 14, 15 and 17 mounted on shafts 16 and 18 for rotary movement about axes X and Y, respectively. The female dies 14 and 15, mounted on shaft 16, are preferably made in two sections split along the center line of the opening, to facilitate sharpening of the dies. Should the cutting edges wear down from extensive use, or otherwise, one section of the female die, say section 15, may be taken off, given a few filing strokes along edges 37 and 38, remounted, and a few revolutions of the mechanism will quickly wear off any conflicting edges. It is timely to mention at this point that male die 17 is desirably made of a relatively harder material than female dies 14 and 15. This will insure that the cutting edges quickly resharpen themselves. Dies 14 and 15 are rigidly held to shaft 16 by screws 39, 40, 41, 42, 43, 44, 45 and 46. More or less may be used, but four screws for each section of the female die ordinarily will be sufiicient. Slots 47, 48, 49, 50, 51, 52, 53 and 54 are elongated relative to the screws diameter so that the dies 14 and 15 may be closed slightly after each sharpening.

As best shown in FIGURES 2 and 3, the male die 17 is secured to shaft 18 by four screws 55, 56, 57 and 58. Since there is no reason to have to adjust this die, no provision is made for adjustment. The die is rigidly held in position, although it is removable.

Although it forms no part of this invention and is not shown in the drawings, provision is usually made on the dies of this type for efiicient removal of the patches which are cut from the blanks or web. One way of accomplishing this result is by providing compressed air and suction nozzles on the dies. A main suction line (not shown) may extend axially through shaft 18 with branches extending radially to the surface of the die. Likewise, a main compressed air line (not shown) may extend axially through the shaft 16 with branches extending to the opening of the female die. Suitable timing mechanism (not shown) may be provided at the ends of the shafts 16 and 18 and connected to vacuum and pressure sources to provide suction or pressure to the surface of the dies at any desired time to aid in the efficient removal of the cut patches or chips from the dies.

Other and further modifications apart from those indicated herein could be made without departing from the spirit of this invention.

I claim:

1. Apparatus for cutting openings in sheet material comprising (a) two opposed, axially parallel rotary carrier members,

(b) cooperating male and female cutting dies having rigid cutting edges carried by said carrier members,

6 said cutting edges having leading and trailing portions adapted for cutting the sheet material perpendicular to the direction of feed, and rounded intermediate cutting edge portions connecting said leading and trailing portions,

(0) means for rotating said carrier members in 0pposite directions to cause a progressive and continuous meshing action of the cutting edges of the dies from the leading cutting edge to the trailing cutting edge,

(d) means shaping said leading cutting edges relative to each other to cause contact to initiate therebetween at a point, then progressively diverge to the intermediate cutting edges, and progressively contime around and to the end of the intermediate cutting edges, and

(e) means shaping said trailing cutting edges relative to each other to cause contact to continue therebetween from the intermediate cutting edges and converge to a point.

2. In a mechanism for cutting openings in a web or blanks of sheet material having two opposed axially parallel rotary carrier members, cooperating male and female cutting dies having rigid cutting edges carried by said carrier members, said cutting edges having leading and trailing portions of appreciable length adapted for cutting the web or blanks perpendicular to the direction of feed, and rounded intermediate cutting edge portions connecting said leading and trailing portions at the ends thereof, said cutting edges being of such effective radii relative to said rotary carrier members as to overlap in all cutting positions, the leading cutting edge of the female die being of greater radial extent at all points in relation to the pitch circle than corresponding parts of the male die and the trailing cutting edge of the male die being of greater radial extent in relation to the pitch circle than corresponding parts of the female die, the improvement which comprises (a) the leading cutting edge of the female die lying in a plane parallel to a plane extending through the axis of its carrier member, and having one point spaced from the ends thereof of slightly greater radial extent than the ends thereof, said leading edge sloping inwardly from said point of greater radial extent to the intersection of the leading cutting edge with the intermediate cutting edges,

(b) the trailing cutting edge of said female die lying in a plane parallel to a plane extending through the axis of its carrier member and having one point spaced from the ends thereof of slightly less radial extent than the ends thereof, said trailing edge sloping outwardly from said point of less radial extent to the intersection of the trailing edge with the intermediate cutting edges.

3. Apparatus according to claim 2 in which the point of greatest radial extent on the leading cutting edge of the female die extends radially a distance of approximately inch further than the radial extent of the ends of said leading cutting edge, and the point of least radial extent on the trailing cutting edge of the female die extends radially a distance of approximately inch less than the radial extent'of the ends of the trailing cutting edge.

4. In a mechanism for cutting openings in a web or blanks of sheet material having two opposed axially parallel rotary carrier members, cooperating male and female cutting dies having rigid cutting edges carried by said carrier members, said cutting edges having leading and trailing portions of appreciable length adapted for cutting the web or blanks perpendicular to the direction of feed, and rounded intermediate cutting edge portions connecting said leading and trailing portions, said cutting edges being of such effective radii relative to said rotary carrier member as to overlap in all cutting positions, the leading cutting edge of the female die being of greater radial extent at all points in relation to the pitch circle than corresponding parts of the male die and the trailing cutting edge of the male die being of greater radial extent in relation to the pitch circle than corresponding parts of the female die, the improvement which comprises (a) the leading cutting edge of the female die lying in a plane parallel to a plane extending through the axis of its carrier member, and being slightly convex in relation to a plane tangent to the die at that point, (b) the trailing cutting edge of said female die lying in a plane parallel to a plane extending through the axis of its carrier member, and being slightly concave in relation to a plane tangent to the die at that point, (c) whereby said male and female dies will contact initially at the center of their leading cutting edges and progressively overlap each other from that point around the periphery of said dies in both directions until the final overlapping occurs at the center of their trailing cutting edges. 5. Apparatus according to claim 4 in which the highest point on the convex leading cutting edge of the female 0 die extends radially a distance of approximately inch further than the radial extent of the ends of said leading cutting edge, and the loW point on the concave trailing cutting edge of the female die extends radially a distance of approximately inch less than the radial extent of the ends of the trailing cutting edges.

References Cited in the file of this patent UNITED STATES PATENTS 378,405 Snyder et a1 Feb. 21, 1888 709,408 Jahnz Sept. 16, 1902 1,202,122 Swift Oct. 24, 1916 1,286,377 Malm Dec. 3, 1918 1,814,867 Swift July 14, 1931 1,835,439 Stahly Dec. 8, 1931 2,640,539 Piper June 2, 1953 2,677,422 Novick May 4, 1954 FOREIGN PATENTS 357,482 Germany Aug. 25, 1922 856,084

France Mar. 4, 1940

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US378405 *Mar 21, 1887Feb 21, 1888Themselves And Claeence MRubber soles
US709408 *Aug 5, 1901Sep 16, 1902Paul Meyer ActiengesellschaftDevice for cutting off pieces of belts, &c.
US1202122 *Apr 1, 1915Oct 24, 1916George W Swift JrRotary punching mechanism.
US1286377 *May 25, 1916Dec 3, 1918Malm Machine CompanyRotary punch-press.
US1814867 *Mar 18, 1930Jul 14, 1931George W Swift Jr IncBlank slitting and slotting machine
US1835439 *Dec 17, 1930Dec 8, 1931Sanitary Public Service CorpMachine for forming toilet seat covers
US2640539 *Jul 12, 1950Jun 2, 1953Powers Samas Account Mach LtdApparatus for cutting lengths from a web of paper, cardboard or similar material
US2677422 *Apr 28, 1950May 4, 1954Smithe Machine Co Inc F LRotary window cutting mechanism
DE357482C *Aug 25, 1922Gandenbergersche MaschinenfabrVorrichtung zum Rundlochen von Papier, Pappe, Leinwand, Blech u. dgl.
FR856084A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3245105 *Jul 8, 1964Apr 12, 1966Calvert B TolleyApparatus for cutting the body of a crab
US3283635 *Dec 21, 1964Nov 8, 1966IbmRotary punching apparatus
US3390423 *Jun 24, 1966Jul 2, 1968Calvert B. TolleyCrab coring machine
US3433107 *Oct 20, 1965Mar 18, 1969Control Data CorpRounded corner card cutter
US4072076 *Nov 10, 1976Feb 7, 1978Timsons LimitedPunching apparatus
US4202230 *Jul 17, 1978May 13, 1980Fuji Photo Film Co., Ltd.Rotary cutter
US4450740 *Feb 18, 1983May 29, 1984Westvaco CorporationRotary envelope cutting apparatus
US4690022 *Jul 11, 1985Sep 1, 1987Mitsubishi Jukogyo Kabushiki KaishaStamping device having identical mount bases for rotatably supporting a cutting tool and an anvil
US5704264 *Aug 31, 1995Jan 6, 1998Kimberly-Clark Worldwide, Inc.Cutting die with elevated stripping land
US5980442 *Jun 10, 1997Nov 9, 1999Hamilton; James T.Apparatus and method of producing a food server with pre-fold of glue panels
US6725751 *Nov 6, 2000Apr 27, 2004Formtek, Inc.Rotary punching apparatus
US20030116004 *Nov 1, 2002Jun 26, 2003Masayuki TanakaHole puncher
US20100300581 *May 26, 2010Dec 2, 2010Kraemer KlausBeverage bottle filling plant with a beverage bottle labeling machine, and a cutting arrangement for a beverage bottle labeling machine
US20110138980 *Dec 1, 2010Jun 16, 2011Daido Kogyo Co., Ltd.Punching unit
CN102120329A *Dec 8, 2010Jul 13, 2011大同工业株式会社Punching unit
CN102120329B *Dec 8, 2010May 13, 2015大同工业株式会社Punching unit
Classifications
U.S. Classification83/341, 83/345, 83/670, 83/595
International ClassificationB31B1/24
Cooperative ClassificationB31B1/24, B31B2201/908
European ClassificationB31B1/24