JPH04136693U

JPH04136693U - rotary drum shear

Info

Publication number: JPH04136693U
Application number: JP5358091U
Authority: JP
Inventors: 和徳河野
Original assignee: 三菱重工業株式会社
Priority date: 1991-06-17
Filing date: 1991-06-17
Publication date: 1992-12-18

Abstract

(57)【要約】【目的】シート切断を行なう回転式ドラムシャのナイ
フの刃先摩耗を抑制し、ナイフ寿命を延ばし、ナイフ調
整，交換ピッチを延ばす。【構成】対向回転する１対のドラム１，２の周面に、
ナイフ３，４をドラム軸方向に複数に分割して固着させ
ると共に、同ドラムをシートの給送方向に対して１，
２、１′，２′の如く直列に、かつシートの切断線をｂ
−ｃ、ｄ−ｅ、ａ′−ｂ′、ｃ′−ｄ′、ｅ′−ｆ′の
如く、各ドラム１，２、１′，２′のナイフ３，４、
３′，４′が分担して切断するよう複数対配設してなる
ものであり、また複数対のドラムのうち少なくとも１対
にバックアップロール３７，３７′、３８，３８′を設
けてなるものである。 (57) [Summary] [Purpose] To suppress the wear of the knife blade of a rotary drumsha that cuts sheets, extend the life of the knife, and extend the knife adjustment and replacement pitch. [Structure] On the circumferential surface of a pair of drums 1 and 2 that rotate oppositely,
The knives 3 and 4 are divided into a plurality of parts in the direction of the drum axis and fixed, and the drum is divided into parts 1 and 4 in the sheet feeding direction.
2, 1', 2' in series, and the cutting line of the sheet is b.
Knives 3, 4 of each drum 1, 2, 1', 2', such as -c, de, a'-b', c'-d', e'-f';
A plurality of pairs of drums 3' and 4' are arranged to share cutting duties, and at least one pair of the plurality of pairs of drums is provided with backup rolls 37, 37', 38, 38'. It is.

Description

[Detailed explanation of the idea]

【０００１】0001

[Industrial application field]

本考案はコルゲートマシン等の段ボールシートの切断に使用される回転式ドラムシャに関するものである。 This invention is a rotary drive used for cutting corrugated sheets such as corrugating machines. It's about Musha.

【０００２】0002

[Conventional technology]

従来この種の装置は回転式ドラムシャと称し、連続的に供給される段ボールシート等の帯状板材を供給方向に略直角に切断するもので、その構造は図４及び図５に示す如く、上下にドラム１，２を有し、それぞれに直線状又は螺旋状のナイフ３，４をドラム１，２の軸方向にわたって固着すると共に、上下のドラム１，２を互いに対向回転させることにより、ナイフ同志が１回転に１回係合するようにし、上下のドラム１，２間に供給される被切断材料をナイフ３，４の係合によりシャ切断する様になっている。 Conventionally, this type of equipment was called a rotary drumsha, and it was used to continuously supply corrugated cardboard sheets. It cuts strip-shaped plate material such as sheet metal at approximately right angles to the feeding direction, and its structure is shown in Figures 4 and 4. As shown in Fig. 5, there are drums 1 and 2 on the upper and lower sides, each of which has a straight or spiral knife. The flaps 3 and 4 are fixed in the axial direction of the drums 1 and 2, and the upper and lower drums 1, By rotating the knives opposite to each other, the knives engage with each other once per rotation. The material to be cut, which is fed between the upper and lower drums 1 and 2, is cut by the engagement of the knives 3 and 4. It is designed to cut the ribbon.

【０００３】さらに構造を図４により詳細に説明すると、ドラム１，２はドラムの軸５，６に取付けられており、その軸５，６の両端は、それぞれ軸受７，８を介してフレーム９に回転自在に支持されている。また軸５，６の両端には、上下に噛合された歯車１０，１１が固着されている。一方、フレーム９の外側には、モータ１２が設置され、その駆動軸１３は軸受１４を介してフレーム１５に回転自在に支持されており、同モータ軸１３の端には歯車１６が固着され、同歯車１６は歯車１１と噛合っている。そしてモータ１２の作動によって、上下のドラム１，２は対向して等速回転される。またドラム１，２の周面には、それぞれナイフ３，４が直線状、或いは螺旋状に取付けられている。なお、図４では直線状となっている。0003 To further explain the structure in detail with reference to FIG. 4, the drums 1 and 2 are connected to drum shafts 5 and 6. Both ends of the shafts 5 and 6 are attached to the frame via bearings 7 and 8, respectively. It is rotatably supported by the arm 9. Also, both ends of the shafts 5 and 6 are engaged with each other vertically. Gears 10 and 11 are fixed. On the other hand, a motor 12 is provided on the outside of the frame 9. is installed, and its drive shaft 13 is rotatably supported by a frame 15 via a bearing 14. A gear 16 is fixed to the end of the motor shaft 13, and the gear 16 is connected to the gear 1. It meshes with 1. Then, by the operation of the motor 12, the upper and lower drums 1 and 2 are It is rotated at a constant speed in the opposite direction. Additionally, knives 3 and 4 are provided on the peripheral surfaces of the drums 1 and 2, respectively. It can be installed in a straight line or in a spiral. In addition, in Figure 4, it is a straight line. .

【０００４】ナイフ３，４の取付け状態は、図５に示す如く、ドラム１，２の取付け面１７，１８にそれぞれ上下のナイフ３，４を沿わせてボルト１９，２０で固定してある。またドラム１，２には、押え金２１，２２がボルト２３，２４で固定してあり、同押え金２１，２２のナイフ３，４側には、調整ボルト２５，２６及び固定用ナット２７，２８が設けてあり、ナイフ３，４の位置を微調整可能にしている。0004 The knives 3 and 4 are mounted on the mounting surfaces 17 of the drums 1 and 2, as shown in FIG. , 18, respectively, and fix them with bolts 19, 20. Ru. Further, presser feet 21 and 22 are fixed to the drums 1 and 2 with bolts 23 and 24. Adjustment bolts 25, 26 and fixing bolts are installed on the knife 3, 4 sides of the presser feet 21, 22. nuts 27 and 28 are provided to allow fine adjustment of the positions of the knives 3 and 4. .

【０００５】回転式ドラムシャは、前述の如く上下のドラム１，２の対向回転によりナイフ３，４同志が係合し、被切断材料の切断を行なうものであるが、このとき上下ナイフは一方の端から係合を始め、ドラム軸方向に連続的に係合が進み、他方の端で係合が解かれる。また回転式ドラムシャでは、計画Ｍａｘ速度まで良好な切味を保持することが装置の生命であるが、前記従来の装置では次のような欠点があった。[0005] As mentioned above, the rotary drum shaft rotates the upper and lower drums 1 and 2 in a counter-rotating manner. 3 and 4 engage to cut the material to be cut, but at this time, the upper and lower If, the engagement starts from one end, the engagement progresses continuously in the direction of the drum axis, and then the other end. The engagement is released. In addition, the rotary drum shaft provides good cutting performance up to the planned maximum speed. However, the conventional devices have the following drawbacks: It was.

【０００６】[0006]

[Problem that the idea aims to solve]

即ち、前記従来の回転式ドラムシャでは、シート切断時上下ドラム１，２の刃先に垂直荷重と側方力が互いに逆になる様に作用する。この荷重成分は上下ドラム１，２に曲げ撓みを与え、これによって上下ナイフ３，４の係合点にギャップが生じ、切味を低下させる。従って上下ドラム１，２の曲げ剛性を高くする必要があった。そこで前記に対する対策として上下ナイフ係合時、予めナイフ間に面圧を与えると、ナイフ刃先がシートに接触して切断されるまでの接触距離があるため、ナイフ同志の摺動及びナイフとシートの摺動によりナイフの摩耗が大となって、ナイフ寿命が短くなり、従ってナイフ係合調整及び交換ピッチが短くなる欠点があった。本考案は前記従来の課題を解決しようとするものである。 That is, in the conventional rotary drum shear, the blades of the upper and lower drums 1 and 2 cut the sheet. First, the vertical load and lateral force act in opposite directions. This load component is Bending deflection is applied to the arms 1 and 2, thereby creating a gap at the engagement point of the upper and lower knives 3 and 4. occurs, reducing sharpness. Therefore, it is necessary to increase the bending rigidity of the upper and lower drums 1 and 2. was there. Therefore, as a countermeasure against the above problem, when engaging the upper and lower knives, make sure that there is a surface between the knives beforehand. When pressure is applied, there is a contact distance between the knife edge and the sheet until it is cut. Therefore, the knife wears out significantly due to sliding between the knives and sliding between the knives and the sheet. Therefore, the knife life is shortened, and therefore the knife engagement adjustment and replacement pitch are shortened. There were drawbacks. The present invention attempts to solve the above-mentioned conventional problems.

【０００７】[0007]

[Means to solve the problem]

このため本考案は、対向回転する１対のドラム周面に、ナイフをドラム軸方向に複数に分割して固着させると共に、同ドラムをシートの給送方向に対して直列に、かつシートの切断線を各ドラムのナイフが分担して切断するよう複数対配設し、また前記複数対のドラムのうち少なくとも１対にバックアップロールを設けてなるもので、これを課題を解決するための手段とするものである。 Therefore, in the present invention, a knife is placed on the circumferential surface of a pair of drums rotating oppositely in the direction of the drum axis. The drum is divided into multiple parts and fixed, and the same drum is installed in series with the sheet feeding direction. Multiple pairs of knives are arranged so that the cutting line of the sheet is shared between the knives on each drum. and a backup roll is provided on at least one pair of the plurality of pairs of drums. It is a means to solve problems.

【０００８】[0008]

[Effect]

切断時に生じる切断荷重は、単位長さ当たり剪断抵抗力にナイフとシートとの接触長さを掛けたものであるので、ドラムシャの軸方向におけるナイフを分割して複数台のドラムシャに設置し、１台当たりの切断幅を小さくすると共に、最終的には全幅を切断するものである。従って１台当たりの分担荷重を軽減出来る。 The cutting load generated during cutting is determined by the shearing resistance per unit length and the force between the knife and the sheet. Since it is multiplied by the contact length, it divides the knife in the axial direction of the drumshaft. The machine is installed on multiple drumshas to reduce the cutting width per machine and to In other words, it cuts the entire width. Therefore, the shared load per unit can be reduced.

【０００９】また切断時に生じる切断荷重を、分割ナイフを装着したドラムシャで第１段階目の部分切断を行い、さらに後部のドラムシャで残部の切断を行い、全幅の切断を完了させる。また前部のドラムシャはドラムにバックアップロールを有しているので、切断荷重の８割程度を分担してもドラムシャの変位は極小に抑えられ、ナイフ刃先の開きはない。また後部のドラムシャでは残部の切断を行なうため、切断荷重は小さくなる。[0009] In addition, the cutting load generated during cutting is reduced in the first stage by a drum shear equipped with a split knife. Partially cut the eye, and then cut the remaining part using the rear drum shaft to cut the entire width. complete. The front drum shaft also has a backup roll on the drum. As a result, the displacement of the drum shaft can be kept to a minimum even if approximately 80% of the cutting load is shared. There is no opening at the knife edge. In addition, in order to cut the remaining part at the rear drumsha, Cutting load becomes smaller.

【００１０】0010

【Example】

以下本考案の実施例を図面の基づいて説明すると、図１は本考案の第１実施例を示す回転式ドラムシャの側面部分断面図であり、回転式ドラムシャを２台、シート流れ方向に直角に近接して配設した図を示しており、図中１，１′は上ドラム、２，２′は下ドラム、３，３′は上ナイフ、４，４′は下ナイフである。さてＮＯ．１回転式ドラムシャの上ドラム１′の上ナイフ３′は、分割されて図１（ｂ）に示すｂ−ｃ間及びｄ−ｅ間に固着してある。また下ドラム２′の下ナイフ４′は分割されて、ｂ−ｃ間、ｄ−ｅ間に固着してある。 The embodiments of the present invention will be explained below based on the drawings. Figure 1 shows the first embodiment of the present invention. FIG. 2 is a side partial cross-sectional view of a rotary drum shaft showing two rotary drum shafts in a system. 1 and 1' are the upper drive 2, 2' are lower drums, 3, 3' are upper knives, and 4, 4' are lower knives. difference Te NO. The upper knife 3' of the upper drum 1' of the single-rotation drum shaft is divided into parts as shown in FIG. It is fixed between b and c and de shown in (b). Also, the bottom of the lower drum 2' The frame 4' is divided and fixed between b and c and between d and e.

【００１１】次にＮＯ．２回転式ドラムシャの上ドラム１の上ナイフ３は分割されてａ′− ｂ′間、ｃ′−ｄ′間、ｅ′−ｆ′間にそれぞれ固着してある。また下ドラム２の下ナイフ４も分割してあって、ａ′−ｂ′間、ｃ′−ｄ′間、ｅ′−ｆ′間にそれぞれ固着してある。更に、ＮＯ．１、ＮＯ．２回転式ドラムシャにおいて、上ドラム１′と下ドラム２′のナイフ３′と４′の分割ナイフは、それぞれ係合する様に配設してある。更に上ドラム１と下ドラム２のナイフ３，４の分割ナイフも、それぞれ係合する様に配設してある。またＮＯ．１回転式ドラムシャに対するＮＯ．２回転式ドラムシャの配置位置は、Ｌ＝Ｒβ〔Ｌ；ドラムシャ間距離、Ｒ；ナイフ刃先までの半径、β；必要同期角度〕となる様に配設してある。[0011] Next, NO. The upper knife 3 of the upper drum 1 of the two-rotation drum shaft is divided into a'- They are fixed between b', between c' and d', and between e' and f', respectively. Also lower drum 2 The lower knife 4 is also divided, between a' and b', between c' and d', and between e' and f'. Each is fixed. Furthermore, NO. 1.No. In a two-rotation drumsha, The split knives 3' and 4' of the upper drum 1' and lower drum 2' are engaged, respectively. It is arranged so that Furthermore, separate knives 3 and 4 of upper drum 1 and lower drum 2 The openings are also arranged so as to engage with each other. Also NO. For single-rotation drum shaft NO. The arrangement position of the two-rotation drum shaft is L = Rβ [L; distance between drum shafts , R: radius to the knife edge, β: required synchronization angle].

【００１２】次に本考案の回転式ドラムシャのシート切断過程を説明すると、シートはＮＯ．１回転式ドラムシャで図１（ｂ）のｂ−ｃ間と、ｄ−ｅ間が全幅に対して分割切断され、さらにシートがＮＯ．２回転式ドラムシャ部に給送され、ＮＯ．１ドラムシャでの切れ残り部であるａ′−ｂ′間、ｃ′−ｄ′間、ｅ′−ｆ′間の切断が行なわれ、この時点でシートは全幅の切断が完了する。なお、ＮＯ．１ドラムシャの切断位置と、ＮＯ．２ドラムシャの切断位置が一致する様に、ドラムシャ間で同期がとられている。0012 Next, the sheet cutting process of the rotary drum shaft of the present invention will be explained. ．． A one-rotation drum shaft divides the entire width between b and c and d in Figure 1(b). The sheet is cut and the sheet is NO. It is fed to the two-rotation drum shaft section, and the NO. 1 do Cuts between a' and b', between c' and d', and between e' and f', which are the uncut parts at the ramsha. Cutting is performed, at which point the sheet has been cut across its entire width. In addition, NO. 1 dora Musha's cutting position and NO. 2. Align the drum shafts so that the cutting positions of the two drum shafts match. synchronization between cameras.

【００１３】この様にシートの切断荷重を、単一ドラムシャ及び２台のドラムシャで分割及び分担するため、個々のドラムシャに作用する負荷が低減されることによって、ドラムの曲げ剛性が低減され、ドラム系のＧＤ²も軽減出来る。更に切断荷重が低減されることによって、ナイフ係合部の接触面圧も小さくなり、ナイフ寿命が大きく延びる。[0013] In this way, since the sheet cutting load is divided and shared between the single drum shear and the two drum shears, the load acting on each drum shear is reduced, thereby reducing the bending rigidity of the drum. The system's GD ² can also be reduced. Furthermore, since the cutting load is reduced, the contact surface pressure of the knife engaging portion is also reduced, and the life of the knife is greatly extended.

【００１４】図２及び図３は本考案の第２実施例を示し、図２は回転式ドラムシャの正面部分断面図、図３は同ドラムシャの側面部分断面図を示す。先ず、図２の３１は上ドラム、３２は下ドラム、３３，３３′、３４，３４′は段付円筒部で、それぞれ上下ドラム３１，３２と１体になっている。また上ドラム３１の軸４１の両端部にはギヤ１０′が、上ドラム３２の軸４２の両端部にはギヤ１１′がそれぞれ固着してある。[0014] 2 and 3 show a second embodiment of the present invention, and FIG. 2 is a front view of a rotary drum shaft. FIG. 3 shows a side partial sectional view of the same drumshaft. First, 31 in Figure 2 is the top The drum, 32 is the lower drum, 33, 33', 34, 34' are stepped cylindrical parts, respectively. The upper and lower drums 31 and 32 are integrated into one body. Also, both ends of the shaft 41 of the upper drum 31 A gear 10' is installed at the upper drum 32, and a gear 11' is installed at both ends of the shaft 42 of the upper drum 32. It's fixed.

【００１５】ギヤ１０′とギア１１′は回転伝達可能に噛み合っており、駆動系は図４に示すドラムシャ側の上ドラム１の歯車１０と上ドラム３１の歯車１０′が中間ギヤを介して連結されており、下ドラム２のギヤ１１と下ドラム３２の歯車１１′も、中間歯車を介して連結されている。従ってモータ１２によって装置は駆動される。また上ドラム３１の軸４１は、フレーム９に軸受７′を介して回転自在に支持されており、下ドラム３２の軸４２は、フレーム９に軸受８′を介して回転自在に維持されている。[0015] Gear 10' and gear 11' are meshed to enable rotation transmission, and the drive system is shown in Figure 4. The gear 10 of the upper drum 1 and the gear 10' of the upper drum 31 on the drum shaft side are intermediate gears. The gear 11 of the lower drum 2 and the gear 11' of the lower drum 32 are also connected via , are connected via an intermediate gear. Therefore, the device is driven by the motor 12. Ru. The shaft 41 of the upper drum 31 is rotatably supported on the frame 9 via a bearing 7'. The shaft 42 of the lower drum 32 is rotatably attached to the frame 9 via a bearing 8'. Currently maintained.

【００１６】一方上ドラム３１、下ドラム３２は、シリンダ系のＧＤ²を極力低減して曲げ剛性を上げるために、円筒３３，３３′及び３４，３４′を用い、バックアップロール３７，３７′、３８，３８′を介して支持されている。またバックアップロール３７，３７′、３８，３８′は回転自在に軸を介してその支持ブラケット３９，３９′、４０，４０′にてフレーム９の横梁に固着してある。また上ドラム３１には分割ナイフ３５ａ，３５ｂ，３５ｃが、下ドラム３２には分割ナイフ３６ａ，３６ｂ，３６ｃがそれぞれボルトにて固着してある。これらはバックアップロール部を除いて装着されている。On the other hand, the upper drum 31 and the lower drum 32 use cylinders 33, 33' and 34, 34' in order to reduce GD ² of the cylinder system as much as possible and increase bending rigidity, and backup rolls 37, 37', 38, 38'. Further, the backup rolls 37, 37', 38, 38' are rotatably fixed to the cross beams of the frame 9 via their shafts by their support brackets 39, 39', 40, 40'. Furthermore, dividing knives 35a, 35b, and 35c are fixed to the upper drum 31, and dividing knives 36a, 36b, and 36c are fixed to the lower drum 32 with bolts, respectively. These are installed except for the backup roll section.

【００１７】次に分割切断形回転式ドラムシャとドラムシャの関係を述べる。図３において、同一位置を切断するため、上下ドラム１，２と上下ドラム３１，３２の両ドラムシャのナイフ係合点間距離をＬとすると、ドラムシャ部のナイフ３，４の係合は分割切断ドラムシャのナイフ係合点を基準にして、係合点からナイフ３，４をそれぞれ角度βだけ、つまりＬ＝Ｒβ（Ｒはナイフ刃先までの半径）となるようにされ、係合時分割切断位置と一致するタイミングとなっている。この様にして前段の分割切断位置を後段のドラムシャが一致させて切断し、全幅の切断を完了させる。[0017] Next, the relationship between the split cutting type rotary drum shaft and the drum shaft will be described. In Figure 3 In order to cut at the same position, both the upper and lower drums 1 and 2 and the upper and lower drums 31 and 32 are used. If the distance between the knife engagement points of the drum shaft is L, then the engagement of the knives 3 and 4 of the drum shaft section is based on the knife engagement point of the split cutting drum shaft, and removes the knives 3 and 4 from the engagement point. Each angle β, that is, L = Rβ (R is the radius to the knife edge) , and the timing coincides with the engagement time-division cutting position. like this The drum shear of the rear stage matches the dividing cutting position of the front stage and cuts, completing the full width cutting. let

【００１８】この過程では両ドラムシャの回転速度とシート速度が同速時に行なわれなければならないので、両ドラムシャ間の軸間距離が極力小さくなる様設置してある。この様に切断荷重を分担するため、ドラム曲げ剛性は低減され、ＧＤ²も大きく軽減出来る。またドラムの変位（逃げ）規制されることによって、ナイフ間の予圧や、ナイフ係合部の接触面圧も小さくなりナイフ寿命が大きく延びる。[0018]In this process, the rotational speed and sheet speed of both drum wheels must be the same, so the distance between the shafts of both drum wheels is set to be as small as possible. Since the cutting load is shared in this way, the drum bending rigidity is reduced and GD ² can also be reduced significantly. Furthermore, by restricting the displacement (relief) of the drum, the preload between the knives and the contact surface pressure of the knife engaging portions are reduced, and the life of the knives is greatly extended.

【００１９】[0019]

【考案の効果】以上詳細に説明した如く本考案によると、ドラム系の曲げ剛性、ＧＤ²を軽減することができ、またシート切断時の作用荷重が小さくなり、ナイフ係合部の接触面圧も小さくなってナイフ刃先摩耗が抑制されナイフ寿命が延びる。従ってナイフ調整及び交換ピッチを延ばすことができる。更に本考案では、分割切断形回転式ドラムシャのドラム系は、バックアップロールによって支持出来るので、高曲げ剛性が得られ、装置全体でのＧＤ²も大きくならず、全体的にコンパクト化を図ることができる。[Effects of the invention] As explained in detail above, according to the invention, the bending rigidity and ^GD2 of the drum system can be reduced, and the applied load when cutting the sheet is reduced, and the contact surface pressure of the knife engagement part is reduced. This also reduces knife edge wear and extends knife life. Therefore, the knife adjustment and replacement pitch can be extended. Furthermore, in this invention, the drum system of the split-cut rotary drum shaft can be supported by backup rolls, so high bending rigidity is obtained, the GD ² of the entire device does not increase, and the overall device can be made more compact. can.

[Brief explanation of drawings]

【図１】本考案の第１実施例に係る回転式ドラムシャの
側面部分断面図及びシート切断状態図である。FIG. 1 is a side partial sectional view and a sheet cut state diagram of a rotary drum shaft according to a first embodiment of the present invention.

【図２】本考案の第２実施例に係る回転式ドラムシャの
正面断面図である。FIG. 2 is a front sectional view of a rotary drum shaft according to a second embodiment of the present invention.

【図３】図２のＹ〜Ｙ断面図及びシート切断状態図であ
る。FIG. 3 is a sectional view taken along YY in FIG. 2 and a sheet cutting state diagram.

【図４】従来の回転式ドラムシャの正面断面図である。FIG. 4 is a front sectional view of a conventional rotary drum shaft.

【図５】図４のＸ〜Ｘ断面図である。FIG. 5 is a sectional view taken along line XX in FIG. 4;

[Explanation of symbols]

１，１′，２，２′ ドラム３，３′，４，４′ ナイフ１０，１０′，１１，１１′ ギヤ３１，３２ドラム３３，３３′，３４，３４′ 段付円筒部３５ａ，３５ｂ，３５ｃ，３６ａ，３６ｂ，３６ｃ分
割ナイフ３７，３７′，３８，３８′ バックアップロール３９，３９′４０，４０′ ブラケット1, 1', 2, 2' Drum 3, 3', 4, 4' Knife 10, 10', 11, 11' Gear 31, 32 Drum 33, 33', 34, 34' Stepped cylindrical part 35a, 35b , 35c, 36a, 36b, 36c Dividing knife 37, 37', 38, 38' Backup roll 39, 39' 40, 40' Bracket

Claims

[Scope of utility model registration request]

Claim 1: A knife is divided into a plurality of parts in the drum axial direction and fixed to the peripheral surfaces of a pair of drums that rotate oppositely,
A rotary drum shaft characterized in that a plurality of drums are arranged in series with respect to the sheet feeding direction, and a plurality of pairs of the same drums are arranged so that the cutting line of the sheet is shared by the knife of each drum.

2. The rotary drum shear according to claim 1, wherein at least one of the plurality of pairs of drums is provided with a backup roll.