RU2458765C1 - Circular shears - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to rolling, particularly, to finishing of strip coiled steel. Proposed shears are used, mainly, for lengthwise cutting of 0.5-2.0 mm-thick steel strips with ultimate strength of σ_B≤470 MPa. Said shears comprises two driven shafts to support disc blades. Shears comprises five pairs of blades that feature diameter D_S=(1.9-2.1)D, where D is shaft OD. Hollow pipe-like shafts feature wall thickness δ equal to (0.08-0.11) D and plugged ends. Central pair of blades is fixed. Through lengthwise opposed slots are made on shafts and furnished with webs supporting central blades. Four vertical blade push rods are arranged in said slots to be displaced by four screws. Said screws thrust against inner cylindrical web at the center of every shaft. Thread pitch of one screw exceeds thread pitch S of another screw. Push rods have two holes, one threaded hole and another hole with diameter equal to 1.03-1.07 of OD of screw that passes through said hole. Extreme push rods have threaded holes with diameter d on one end and smooth holes d'₁=(1.03…1.07)d₁ on opposite end. Intermediate push rods feature opposite distribution of holes with diameters d₂<d₁ and d'₂=(1.03…1.07)d₂, where d₂ is threaded hole diameter, d'₂ is smooth hole diameter.

EFFECT: higher efficiency, lower operating costs.

5 cl, 1 dwg, 1 ex

Description

The invention relates to rolling production and can be used for longitudinal cutting (dissolution) of sheet steel strip.

To reduce the width of rolled cold and hot rolled strips, disc shears of various designs are widely used, containing several pairs of knives (upper and lower) mounted on two drive shafts. The designs of existing disc scissors are described in sufficient detail, for example, in the book by A. A. Korolev “Design and calculation of machines and mechanisms of rolling mills”. M .: Metallurgy, 1985, p. 241-248.

Known disc scissors (a machine for slitting stripes in which corrective feed rates and cutting speeds are applied when changing the diameter of the unwinding and reeling rolls in order to obtain optimal cutting conditions (see Japanese patent class B23C 3/13, No. 48-12343, publ. 26.01.78 g.).

The disadvantage of such disk shears is the need to remove the disk knives from the support shafts if it is necessary to change the width of the spreading strips and replace the distance rings between the knives, which reduces the performance of the unit and requires additional costs.

The closest analogue to the claimed device are disc scissors according to the patent of the Russian Federation No. 2084315, class. B23D 19/06, publ. in BI No. 20, 1997

These scissors contain two drive shafts located in the supports, with installed circular knives in them, made with the possibility of changing the horizontal distance between them, and are characterized by the presence of an extreme pair of knives of different diameters with a lower drive knife, and the non-drive knife of this pair is made with a diameter Dв = D + 2S + (2.4 ... 2.6) δ, where:

D are the diameters of the knives of all other pairs;

S is the thickness of the strip;

δ is the vertical overlap of the upper and lower knives.

A disadvantage of these disc scissors is also the need to remove the disc scissors from the support shafts if it is necessary to change the width of the spreading strips and replace the distance rings between the knives.

Indeed, as follows from the aforementioned book by A.A. Korolev (p. 242-243 and Fig. VII, 3), the distance between the knives is fixed by distance rings, the width of which is determined by the necessary width of the finished (loose) strips. Thus, to go to a different width of these strips, it is necessary to remove the blade knives and spacer rings from the shafts one by one, replacing the latter with rings of a different width, and when manufacturing sizes (widths) of finished strips new for these scissors, it is also necessary to manufacture spacer rings of other sizes, which, Naturally, it increases the cost of production.

An object of the present invention is to increase the performance of circular shears in the longitudinal dissolution of strip steel coils and reduce production costs.

To solve this problem, the proposed disc scissors, mainly for cutting strip steel with a thickness of 0.5 ... 2.0 mm with a tensile strength σv≤470 MPa, containing two drive shafts placed in supports, with mounted on them disc knives made with the possibility of changing the horizontal distance between them, unlike the closest analogue, the scissors contain five pairs of knives with a diameter Dн = (1.9 ... 2.1) D, their shafts are hollow in the form of pipes with a wall thickness δ equal to 0.08 ... 0.11 outer diameter D, and with end caps at their ends, with this middle pair of knives is non-movable, through shafts are made through longitudinal slots, opposite to each other, with a width equal to b = δ, and with jumpers between them, and four vertical pushers of knives move in the slots, each is coupled to the corresponding knife with one end thereof, moreover, the pushers are moved in the slots with four screws abutting against the inner jumper of a cylindrical shape in the middle of the length of each shaft, in addition, the thread pitch of one screw is twice as large as the step S of the other screw located with it in the common half ala; and in the pushers, two holes are made: one is threaded, the other with a diameter equal to 1.03 ... 1.07 of the outer diameter of the thread of the screw passing through this hole; the extreme pushers are made with threaded holes with a diameter of d ₁ at one end and with smooth holes d ' ₁ = (1,03 ... 1,07) d ₁ at the other end, and the intermediate pushers are made with the opposite distribution of holes with diameters d ₂ <d ₁ and d ' ₂ = (1.03 ... 1.05) d ₂ ; the simultaneous and in one direction rotation of each two screws in one half of the shaft can be achieved with the help of gears located on the outer ends of the screws and an intermediate gear between them; the maximum ratio of the horizontal distances between the circular knives to their minimum distances l _min can be 5.5 ... 5.7, and the value l _min = (1.13 ... 1.25) b _n , where b _n is the width of the cutting edge of the knife .

The given device parameters are obtained empirically and are empirical.

The essence of the proposed technical solution is to create such a design of disc scissors in which the distances between the knives can be changed without removing the shafts from their supports and without removing the knives from the shafts, as well as without the use of distance rings of the desired width.

The inventive disc (one of their shafts) scissors are schematically shown in figure 1 (Roman numerals - numbers of knives).

The tubular shaft 1 of the scissors contains four opposite horizontal slots 2, and circular caps 3 are fixed at both ends of the shaft, containing trunnions 4 included in the bearings of the bearings, one of the trunnions being connected to the scissors drive. Each plug has holes for the screws 5 and 6 lying in the common plane, the upper of which (in FIG. 1) 5 has a thread pitch 2S, and the lower 6 has a thread with a pitch S.

At the ends of the screws gears 7 are engaged, engaging with the intermediate gears 8, mounted on the pins 4. Thus, both screws rotate in the same direction - counterclockwise or clockwise. All screws abut against jumper 9 mounted in the middle of the shaft.

On each shaft there are five (I ... V) circular knives 10 with the same width b _{n of the} cutting surface, of which III (middle) is not movable on the surface of the shaft. The movement of knives I, II, IV and V is carried out by four pushers of knives 11 during rotation of the heads 12 of screws 5 and 6. In each pusher attached to the corresponding knife with the fastener 13, two holes are made: one (14) is threaded, the other (15) - smooth, ensuring the absence of contact of the pusher with the screw.

To strengthen the shafts inside them, four circular segments 16 can be arranged on their walls, parallel to the pushers with a height h _c = (1.3 ... 1.6) δ and with their length equal to the distance from the middle bridge 9 to the end cap 3. To avoid dirt and foreign particles entering the crevices of the shaft between the knives can, for example, be wrapped with insulation tape.

The device operates as follows. If it is necessary to switch to a different width of the spreading lanes by rotating the heads 12 of the screws 5 and 6, the plungers 11 and the disk knives 10 are driven horizontally. In this case, the extreme pushers (and knives I and V) move twice as much as the middle pushers (and knives II and IV), and the middle knife III remains motionless. As a result of this, the time required to switch to a new size (width) of the spreading bands is reduced several times. Since the knives of the upper and lower shafts can be installed with vertical overlapping during dissolution, some “skew” of the shelves between adjacent knives is possible (all knives of each shaft are installed in the same position - to the right or left of the knives paired with them). This can lead to the appearance of unwanted scratches at the contact points of the cut metal with the edge of the knife. Therefore, the outer edges of the knives in contact with the metal should be blunted.

An experimental verification of the inventive circular knives was carried out in sheet rolling workshop No. 7 of OJSC Magnitogorsk Metallurgical Plant. For this purpose, scissors are tested with various parameters in their dissolution steel strip thickness of 0.5 ... 2.0 mm on various widths and σ _in = 390 ... 500 MPa.

The best results (high-quality strip yield between 99.2 ... 99.8%) were achieved using the proposed disc scissors. Deviation from their recommended parameters worsened the achieved indicators.

So, at D _n <1.9 D, the wear of the knives increased, and at D _n > 2.1 D, the consumption of expensive steel for the manufacture of knives increased without any improvement in their work. Δ = 0.11D was recognized as the maximum optimal wall thickness of the shafts, and for δ <0.08D, residual twisting of the shafts was observed.

When the slit width and b <δ, the thickness of the pushers decreased, which caused their immediate deformation, and when b> δ the shafts were weakened, which led to their deflection and to a deterioration in the quality of the strip cut. An increase in the ratio of the pitch of the thread of screws more than 2 accelerated the wear of screws with a fine pitch, and with this ratio of less than 2, the time for reconfiguring the scissors to a different strip width increased.

In the aspect of saving metal and reducing labor costs, it is recognized that it is expedient to make screws with a thread pitch S with a diameter less than that of screws with a thread pitch 2S, and the magnitude of this difference will depend on the specific working conditions of the scissors and the nature of their manufacture.

The diameters of the smooth holes d ' ₁ <1,03d ₁ and d' ₂ <1,03d ₂ in some cases led to the locking of the pushers (due to contamination of the screw threads), and holes with d ' ₁ > 1,07d ₁ and d' ₂ > 1,07d ₂ weakened pushers with known negative consequences.

With the ratio of the distances between the knives lmax / lmin <5.5, the technical capabilities of the scissors decreased (as well as with lmin> 1.25b _n ). At lmax / lmin> 5.7, the roll deflection was unacceptably increased, and at lmin <1.13b _n , twisting of excessively narrow strips was observed after cutting.

A decrease in the height of the inner segments (h _with <1.3δ) and their length did not give the desired increase in the stiffness of the shafts (for strips with a thickness of 2 mm with σv = 470 MPa), and for h _c > l, 68 the costs of manufacturing segments unjustifiably increased.

Disc scissors, taken as the closest analogue (see above), were not used in the experiments due to their apparent discrepancy with the purpose of the present invention. Thus, an experimental verification confirmed the acceptability of the technical solution found to achieve the goal, its advantage over a known object.

The feasibility study showed that the use of the proposed disc scissors reduces the downtime associated with the transition to a new width of cut strips by at least 10 times, which increases the productivity of scissors by almost 30% with a corresponding reduction in production costs and the cost of finished strips.

Concrete example

Five-pair disc scissors (see figure 1) are intended for dissolution into four strips of rolled strip steel with a width of 830 mm and a thickness of 0.5 ... 2.0 mm from steel with σv≤470 MPa.

Knife parameters: Dн = 250 mm; bn = 25 mm. Dн = 2D, i.e. D = 250/2 = 125 mm.

The length of the tubular part of the shafts is L = 820 mm, δ = 0.095 × D = 0.095 × 125≈12 mm, b = δ = 12 mm, i.e. the inner radius of the shaft R = (D-2δ) / 2 = 50.5 mm Material - steel 45.

The length of the circular segments is 40 mm; their height hс = 1.45 × δ = 1.45 × 12 = 17.4 mm, width bс = 76.2.

Values: lmin = 1.2 × bn = 1.2 × 25 = 30 mm; lmax (maximum distance between knives) = 5.6 × lmin = 5.6 × 30 = 168 mm.

Pusher height H = 140 mm; dimensions of their cross section: b = 12 mm, b '= 20 mm.

Screw thread - metric; S = 1.25 mm; 2S = 2.5 mm; screw diameter in increments of Sd ₂ = 12 mm, in increments of 2S-d ₁ = 18 mm.

Diameters of smooth holes: d ' ₁ = 1.05 × d ₁ = 1.05 × 18≈19 mm; d ' ₂ = 1.04 × d ₂ = 1.04 × 12≈12.5 mm.

Claims (5)

1. Disk shears, mainly for longitudinal cutting of strip steel with a thickness of 0.5-2.0 mm with a tensile strength σv≤470 MPa, containing two drive shafts placed in supports, with mounted on them disk knives made with the possibility of changing the distance between horizontally, characterized in that they contain five pairs of knives with a diameter Dн = (1,9-2,1) D, where D is the outer diameter of the shaft, the shafts of which are hollow in the form of pipes with a wall thickness δ equal to (0, 08-0.11) D, and with end caps at their ends, while the average pair of knives you filled with non-movable, moreover, through shafts made through longitudinal slots opposite each other, with a width of b = δ, and with jumpers between them, on which the middle knives are mounted, and four vertical pushers of knives are located in the slots, each of which is engaged with with the corresponding knife at one end and with the possibility of moving in the slots with four screws abutting against the inner jumper of a cylindrical shape in the middle of the length of each shaft, the thread pitch of one screw being twice as large as the cutting pitch S of another screw located with it in the common half of the shaft, while the pushers are made with two holes, one of which is threaded, and the other with a diameter equal to 1.03-1.07 of the outer diameter of the screw thread passing through this hole, and extreme pushers are made with threaded holes with a diameter of d ₁ at one end and with smooth holes d ' ₁ = (1,03 ... 1,07) d ₁ at the other end, and intermediate pushers with the opposite distribution of holes with diameters d ₂ <d ₁ and d ' ₂ = (1.03 ... 1.07) d ₂ , where d ₂ is the diameter of the threaded hole, d' ₂ is the diameter of the smooth wow hole. 2. Disc scissors according to claim 1, characterized in that the simultaneous and in one direction rotation of each two screws in one half of the shaft is provided by gears located on the outer ends of the screws and an intermediate gear between them. 3. Disk shears according to claim 1, characterized in that the maximum ratio of the distances between the disk knives horizontally to their minimum distance (lmin) is 5.5-5.7. 4. Disc shears according to claim 1, characterized in that the value lmin = (1.13 ... 1.25) bn, where bn is the width of the cutting surface of the knife. 5. Disc scissors according to claim 1, characterized in that four circular segments are located inside the shafts on their walls parallel to the pushers with a height hc = (1.3 ... 1.6) δ and with their length equal to the distance from the middle bridge to end caps.