Scrap cutting machine

Abstract

The present application provides a scrap cutting machine capable of efficiently and rapidly cutting scrap material delivered from a press machine. A scrap cutting machine (50) is provided at a rear stage of a press machine to cut scrap material delivered from the press machine. The scrap cutting machine (50) includes a slide (54) reciprocally driven in the up-down direction by a rotation-stopping yoke mechanism (57), an upper blade (55) mounted to the slide (54), and a lower blade (56) mounted to a frame (52) as a fixed portion to cut the scrap material in cooperation with the upper blade (55). The shearing angle formed by the upper blade (55) and the lower blade (56) gradually decreases from the start of cutting the scrap material to the end of cutting the scrap material. In the case of cutting the scrap material within a cutting allowance limit, the angle at which the driving torque of a crank shaft (59) of the rotation-stopping yoke mechanism (57) is constant from the start of cutting to the end of cutting is provided.

Description

TECHNICAL FIELD

[0001] The present application relates to a scrap cutting machine, and particularly to a scrap cutting machine capable of cutting a scrap material fed from a press machine at high efficiency and high speed. BACKGROUND

[0002] As such a scrap cutting machine, there are a scrap cutting machine in which a moving blade (cutting blade) is reciprocated in the up-and-down direction by a crank mechanism or the like to cut a scrap material between the moving blade and a fixed blade, or a scrap cutting machine in which a cutting blade is directly attached to the lower end of a link connected to a crank shaft, and the cutting blade is guided in the vertical direction near the cutting portion.

[0003] Further, as the cutting blade, there are a cutting blade having a shear angle of 0 degree or a cutting blade having a certain shear angle. Here, the shear angle refers to the angle between the moving blade and the fixed blade.

[0004] The smaller the shear angle is, the greater the pressing force required at the time of cutting is, and the mechanical rigidity of the cutting device itself needs to be increased, and further, the inertia of the driving portion is increased, which is not suitable for high speed. On the other hand, if the shear angle is increased, the stroke of the moving blade from the start to the end of cutting is increased, and the device is upsized, which is not suitable for high speed.

[0005] On the other hand, in Patent Literature 1, a cutting machine in which a cutting blade is driven by a link mechanism is proposed.

[0006] The cutting machine described in Patent Literature 1 is a cutting machine in which a moving blade is crossed with respect to a fixed blade to cut a thin workpiece, and the moving blade (tool holder) is suspended from a table by being supported by two swing arm shafts, thereby being configured as a four-link mechanism. One of the two swing arms is swung by a crank mechanism, whereby the moving blade is swung while descending, the moving blade is crossed with the fixed blade in a diagonal direction, and the cutting-in angle (shear angle) of the moving blade is gradually reduced, and the workpiece is sequentially broken from one end to the other end.

[0007] PRIOR ART DOCUMENTS

[0008] PATENT LITERATURE

[0009] Patent Literature 1: Japanese Patent Application Laid-Open No. 2009-107096 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] The cutting machine described in Patent Literature 1 cuts a workpiece from one end to the other end by gradually reducing the cutting-in angle of a moving blade by swinging the moving blade, but since the tool holder of the moving blade is swung, left and right vibrations occur, and it is not suitable for high speed.

[0012] In addition, the cutting machine described in Patent Literature 1 gradually reduces the cutting-in angle (shearing angle) of the moving blade by swinging the moving blade when cutting a workpiece, as a result of which it is possible to suppress the breaking of the cut of the workpiece at the final stage of cutting to make the cut surface uniform and neat, but the shearing angle is not gradually reduced in consideration of the pressing ability at the time of cutting.

[0013] The present application was completed in view of such circumstances, and aims to provide a scrap cutting machine capable of efficiently and at high speed cutting a scrap material fed out from a press machine.

[0014] Means for solving the problem

[0015] To achieve the above object, the first aspect of the present application is a scrap cutting machine provided in a rear stage of a press machine to cut a scrap material fed out from the press machine, characterized by comprising: a slide member reciprocally driven in the up-down direction by a crank mechanism; an upper blade mounted to the slide member; and a lower blade mounted to a fixed portion to cut the scrap material by cooperation with the upper blade, wherein a shearing angle formed by the upper blade and the lower blade is gradually reduced from the start of cutting the scrap material to the end of cutting, and in the case of cutting a scrap material within a cutting allowable limit, there is an angle at which a driving torque of a crank shaft of the crank mechanism is constant from the start of cutting to the end of cutting.

[0016] According to the first aspect of the present application, the shearing angle is gradually reduced from the start of cutting the scrap material to the end of cutting, and in particular, in the case of cutting a scrap material within a cutting allowable limit, there is an angle at which a driving torque of a crank shaft of the crank mechanism that reciprocally drives the slide member in the up-down direction and on which the upper blade is mounted is constant. Thus, the driving torque of the crank shaft at the time of cutting a scrap material within a cutting allowable limit can be minimized, and the minimization of inertia, stroke, and vibration, the downsizing of the device, and the efficient and high-speed cutting of the scrap material can be achieved.

[0017] In the scrap cutting machine of the second aspect of the present application, the scrap material within the cutting allowable limit is determined by the thickness of the material and the shearing resistance.

[0018] The shearing angle is determined based on the scrap material within the cutting allowable limit, and therefore the scrap cutting machine of the present application can of course efficiently and at high speed cut a scrap material within the cutting allowable limit.

[0019] In the scrap cutting machine of the third aspect of the present application, when a driving torque applied to a crank shaft of the crank mechanism is set as T, and a crank radius of the crank shaft is set as r, a tangential force F of the crank shaft in a tangential direction is expressed by the following equation,

[0020] F = T / r,

[0021] when a rotation angle of the crank shaft from a top dead center is set as θ, a pressing force P of the upper blade is expressed by the following equation,

[0022] P = F / (sin θ * n * s) = T / (r * sin θ * n * s),

[0023] where n is 1 for an asymmetrically inclined blade and 2 for a symmetrically inclined blade, and s is a safety factor,

[0024] when a thickness of the scrap material of the cutting permission limit is set as t, a shearing resistance is set as Kfc, and the shearing angle is set as α, the shearing angle α is expressed by the following equation,

[0025] α = -tan -1 (Kfc * t 2 / 2P) = -tan -1 (Kfc * t 2 * n * s * r * sin θ / 2T).

[0026] Note that the symbol * in the above equation indicates multiplication.

[0027] In the scrap cutting machine of the fourth aspect of the present application, a coordinate (x, y) on a blade tip of a cutting blade of at least one of the upper blade and the lower blade in an xy coordinate system in which a length direction of the cutting blade is set as an x axis and a direction orthogonal to the x axis is set as a y axis is expressed by the following equation,

[0028] x = (r / A) * (π - θ),

[0029] y = -r * (1 + cos θ),

[0030] where A = Kfc * t 2 * n * s * r / 2T.

[0031] The blade shape of the cutting blade is expressed by the coordinate (x, y) on the blade tip of the cutting blade in the xy coordinate system, and the other blade shape is made horizontal, so that the upper blade and the lower blade have the shearing angle α.

[0032] In the scrap cutting machine of the fifth aspect of the present application, the crank mechanism is preferably a stop rod yoke mechanism.

[0033] In the scrap cutting machine of the sixth aspect of the present application, the cutting edge of at least one of the upper blade and the lower blade has an asymmetrically inclined edge that is asymmetric with respect to the center of the cutting edge, or a symmetrically inclined edge that is symmetric with respect to the center of the cutting edge.

[0034] The cutting edge can be an asymmetrically inclined edge (single blade) or a symmetrically inclined edge (double blade). The inclination angles are different in the single blade and the double blade, but the heights of the blades are the same.

[0035] Effects of the Invention

[0036] According to the present application, by optimizing the shearing angle formed by the upper blade and the lower blade, the scrap material fed from a press machine can be cut efficiently and at high speed. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a configuration diagram of a press production line including the scrap cutting machine of the present application.

[0038] Figure 2 is a front view of the scrap cutting machine.

[0039] Figure 3 is a diagram for explaining the pressing force applied to the cutting edge by the driving torque of the crank shaft.

[0040] Figure 4 is a diagram showing the types of the blade shape of the cutting edge.

[0041] Figure 5 is a diagram showing the relationship between the position of the cutting edge (upper blade) of the double blade and the rotation angle of the crank shaft.

[0042] Figure 6 is a diagram for explaining the relationship between the pressing force applied to the cutting edge having an inclination angle and the shearing area of the scrap material that can be sheared by the pressing force.

[0043] Figure 7 is a graph showing an example of the blade shape of the cutting edge.

[0044] Figure 8 is a chart showing a part of the calculation results of the xy coordinates and the like on the blade tip of the cutting edge.

[0045] Figure 9 is a chart showing another part of the calculation results of the xy coordinates and the like on the blade tip of the cutting edge.

[0046] Figure 10 is a graph showing the blade shape of the cutting edge in which the xy coordinates of 0 to 50 points on the blade tip of the cutting edge are plotted.

[0047] Explanation of Reference Numerals:

[0048] 10 uncoiler

[0049] 20 leveller

[0050] 30 feeder

[0051] 40 press machine

[0052] 50 scrap cutter

[0053] 51 column

[0054] 52 frame

[0055] 53 guide

[0056] 54 slider

[0057] 54A opening

[0058] 55 upper blade

[0059] 56 lower blade

[0060] 57 stop rod yoke mechanism

[0061] 58 slider block

[0062] 59 crank shaft

[0063] 59A eccentric portion

[0064] 60 scrap conveyor

[0065] 70 scrap material DETAILED DESCRIPTION

[0066] Hereinafter, a preferred embodiment of the scrap cutter according to the present application will be described in detail with reference to the accompanying drawings.

[0067] Figure 1 is a configuration diagram of a press production line including the scrap cutter according to the present application.

[0068] Figure 1 The press production line illustrated is configured to have an uncoiler 10, a leveller 20, a feeder 30, a press machine 40, a scrap cutter 50, and a scrap conveyor 60 arranged in this order.

[0069] The uncoiler 10 is a material feeding device that unwinds a material (a coil material) wound in a coil shape around a roll and feeds the material while controlling the deflection of the material after being unwound.

[0070] The flattening machine 20 is arranged between the unwinding machine 10 and the feeder 30, and deforms the coil material alternately in the up-and-down direction by sandwiching the coil material between a plurality of rollers arranged alternately, thereby eliminating the strain of the coil material having a bend (Japanese: maki-kebi).

[0071] The feeder 30 is a material conveying device that feeds the coil material into a die of the press machine 40 at a certain interval.

[0072] The press machine 40 cuts the shape of a product and the like from the coil material.

[0073] The scrap cutting machine 50 is arranged at a rear stage of the press machine 40, cuts the scrap material (punching scrap of the coil material) fed out from the press machine 40 into a size easy to handle, and discharges the cut scrap material to the scrap conveyor 60. Note that the scrap cutting machine 50 of this example is operated in synchronization with the press machine 40.

[0074] Figure 2 is a front view of the scrap cutting machine.

[0075] Figure 2 The scrap cutting machine 50 illustrated is configured of a frame 52 functioning as a fixed portion fixed by a column 51, a slide 54 guided in the up-and-down direction by a guide 53 within the frame 52, an upper blade (moving blade) 55 attached to the slide 54, a lower blade (fixed blade) 56 attached to the frame 52, and a scotch yoke mechanism 57 as one type of crank mechanism that reciprocally drives the slide 54 in the up-and-down direction.

[0076] The scotch yoke mechanism 57 of this example is provided with a slider 58 movably arranged in a direction (left-and-right direction) orthogonal to the moving direction of the slide 54, i.e., the up-and-down direction, within a rectangular opening portion 54A formed in the slide 54, and a crank shaft 59 that transmits a rotational driving force by a not-illustrated servo motor, and an eccentric portion 59A of the crank shaft 59 rotatably penetrates the slider 58 via a bearing.

[0077] According to the scotch yoke mechanism 57, if the crank shaft 59 is rotated one turn, the slider 58 reciprocates once in the up-and-down direction and the left-and-right direction in accordance with the eccentric amount (crank radius) of the eccentric portion 59A. The left-and-right direction movement of the slider 58 is not transmitted to the slide 54 through the opening portion 54A formed in the slide 54, and only the up-and-down direction movement of the slider 58 is transmitted to the slide 54, as a result of which the slide 54 is reciprocally driven in the up-and-down direction.

[0078] By employing the scotch yoke mechanism 57 as the crank mechanism, the movement of the upper blade 55 as the moving blade becomes sinusoidal movement, and in addition, the slide 54 to which the upper blade 55 is attached transmits the driving force only in the up-and-down direction, and thus it is possible to control the left-and-right vibration.

[0079] The waste material delivered from the press machine 40 is disposed between the upper blade 55 and the lower blade 56 of the waste cutting machine 50 during the period of the gap between the upper blade 55 and the lower blade 56 (for example, the period of the range of ±90 degrees if the rotation angle of the crank shaft 59 at the top dead center is set to 0 degree) and then, the waste material is cut by the cooperation of the upper blade 55 and the lower blade 56 due to the descent of the upper blade 55.

[0080] Next, the blade shape of the cutting blade of at least one of the upper blade 55 and the lower blade 56 is described. Note that the blade shape of the cutting blade described below is the blade shape of the upper blade 55.

[0081] The waste cutting machine 50 cuts various waste materials different in material, plate thickness, and the like of the waste material, but in the present example, in order to be able to cut the waste material within the allowable limit (cutting allowable limit waste material) with high efficiency, the shearing angle made by the upper blade 55 and the lower blade 56 is designed as shown below.

[0082] The shearing angle made by the upper blade 55 and the lower blade 56 of the waste cutting machine 50 is gradually reduced from the start of cutting of the waste material to the end of cutting, and in the case of cutting the cutting allowable limit waste material, has an angle that is able to make the driving torque of the crank shaft of the crank mechanism constant from the start of cutting to the end of cutting.

[0083] Figure 3 is a diagram for explaining the pressing force of the cutting blade applied by the driving torque of the crank shaft.

[0084] As shown in Figure 3 , when the driving torque applied to the crank shaft is set to T and the crank radius is set to r, the tangential force F in the tangential direction of the crank shaft is expressed by the following equation,

[0085] F = T / r.

[0086] In addition, when the rotation angle of the crank shaft from the top dead center is set to θ, the pressing force P of the cutting blade is expressed by the following equation,

[0087] [Equation 1]

[0088] P = F / (sin θ * n * s) = T / (r * sin θ * n * s)

[0089] where n: 1 for the asymmetrically inclined blade and 2 for the symmetrically inclined blade, and s: safety factor.

[0090] Figure 4 is a diagram showing the types of the blade shape of the cutting blade.

[0091] Figure 4The cutting edge shown in (A) is an asymmetrical inclined edge that is asymmetrical with respect to the center of the cutting edge. It is a single-edged blade that cuts from one end of the waste material to the other when cutting the waste material.

[0092] Figure 4 The cutting edge shown in (B) is a symmetrical inclined edge that is symmetrical about the center of the cutting edge. It is a double-edged blade that cuts from both ends of the waste material toward the center when cutting the waste material.

[0093] Figure 5 It is a diagram showing the relationship between the position of the cutting edge (upper edge) of a double-edged blade and the rotation angle of the crankshaft. Figure 5 (A) to (E) represent the positions of the upper blade from the start to the end of cutting the waste material.

[0094] Figure 5 (A) indicates the position of the upper cutting edge 55 when the crankshaft rotates at an angle θa. Figure 5 The position of the upper cutting edge 55 shown in (A) is the position when the upper cutting edge 55 descends as the crankshaft rotates and initially contacts the scrap material 70. The scrap material 70 is cut from this position of the upper cutting edge 55.

[0095] Figure 5 (C) indicates the position of the upper cutting edge 55 when the crankshaft rotates at an angle θc.

[0096] Figure 5 The position of the upper blade 55 shown in (C) indicates the position when the upper blade 55 descends further and the uppermost point of the upper blade 55 (the center of the upper blade 55) reaches the upper surface of the waste material 70.

[0097] Figure 5 (B) indicates the position of the upper cutting edge 55 when the crankshaft rotation angle is between angle θa and angle θc, and a portion of the upper cutting edge 55 reaches the lower surface of the scrap material 70. It should be noted that... Figure 5 On (B), reference numerals 70A and 70B indicate a shearing surface capable of being cut under the pressure of the upper blade 55 applied at that location.

[0098] Upper blade 55 from Figure 5 The position shown in (A) to Figure 5 Between the positions shown in (C), the shearing angle between the upper blade 55 and the lower blade 56 gradually decreases with the stroke of the upper blade 55, and has an angle that enables the driving torque of the crankshaft of the crank mechanism to remain constant when cutting scrap material within the allowable cutting limit.

[0099] In addition, from Figure 5 The position shown in (A) to Figure 5The stroke length k (angles θa to θc) of the upper cutting edge 55 at the position shown in (C) (angles θa to θc of the crankshaft) becomes the upper cutting edge 55 located at... Figure 5 The gap k between the uppermost point of the upper blade 55 and the upper surface of the waste material 70 at the position shown in (A) is caused by the shearing angle of the upper blade 55.

[0100] Figure 5 (E) indicates the position of the upper cutting edge 55 when the crankshaft reaches angle θe (slider 54 is the bottom dead center). When the upper cutting edge 55 reaches... Figure 5 When the position shown in (E) is reached, the cutting of waste material 70 ends.

[0101] Upper blade 55 from Figure 5 The position shown in (C) to Figure 5 The stroke length of the position (angle θc ~ angle θe of the crankshaft) shown in (E) is consistent with the thickness t of the scrap material 70.

[0102] Figure 5 (D) indicates the position of the upper edge 55° between the rotation angles of the crankshaft and the angles θc and θe.

[0103] With the upper blade 55 from Figure 5 The position shown in (C) is towards Figure 5 The position shown in (E) decreases, as Figure 5 As shown in (C), for the cutting residue of scrap material 70, its height and width gradually decrease together. Therefore, from Figure 6 The position shown in (C) to Figure 6 The pressing force of the upper blade 55 required for cutting the scrap material 70 between the positions shown in (E) also gradually decreases with the stroke of the upper blade 55, so the crankshaft torque will not be insufficient.

[0104] Figure 7 This diagram illustrates the relationship between the pressing force applied to the cutting edge and the shear area of ​​the waste material that can be sheared under that pressing force. It should be noted that, in this example, the upper cutting edge 55, which serves as the moving edge, is an asymmetrical or symmetrical inclined edge, and the lower cutting edge 56, which serves as the fixed edge, is a horizontal edge without inclination. As a result, the upper cutting edge 55 moves in the vertical direction, so the inclination angle of the cutting edge (upper cutting edge 55) corresponds to the shearing angle.

[0105] exist Figure 7 In this context, when the shearing angle, which corresponds to the inclination angle of the cutting blade, is set to (-α) and the thickness of the scrap material 70 is set to t [mm], the shearing area S [mm²] of the scrap material 70 that can be sheared under the action of the pressing force P [N] applied to the cutting blade is... 2 Expressed as follows:

[0106] [Math. 2]

[0107] S = P / Kfc = t 2 (2 tan a).

[0108] Note that Kfc is a shear resistance (N / mm 2 ).

[0109] When the formula of [Math. 1] is substituted into the formula of [Math. 2] for P, the shear angle a is arranged, the shear angle a can be expressed by the following formula,

[0110] [Math. 3]

[0111] a = - tan -1 (Kfc * t 2 / 2P) = - tan -1 (Kfc * t 2 * n * s * r * sin θ / 2T).

[0112] The shear angle a shown in the formula of [Math. 3] is an angle that gradually decreases from the start of the cutting of the scrap material to the end of the cutting (with the rotation angle θ of the crank shaft as a variable). In addition, this shear angle a is an angle that enables the cutting of the scrap material from the start of the cutting to the end of the cutting while keeping the driving torque T of the crank shaft constant (in the maximum torque output state) in the case where the scrap material of the cutting allowance limit determined by the plate thickness t and the shear resistance Kfc is cut.

[0113] According to the scrap cutter 50 of the above-described structure, it is possible to reduce the driving torque T of the crank shaft (the rated torque of the servo motor that drives the crank shaft) required when cutting the scrap material of the cutting allowance limit, and in addition, it is possible to reduce the inertia of the portion that reciprocates in the vertical direction including the slider 54 and the upper blade 55, and to cut the scrap material fed out from the press machine efficiently and at high speed.

[0114] Next, the blade shape of the cutting blade having a slope corresponding to the shear angle a shown in the formula of [Math. 3] is described using two-dimensional coordinates. Note that the blade shape of the cutting blade is specified in an xy coordinate system in which the length direction of the cutting blade is set as the x-axis direction and the moving direction of the cutting blade is set as the y-axis direction.

[0115] When Kfc * t 2 *n*s*r / 2T in the formula of [Math. 3] is set as A, the formula of [Math. 3] can be rewritten as the formula of [Math. 4].

[0116] [Math. 4]

[0117] a = - tan -1 (A * sin θ)

[0118] ∴ tan α = -A * sin θ

[0119] In the case where the slope of the blade tip of the cutting blade in the xy coordinate system is set as dy / dx, the slope dy / dx of the blade tip can be expressed by the following equation based on the equation of [Math. 4],

[0120] [Math. 5]

[0121] dy / dx = tan α = -A * sin θ.

[0122] On the other hand, the y coordinate on the blade tip of the cutting blade is expressed by the following equation according to the rotation angle θ of the crank shaft and the crank radius r,

[0123] [Math. 6]

[0124] y = -r * (1 + cos θ).

[0125] If the equation of [Math. 6] is differentiated with respect to θ, it can be expressed by the following equation,

[0126] [Math. 7]

[0127] dy / dθ = r * sin θ.

[0128] According to the equation of [Math. 5] and the equation of [Math. 7], the following equation holds.

[0129] [Math. 8]

[0130] dx / dθ = (dy / dθ) / (dy / dx) = (r * sin θ) / (-A * sin θ) = -r / A

[0131] If the equation of [Math. 8] is integrated with respect to θ, the x coordinate on the blade tip of the cutting blade can be expressed by the following equation,

[0132] [Math. 9]

[0133] x = -(r / A) * θ + C = -(r / A) * θ + (r / A) * π = (r / A) * (π - θ)

[0134] where C: integration constant, A = Kfc * t 2 *n * s * r / 2T.

[0135] Therefore, the coordinates (x, y) on the blade tip of the cutting blade are expressed by the following equation according to the equation of [Math. 6] and [Math. 9],

[0136] [Math. 10]

[0137] x = (r / A) * (π - θ)

[0138] y = -r(1 + cos θ)

[0139] where A = Kfc*t 2 *n*s*r / 2T, θ: 0 ~ π.

[0140] Further, when set to y = -r(1 + cos θ) = h (h0≤ h ≤ hi: h0is a cutting end height, hiis a cutting start height),

[0141] cos θ = -h / r - 1

[0142] ∴ θ = cos -1 (-h / r - 1)

[0143] [mathematical formula 10] The formula can be rewritten as the following formula,

[0144] [mathematical formula 11]

[0145] x = (r / A) {π - cos -1 (-h / r - 1)}

[0146] y = h

[0147] where A = Kfc*t 2 *n*s*r / 2T.

[0148] Figure 7 is a graph showing an example of a blade shape of a cutting blade.

[0149] The blade shape of the cutting blade can be calculated, for example, by appropriately assigning the constant and the variable h in the formula of [mathematical formula 11]. Note that the details will be described later.

[0150] Figure 7 (A) of shows a blade shape when the cutting blade is a single blade, Figure 8 (B) of shows a blade shape when the cutting blade is a double blade.

[0151] As shown in (A) and (B) of Figure 9 , the height of the cutting blade is the same in the single blade and the double blade, but the inclination angle corresponding to the shearing angle α is larger in the double blade than in the single blade.

[0152] Next, the formula of [mathematical formula 11] is input with the constants shown below, and further, when the difference (hi-h0= 6 [mm]) between the cutting start height hiand the cutting end height h0of the cutting blade is equally divided into 50, the x coordinates corresponding to each y coordinate on the blade tip of the cutting blade are calculated.

[0153] <Constants>

[0154]

[0155] Figure 8 and Figure 9 are graphs showing the calculation results of the xy coordinates and the like of the cutting edge.

[0156] Figure 8 indicates the calculation results of the xy coordinates and the like of 0 to 25 points of 51 points of the y coordinates on the tip of the cutting edge and the x coordinates corresponding to the y coordinates when the height of the cutting edge (the difference between the cutting start height and the cutting end height) is equally divided by 50, Figure 9 indicates the calculation results of the xy coordinates and the like of the remaining 26 to 50 points.

[0157] In addition, in Figure 8 and Figure 9 , in addition to the xy coordinates of 0 to 50 points, the rotation angle θ [rad], [deg] of the crank shaft and the shearing angle α [rad], [deg] corresponding to 0 to 50 points, respectively, are also shown. Note that, Figure 10 and Figure 8 the x-offset in

[0158] Figure 9 is a graph showing the blade shape of the cutting edge in which the xy coordinates of 0 to 50 points on the tip of the cutting edge shown in Figure 10 and ​ are plotted.

[0159] ​ The graph shown in

[0160] [Others]

[0161] In the present embodiment, the inclination is not provided in the lower blade (fixed blade), but the inclination that continuously changes is provided in the upper blade (moving blade), whereby the shearing angle α formed by the fixed blade and the moving blade is continuously changed from the start of the cutting of the waste material to the end of the cutting, but on the contrary, the inclination can not be provided in the moving blade, but the inclination that continuously changes can be provided in the fixed blade, whereby the shearing angle α formed by the fixed blade and the moving blade is continuously changed from the start of the cutting of the waste material to the end of the cutting.

[0162] In addition, in the present embodiment, as the crank mechanism that reciprocally drives the upper blade (moving blade) in the up-and-down direction, a dead lever yoke mechanism is adopted, but it is not limited thereto, and for example, a slider-crank mechanism that links the eccentric portion of the crank shaft and the slider by a connecting rod can be applied. In the case where the connecting rod ratio (connecting rod length / crank radius) of the slider-crank mechanism is relatively large, the slider moves in a substantially sinusoidal manner, and thus the calculation formula used in the dead lever yoke mechanism can be used as it is. Note that the larger the connecting rod ratio, the more suitable it is for high speed.

[0163] In addition, the present application is not limited to the above-described embodiments, and various modifications can of course be made within the scope of the present application.

Claims

1. A scrap cutting machine provided in a rear stage of a press machine, and cutting a scrap material fed out from the press machine, characterized by comprising: a slide driven in an up-and-down direction by a crank mechanism; an upper blade attached to the slide; and a lower blade attached to a fixed portion, and cutting the scrap material by cooperation with the upper blade, wherein a shearing angle formed by the upper blade and the lower blade is an angle that gradually decreases from a start of cutting the scrap material to an end of cutting the scrap material, and in a case where a driving torque of a crank shaft of the crank mechanism is constant and the scrap material of a cutting allowable limit is cut, the shearing angle at a shearing position of the scrap material gradually decreases as a pressing force of the upper blade gradually increases from the start of cutting the scrap material to the end of cutting the scrap material according to a rotation angle of the crank shaft, and a relationship between the pressing force of the upper blade and a shearing area of the scrap material based on the shearing angle at the shearing position is maintained as a constant angle.

2. The scrap cutting machine according to claim 1, wherein the scrap material of the cutting allowable limit is determined by a thickness of the material and a shearing resistance.

3. The scrap cutting machine according to claim 1, wherein in a case where a driving torque applied to a crank shaft of the crank mechanism is T, and a crank radius of the crank shaft is r, a tangential force F in a tangential direction of the crank shaft is expressed by the following equation, F = T / r, and in a case where a rotation angle of the crank shaft from a top dead center is θ, a pressing force P of the upper blade is expressed by the following equation, P = F / (sin θ * n * s) = T / (r * sin θ * n * s), wherein n is 1 for an asymmetrically inclined blade, and 2 for a symmetrically inclined blade, and s is a safety factor, and in a case where a thickness of the scrap material of the cutting allowable limit is t, a shearing resistance is Kfc, and the shearing angle is α, the shearing angle α is expressed by the following equation, α = t / Kfc.

4. The scrap cutting machine according to claim 3, wherein in a case where a coordinate (x, y) on a blade tip of a cutting blade of at least one of the upper blade and the lower blade in an xy coordinate system in which a length direction of the cutting blade is an x axis, and a direction orthogonal to the x axis is a y axis, the coordinate (x, y) is expressed by the following equations, x = (r / A) * (π - θ), y = -r(1 + cos θ).

5. The scrap cutting machine according to any one of claims 1 to 4, wherein the crank mechanism is a dead center rod yoke mechanism.

6. The scrap cutting machine according to any one of claims 1 to 4, wherein the cutting blade of at least one of the upper blade and the lower blade is a cutting blade having an asymmetrically inclined blade that is asymmetric with respect to a center of the cutting blade, or a symmetrically inclined blade that is symmetric with respect to the center of the cutting blade. ​ ​ ​ ​ ​ ​ ​ ​ ​ a = -tan －1 (Kfc*t 2 / 2P) = -tan －1 (Kfc*t 2 *n*s*r*sin θ / 2T). ​ ​ ​ ​ where A = Kfc*t 2 n*s*r / 2T. ​ ​ ​ ​

Images