JP2002292495A - Cutting device for hot billet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting device for a hot billet capable of drastically improving the life of a blade to a large extent as well as reducing cutting loss of a grinding stone at the time of re-cutting. SOLUTION: The cutting device 5 for the hot billet has a substantially tubular revolving blade 6 having a plurality of blades 8 in the circumferential direction and by rotating the revolving blade 6 and pressing the blade to the surface of the hot billet, the surface of the hot billet is cut. The cutting edge 8a of the blade 8 is quench-treated by quenching depth of the smaller cutting limit blade length T between a cutting limit blade length decided by the cutting limit torque owing to lowering of the rotation speed of the revolving blade 6 and a cutting limit blade length decided from the limit pressing force of the pressing means 10 to press the revolving blade 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for cutting a hot billet, and more particularly, to a bump formed at a joint between a trailing end of a preceding billet and a leading end of a succeeding billet after rough rolling. The present invention relates to a hot billet cutting device suitable for use in a hot slab joint ridge removal device for removing a portion.

[0002]

2. Description of the Related Art In recent hot rolling of steel, poor biting at the tip of a slab, narrowing of the rear end of a slab, trouble running on a run-out table at the tip of a slab, and dimensional defects at the front and rear ends of a slab. In order to prevent such a situation, so-called endless rolling is employed, in which the rear end of the preceding steel slab and the front end of the succeeding steel slab are successively rolled while being successively joined between the rough rolling and the finish rolling. In the endless rolling, a joining device for joining a preceding steel slab and a following steel slab includes a device using induction heating and a device using friction welding.

[0003] In this endless rolling, when the rear end of the preceding slab and the front end of the following slab are joined, a bulge protruding from the front and back surfaces of the slab is generally formed at the joint. It is a target. When the slab joined with this ridge is finish-rolled, the ridge falls down, the base material of the slab becomes extremely thin with the increase in the number of passes, and eventually the plate breaks. There is.

[0004] In order to prevent the plate breakage, various devices have been proposed for removing a raised portion generated at a joint portion before finish rolling. For example, Japanese Patent Application Laid-Open No. 63-160707 discloses that a raised portion and an oxide scale generated at a joint are
There is disclosed a hot rolling facility for cutting and removing a plurality of blades having different heights attached to a vertically movable tool rest. Further, Japanese Patent Application Laid-Open No. Hei 7-241601 discloses a protruding portion removing apparatus for cutting and removing a protruding portion generated at a joint portion by rotating a rotary blade having a plurality of blades extending in the width direction of a steel piece. I have.

A protruding portion removing apparatus for removing a protruding portion by rotating a rotary blade as disclosed in Japanese Patent Application Laid-Open No. Hei 7-241601 is, for example, a continuous hot rolling equipment for hot-rolled steel strip shown in FIG. Applied to The rolling equipment includes a rough rolling mill 101, a coil box 102 for winding and rewinding a billet after the rough rolling, and a crop shear 10 for removing a defective shape portion at a leading end and a trailing end of the billet.
3, a movable joining device 104 for joining by heating and pressing the rear end of the preceding steel slab S1 and the front end of the following steel slab S2;
A protruding portion removing device 105 having a rotary blade 106 for removing a protruding portion formed at a joining portion between a rear end portion of the preceding steel piece S1 and a front end portion of the following steel piece S2 by rotational driving; A plurality of stands F for continuously rolling the finished billet
1, F2...

Accordingly, the billet roughly rolled by the rough rolling mill 101 is wound up by the coil box 102, and when the billet is unwound, the defective shape at the leading end and the trailing end is removed by the crop shear 103. You. Then, the rear end of the preceding preceding steel slab S1 and the front end of the following succeeding steel slab S2 are joined by the joining device 104. At the time of this joining, as shown in FIGS. 7A and 7B, a raised portion S4 is formed at the joined portion S3 and an unjoined portion S5 is formed at both ends in the width direction, and the raised portion S4 is formed by the raised portion removing device 105. Is removed by the rotary blade 106. Then, the steel slab from which the protruding portion S4 has been removed is rolled to a predetermined thickness by the finish rolling mill 107 to be a product.

Here, the structure of the bump removing device 105 will be described in more detail with reference to FIG. As shown in FIG. 7, the protruding portion removing device 105 includes a pair of upper and lower rotating blades 1 installed on upper and lower sides of a preceding steel piece S1 and a following steel piece S2.
06, a bearing box (not shown) for rotatably supporting both ends of the rotary shaft 109 of each rotary blade 106, and a pressing cylinder 110 for raising and lowering the bearing box with respect to the joint S3. A drive motor (not shown) is connected to the rotating shaft 109 of each rotary blade 106, and the rotary motor 106 is driven to rotate by this drive motor. And
Each rotary blade 106 has a preceding billet S1 on the surface of the cylindrical body.
And a plurality of blades 108 extending in the width direction of the succeeding billet S2. Each rotary blade 106 has a steel slab S1,
By rotating the upper and lower blade gaps to the sheet thickness equivalent (usually 1 to 5 mm thinner than the sheet thickness) by operating the pressure reduction cylinder 110 while rotating in the rotation direction opposite to the conveyance direction of S2, the preceding billet The raised portion S4 formed at the joint S3 between the rear end of S1 and the front end of the subsequent billet S2 is
8 to remove by cutting.

[0008]

However, this conventional device for removing a raised portion of a joint has the following problems. That is, as shown in FIG. 8, the blade 108 of the rotary blade 106 has a substantially triangular cross section, and the blade is hardened 108 a prior to using the rotary blade for smooth cutting. Used in state. If the cutting of the protruding portion S4 is continued, the cutting edge is worn and the use limit is reached, so that re-cutting is generally performed at that time. In this re-cutting, the hardened layer 108a
Is about the same hardness as the blade cutter (Shore hardness Hs>
70), and the processing is difficult, so that re-cutting was performed after grinding and removing the quenched layer 108a with a grindstone. For this reason, the depth of the quenched layer 108a is determined randomly, and when the depth is deep, the portion to be ground by the grindstone becomes large, resulting in a large grinding loss.

In the above-mentioned re-cutting, if a material harder than the quenched layer 108a, for example, a diamond tool, is used for the cutting cutter, a portion to be ground by a grindstone becomes unnecessary, so that no grinding loss occurs. However, these tools are expensive and are not suitable for use. There is also a method of annealing the quenched layer 108a of the cutting edge to soften the hardness and using a normal cutting cutter. However, this method is rather expensive, and is not an appropriate method.

On the other hand, when the quenching depth of the quenched layer 108a is made shallow, the quenched layer 108a disappears during use, and the tool life is shortened due to abnormal wear of the blade, or cutting defects occur. There was a problem.
Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to reduce a grinding loss caused by a grindstone at the time of re-cutting, and to greatly increase a tool life of a hot billet. To provide a cutting device.

[0011]

In order to solve the above-mentioned problems, the present invention provides an apparatus for cutting a hot steel billet having a substantially cylindrical rotary blade having a plurality of blades in a circumferential direction. A cutting device for a hot billet, wherein the rotating blade is pressed against the surface of the hot billet while rotating, and the cutting edge of the hot billet is cut by the rotating speed of the rotating blade. The quenching depth of the smaller cutting edge of the cutting limit blade length determined from the cutting limit torque due to reduction and the cutting limit blade length determined from the limiting pressing force of the pressing means for performing the pressing,
It is characterized by being quenched.

According to a second aspect of the present invention, there is provided an apparatus for cutting a hot billet, comprising a substantially cylindrical rotary blade having a plurality of blades in a circumferential direction. A cutting device for a hot billet, which cuts the surface by pressing against the surface of the billet, wherein the cutting edge of the blade is a cutting limit blade length determined from a cutting limit torque due to a decrease in rotation speed of the rotary blade. And a quenching process at a quenching depth corresponding to a sum of a smaller value of a cutting limit blade length determined from a limit pressing force of pressing means for performing the pressing and a quenching error.

Here, the cutting limit blade length means a wear amount limit value for compensating that cutting is possible when the blade is worn.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic explanatory view of a continuous hot rolling facility to which a hot billet cutting device according to the present invention is applied. FIG. 2 is a schematic side view of the cutting device in FIG. FIG. 3 is an enlarged view of an arrow A portion in FIG. FIG.
Is a graph showing the relationship between the load F of the rolling cylinder and the blade edge width H. FIG. 5 shows the torque Tr of the rotary blade and the blade width H.
6 is a graph showing a relationship with the graph.

In FIG. 1, the rolling equipment to which the present invention is applied is, like the rolling equipment shown in FIG. 6, a rough rolling mill 1 and a coil box for winding and rewinding a steel piece after rough rolling. 2, a crop shear 3 for removing a defective shape portion at the leading end and the trailing end of the billet, and a movement for heating and pressing and joining the trailing end of the preceding billet S1 and the leading end of the succeeding billet S2. And a joining device 4 of a type. For the heating by the joining device 4, an induction heating device for inductively heating the front and rear ends of the steel slabs S1 and S2 by an alternating magnetic field is used, but the heating and joining may be performed by friction welding. And
On the exit side of the joining device 4, there is provided a ridge removing device 5 for removing a ridge formed at a joining portion between the rear end of the preceding steel slab S1 and the tip of the following steel slab S2. Further, a finishing mill 7 including a plurality of stands F1, F2,... That continuously rolls the steel piece from which the protrusions have been removed is provided on the exit side of the protrusion removal device 5. The cutting device according to the present invention is used as the ridge removing device 5.

The steel slab roughly rolled by the rough rolling mill 1 is wound up by the coil box 2 and then unwound by the crop shear 3 when it is unwound. Then, the joining device 4 joins the rear end of the preceding preceding steel slab S1 and the front end of the following succeeding slab S2. At the time of this joining, as shown in FIGS. 7A and 7B, the joining portion S
3 and a non-joined portion S5 is formed at both ends in the width direction. Then, the protruding portion S4 is removed by the protruding portion removing device 5, and the steel pieces S1 and S2 from which the protruding portion S4 has been removed are rolled to a predetermined thickness by the finish rolling mill 7 to be a product.

Here, the structure of the ridge removing device (cutting device) 5 will be described in detail with reference to FIGS. 1 and 2. A pair of upper and lower substantially cylindrical rotary blades 6 installed on both upper and lower sides of a billet S2; a bearing box (not shown) rotatably supporting both ends of a rotary shaft 9 of each rotary blade 6; And a pressure cylinder 10 for raising and lowering the box. Each bearing box is lowered by the load F by the pressing cylinder (pressing means) 10, and the rotary blade 6 is pressed against the joint S3.
A drive motor (not shown) is connected to the rotation shaft 9 of each rotary blade 6, and the rotary motor 6 is driven to rotate by this drive motor. Each rotary blade 6 is provided with a plurality of substantially triangular blades 8 extending in the width direction of the preceding steel piece S1 and the following steel piece S2 on the surface of a cylindrical body. As shown in FIG. 3, a hardened 8a
Is given. The quenching depth of the cutting edge is determined based on the cutting limit blade length T and the quenching error ε, as described later. The hardness after quenching 8a is Shore hardness Hs
Is greater than 70.

Then, cutting is performed by pressing the rotary blade against the surface of the steel slab. That is, while the pair of upper and lower rotary blades 6 rotate in the rotation direction opposite to the conveying direction of the billets S1 and S2, the upper and lower blade gaps are reduced.
0, the rear end of the preceding steel piece S1 and the succeeding steel piece S
The protruding portion S4 formed at the tip of No. 2 is cut and removed.

If the cutting of the protruding portion S4 is continued, the cutting edge of the blade 8 which has been hardened 8a along with the cutting is changed in the direction in which the blade 8 extends (radial direction of the rotary blade) as shown in FIG. N
And the edge width H in the direction orthogonal to the N direction gradually increases. When the cutting edge width H increases, as shown in FIG. 4, the load F applied to the pressing cylinder 10 gradually increases, and when the cutting edge width H reaches a predetermined value H ₁ (mm),
Load F pressure cylinder 10, the limit load F ₁ which reduction of pressure cylinder 10 is disabled. When the blade edge width H increases, the torque Tr for rotating the rotary blade 6 gradually increases as shown in FIG.
_{At 2} (mm), the torque Tr of the rotary blade 6 becomes a limit torque Tr _{1 at} which the rotation speed is reduced, the cutting edge is clogged, and cutting becomes impossible.

In determining the cutting limit blade length T described above,
The pressing force of the pressing means, that is, the distance T ₁ from the portion where the cutting edge width H ₁ (mm) determined by the limit load F ₁ of the pressing cylinder 10 crosses to the tip of the cutting edge (this distance T ₁ is calculated from the limit pressing force of the pressing means and determined is defined as a cutting limit blade length), the distance T ₂ of the from part edge width H ₂ defined from the limit torque Tr ₁ of the rotary blade 6 (mm) to traverse to the tip of the cutting edge (in the distance T ₂ rotating blade (Defined as the cutting limit blade length determined from the cutting limit torque due to the rotation speed decrease) is defined as the cutting limit blade length T. The cutting limit blade length T determined in this way is defined as the quenching depth, and the rotary blade 6
Before being used for cutting and removing the raised portion S4, a quenching process is performed. In this way, the quenching depth of the cutting edge is minimized as required by the specifications of the device.

The cutting of the raised portion S4 by the rotary blade 6 with the quenching depth being the cutting limit blade length T is continued, and before the blade edge of the quenched blade 8a wears and the blade edge width becomes the above-mentioned H, And re-cutting is performed. When performing this re-cutting, as described above, since the quenching depth of the cutting edge is the minimum required from the specifications of the apparatus, the portion to be ground by the grindstone is small, and there is almost no grinding loss. In addition, the hardened layer 8a does not disappear during use, and the tool life is not shortened due to abnormal wear of the rotary cutter 6. In addition, since re-cutting is performed before the cutting becomes impossible due to a decrease in the rotation speed or the rolling-down cylinder cannot be lowered due to a rise in the torque, a cutting defect does not occur.

As shown in FIG. 3 (b), it is preferable that the hardening depth of the cutting edge of the rotary blade 6 is a distance obtained by adding the hardening error ε to the aforementioned cutting limit blade length T. Even if a quenching error sometimes occurs, the quenching depth does not fall below the cutting limit blade length T due to the error. The value of the quenching error ε may be determined empirically. The embodiment of the present invention has been described above, but the present invention is not limited to this, and various changes can be made. For example, the shape of the blade 8 of the rotary blade 6 is not limited to the substantially triangular cross section shown in FIG.

[0023]

As described above, according to the hot billet cutting apparatus according to the first aspect of the present invention, the quenching depth of the cutting edge of the rotary blade is limited to the cutting limit due to a decrease in the rotation speed of the rotary blade. It is determined by the smaller of the cutting limit blade length determined by the torque and the cutting limit blade length determined by the limit pressing force of the pressing means for pressing the rotary blade. For this reason, the quenching depth of the cutting edge is minimized as required by the specifications of the equipment, reducing the grinding loss due to the grindstone at the time of re-cutting, and significantly improving the tool life without quenching layer disappearing during use. Can be done.

According to the apparatus for cutting a hot billet according to the second aspect of the present invention, the hardening depth of the cutting edge of the rotary blade is determined by the cutting limit torque due to the reduction in the rotation speed of the rotary blade. The quenching depth is determined by the sum of the quenching error and the smaller value of the cutting limit blade length determined from the length and the limit pressing force of the pressing means that presses the rotary blade. The hardening depth which does not fall below the cutting edge length and can always maintain the cutting edge length can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a continuous hot rolling facility to which a hot billet cutting device according to the present invention is applied.

FIG. 2 is a schematic side view of the cutting device in FIG.

FIG. 3 is an enlarged view of a portion indicated by an arrow A in FIG. 2;

FIG. 4 is a graph showing a relationship between a load F of a rolling-down cylinder and a blade edge width H;

FIG. 5 is a graph showing a relationship between a torque Tr of a rotary blade and a blade edge width H;

FIG. 6 is a schematic explanatory view of a continuous hot rolling facility to which a conventional hot slab joining ridge removal device is applied.

7A and 7B show the ridge removing device in FIG. 6, wherein FIG. 7A is a schematic side view, FIG. 7B is a schematic plan view, and FIG. 7C is a schematic front view.

FIG. 8 is an enlarged view of a portion indicated by an arrow B in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rough rolling mill 2 Coil box 3 Crop shear 4 Joining device 5 Ridge removal device (cutting device) 6 Rotary blade 6a Abrasion part 7 Finish rolling mill 8 Blade 8a Hardening 9 Rotary shaft 10 Press-down cylinder (pressing means) S1 Leading steel piece S2 Trailing billet S3 Joint S4 Ridge S5 Unjoint H Cutting edge width T Cutting edge length ε Hardening error

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B23K 101: 16 B23K 101: 16 F term (reference) 3C022 AA02 AA07 AA10 DD08 DD13 DD17 JJ00

Claims (2)

[Claims] A rotary cutter having a plurality of blades in a circumferential direction, wherein the rotary cutter is pressed against a surface of a hot slab while rotating the rotary cutter to cut the surface; A cutting device for cutting a billet, wherein the cutting edge of the blade has a cutting limit blade length determined from a cutting limit torque due to a reduction in rotation speed of the rotary blade and a cutting limit blade length determined from a limit pressing force of a pressing unit that performs pressing. A hot billet cutting device characterized by being quenched at a quenching depth corresponding to the smaller blade length. 2. A hot working machine comprising a rotary cutter having a substantially cylindrical shape having a plurality of blades in a circumferential direction, wherein the rotary cutter is pressed against the surface of a hot slab while rotating. A cutting device for a billet, wherein the cutting edge of the blade has a cutting limit blade length determined from a cutting limit torque due to a reduction in rotation speed of the rotary blade and a cutting limit blade length determined from a limit pressing force of a pressing unit that performs pressing. An apparatus for cutting a hot billet, which is quenched at a quenching depth corresponding to a sum of a smaller value and a quenching error.