Sheet metal processing equipment

Abstract

To provide a sheet metal processing apparatus that can efficiently manufacture high-quality component materials. [Solution] The sheet metal processing apparatus 10 is capable of cutting a sheet metal 12 formed to have a predetermined thickness using thin cutting sections 40 and 50. The apparatus includes a first cutting section 40 capable of cutting the sheet metal 12 in a predetermined position within the thickness range of the sheet metal 12, a second cutting section 50 capable of entering the thickness range of the sheet metal 12 with a different shape from the first cutting section 40 and cutting the sheet metal 12, and a control device 23 that allows the apparatus to select the cutting section to cut the sheet metal 12 from among a plurality of cutting sections, and is configured to cut the sheet metal 12 using a blade tip suitable for the situation in which the sheet metal 12 is cut.

Description

Technical Field

[0001] The present invention relates to a plate processing apparatus capable of processing a plate material by cutting.

Background Art

[0002] Conventionally, in order to manufacture components (structural members) constituting a building, a configuration using a plate processing apparatus that processes a plate material with a cutting member formed in a thin plate shape is known. For example, as a structural member used for a wall or floor portion constituting a house, a heat insulating material made of a foamed resin having heat insulating properties may be used, and a plate processing apparatus is used to process this heat insulating material into a required size. And, as a plate processing apparatus, a method has been proposed in which a cutting member is moved in the thickness direction of the plate material with respect to the positioned plate material to generate a cut in the plate material, and a high-quality structural member is manufactured by restricting deformation of the cutting member and movement of the plate material (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, while the cutting member may require rigidity due to the reaction force from the plate material, increasing the rigidity of the cutting member increases the size of the cutting member, and problems such as difficulty in efficiently manufacturing small structural members may occur. That is, there may still be room for improvement in the configuration for efficiently manufacturing high-quality structural members.

[0005] The present invention has been made to solve the above-described problems, and an object thereof is to provide a plate processing apparatus capable of efficiently manufacturing high-quality structural members. [Means for solving the problem]

[0006] To achieve this objective, the sheet metal processing apparatus described in claim 1 is: A sheet metal processing apparatus capable of cutting a sheet metal formed to have a predetermined thickness by a cutting section formed to be thin, A first cutting section capable of cutting the plate material in a fixed cutting position, The plate material can be cut in a fixed cutting position, and the shape of the portion that enters the thickness range of the plate material is different from that of the first cutting portion, The device is characterized by comprising a selection means that allows selecting a cutting section for cutting the plate material from among a plurality of cutting sections, including the first cutting section and the second cutting section.

[0007] The sheet metal processing apparatus described in claim 2 is the sheet metal processing apparatus described in claim 1, The first cutting section includes a cutting edge provided within the thickness range of the plate material that enables cutting of the plate material in either one continuous direction or the opposite direction in a given cutting position, The second cutting portion is characterized by having a cutting edge for cutting the plate material on one continuous direction side of the plate material in the cutting position, and an edge portion without a cutting edge on the opposite direction side. [Effects of the Invention]

[0008] According to the sheet metal processing apparatus described in claims 1 and 2, the sheet metal can be cut by switching between a first cutting section and a second cutting section, each having a different shape within the sheet metal's thickness range, using a selection means. This allows the cutting section to be selected to suit the situation in which the sheet metal is being cut. For example, in situations where rigidity is required in the cutting section, the sheet metal can be cut using the first cutting section, which has high rigidity, and in situations where fine-shaped cutting is required, the sheet metal can be cut using the second cutting section. Thus, the cutting section can be selected according to the situation in which the component members are to be manufactured. This has the effect of efficiently manufacturing high-quality component members. [Brief explanation of the drawing]

[0009] [Figure 1] Front view showing sheet metal processing equipment [Figure 2] Front view showing the cutting positions of the first and second cutting sections. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the accompanying drawings. Figure 1 is a front view showing a sheet metal processing apparatus 10 as an embodiment. Figure 1 schematically shows the configuration of the sheet metal processing apparatus 10, with the electrical connections between the control device 23 and each drive mechanism indicated by solid lines with arrows, and the sheet metal operating mechanism 26 indicated by a dashed line. In addition, for ease of understanding, the operating direction of the parts operated by each drive mechanism is indicated by arrows in Figure 1.

[0011] The sheet metal processing apparatus 10 is a device capable of cutting sheet metal 12, which is formed to have a certain thickness (for example, 100 mm), with a cutting member 11 that is formed in the shape of a thin sheet. It is configured to be able to manufacture one or more components (for example, thermal insulation material) from a single sheet of sheet metal 12. As shown in Figure 1, the sheet metal processing apparatus 10 has the sheet metal 12 to be processed placed on a support base 22 attached to a frame 21 placed on the floor surface F, and the relative position and orientation of the sheet metal 12 and the cutting member 11 are controlled by the control device 23 to process the sheet metal 12.

[0012] In the following explanation, the operation of the cutting member 11 that cuts (divides) the sheet metal 12 to manufacture the constituent members will be described as follows: the operation of the cutting member 11 that moves in the thickness direction of the sheet metal 12 to create a cut in the sheet metal 12 will be called the cutting operation; the operation of the cutting member 11 that moves in the opposite direction to the cutting operation to extract the cutting member 11 from the sheet metal 12 will be called the extraction operation; the direction that intersects (is perpendicular to) the thickness direction of the sheet metal 12 (i.e., the continuous direction in which the sheet metal 12 is continuous) will be called the direction of movement, and the operation of the cutting member 11 that moves relative to the sheet metal 12 in the direction of movement will be described as the division and progression operation.

[0013] The sheet metal processing device 10 can cut sheet metal 12 using only a cutting-and-advancing motion. Furthermore, by performing a cutting-and-advancing motion after a cutting motion, a portion of sheet metal 12 can be cut from a point away from the end face. Additionally, by performing an extraction motion after a cutting-and-advancing motion, a portion of sheet metal 12 can be cut all the way to a point away from the end face. The sheet metal processing device 10 can manufacture component members by combining these cutting, cutting-and-advancing, and extraction motions, and can manufacture not only rectangles but also other shapes such as trapezoids and triangles.

[0014] As shown in Figure 1, the sheet metal processing apparatus 10 includes a cutting member 11, a lower limiting member 13, a control device 23, an upper operating mechanism 24, a lower operating mechanism 25, a sheet metal operating mechanism 26, and a sheet metal positioning mechanism 27. The cutting member 11 is composed of two cutting members 11a and 11b, with a first cutting portion 40 formed by a part of the first cutting member 11a, and a second cutting portion 50, which has a different shape from the first cutting portion 40, formed by a part of the second cutting member 11b.

[0015] The cutting member 11 is composed of two cutting members 11a and 11b integrated by a fixing member 29, and the fixing member 29 is attached to a part of the upper operating mechanism 24 (the pivot axis 28a of the upper operating part 28). The upper operating part 28 is capable of sliding in the vertical direction (up and down direction in Figure 1) and the horizontal direction (left and right direction in Figure 1), and the cutting member 11 is configured to move relative to the plate material 12.

[0016] The plate material operating mechanism 26 is composed of a clamping mechanism for clamping the end of the plate material 12, a moving mechanism for moving the clamping mechanism back and forth, and a drive motor for operating each part of the mechanism, and is configured to allow the plate material 12 to move in one direction (the direction perpendicular to the plane of the paper in Figure 1). The movement of the cutting member 11 by the upper operating mechanism 24 and the movement of the plate material 12 by the plate material operating mechanism 26 are controlled by the control device 23.

[0017] The plate positioning mechanism 27 is a mechanism that positions the plate material 12 by restricting its movement. The plate positioning mechanism 27 includes a positioning member 27a that is movable along the direction in which the plate material 12 is continuous, intersecting the thickness direction of the plate material 12, and an operating mechanism that operates the positioning member 27a. The positioning member 27a operates by contacting and pressing the peripheral end face of the plate material 12 from both sides, thereby restricting the movement of the plate material 12 when the plate material 12 is cut by the cutting member 11.

[0018] The upper operating mechanism 24 is a mechanism that operates the cutting member 11 relative to the plate material 12. The upper operating mechanism 24 is provided with an operating mechanism that allows the cutting member 11 to rotate more than 360 degrees around the vertical rotation center axis C1, and an operating mechanism that allows it to rotate more than 180 degrees around the horizontal rotation center axis C2, and is configured so that the orientation of the cutting member 11 relative to the plate material 12 can be changed by the control device 23. By rotating the cutting member 11 around the rotation center axis C2, the cutting sections 40 and 50 located on the lower side of the cutting member 11 can be switched, and the cutting section for cutting the plate material 12 can be selected. The characteristic configuration and effects of the cutting member 11 will be described later with reference to Figure 2.

[0019] The lower limiting member 13 is located on both sides in the thickness direction of the lower end portion of the cutting member 11 with respect to the lower end portion, and is a member that limits the displacement amount of the lower end portion in the thickness direction within a certain range. The lower limiting member 13 is provided at a height position where the lower end portion of the cutting member 11 can enter. The lower limiting member 13 is attached to the lower operating mechanism 25 (see FIG. 1) and is configured to be operable in synchronization with the moving operation of the cutting member 11 by the upper operating mechanism 24.

[0020] Note that the lower limiting member 13 does not necessarily need to be configured to be movable in the thickness direction of the cutting member 11. For example, an integrated lower limiting member 13 having a gap portion with a certain interval as a limiting portion and a gap portion (a guiding portion) that gradually expands on one side (for example, the upper side) of the limiting portion is configured so that the gap width of the limiting portion does not fluctuate. The cutting member 11 may be guided from the guiding portion to the limiting portion with respect to this lower limiting member 13 to limit the movement of the cutting member 11 in the thickness direction. Further, the limiting portion does not necessarily need to be constituted by a flat surface, and may be constituted by other shapes such as including a curved portion. Also, the lower limiting member 13 and the lower operating mechanism 25 do not necessarily need to be provided and may be omitted, and a configuration in which cutting is performed using only the upper operating mechanism 24 may be adopted.

[0021] When processing the plate material 12, the control device 23 is a device that performs various controls including control for relatively displacing the cutting member 11 and the plate material 12. The control device 23 is constituted by, for example, a personal computer, and includes a ROM as a storage device that stores a processing program (a program for controlling the operations of each part including the upper operation mechanism 24, the lower operation mechanism 25, the plate material operation mechanism 26, and the plate material positioning mechanism 27), a RAM that temporarily stores processing data, a CPU as an arithmetic processing unit, an information input device for inputting the processing data necessary for manufacturing parts by processing the plate material 12, a keyboard, a mouse, a display, etc. Note that the control device 23 does not necessarily have to be constituted by one personal computer, and instead of this or in addition to this, a device such as a sequencer using a relay circuit may be used, or a configuration in which a plurality of computers share the control may also be used.

[0022] Next, referring mainly to FIG. 2, the cutting member 11 will be described in detail. FIG. 2(A) shows a fixed posture (a fixed cutting posture) in which the first cutting part 40 can enter within the thickness range of the plate material 12 and perform a cutting progress operation. FIG. 2(B) shows the cutting posture of the second cutting part 50. The cutting parts 40 and 50 of the cutting member 11 are formed into a shape capable of cutting the plate material 12 by relatively moving along the plate surface of the plate material 12 while maintaining a fixed posture after entering within the thickness range of the plate material 12. In a situation where the cutting parts 40 and 50 can cut the plate material 12, the fixed posture is maintained, and the posture in which the cutting parts 40 and 50 can cut the plate material 12 without performing a rotation operation or a movement in the thickness direction is defined as the fixed cutting posture.

[0023] The first cutting section 40 is configured to have a different shape in the portion that enters the thickness range of the plate material 12 compared to the second cutting section 50. Specifically, it differs in the outer shape formed by the cutting edges 42 and 52, the inclination angle of the inclined sections 43 and 53, the size of the cutting sections 40 and 50, and the presence or absence of an edge 55 where the cutting edge 52 is not formed. The cutting member 11 is configured to be able to rotate around the pivot axis C2, and is configured to allow selection of whether to use the first cutting section 40 or the second cutting section 50 to cut the plate material 12.

[0024] The operating mechanism for rotating the cutting member 11 (part of the upper operating mechanism 24) can be configured using an electrically operated motor or an operating mechanism using hydraulics or pneumatics, and the rotational movement of the cutting member 11 can be controlled by the control device 23 as a selection means. The control of the upper operating mechanism 24 may include control to select the cutting sections 40 and 50 to be used for cutting the plate material 12, depending on the shape, size, and material of the component manufactured by processing the plate material 12.

[0025] The cutting member 11 is made of a thin metal plate and is formed to have a substantially constant thickness for the majority of the piece. The first cutting section 40 has a main body 41, a cutting edge 42 capable of cutting the plate material 12, and an inclined section 43 formed so that the thickness decreases from the main body 41 to the cutting edge 42. The second cutting section 50 also has a main body 51, a cutting edge 52 capable of cutting the plate material 12, and an inclined section 53 formed so that the thickness decreases from the main body 51 to the cutting edge 52, similar to the first cutting section 40.

[0026] The first cutting portion 40 can be formed as a part of the first cutting member 11a, which is made from a single metal plate. The first cutting member 11a can be constructed by sandwiching both sides in the thickness direction (the dotted line portion in Figure 2(A)) of the end of the main body portion 41 away from the tip 44 of the blade edge 42 (the upper side in Figure 2(A)) between fixing members 29 and fixing it to the fixing members 29 using fasteners such as bolts.

[0027] The second cutting portion 50 can be formed as a part of the second cutting member 11b, which is made from a single metal plate. The second cutting member 11b, like the first cutting member 11a, can be constructed by sandwiching both sides in the thickness direction of one end of the main body portion 51 away from the tip of the blade edge 52 (the lower side in Figure 2(A)) between fixing members 29 and fixing it to the fixing members 29 using fasteners such as bolts.

[0028] The fixing member 29 is preferably set to a length that allows it to fix the entire first cutting member 11a in the thickness direction in the direction of travel (left-right direction in Figure 2) during the cutting process, and is preferably made of a highly rigid metal. This suppresses deformation of the cutting portions 40 and 50 when cutting the plate material 12, making it easier to manufacture high-quality components.

[0029] The cutting edge 42 of the first cutting section 40 is configured such that two cutting edges 42a and 42b, which are long and continuous portions extending diagonally from the tip 44 of the cutting edge 42, have a symmetrical shape. The two cutting edges 42a and 42b can be configured, for example, in the shape of an approximately isosceles triangle with the interior angle of the tip 44 set to approximately 110 degrees.

[0030] The two cutting edges 42a and 42b are set to a length such that a portion including the tip 44 protrudes from the plate material 12 when the cutting position is set to allow for cutting and advancing movement, and the cutting edge 42 is positioned throughout the entire length within the thickness range of the plate material 12. In other words, the cutting edges 42a and 42b are provided within the thickness range of the plate material 12, enabling cutting of the plate material 12 in both one continuous direction (right side in Figure 2(A)) and the opposite direction (left side in Figure 2(A)) when the cutting position is set. As a result, after the first cutting section 40 enters the thickness range of the plate material 12, it can assume a constant cutting position that allows it to advance while cutting the plate material 12 in either of the two directions (left side and right side in Figure 2(A)) where the two cutting edges 42a and 42b are formed, thereby making it easier to efficiently manufacture the constituent members.

[0031] The cutting edge 52 of the second cutting section 50 is composed of a main cutting edge 52a, which is a long, continuous portion extending diagonally downwards, and a secondary cutting edge 52b, which is a short, continuous portion extending from the tip 54 of the main cutting edge 52a toward the opposite direction (upper right side in Figure 2(B)). On the side of the second cutting section 50 where the secondary cutting edge 52b is formed, an edge portion 55 is provided where the cutting edge 52 is not formed. In other words, in the cutting position, the cutting edge 52 (main cutting edge 52a) for cutting the plate material 12 is provided on one continuous direction side of the plate material 12 (left side in Figure 2(B)) of the second cutting section 50 so as to extend over the entire length within the thickness range of the plate material 12, and on the opposite direction side, an edge portion 55 is provided where the cutting edge 52 is not formed within the thickness range of the plate material 12 in the cutting position. Therefore, in situations where the second cutting section 50 stops moving within the thickness range of the plate material 12, it is possible to avoid the cutting surface being damaged by the cutting edge 52 located on the opposite side of the direction of movement, making it easier to manufacture high-quality components.

[0032] Furthermore, the second cutting section 50 is set so that the angle between the main cutting edge 52a and the edge 55 is approximately 45 degrees, and is formed in a roughly triangular shape with a smaller angle towards the tip than the first cutting section 40. When making a cut in the plate material 12 using the cutting operation with the second cutting section 50, the edge 55 can be controlled to be in the same direction as the thickness direction of the plate material 12 (up and down direction in Figure 2), as shown in Figure 2(B). As a result, the edge 55 of the second cutting section 50 can enter the plate material 12 while remaining perpendicular to the thickness range during the cutting operation, and the side on which the edge 55 is formed can be cut so that it is in the same direction as the thickness direction of the plate material 12. Therefore, it is possible to easily form fine shapes and increase the yield, and it is also possible to easily avoid making cuts in a part of the component, making it easier to manufacture high-quality components.

[0033] Thus, with the sheet metal processing apparatus 10, the control device 23 can control the first cutting section 40 and the second cutting section 50, which have different shapes within the thickness range of the sheet metal 12. Therefore, the sheet metal 12 can be cut by selecting either the cutting section 40 or 50, which has a cutting edge suitable for the situation in which the sheet metal 12 is being cut.

[0034] Here, the first cutting section 40 and the second cutting section 50 can be configured to have multiple types of cutting sections with different shapes within the thickness range of the plate material 12. For this reason, the first cutting member 11a and the second cutting member 11b may be integrated to form the cutting member 11, or a single cutting member made from a single metal plate may be configured to include a shaped portion as the first cutting section 40 and a shaped portion as the second cutting section 50.

[0035] Furthermore, while the control device 23 has provided an example in which two cutting sections 40 and 50 with different shapes are provided as cutting sections within the thickness range of the plate material 12, it is also possible to configure the system to include three or more cutting sections. For example, one cutting member 11 may include three cutting sections.

[0036] Furthermore, it is preferable that the first cutting section 40 and the second cutting section 50 are configured to have different lengths in the direction of the cutting process when they enter the thickness range of the plate material 12 (length in the left-right direction in Figure 2). This allows for a significant difference in rigidity even when the two cutting sections 40 and 50 are made of the same plate thickness. The ratio of the lengths in the direction of the cutting process is often set so that the longer length is 1.5 times or more than the shorter length, and Figure 2 illustrates a case where the first cutting section 40 is set to be approximately twice as long as the second cutting section 50.

[0037] Furthermore, the first cutting section 40 and the second cutting section 50 are often configured to have different angles between the direction of the cutting motion and the cutting edge at the leading end of the cutting motion when they enter the thickness range of the plate material 12 and perform the cutting motion. For example, the angles between the direction of the cutting motion and the cutting edge at the leading end of the cutting motion are often configured to be 5 degrees or more different. Figure 2 illustrates a case where the first cutting section 40 is approximately 55 degrees and the second cutting section 50 is approximately 45 degrees, resulting in an angle difference of approximately 10 degrees.

[0038] The cutting edges 42, 52 and the edges 55 of the two cutting sections 40, 50 may be of different shapes. For example, they may not be limited to straight lines, but may include curved sections, or they may be formed in a bent shape or other shapes.

[0039] Furthermore, while an example was given of a case where two cutting sections 40 and 50 are switched by the rotational movement of the cutting member 11, it is not necessarily required that the cutting sections be switched by rotational movement. For example, a mounting and fixing section that supports multiple cutting members 11 in a selectable manner is installed on the upper operating section 28, and multiple cutting members 11 of different shapes can be stored in the storage position for storing the cutting members 11. The control device 23 can then control the operation to replace and attach the cutting members 11 stored in the storage position to the mounting and fixing section as needed, thereby enabling the selection of multiple cutting members 11.

[0040] Furthermore, a cutting member movement limiting section may be provided that contacts the two cutting sections 40, 50 (main body sections 41, 51) in the thickness direction to limit the movement (displacement) of the main body sections 41, 51 during the cutting and cutting operations. It is preferable to configure the cutting member movement limiting section so that a common cutting member movement limiting section can be used for both cutting sections 40, 50. For example, a cutting member movement limiting section may be provided that is movable in the thickness direction of the cutting sections 40, 50 (main body sections 41, 51) in the cutting position. In a separated position where the cutting member movement limiting section is separated from the main body sections 41, 51, the cutting section for cutting the plate material 12 can be selected by the rotational movement of the cutting member 11. During the cutting operation in which the cutting member 11 cuts the plate material 12, the cutting member movement limiting section may be moved closer to an operating position that is close to or in contact with the main body sections 41, 51.

[0041] Furthermore, in the extraction operation of the cutting member 11, a plate material movement limiting part may be provided that contacts the upper surface of the plate material 12 near the cutting member 11, thereby restricting the upward movement of a part of the plate material 12 together with the cutting member 11. It is preferable to use a common plate material movement limiting part for both cutting sections 40 and 50. For example, the two cutting members 11a and 11b may be integrated so that even when the main bodies 41 and 51 of the two cutting sections 40 and 50 rotate around the pivot axis 28a in the cutting position, they remain below the fixing member 29, and the plate material movement limiting part may be positioned near the bottom of the fixing member 29 in the cutting position.

[0042] Furthermore, it is preferable to configure the lower limiting member 13 so that a common lower limiting member 13 can be used for both cutting sections 40 and 50. For example, it is preferable to integrate the two cutting members 11a and 11b so that, in the rotational operation to select one of the two cutting sections 40 or 50, the tips of the cutting edges 42 and 52 of the two cutting sections 40 and 50 are in substantially the same position in the cutting position.

[0043] It should be noted that the present invention is not limited to the embodiments described above, and it can be easily inferred that various improvements and modifications are possible without departing from the spirit of the invention. For example, it may be implemented in the following modified form.

[0044] For example, in the above embodiment, the cutting member 11 starts the cutting operation from the upper side of the plate material 12, and the plate material 12 is positioned with its thickness in the vertical direction. However, the invention is not limited to this, and other arrangements are possible, such as arranging the cutting member 11 to start the cutting operation from the lower side of the plate material 12. That is, the cutting operation may be performed by rising and the extraction operation by descending, the plate material 12 may be positioned diagonally instead of horizontally, or the plate material 12 may be positioned vertically and the cutting member 11 may move horizontally to perform the cutting and extraction operations.

[0045] Furthermore, although the above embodiment described a case in which foamed resin insulation material is processed by the sheet material processing apparatus 10, the apparatus is not limited to this, and sheet materials formed from other materials may be processed, or sheet materials intended to have functions other than insulation (for example, soundproofing) may be processed. Also, although the case described was in which the sheet material 12 to be processed by the sheet material processing apparatus 10 is composed of a single material, the apparatus is not limited to this, and may be composed of multiple types of materials by laminating multiple layers, or may be laminated sheet materials that include one or more functional layers, such as a reflective layer such as aluminum foil that can reflect light and heat, or a waterproof layer such as a resin film that can block water, on at least one surface in the thickness direction. In this case as well, the sheet material processing apparatus 10 may be equipped with two or more cutting sections suitable for the material and specifications of each sheet material, and the control device 23 may be used to control the selection of the cutting section so that processing suitable for each sheet material is possible. [Industrial applicability]

[0046] As described above, this invention is suitable for a sheet metal processing apparatus capable of cutting sheet metal. [Explanation of Symbols]

[0047] 10: Plate processing device, 11: Cutting member, 12: Plate material, 23: Control device (part of the selection means), 24: Upper operating mechanism (part of the selection means), 40: First cutting section, 41: Main body, 42: Blade tip, 50: Second cutting section, 51: Main body, 52: Blade tip, 55: Edge

Claims

1. A sheet metal processing apparatus capable of cutting a sheet metal formed to have a predetermined thickness by a cutting section formed to be thin, A first cutting section capable of cutting the plate material in a fixed cutting position, The plate material can be cut in a fixed cutting position, and the shape of the portion that enters the thickness range of the plate material is different from that of the first cutting portion, A sheet metal processing apparatus characterized by comprising a selection means that enables the selection of a cutting section for cutting the sheet metal from among a plurality of cutting sections, including the first cutting section and the second cutting section.

2. The first cutting section includes a cutting edge provided within the thickness range of the plate material that enables cutting of the plate material in either one continuous direction or the opposite direction in the cutting position, The sheet metal processing apparatus according to claim 1, characterized in that the second cutting section is provided with a cutting edge for cutting the sheet metal on one continuous direction side of the sheet metal in the cutting position, and an edge portion without a cutting edge is provided on the opposite direction side.

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