JP5513261B2 - Alignment transport device - Google Patents

Description

  The present invention relates to an alignment conveyance device. Specifically, the present invention relates to an alignment transport device that transports sticky solids and the like.

Due to the difficulty of automatically aligning and transporting solids that are irregular and soft, and in some cases, contain much moisture, there is no progress in apparatus or unmanned processing in the production process of processed foods.
Further, automatic alignment and conveyance is a frequent problem in the development of new products such as frozen foods. In particular, in the recent food processing industry, it is necessary to use various marine products and agricultural products as ingredients, regardless of whether they have been cooked.
However, since most of these ingredients are flexible and irregular in shape, they are easily damaged by mechanical processing, and are more likely to be stuck, making it difficult to align and convey the machine accurately. For this reason, there are many dangers, but there is often no choice but to rely on human hands.

  2. Description of the Related Art Conventionally, as a technique for automatically aligning and transporting a large amount of target solid matter supplied regardless of a transported object, an object such as a rotary feeder separates and aligns the target object in the transport process (for example, Patent Document 1). Or a phototube sensor or an image sensor that detects the number of passages (for example, see Patent Document 2). These techniques are used in a wide range of fields such as transportation of electronic parts and industrial parts, and in the food field, they are used particularly in automatic alignment and transportation processes such as confectionery.

  However, in the above transport technology, when transporting solids whose weight and shape are not uniform, the solids are not separated one by one, but a plurality of them are transported in layers or an intermittent state due to blockage occurs. Problems often occur. In particular, it is not suitable for a small number of conveyances, and there is a problem in that individual conveyance times vary. Furthermore, when the target solid matter is wet or has viscosity, the solid matter sticks to the feeder or the solid matter sticks to each other, and stable conveyance cannot be expected.

  In order to solve these problems, various techniques have been proposed. For example, food solids are adsorbed one by one through the suction holes provided in the rotating drum, and further, separated, sucked and counted by the jet air nozzle and the suction nozzle installed oppositely inside and outside the drum, and when the quantity reaches a specified value, Food solids are adsorbed one by one by an invention that stops jet air (see, for example, Patent Document 3) or an adsorption pad similarly provided on a rotating drum, and after the adsorption by jet air is released, it is counted by the chute. For example, an invention in which the shutter opens when the quantity reaches a specified value (see, for example, Patent Document 4).

  These inventions are effective for separating and counting and transporting irregular solids that are randomly transported one by one. However, the solids are not always adsorbed to each adsorption hole provided in the drum, and the necessary number is finally conveyed as long as it is a method of counting from 0 to the set number. The required time varies until Therefore, when the next process is operating at a predetermined time interval, the synchronization with the next process may not be achieved.

  On the other hand, there is a method in which an object is adsorbed, counted and transported by an arm having one or a plurality of vacuum suction ports as a method of adsorbing, counting and transferring the object in the same manner. This is superior in terms of counting fragile items within a predetermined time and filling or fixing them in place, but the object is shaped and dried, and positioning during adsorption is excellent. It is a premise that it is made. Therefore, in the case of transporting a solid material that is indeterminate and sticky and difficult to be separated and positioned in advance, the possibility of an adsorption error is large, and thus it cannot be applied as it is.

Under these circumstances, there is a technology that makes it possible to synchronize with the next process that is operating at a fixed time interval, and can accurately convey the set number of pieces. After adsorbing with a larger number of adsorption nozzles, adsorption detection is performed with a pressure sensor, and food solids are separated from the adsorption nozzle that has been charged more than the specified number, and finally at a specified time interval, the specified number (For example, refer to Patent Document 5).
That is, Patent Document 5 describes the apparatus shown in FIG. 6, and in this apparatus, a rose freezing wedge 101 as a food solid is transferred from the hopper 102 including the electromagnetic vibrator 103 to the table unit 104 as needed. Supplied. A freezing core 101 is present at the tips of the six suction nozzles 114 that descend at a fixed position. The suction nozzle 114 is moved up and down by the air cylinder 111. Above each nozzle, a pressure sensor 112 for confirming adsorption and a flexible negative pressure path 109 are installed, and are connected to a vacuum pump 116 via a header 107.

JP 2006-347578 A JP-A-10-120149 Japanese Patent Laid-Open No. 9-12143 JP-A-53-51874 JP 2002-173103 A

  However, the technique of Patent Document 5 does not require pre-positioning of an object, and is effective for a soft, moisture-containing surface and sticky, but in order to adsorb food solids once. It is necessary to arrange them so that there is no gap, and since they are adsorbed from the food solids near the adsorption nozzle, they are not necessarily discharged in the order in which they are charged. Further, when it is desired to transport a large amount of food solids at a time, it becomes difficult to accurately count and convey a set number, and at the same time, the required number of vacuum suction nozzles increases and the size of the machine also increases.

  The present invention has been devised in view of the above points, and there is no need for prior positioning of solids, and solids can be aligned and transported in the order in which solid, sticky solids are introduced. An object of the present invention is to provide an alignment transport device.

  In order to achieve the above-described object, an alignment transport device according to the present invention has a container in which a through-hole is formed and a plurality of concave and convex portions are formed on the inner surface of the through-hole, and a central axis of the through-hole. A first motion applying unit that moves the container; and a second motion applying unit that reciprocates the container along a central axis of the through hole.

Here, even if the solid material to be conveyed is sticky due to the uneven part, it becomes difficult to stick to the inner surface of the through hole, and the solids are easily separated due to resistance variation, and a large number of simultaneous conveyances Can be prevented.
In addition, since the first motion imparting unit and the second motion imparting unit apply different vector forces to the lump of solid matter on the uneven portion formed on the inner surface of the through hole of the container, the solid matter Can be separated individually and can help to deliver solids.

  Moreover, in the alignment conveyance apparatus of this invention, it is preferable that a 1st motion provision part rotates a container.

  Further, in the aligning and conveying apparatus of the present invention, when the moving speed of the forward movement and the moving speed of the backward movement are different from each other in the reciprocating movement, the solid object is obtained even when the container is parallel to the ground contact surface of the aligning and conveying apparatus. Can be easily conveyed in a certain direction.

  In the aligning and conveying apparatus of the present invention, when the container has a cylindrical shape, the solids pass in a line near the bottom of the circle, so that the separated solids are easily aligned.

  Further, when the aligning and conveying apparatus of the present invention includes an inclined portion that inclines the container at a predetermined angle with respect to the grounding surface of the aligning and conveying apparatus, the container is parallel to the grounding surface of the aligning and conveying apparatus. It is easy to convey the separated solid in a certain direction.

  Moreover, in the aligned conveying apparatus of the present invention, when the concavo-convex portion is located along a cross section that is substantially orthogonal to the central axis of the through hole, it becomes easier to smoothly convey the solid matter, and the time from charging to discharging can be shortened. .

  Moreover, in the aligned conveying apparatus of the present invention, when the ratio of the total area of the convex portion is 30 to 70% of the total area of the inner surface of the through hole, the solid material having adhesiveness is particularly difficult to stick to the inner surface of the through hole. .

  The aligning and conveying apparatus according to the present invention can align and convey solids in the order in which solid and sticky solids are charged without the need for prior positioning of the solids.

It is a schematic side view which shows an example of the alignment conveyance apparatus of this invention. It is a schematic perspective view of the alignment conveyance apparatus of FIG. It is a schematic perspective view which shows an example of the cylindrical container which comprises the alignment conveyance apparatus of this invention. It is a schematic sectional drawing when cut along the AA line of FIG. It is a schematic enlarged view of the delivery machine with a hopper which comprises the alignment conveyance apparatus of this invention. It is the schematic which shows the conventional count filling apparatus of food solid substance.

Hereinafter, embodiments of the present invention will be described with reference to the drawings to facilitate understanding of the present invention.
FIG. 1 is a schematic side view showing an example of the aligning and conveying apparatus of the present invention. FIG. 2 is a schematic perspective view of the alignment transport device of FIG. FIG. 3 is a schematic perspective view showing an example of a cylindrical container constituting the aligning and conveying apparatus of the present invention.
The aligning and conveying apparatus 1 of the present invention includes a cylindrical container 2 in which a through hole 2A is formed and a plurality of concave and convex portions are formed on the inner surface of the through hole 2A. The cylindrical container 2 is provided with a rotation guide 3 for preventing displacement in a direction substantially orthogonal to the longitudinal direction of the cylindrical container 2 and a stopper 4 for preventing displacement of the cylindrical container 2 in the longitudinal direction. It has been. The cylindrical container 2 is installed on the table 14.
In addition, the aligning and conveying apparatus 1 according to the present invention includes a rotation drive motor (an example of a first motion imparting unit) 6 that rotates the cylindrical container 2 around the central axis of the through hole 2A. A force rotating in a certain direction is transmitted from the rotational drive motor 6 to the cylindrical container 2 via the rotation transmission belt 5, and the cylindrical container 2 rotates.
In addition, the alignment transport device 1 of the present invention includes a vibration drive motor (an example of a second motion imparting unit) 12 that reciprocates the cylindrical container 2 along the central axis of the through hole 2A.
A vibration guide 7 and a vibration guide rail 8 are attached to the lower side of the table 14. A force of a predetermined swing width transmitted from the vibration drive motor 12 via the vibration transmission member 13 and the vibration transmission shaft 11 is reciprocated along the longitudinal direction of the cylindrical container 2 by the vibration guide 7 and the vibration guide rail 8 (front and rear). It is converted into motion and transmitted to the cylindrical container 2, and the cylindrical container 2 reciprocates.
That is, as shown in FIG. 3, a force that rotates in the rotational direction 21 by the rotational drive motor 6 and a force that reciprocates in the vibration direction 22 by the vibration drive motor 12 are applied to the cylindrical container 2, and the cylindrical container 2 rotates. And reciprocate.
The rotation transmission belt 5 directly transmits force to the cylindrical container 2, but the vibration transmission member 13 and the vibration transmission shaft 11 directly transmit the reciprocating force to the table 14 and are installed on the table 14. The cylindrical container 2 is reciprocated.

  Here, as long as the container can be moved around the central axis of the through-hole, the container does not necessarily have to be rotated. For example, the container moves 90 ° from the 0 ° position to one side around the central axis of the container. After returning to the 0 ° position, the pendulum movement may be performed by moving 90 ° to the other side and returning to the 0 ° position.

Moreover, as shown in FIG. 3, the recessed part 23 and the convex part 24 are not helical, but are located alternately along the cross section substantially orthogonal to the center axis line of 2 A of through-holes.
FIG. 4 is a schematic cross-sectional view taken along the line AA in FIG. 3. As shown in FIG. 4, a portion near the lowermost portion of the cylindrical container 2 is treated with an octopus ( This is an example of a solid.) 25 passes in a row.

  A delivery machine 16 is connected to one end of the cylindrical container 2. Further, the other end of the cylindrical container 2 is located on a transporter 19 having a belt band 20.

The delivery device 16 includes a hopper 15, a pair of auxiliary rollers 17, and a belt band 18, and is installed on the table 14 together with the cylindrical container 2.
Here, the delivery device 16 continuously supplies the solid matter such as the processed octopus to the cylindrical container 2. The belt band 18 is a transport mechanism whose speed and rotation direction are controlled by a sensor or the like. The auxiliary roller 17 is configured so that the central axis of the auxiliary roller 17 is substantially perpendicular to the belt band 18 and the front end surface of the auxiliary roller 17 is the belt band 18 so as not to send a large amount of amorphous solid material to the cylindrical container 2 at one time. It is installed so that it is substantially parallel to and sandwiches the amorphous solid.
Furthermore, it is preferable to install the auxiliary roller 17 so that the center axis of the auxiliary roller 17 is substantially parallel to the belt band 18 and to form a predetermined space between the belt band 18.
In addition, a wide-range photoelectric sensor is provided in the vicinity of the supply port of the delivery device 16 to the cylindrical container 2 to confirm that a large amount of amorphous solid material is not supplied to the cylindrical container 2 at the same time. It is preferable to control the belt band 18 in accordance with the detection of this.

FIG. 5 is a schematic enlarged view of a feeder with a hopper constituting the aligning and conveying apparatus of the present invention. As shown in FIG. 5, the octopus 25 is supplied to the hopper 15 of the feeder 16 having the belt band 18 as needed.
In addition, the octopus 25 is thawed when processed, and the octopus 25 sticks to each other due to the water content of the octopus 25. When a large number of octopuses 25 stick, it becomes difficult to separate. Therefore, the delivery device 16 is a mechanism that can smoothly and sequentially send out the octopus 25 to the cylindrical container 2 by the auxiliary roller 17 and the belt band 18.

  Further, the table 14 is supported by a gantry 9 having an inclination adjusting leg portion (an example of an inclined portion) 10. A vibration drive motor 12 is attached to the gantry 9. Further, the gantry 9 is tilted with respect to the ground contact surface of the aligning and conveying apparatus 1 by the tilt adjusting legs 10, so that the table 14 supported by the gantry 9 and the cylindrical container 2 installed on the table 14 are also included. Inclined with respect to the ground contact surface of the aligning and conveying apparatus 1. The cylindrical container 2 is inclined with the one end side of the cylindrical container 2 connected to the delivery device 16 facing up and the other end side of the cylindrical container 2 facing down.

Here, the container does not necessarily have a cylindrical shape as long as it is a container in which a through hole is formed and a plurality of concave and convex portions are formed on the inner surface of the through hole. , Square) or oval containers.
In addition, the alignment transport device of the present invention has a container in which a through-hole is formed and a plurality of uneven portions are formed on the inner surface of the through-hole, and a first motion imparting that moves the container about the central axis of the through-hole. And a second motion imparting section that reciprocates the container along the central axis of the through hole, the container is not necessarily inclined by a predetermined angle with respect to the ground contact surface of the aligning and conveying device by the inclination adjusting leg. It does not have to be inclined. However, by tilting the container at a predetermined angle with respect to the ground contact surface of the alignment transport device, the separated solid matter can be transported in a certain direction as compared with the case where the container is parallel to the ground contact surface of the alignment transport device. It is preferable because it is easy.
In addition, even when the container is parallel to the ground contact surface of the aligning and conveying apparatus, the second motion imparting unit, for example, increases the feeding speed and returns so that the moving speed of the forward movement and the moving speed of the backward movement are different. By reciprocating the container so as to slow down, it becomes easy to convey the solid matter in a certain direction.

The tube diameter of the cylindrical container 2 is preferably 30 to 70 mm, and the length is preferably 500 to 1000 mm. The cylindrical container 2 is preferably made of resin or metal.
Moreover, it is preferable that the ratio of the total area of the convex part 24 is 30 to 70% of the total area of the inner surface of 2 A of through-holes. Further, if a plurality of uneven portions are formed on the inner surface of the through hole 2A, the uneven portion may be formed directly on the inner surface of the through hole 2A of the cylindrical container 2, or the uneven portion may be formed directly on the inner surface of the through hole. Another cylindrical container thus formed may be inserted into the through hole 2A of the cylindrical container 2 in which the concave and convex portions are not formed on the inner surface of the through hole 2A.
The tube diameter of another cylindrical container is preferably 40 to 60 mm and the length is preferably 600 to 900 mm, and the material of the other cylindrical container is preferably stainless steel. Moreover, it is preferable that the ratio of the total area of the convex part of another cylindrical container is 40 to 60% of the total area of the through-hole inner surface of another cylindrical container.

Further, for example, when the tube diameter of the cylindrical container 2 is 20 mm, there is a possibility that the solid matter that can be transported is limited, and when the tube diameter is 80 mm, if the solid matter is small, there is a possibility that it cannot be transported. Therefore, it is not preferable.
In addition, when the length of the cylindrical container 2 is 400 mm, there is a possibility that the rotational force cannot be sufficiently applied to the solid matter, and when the length is 1100 mm, it may take time to carry out. This is not preferable because of its properties.
Moreover, when the ratio of the total area of the convex part 24 is less than 30% of the total area of the inner surface of the through-hole 2A, or when it exceeds 70%, the conveyed solid matter has adhesiveness. Since it may stick to the inside of the cylindrical container 2, it is not preferable.

  The rotational speed of the cylindrical container 2 is preferably 1 to 8 times / second, more preferably 2 to 4 times / second. The reciprocating speed of the cylindrical container 2 is 1 to 8 times / second, the pretension width is preferably 3 to 16 mm, 2 to 5 times / second, and the pretension width is 3 to 10 mm. preferable.

Further, for example, when the cylindrical container 2 is not rotated, solids cannot be separated individually, and when the rotational speed is 9 times / second or more, the solids may stick to the inside of the cylindrical container by centrifugal force. It is not preferable.
Further, for example, when there is no reciprocal movement of the cylindrical container 2, solids cannot be separated individually, and when the reciprocating speed is 9 times / second or more, the solids may be discharged without rotating. Therefore, it is not preferable. Moreover, when the swing width of the reciprocating motion is less than 3 mm or 17 mm or more, the carry-out position may be sparse when it is too small or too large.

  In addition, the inclination angle of the cylindrical container 2 with respect to the ground contact surface of the alignment transport device 1 is preferably 5 to 18 °, and more preferably 9 to 14 °. For example, when the inclination angle of the cylindrical container 2 with respect to the ground contact surface of the aligning and conveying apparatus 1 is 4 °, it may take time to carry out the solid matter and it may not be carried out smoothly. When it is 19 °, the solid matter rotates. However, it is not preferable because it may be unloaded before separation.

  In addition, for the operation and control of the alignment transport device 1 of the present invention, any suitable method, for example, a method combining detection by a photoelectric sensor and control by a personal computer, a method using a microcomputer, or pre-operation of each part, A control method using a programmable logic controller (Programmable Logic Controller = PLC) to which a stop, an operation interval, and the like are input is adopted.

Example 1
An octopus 25 that is an indefinite shape is fed from the feeder 16 with the hopper 15 to the cylindrical container 2 having a tube diameter of 50 mm, a length of 600 mm, and the ratio of the total area of the convex portion 24 being 50% of the total area of the inner surface of the through-hole 2A. A fixed amount was supplied.
Further, the table 14 on which the cylindrical container 2 was placed was tilted at an angle of 12 ° with respect to the ground contact surface of the aligning and conveying apparatus 1 by the tilt adjusting leg 10.
Further, the cylindrical container 2 is rotated in the rotational direction 21 at a speed of 3 times / second by the rotational drive motor 6 and reciprocated at a speed of 3 times / second in the vibration direction 22 by the vibration drive motor 12 (pretend width). 5 mm) and the octopus 25 were individually separated and discharged from the cylindrical container 2 to the transporter 19.
These steps were repeated intermittently and automatically.
As a result, there is no change in the state of the octopus 25 when the octopus 25 is loaded into the hopper 15 and when the octopus 25 is ejected from the cylindrical container 2, and the individual alignment conveyance is performed at a speed of 1.25 per second in the order of loading into the hopper 15. We were able to.

(Example 2)
The octopus 25 was transported in the same manner as in Example 1 except that the length of the cylindrical container 2 was 900 mm and the rotational speed of the cylindrical container 2 was 2 times / second.
As a result, there is no change in the state of the octopus 25 when the octopus 25 is charged into the hopper 15 and when the octopus 25 is discharged from the cylindrical container 2, and the individual alignment transport is performed at a speed of 1.1 per second in the order of loading into the hopper 15. We were able to. Further, the interval between the octopus was enlarged 1.14 times as compared with the case of Example 1.

(Example 3)
The octopus 25 was transported in the same manner as in Example 1 except that the swing width was 15 mm and the reciprocating speed was 4 times / second.
As a result, there is no change in the state of the octopus 25 when the octopus 25 is charged into the hopper 15 and when the octopus 25 is discharged from the cylindrical container 2, and the individual alignment transport is performed at a rate of 1.6 per second in the order of loading into the hopper 15. We were able to. Further, the interval between the octopuses was reduced by 0.78 times compared to the case of Example 1.

(Example 4)
The octopus 25 was transported in the same manner as in Example 1 except that the table 14 on which the cylindrical container 2 was placed was tilted at an angle of 14 ° with respect to the ground contact surface of the alignment transport device 1 by the tilt adjustment legs 10. .
As a result, there is no change in the state of the octopus 25 when the octopus 25 is charged into the hopper 15 and when the octopus 25 is discharged from the cylindrical container 2, and since the inclination angle is increased, the time for the octopus 25 to rotate within the cylindrical container 2 Since the time from the loading to the discharging is reduced, it was possible to carry out the individual alignment conveyance at a speed of 1.4 pieces per second in the order of loading into the hopper 15. Further, the interval between the octopuses was reduced to 0.89 times as compared with the case of Example 1.

(Comparative Example 1)
The octopus 25 was transported in the same manner as in Example 1 except that the cylindrical container 2 in which the uneven portion was not formed on the inner surface of the through hole 2A was used.
As a result, the octopus 25 having adhesiveness sticks to the inside of the cylindrical container 2 and stable supply cannot be expected in the order of loading into the hopper 15, and the octopus 25 cannot be transported in the order of loading.

(Comparative Example 2)
The octopus 25 was transported in the same manner as in Example 1 except that the cylindrical container 2 was not reciprocated.
As a result, the octopus 25 in the cylindrical container 2 lacks a means for applying a force in the transport direction. Therefore, it takes a long time from when the octopus 25 is inserted to when the octopus 25 is ejected. Could not be transported.

(Comparative Example 3)
The octopus 25 was transported in the same manner as in Example 1 except that the table 14 on which the cylindrical container 2 was placed was not inclined and was made substantially parallel to the ground contact surface of the alignment transport device 1.
As a result, although the octopus 25 could be arranged and transported in the order of loading, it took a long time until the octopus 25 was thrown out and discharged.
Further, the table 14 on which the cylindrical container 2 is placed is made substantially parallel to the grounding surface of the aligning and conveying apparatus 1, and the same as in the first embodiment except that the uneven portion on the inner surface of the through hole 2A is formed in a spiral shape. The octopus 25 was transported in the same manner. Similarly, although the octopus 25 could be aligned and transported in the order of loading, it took a long time to be discharged after the octopus 25 was loaded.

(Comparative Example 4)
The octopus 25 was conveyed in the same manner as in Example 1 except that the auxiliary roller 17 and the feeder 16 with the hopper 15 were not used.
As a result, a large amount of the octopus 25 may be thrown into the cylindrical container 2 at a time, making it difficult to carry out stable conveyance.

As described above, the aligning and conveying apparatus of the present invention rotates the cylindrical container by the rotary drive motor that rotates the cylindrical container about the central axis of the through hole, and also the cylindrical container along the central axis of the through hole. Since the cylindrical container is reciprocated by the vibration drive motor that reciprocates, the forces of different vectors are applied to the solid lump on the concave and convex portions formed on the inner surface of the through hole of the cylindrical container. The lumps can be separated individually and the solids can be sent out. Therefore, it is not necessary to pre-position the solid material, and the solid material can be aligned and conveyed in the order in which the irregular and sticky solid material is charged.
In addition, since the solids can be aligned and transported in the order in which the solids are charged, the previously charged solids do not stay in the aligning and transporting device longer than the solids charged later. Is.

  In addition, since the concave portions and the convex portions are not spiral but are alternately positioned along a cross section substantially orthogonal to the central axis of the through hole, even if the solid material to be conveyed has adhesiveness, In addition to being difficult to stick to the inner surface, due to resistance variation, solids can be easily separated from each other, and a large number of simultaneous conveyances can be prevented.

  Moreover, since a solid substance is supplied to a cylindrical container by a sending-out machine, variation in required time can be suppressed.

DESCRIPTION OF SYMBOLS 1 Alignment conveyance apparatus 2 Cylindrical container 2A Through-hole 3 Rotation guide 4 Stopper 5 Rotation transmission belt 6 Rotation drive motor 7 Vibration guide 8 Vibration guide rail 9 Mount 10 Inclination adjustment leg 11 Vibration transmission shaft 12 Vibration drive motor 13 Vibration transmission member 14 Table 15 Hopper 16 Feeder 17 Auxiliary roller 18 Belt band 19 Conveyor 20 Belt band 21 Direction of rotation 22 Direction of vibration 23 Concave part 24 Convex part 25 Octopus

Claims (5)

A container in which a through hole is formed and a plurality of concave and convex portions are formed on the inner surface of the through hole;
A first motion imparting section that rotationally moves the container around the central axis of the through hole;
A second motion imparting unit configured to reciprocate the container along the central axis of the through-hole. A container in which a through hole is formed and a plurality of concave and convex portions are formed on the inner surface of the through hole;
A first motion imparting section for pendulum motion of the container about the central axis of the through hole;
An alignment transport device comprising: a second motion imparting unit that reciprocates the container along the central axis of the through hole . The alignment transport apparatus according to claim 1, wherein, in the reciprocating motion, the moving speed of the forward movement is different from the moving speed of the backward movement. The alignment conveyance device according to claim 1, wherein the container has a cylindrical shape. The alignment conveyance device according to any one of claims 1 to 4, wherein the uneven portion is located along a cross section substantially orthogonal to a central axis of the through hole .

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