JPH0597105A - Spherical object packaging method - Google Patents

Abstract

PURPOSE:To package a spherical object easily and beautifully by a method wherein after a spherical object is placed at the center of a rectangular packaging paper, corners on one diagonal of the packaging paper is lifted, and both side edges are folded in to ward the spherical object side, and at the same time, corners on the other diagonal are lifted and fixed to each other. CONSTITUTION:When a spherical object such as a lettuce, etc., is packaged, an object to be packaged A is placed at the center of a rectangular packaging paper first. Then, one corner (1a) of the packaging paper is lifted, and at the same time, the centers of respective edges (1e), (1f) of both sides of the corner are folded in to ward the object to be packaged A side, and the corner (1a) is placed on the top of the object to be packaged A. Then, another corner (1c) which is located on the opposite side from the corner (1a) is placed on the top of the corner (1a). Then, remaining corners (1b), (1d) on a diagonal are converged and fixed on the top of the object to be packaged A. By this method, an object to be packaged can be easily and beautifully packaged by the minimum necessity of a packaging paper, without generating an exposed part or the protruding of a sleeve part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging method for mechanically wrapping spherical objects such as vegetables such as lettuce and fruits such as ponkan into a wrapping paper.

[0002]

2. Description of the Related Art Conventionally, in order to maintain the freshness of vegetables, fruits, etc., it has been conventionally wrapped in a synthetic resin wrapping paper and shipped, and this wrapping work was performed manually. However, the work efficiency was poor and the packaging took time and labor. Therefore, in order to save the labor of packaging, a packaging machine for mechanically packaging is known. For example, the techniques disclosed in JP-A-3-133710 and JP-A-3-162215 are available. The former has a structure in which a package is placed in the center of the wrapping paper, the packaged object is wrapped when descending in the guide hole, and the packaged object is bound at the upper part of the packaged object. In the latter case, one of the diagonal corners is folded upward, the other corner is folded and overlapped, and then the remaining diagonal corners are sequentially wrapped.

[0003]

However, in the case of the conventional packaging method, in the case of the former technique, as shown in FIG. 15, the central portion of the side does not reach the top of the object to be packaged A and the exposed portion is not exposed. That is, a occurs. In such a case, not only the freshness is deteriorated and damage is caused, but also the appearance is poor and the commercial value is lowered. To solve this, it is necessary to make the wrapping paper large, which is wasteful and makes the wrapping paper bulky.

In the case of the latter technique, when the first pair is folded and wrapped and the remaining corners are folded and wrapped, the sleeve portion b comes out as shown in FIG. These sleeves do not come out when folded manually, so they do not come out, but when mechanically wrapped, they do not come out and the shape after packaging does not become spherical and the appearance is not good. is there.
In order to solve this, an arm that can be folded like a human hand is required, but it is very difficult to match the shape of the object to be packaged A and control, and the device becomes large, resulting in cost increase.

[0005]

In order to solve such a problem, the present invention places an article A to be packaged in the central portion of a rectangular wrapping paper 1 and one corner of the wrapping paper 1 is placed. When the part 1a is lifted, the central portions of the sides 1e and 1f on both sides thereof are folded to the side of the object to be packaged A, the corner 1a is covered on the upper part of the object to be packaged A, and then the corner 1a and a corner on the diagonal side. The portion 1c is covered on the upper side of the corner 1a, and the remaining diagonally opposite corners 1b and 1d are converged to the upper side of the article A to be fastened to the rear side of the packaging table 20 on the upper surface of the main body of the packaging apparatus B. The wrapping paper supply section E is arranged and the wrapping table 20
A packaging device in which an opening 20a is provided in the center, a packaging portion C is arranged below the opening 20a, and a fastening device D rotatable from the side of the packaging table 20 above the opening 20a is arranged. 20a is formed in a substantially T-shape, and the corners 1a, 1b, 1d of the wrapping paper 1 are connected to the tops 20b, 2 of the opening 20a.
The folding guides 21 and 21 are arranged on both sides of the base of the top portion 20b in the same direction as 0d and 20e.

Further, in the above packaging apparatus, a horizontal rod 15a is provided laterally on the upper end of a push-up arm 15 for converging the diagonally opposite corners 1b and 1d to the upper side of the article A to be packaged, and the center of the horizontal rod 15a is provided. The chuck auxiliary guide 49 made of flexible synthetic resin is provided on the upper surface of the folding second arm 12 in which the corner portion 1c is formed in a concave shape and the corner portion 1c is covered above the corner portion 1a.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The problems to be solved by the present invention and the means for solving the problems are as described above. Next, the structure of the embodiments shown in the accompanying drawings will be described. 1 is a side view of the entire packaging device of the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a perspective view showing a packaging part of the packaging device, FIG. 4 is a side view of a mounting table, FIG. 5 is a side view of a holding arm, and FIG. Is a side view of the folding first and second arms,
FIG. 7 is a side view of a sandwiching plate and a sandwiching rod, FIG. 8 is a front view of the same, FIG. 9 is a side view of a lifting arm, FIG. 10 is a perspective view showing a state immediately before a chuck, and FIG. 11 is a perspective view of a state in which a mounting table is lowered. FIG. 12 is a perspective view of the mounting table, FIG. 13 is a view showing another embodiment of the push-up arm, and FIG. 14 is a view showing the order of packaging. However, FIGS. 4 to 9 are views accurately rotated by 45 degrees.

Referring to FIG. 14, the wrapping method of the present invention will be described. A wrapping material A such as lettuce is placed substantially in the center of a rectangular wrapping paper 1 and both corners 1a on both sides of the wrapping paper 1 are placed. Side 1
e. If the center of 1f is folded as shown in (a), the corner 1a is covered and wrapped as shown in (b), and then the corner 1a
The diagonal corner 1c is covered over the corner 1a as shown in FIG. Furthermore, the remaining corners 1b and 1d on both sides are (d)
As described above, the package A is lifted to the upper side and wrapped, and the corners 1b and 1d are twisted and fixed as shown in (e) to finish the packaging. However, as for the method of fastening, even if you stick a sticker,
Alternatively, the method does not matter even if heat is applied to melt and fix.

The overall structure of the packaging device for performing the above-described packaging will be described with reference to FIGS. 1 and 2. A placing table 2 for the article A to be packaged is arranged on the right side of the main body of the packaging device B, and the packaged product A is arranged on the left side after packaging. A product storage box 3 is provided. The packaging device B is provided with a packaging unit C in the front center, a fastening device D in the upper left, and a wrapping paper supply unit E in the rear. The emergency stop switch 4 is located in the center of the front upper part, and the power switch or automatic / manual is located in the lower front. An operation panel 5 including a changeover switch, a twisting number setting switch of the fastening device D, and their display lamps is provided, manual switches 6a and 6b are provided on the upper left front surface, and a foot is provided at the front of the packaging device B. A switch 7 is provided.

Then, the packaging section C is provided in the lower front portion of the packaging apparatus B.
A cam drive motor M1 for rotating a cam drive shaft 35, which is provided with a fixed cam chain for driving the CAM, and a wrapping paper supply unit E at the upper rear part.
Of the wrapping paper conveyance motor M2, and a wrapping paper table swinging motor M for adhering one sheet on the front end of the wrapping paper 1 to the attachment 8 below
3, a fastening device turning motor M4 for reciprocally turning the fastening device D to the packaging portion C is installed in the upper part thereof, and inside the fastening device D, an elevating motor M5 for operating the chuck and moving the head 67 up and down, A pinhole motor M6 for rotating the chuck body 70 is incorporated.

In such an overall structure, when the packaging work is automatic, when the operator turns on the power and the foot switch 7 is stepped on from the standby state, one wrapping paper 1 is fed from the wrapping paper feeding section E to the wrapping table 20. When the operator is transported to the upper part and picks up the article A to be packed from the mounting table 2 and mounts it on the mounting table 9 of the packaging section C, which will be described later, the sensor detects and the packaging section C performs the packaging, and the fastening is performed. The device D pivots to the packaging section C, fastens and returns, and the operator puts the packaged product into the storage box 3. And foot switch 7
The above operation is repeated when is depressed. Since the fastening device D rotates the front of the operator to the left and right, it is dangerous to have a face or a hand on the packaging portion C above the packaging table 20. Therefore, when the foot switch 7 is stepped on, the packaging portion C operates. However, it is possible to automatically operate the wrapping paper supply unit E when the wrapping is completed. In the case of manual operation, when the manual switch 6a or the foot switch 7 is turned on, the wrapping paper 1
Is supplied, and when the manual switch 6b is pressed, the packaging section C
Then, the fastening device D is sequentially operated.

The structure of the wrapping portion C, which is an essential part of the present invention, will be described in detail. A substantially T-shaped opening 20a is provided in the center of the wrapping base 20 as shown in FIGS. Two
The top 20b of 0a is the corner 1a of the wrapping paper 1 in FIG.
And the packaging table A, which will be described later, conforms to the direction of
When it is placed on the top and the mounting table 9 is lowered, the corner 1a of the wrapping paper 1 is guided by the opening where the top 20b is located, and the wrapping paper 1 is lifted in the curved surface, and the central side of the opening. The folding guides 21 and 21 are provided on both sides of the base so that the sides 1e and 1f of the wrapping paper 1 are folded to the center side (the side of the article A to be wrapped). The folding guide 21 is made of a flexible synthetic resin or the like, and is formed in a triangular shape so as to prevent the article A to be packaged from being bent and damaged when passing through the center of the opening 20a. The wrapping paper 1 is not damaged even when it is folded down. And, a central portion 2 on a diagonal line facing the opening portion where the top portion 20b is located.
0c has a curved shape so that the corner 1c of the wrapping paper 1 can be lifted to a curved shape along the article A to be packed, and the other top 20
The d. 20e guides the corners 1b, 1d of the wrapping paper 1 so as to form a sleeve portion which is bent in a V shape.

Further, a sensor 22 such as an optical sensor or a proximity sensor for detecting the article A to be packaged is provided at an arbitrary position of the opening 20a, and when the packaging operation is carried out automatically, the article to be packaged after packaging is packaged. If you fail to pick up item A,
If the article A to be packaged still exists on the mounting table 9, the fastening device D is prevented from rotating to the front.

The packaging unit C housed in the main body of the packaging device B
As shown in FIGS. 3 to 9, a mounting table 9 is arranged in the center, and a holding arm 10 and a folding first arm 1 are provided around the mounting table 9.
1, a second folding arm 12, a sandwiching plate 13, a sandwiching rod 14, and a pushing-up arm 15 are provided, and they are lifted or rotated by the rotation of the driven arm that is in contact with the cam.

As shown in FIG. 4, the mounting table 9 has sponges 9a, 9a, ...
Is fixed, and the support rods 9b, 9b ... Are projected on the bottom surface and are fitted into the insertion holes opened on the support base 23. The mounting table 9 needs to be vertically adjusted according to the size of the article A to be packaged (however, the size of the wrapping paper is also changed at the same time). , Or the support rods 9b ', 9b' ... are made long as shown in FIG. 12, and the support rods 9b ', 9b' ... are opened at regular intervals. It is possible to change the height by inserting the locking pin 24 into the hole. A nut or the like may be screwed instead of the locking pin.

A support rod 23 is provided on the back surface of the center of the support base 23.
a is projected and is supported by a support pipe 25 via a spring so as to be able to descend by a certain distance.
6 is provided and the switch 26 is provided when the article A to be packaged is placed.
Is turned on to drive the cam drive motor M1 to start the wrapping, and the lower end of the support pipe 25 is driven by the center of the driven arm 30 and the roller 30 at the tip.
a is brought into contact, the roller 30b at the other end of the driven arm 30 is brought into contact with the cam 36, and the driven arm 30 is rotated by the rotation of the cam 36, and the mounting table 9 is moved up and down.

A pair of left and right holding arms 10 are provided as shown in FIGS. 3 and 5, and one of them will be described. The upper portion is bent in an inverted L shape, and the holding body 10a is horizontally moved through a hinge 10b at the tip. An upper end of a holding band 17 made of a flexible synthetic resin or the like is fixed to the holding body 10a so that the holding band 17 hangs downward so that the hinge 10b can rotate when the article A to be wrapped is wrapped. Both sides of the holder 10a are formed in a ring shape so that the rubber cord 16 can be locked.
The lower end of the holding arm 10 is pivotally supported by a shaft 27, and an arm 10c is projected downward to pivotally connect with a link 29.
The lower end of 9 is pivotally connected to the upper part of the elevating rod 42, and a spring 43 is externally fitted to the lower part of the elevating rod 42, and one end of a driven arm 31 of a washer 44 that locks the spring 43 is brought into contact therewith. The roller 31 a at the other end of 31 is in contact with the cam 37. By the rotation of the cam 37, the driven arm 31 is rotated like a seesaw to raise the elevating rod 42, and the holding arm 10 is rotated to the center with the lowering of the mounting table 9 from the upper part of the article A to be packaged. The lower part is wrapped with the wrapping paper 1.

The folding first arm 11 and the folding second arm 12 are arranged so as to face each other as shown in FIGS. 3 and 6, and are formed in a U shape in a front view, and have a triangular shape in a plan view at an upper end. The folding plates 11a and 12a made of synthetic resin are fixedly provided as curved surfaces so as to follow the shape of the article A to be packaged when viewed from the front. The folding plates 11a and 12a are T-shaped so that the stays 47 and 48 have a curved base side.
First folding arm 11 and second folding arm 12
It is fixed to. Then, the rubber cord 16 is locked to the stays 47 and 48.

Further, a chuck auxiliary guide 49 is fixedly provided on the upper surface of the tip of the second folding arm 12, and the chuck auxiliary guide 49 is made of a flexible and slippery synthetic resin in a "pit" shape in front view. As shown in FIG. 10, when the corners 1b and 1d of the wrapping paper 1 are lifted by the push-up arm 15 to be described later, the tips of the wrapping paper 1 are erected so as to be easily chucked, and are sandwiched by the chuck body 70. In such a case, the wrapping paper 1 is bent toward the center side, and when it is rotated backward and returned to the original position, the wrapping paper 1 is prevented from being easily pulled out.

The lower ends of the first folding arm 11 and the second folding arm 12 are pivotally supported by shafts 45 and 46, the bases of which are pivotally connected to links 50 and 51, and the other ends of the links 50 and 51 are driven arms 32a. The rollers 32c and 32d at the other ends of the driven arms 32a and 32b are pivotally connected to the cam 32a and the cams 38a and 38d, respectively.
It is in contact with b. By the rotation of the cams 38a and 38b, first, the folding first arm 11 is rotated to move the corner portion 1
The side a is folded over the article A, and the second folding arm 12 is rotated to fold the corner 1c side over the folding plate 11a above the article A. The arm 11 is returned to its original position, and the folding second arm 12 is maintained in that position until it is chucked.

As shown in FIG. 3, FIG. 7, and FIG. 8, the sandwiching plate 13 and the sandwiching rod 14 are arranged so as to face each other in the front and rear, and the sandwiching plate 13 has a sponge 13a or the like attached to the opposite side faces. To prevent damage when sandwiching the wrapping paper 1, and to form an inverted L shape with a curved inside so that the upper inner end 13b extends to the center side as much as possible to accommodate the size of the object A to be packaged. Then, the wrapping paper 1 can be sandwiched. The sandwiching rod 14 is located inside the sandwiching plate 13 and below the upper inner end 13b, and the ring portion 1 through which the rubber cord 16 is inserted at the upper end.
4a is provided, and the lower end is fixed to the shaft 52.

The lower end of the sandwiching plate 13 is also fixed to the shaft 52, an arm 57 is fixedly mounted on the shaft 52, 52, and the other ends of the arms 57, 57 are pivotally connected to links 54, 54, respectively.
The lower ends of the links 54 and 54 are pivotally connected to the elevating rod 53, and a spring 55 is externally fitted to the lower portion of the elevating rod 53 to form a washer 56.
It is locked in. One end of the driven arm 33 of the washer 56 abuts, and the roller 33a at the other end of the driven arm 33 is in contact.
Is brought into contact with the cam 39, and by the rotation of the cam 39, the elevating rod 53 is raised via the driven arm 33, and the sandwiching plate 1
3 and the sandwiching rod 14 are closed and the corner 1b.1 of the wrapping paper 1 is closed.
It sandwiches the sleeve of d. Then, the push-up arm 1 described later.
It remains closed until 5 is raised, at which time the rubber cord 1
6 wraps the wrapping paper 1 that wraps the article A to be wrapped around it in a spherical shape and closely adheres it to form a neat shape. Then, the sandwiching plate 13 and the sandwiching rod 14 are opened thereafter.

As shown in FIGS. 8 and 9, a pair of push-up arms 15 are arranged on the left and right sides, and the upper portion thereof is formed in a V shape when viewed from the front. Yoko rod 15a
As shown in FIGS. 9 and 10, the center of each is formed in a concave shape, and the corner portion 1b of the wrapping paper 1 when the push-up arm 15 rises is formed in the concave portion.
・ The sleeves on the 1d side are put together. However,
The shape of the concave portion of the horizontal rod 15a may be V-shaped or U-shaped as shown in FIG.

A sponge 15b is attached to the inside of the lower portion of the push-up arm 15 which is bent in a "V" shape.
At the time of raising 5, the wrapping paper 1 is made to closely adhere to the article A to be packaged. Then, the central portion of the push-up arm 15 is inserted and supported by the pipe 59, and the pipe 59 is pivotally supported by the shaft 60, and when the push-up arm 15 is raised, the horizontal rod 15a shown in FIG.
The pipe 59 rotates to guide the push-up arm 15 so as to wrap the wrapping paper 1 along the article A as indicated by the locus F in FIG. The lower end of the push-up arm 15 is in contact with the driven arm 34, and the roller 34a at the other end of the driven arm 34 is connected to the cam 4 by the cam 4.
0, and the driven arm 34 is rotated by the rotation of the cam 40.
The push-up arm 15 is raised via the, and the upper end is pushed up in a parabolic shape as described above. The push-up arm 15 was lowered by the weight of the driven arm 34. However, since the push-up arm 15 and the driven arm 34 may be caught during the lowering, the weight 61 is attached to the lower end to force the descent. Alternatively, the lower end of the push-up arm 15 and the tip of the driven arm 34 are connected by a chain or the like so as to eliminate a catch and to surely descend.

As described above, since the wrapping paper 1 is opened as it is after being wrapped in the wrapping portion C, the corners gathered at the upper end are fixed by the fastening device D. In this embodiment, the fastening device D has its corners twisted, but it may be heated to melt and fuse, or a seal may be attached. As shown in FIG. 1, the fastening device D of the present embodiment has an inverted L-shaped arm 65 protruding upward from the side of the body of the packaging device B.
A fastening device D is provided at the tip, and a cover 6 of the fastening device D is provided.
A touch sensor is attached to the surface 6 of the fixing device D, so that the rotation is stopped when an operator or the like touches the fixing device D when the fixing device D is rotated, thereby ensuring safety.

A head 67 is provided at the center of the lower portion of the fastening device D, and a pusher 69 for raising and lowering the head 67 by rotating the raising and lowering shaft by the raising and lowering motor M5, and a chuck protruding in a V shape. An arm 68 is provided, and a chuck body 70 made of a non-slip material such as rubber is provided at the tip of the chuck arm 68 as shown in FIG. 10. The chuck body 70 is formed with a concave portion at the center so as to further prevent slipping. is doing. Then, the head 67 is a pinhole motor M6.
It is rotated halfway before being lowered by the corner 1b of the wrapping paper 1.
Make sure that 1d does not stick out of the chuck arm 68,
When the elevating shaft switched by the solenoid is lowered, the chuck arms 68 are closed and the corner portion 1b of the wrapping paper 1 is closed.
The upper part of the 1d sleeve is chucked and rotated by the pinnacle motor M6 to be fixed. The number of twists can be selected by a switch on the operation panel 5. Then, the arm 65 rotates back to the original position and returns to the mounting table 9
Is raised, the packaging is completed, and it is put into the storage box 3 by the operator.

[0027]

With the above-mentioned structure, since the structure according to claim 1 is adopted, it becomes possible to wrap the object to be packaged neatly with the minimum necessary amount of wrapping paper without protruding of the exposed portion or the sleeve portion. It became easier to do the work.

Further, according to the second aspect of the present invention, both sides of one corner can be neatly folded inward, and the protrusion of the sleeve is eliminated. Since the sleeve portions lifted from both sides can be collectively lifted without spreading, the exposed portions are eliminated when chucking, and the chuck margin is surely obtained and chuck mistakes are eliminated. Of.
Further, since it is configured as in claim 4, the sleeve portions lifted from both sides are raised upward to facilitate chucking, and when pulling out the folding second arm, it is easily bent and slipped inward, which may damage the wrapping paper. There is no.

[Brief description of drawings]

FIG. 1 is an overall side view of a packaging device of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a perspective view showing a packaging unit of the packaging device.

FIG. 4 is a side view of a mounting table.

FIG. 5 is a side view of a holding arm.

FIG. 6 is a side view of a folding arm.

FIG. 7 is a sectional view of a sandwiching plate and a sandwiching rod.

FIG. 8 is a front view of the same.

FIG. 9 is a side view of a push-up arm.

FIG. 10 is a perspective view showing a state immediately before chucking.

FIG. 11 is a perspective view of a state where the mounting table is lowered.

FIG. 12 is a perspective view of a mounting table.

FIG. 13 is a view showing another example of the push-up arm.

FIG. 14 is a diagram showing the order of packaging.

FIG. 15 is a diagram showing a conventional packaging method.

FIG. 16 is a diagram showing a conventional packaging method.

[Explanation of symbols]

 A wrapping object B wrapping device C wrapping unit D fastening device E wrapping paper supply unit 1 wrapping paper 1a, 1b, 1d corner 12 folding second arm 15 push-up arm 15a side bar 20 wrapping base 20a opening 20b / 20d. 20e Top 21 Folding guide 49 Chuck auxiliary guide

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seto Takeno 1-32, Chayamachi, Kita-ku, Osaka-shi, Osaka Yanma Agricultural Machinery Co., Ltd.

Claims (4)

[Claims] 1. A wrapping material A is provided at the center of a rectangular wrapping paper 1.
Is placed, and when one corner 1a of the wrapping paper 1 is lifted, the central portions of the sides 1e and 1f on both sides thereof are folded toward the object to be packaged A, and the corner 1a is covered on the upper part of the object to be packaged A, Next, the corner 1a and the corner 1c on the diagonal side are covered on the upper side of the corner 1a, and the remaining diagonal corners 1b and 1d are converged and fixed on the upper side of the article A to be packaged. A method for packaging a spherical object, characterized by: 2. A wrapping paper supply section E is disposed behind the wrapping table 20 on the upper surface of the main body of the wrapping apparatus B, and an opening 2 is provided at the center of the wrapping table 20.
0a is provided, and the packaging part C is arranged below the opening 20a,
A packaging device for wrapping an article A to be packaged by a packaging section C by the packaging method according to claim 1, wherein a fastening device D rotatable from the side of the packaging table 20 is arranged above the opening 20a. 20a is formed in a substantially T-shape, and the corners 1a, 1b, 1d of the wrapping paper 1 are connected to the tops 20b, 2 of the opening 20a.
A spherical object packaging device characterized in that folding guides 21 and 21 are arranged on both sides of the base of the top portion 20b in the same direction as 0d and 20e. 3. A wrapping paper supply section E is disposed behind the wrapping table 20 on the upper surface of the main body of the wrapping apparatus B, and an opening 2 is provided at the center of the wrapping table 20.
0a is provided, and the packaging part C is arranged below the opening 20a,
A wrapping device for wrapping an object to be packaged A by a wrapping part C by a wrapping part C by arranging a fastening device D rotatable from the side part of the wrapping table 20 above the opening 20a. A horizontal rod 15a is horizontally provided on the upper end of the push-up arm 15 that converges the corners 1b and 1d to the upper side of the article A to be packaged.
A spherical object packaging device characterized in that a central portion of the horizontal rod 15a is formed in a concave shape. 4. A wrapping paper supply section E is arranged behind the wrapping table 20 on the upper surface of the main body of the wrapping apparatus B, and an opening 2 is provided at the center of the wrapping table 20.
0a is provided, and the packaging part C is arranged below the opening 20a,
A wrapping apparatus for wrapping an object to be wrapped A by the wrapping section C by arranging a fastening device D rotatable from the side of the wrapping table 20 to the upper side of the opening 20a. A spherical object packaging device characterized in that a chuck auxiliary guide 49 made of a flexible synthetic resin and having a shape of a front side is provided on the upper surface of the folding second arm 12 for covering the upper side of the corner 1a with 1c.