JP2001088318A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet recording apparatus which can stably supply ink from an ink tank. SOLUTION: An ink tank 20 prevents by a seal member 66 ink supplied from a first ink chamber 52 and a second ink chamber 54 from leaking to the outside. The seal member 66 has a preliminarily formed hole part crushed by a compression holder 68 urged by a spring 70 and therefore is sealed. Springs 28 and 70 are compressed by moving the ink tank 20 towards a port 22. As a result, the compression holder 68 is separated from the seal member 66 and the crushed hole part 72 is restored, so that a pipe 26 is inserted to the hole part 72. Ink can be supplied without losing a sealing performance even in the pipe of a large diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly, to an ink jet recording apparatus having an improved connection structure of a connection for supplying ink from an ink tank to a recording head.

[0002]

2. Description of the Related Art An ink jet recording apparatus in which a supply path between a recording head and an ink tank is detachably used. The supply channel is configured to be detachable,
The following structure is disclosed to keep the ink liquid-tight.

[0003] For example, Japanese Patent Application Laid-Open No. Hei 9-1887967 (US Pat. No. 5,815,182) (hereinafter referred to as Conventional Example 1) discloses that a connection portion with a head is formed of a rubber having a slit, and ink is used. A structure is disclosed in which a slit is opened by allowing a needle to be supplied to enter the slit, and the slit is sealed by the elastic force of rubber.

Japanese Patent Application Laid-Open No. H10-128992 (US Pat. No. 5,825,387) (hereinafter referred to as Conventional Example 2) and US Pat. No. 5,854,646 (hereinafter referred to as Conventional Example 3) disclose an elastic force on the ink tank side. 1 shows a structure in which a supply path is closed by a ball urged by the above. This is to ensure the liquid tightness of the ink tank by the ball, in addition to the elastic force of the rubber.

Further, Japanese Patent Application Laid-Open No. Hei 5-318661 (hereinafter referred to as Conventional Example 4) discloses an ink jet recording apparatus provided with a tube in which a head is detachable and connected by a thin and deformable elasticity imparting member. A structure capable of supplying ink is disclosed.

[0006]

In the ink jet recording apparatus of the prior art 1, since the needle is inserted into the slit, the elastic force of the rubber provided with the slit decreases with time, and there is a possibility that the ink may leak. .

Further, in the ink jet recording apparatuses of Conventional Examples 2 and 3, since the supply path is closed by the ball, ink does not leak even if the sealing property of the slit is deteriorated as in Conventional Example 1 described above. However, after the sealing property of the slit is reduced, when the needle is pulled out of the slit, it can be estimated that the ink leaks while the ball closes the supply path after the needle comes off.

Although a needle having a small diameter can be made to enter a slit made of rubber or the like in a liquid-tight manner, a pressure loss at the time of ink supply in a flow path of the needle becomes large, and ink supply at the time of printing is increased. There is a possibility that print blurring due to shortage may occur. If a pipe having a large diameter (large cross-sectional area of the flow path) is used to avoid this, a large force is required to widen the slit, and as a result, the slit may be torn, and the liquid-tight connection cannot be performed. There is an inconvenience.

Furthermore, in the prior art example 4, the connection is made by a thin and deformable elasticity imparting member, but no detailed configuration is disclosed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned disadvantages, and has as its object to provide an ink jet recording apparatus capable of supplying liquid-tight ink from an ink tank to a recording head.

[0011]

In order to achieve the above object, according to the present invention, ink is supplied from an ink tank to a recording head, and ink is discharged from the recording head onto recording paper to perform recording. An ink jet recording apparatus that performs, an ink tank in which ink is stored, an elastically deformable valve body that seals an opening of the ink tank from the outside, a hole that penetrates the valve body, and is capable of expanding and contracting, A pressing means for closing the hole by pressing a valve body, a flow path communicating with the recording head are formed therein, and a pipe member insertable into the hole and the ink tank are loaded into the recording head. And releasing means for releasing the pressing action of the pressing means on the valve body to restore the hole and allowing the pipe member to be inserted into the hole.

The operation of the first aspect of the present invention will be described.

In the ink tank, the hole of the valve body is normally closed (crushed) by the pressing action of the pressing means, so that the ink does not leak to the outside. When ink can be supplied from the ink tank to the recording head, the pipe member is released by releasing the pressing action of the pressing means against the valve body by the releasing means and restoring the hole by the elastic deformation force of the crushed valve body. Into the hole. At this time, since the pipe member is inserted while the pressing force of the pressing means is released, the hole wall surface closely adheres to the outer peripheral surface of the pipe member, and ink leakage does not occur. The tip of the pipe member reaches the inside of the ink tank, and ink is supplied to the recording head via the flow path of the pipe member.

Further, in the present invention, since the pipe member is inserted by restoring the hole formed in advance in the elastically deformable valve body, even a pipe member having a large sectional area can be easily inserted and the pipe member can be easily inserted. The hole wall surface closely adheres to the outer peripheral surface of the member, so that the sealing property can be secured. Accordingly, it is possible to suppress the pressure loss of the ink supplied from the ink tank to the recording head, and to perform a good ink supply.

According to a second aspect of the present invention, in the first aspect of the present invention, the pressing means is mounted on an outer peripheral portion of the valve body and moves in the axial direction to expand and contract the hole, And a biasing member for biasing the compression holder in a direction to close the portion. The release means is provided on the pipe member side, and moves the compression holder in a direction to press the compression holder and restore the hole. A release member, wherein the release member is pressed against the compression holder by bringing the ink tank and the pipe member close to each other.

The operation of the invention according to claim 2 will be described.

According to the present invention, when the ink tank and the pipe member are brought closer to each other, the release member presses the compression holder in the direction in which the hole is restored. The hole of the valve body that has been restored is restored. Therefore, the pipe member can be easily inserted into the hole of the valve simply by bringing the ink tank and the pipe member close to each other.

According to a third aspect of the present invention, in the first or the second aspect of the present invention, the protective cover for shielding the communication port of the flow path from the outside and the pipe member when the pipe member enters the hole of the valve body. An exposure member for moving the protective cover in the axial direction of the pipe member.

The operation of the invention according to claim 3 will be described.

When the pipe member is not inserted into the ink tank, the communication port formed at the tip of the pipe member is shielded from the outside by the protective cover,
This prevents the ink attached to the vicinity of the communication port from solidifying and clogging the communication port. On the other hand, when the pipe member is inserted into the hole of the valve body, the protection member is retracted in the pipe axial direction by the exposure member to expose the communication port to the outside, thereby forming the pipe member flow path (communication port). Make sure it communicates with the ink tank.

According to a fourth aspect of the present invention, in the first aspect of the invention, the ink tank is provided with a capillary member impregnated with ink and provided with an air communication hole. A first ink chamber, a second ink chamber having an ink free liquid level communicating with the first ink chamber and communicating with the recording head, and a meniscus disposed at a communication portion between the first ink chamber and the second ink chamber. And a forming member.

The operation of the invention according to claim 4 will be described.

When the recording head is connected to the ink tank, as the recording head ejects ink, ink is supplied from the capillary member of the first ink chamber to the second ink chamber due to negative pressure due to ink consumption. It is supplied to the recording head via a pipe member. When the ink in the first ink chamber is depleted, the air supplied from the air communication hole breaks the ink meniscus film formed by the ink meniscus forming member, and the air is gradually supplied, and the negative pressure in the second ink chamber becomes constant. Is held. Therefore, the ink can be stably ejected from the recording head.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the hole is closed by a pressing means on the pipe member side of the hole. In this case, a funnel-shaped guide portion is formed even when the device is provided.

The operation of the present invention will be described.

In the case where the pipe member approaches the valve body with the hole closed, if the positional accuracy is low, it may be difficult or impossible to insert the pipe member into the hole. However, in the present invention,
Even if the positional accuracy is low, since the funnel-shaped guide portion is provided on the pipe member side of the hole when the hole is closed, the pipe member is guided into the hole via the guide portion and is smoothly inserted.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the distal end of the pipe member has a tapered shape in which a sectional area decreases toward the distal end. Features.

The operation of the present invention will be described below.

When the pipe member approaches the valve body in a state where the hole is closed, if the positional accuracy is low, there is a possibility that the inconvenience that the pipe member is difficult to insert or cannot be inserted into the hole may occur. However, in the present invention,
Even if the positional accuracy is low, the tip is tapered, so that the pipe member can be smoothly inserted into the hole.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet recording apparatus according to a first embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 2, a sheet 1 conveyed by a conveying roller 12 is
4, the transport direction of the paper 14 (sub-scanning direction, arrow A)
The carriage 16 is arranged so as to be movable in a main scanning direction (direction of arrow B) intersecting with the direction (arrow B). The carriage 16 includes a recording head 18 that ejects black, yellow, magenta, and cyan inks toward the paper 14.

An ink tank 20 for supplying ink to the recording head 18 is configured to supply ink to the recording head 18 via a port 22.

As shown in FIG. 1, a port 22 protruding above the recording head 18 has a cylindrical base 24.
A pipe 26 disposed inside the base 24 and having a tip protruding from above, a spring 28 wound around the pipe 26, and a protective cover 30 supported by the spring 28.
It is basically composed of

The pipe 26 has a passage 32 formed therein, which communicates with the recording head 18. The pipe 26 communicates with the outside through a horizontal hole 34 formed near the tip. The tip of the pipe 26 is formed in a hemispherical shape, protrudes outside through a hole 36 formed in the protective cover 30, and is shielded from the outside by a lip seal 38 disposed in the hole 36. Have been. Therefore, it is possible to prevent the ink near the horizontal hole 34 from drying and clogging the horizontal hole 34.

The protective cover 30 has a flange 40 formed at a lower end thereof engaged with a protruding portion 42 of the base 24 and an upper portion supported by a spring 28. Therefore, the protection cover 30 moves up and down (in the direction of arrow C) due to the expansion and contraction of the spring 28, and changes the length of the pipe 26 exposed to the outside of the protection cover 30.

Also, on the outer edge of the upper surface of the protective cover 30,
The protrusion 44 is formed in contact with a flange portion 94 of the compression holder 68 described later, and a tapered surface 46 for pressing the seal member 66 is formed on the inner peripheral side.

Further, on the upper surface of the protective cover 30, an ink absorber 48 for impregnating the ink removed from the pipe 26 by the lip seal 38 when the pipe 26 is extracted from the ink tank 20 is provided.

On the other hand, the ink tank 20 is
9 has a first ink chamber 5 in which a capillary member 50 is disposed.
2, a second ink chamber 54 in which ink can freely flow,
It is basically composed of a connection portion 56 for holding the ink in a liquid-tight manner and supplying the ink to the port 22 in a liquid-tight manner.

The first ink chamber 52 is formed at the uppermost part of the housing 49, is impregnated with ink inside the capillary member 50, and is opened to the atmosphere through the air opening hole 58. In addition, it communicates with the second ink chamber 54 via an ink meniscus forming member 60 in which a minute opening is formed. Therefore, the first ink chamber 52 and the second ink chamber 54 are connected to the recording head 1 via the connection portion 56 (port 22).
When the ink is communicated with 8, the ink in the capillary member 50 moves to the second ink chamber 54 via the ink meniscus forming member 60 due to the negative pressure of the recording head 18. In addition,
When the ink in the capillary member 50 of the first ink chamber 52 is depleted, the ink is formed in the opening of the ink meniscus forming member 60 by the negative pressure of the second ink chamber 54 increased by the consumption of the ink from the first ink chamber 52. Supply by breaking the ink meniscus film. Therefore, the second ink chamber 54 that can stably supply ink to the recording head 18 communicates with the connection portion 56 through the communication hole 62.

The connecting portion 56 has a hole 64 formed in a lower portion of the housing 49 and a seal member 66, a compression holder 68 for crushing the seal member 66 to secure sealing performance, and a compression holder 68. Biasing spring 70
It is basically composed of

As shown in FIG. 3, the seal member 66 is a substantially cylindrical body having a hole 72 having a diameter of 1 to 2 mm penetrating in the axial direction. The material of the seal member 66 is preferably butyl rubber having excellent expected permeability. The thickness of the seal member 66 is set to 1 to 2 in order to crush the hole 72 by pressing.
mm is good. The hole 72 includes a conical guide portion 74 for guiding the pipe 26 therein, a seal portion 76 having a substantially constant cross-sectional area continuous with the guide portion 74, and an enlarged diameter portion 78 that expands again. Further, a flange 80 which abuts on a tapered surface 46 formed on the protective cover 30 is provided on the outer periphery of the distal end on the guide portion 74 side, and a tapered surface 90 of a compression holder 68 described later is provided on an outer periphery on the guide portion 74 side. Tapered surface 81
Are formed. A flange 82 that is locked to the projection 84 of the housing 49 is formed on the enlarged diameter portion 78 side so as to protrude outward.

Therefore, the flange 8 of the sealing member 66
A projection 84 formed in the hole 64 of the housing 49 on the second side.
The flange 82 is inserted into the opening 86 of the
Are locked by the projection 84. As a result, the flange 8
The opening 86 is closed by 2, and the ink that has reached the connecting portion 56 from the second ink chamber 54 via the communication hole 62 enters only the enlarged diameter portion 78 of the seal member 66.

A cylindrical guide member 88 is provided on the projection 84 of the hole 64 so that the compression holder 68 guided by the inner peripheral surface and urged by the spring 70 can move in the direction of arrow D. Have been.

The inner circumferential surface of the compression holder 68 has a tapered surface 9.
A base portion 92 that is set to 0, and a flange portion 94 that protrudes in an L-shape toward the outer periphery at the tip of the base portion 92 are formed. The flange portion 94 abuts the step 96 of the hole portion 64,
Alternatively, the moving range of the compression holder 68 is restricted by the flange portion 94 abutting on the guide member 88 (see FIGS. 4 and 7). A spring 70 is provided between the projection 84 and the compression holder 68, and the tapered surface 90 of the compression holder 68 urged in the direction of arrow D by the elastic force of the initially compressed spring 70 changes the tapered surface 81 of the seal member 66. Is pressed, whereby the hole 72 (seal portion 76) for communicating the second ink chamber 54 with the outside is crushed and sealed from the outside. As a result, the ink that has reached the enlarged diameter portion 78 of the seal member 66 from the second ink chamber 54 via the communication hole 62 is prevented from leaking to the outside.

Here, the relationship between the springs 28 and 70 will be described with reference to FIG. FIG. 5 shows the relationship between the force acting on the spring 28 and the spring 70 and the amount of displacement (the contraction direction is assumed to be positive), and the broken line portion of the spring 70 indicates the initial compression. Therefore, only the spring 28 is compressed until the compression force of the spring 28 and the spring 70 is balanced (the displacement of the spring 28 becomes A). This is because when the pipe 26 is inserted into the seal member 66, the protective cover 30 presses the compression holder 68 until the pipe 26 contacts the guide portion 74 of the seal member 66, and the compression holder 68 is removed from the seal member 66. This is to prevent the seal portion 76 from opening apart.

The operation of the thus configured ink jet recording apparatus 10 will be described.

First, the ink tank 20 is made to approach the recording head 18 from above, so that the port 22 enters the hole 64. As a result, as shown in FIG. 4, the protrusion 44 of the protective cover 30 contacts the flange 94 of the compression holder 68.

Here, the spring 70 is
Since the initial compression is stronger than that of the spring 28, the spring 28
Only the displacement is compressed (see FIG. 5, displacement amount 0 to displacement amount A).
As a result, the protective cover 30 moves downward together with the ink tank 20, and the pipe 26 protrudes from the protective cover 30 and abuts the guide portion 74 of the seal member 66 (see FIG. 6).

At this time, the hemispherical tip of the pipe 26 is guided by the conical guide portion 74 and moves toward the axial center of the hole 72. That is, even if the positional accuracy between the pipe 26 and the hole 72 of the seal member 66 is low, the guide 74 guides the pipe 26 to a predetermined position.

Further, when the ink tank 20 is pushed downward, the compression force of the spring 28 and the spring 70 is balanced, and the spring 70 also starts to be compressed, and is compressed until the flange 94 of the compression holder 68 comes into contact with the guide member 88. Is done. As a result, the tapered surface 90 of the compression holder 68 is separated from the tapered surface 81 of the seal member 66. Accordingly, the pressing force acting on the seal member 66 from the compression holder 68 is released, and the crushed seal portion 76 is restored to the original shape, that is, the hole having a circular cross section by the elastic force of the rubber. The tip is inserted (Fig. 7
See FIG. 5, displacement amount A to displacement amount B). At this time, since the tip of the pipe 26 has a hemispherical tapered shape, the hole 72
Easy to enter.

Thereafter, the flange 9 of the compression holder 68
When the compression of the spring 70 is stopped by the contact of 4 with the guide member 88, only the spring 28 is compressed (see FIG. 5, displacement amount B to displacement amount C). As a result, the protective cover 30 moves further downward, and most of the pipe 26 is exposed to the outside. Accordingly, the pipe 26 penetrates through the seal portion 76 of the seal member 66 of the ink tank 20 that has moved downward, and the horizontal hole 34 (the pipe 26
(See FIG. 8). That is, pipe 2
The passage 32 of No. 6 communicates with the second ink chamber 54. As a result, ink is supplied from the first ink chamber 52 and the second ink chamber 54 to the recording head 18 by the negative pressure of the recording head 18. At this time, the protective cover 3
The tapered surface 46 formed on the projection 44 of the
6 is pressed against the flange 80. As a result, the sealing member 6
The wall surface forming the sealing portion 76 of the sixth embodiment adheres tightly to the outer peripheral surface of the pipe 26 to ensure the sealing performance.

When removing the ink tank 20 from the port 22, the above procedure is reversed. That is,
By moving the ink tank 20 upward, the pipe 26 is extracted from the seal portion 76 of the seal member 66, and the tapered surface 81 of the seal member 66 is pressed by the tapered surface 90 of the compression holder 68 to push the seal portion 76. Crush to ensure sealability.

As described above, in the ink jet recording apparatus 10 according to this embodiment, the pipe 26
A hole 72 (seal portion 76) corresponding to the diameter of the ink tank 20 is formed.
In order to make the recording head 18 and the ink tank 20 communicate with each other by making the recording head 18 enter, the urging state of the compression holder 68 is released and the hole 72 is restored, so that the sealing portion 7 is restored.
6 to enter smoothly. Moreover, the protective cover 30
By pressing the compression holder 68 by the tapered surface 46 of the sealing member 66, the sealing member 66 is brought into close contact with the pipe 26, and the sealing performance is ensured.

As described above, since the seal portion 76 (hole portion 72) is formed in the seal member 66 in advance, even if the pipe 26 having a large diameter is inserted through the seal portion 76, the sealing property of the seal member 66 is impaired. Never be. Further, since the connection can be made with the pipe 26 having a large diameter, the pressure loss of the ink supply can be reduced, and the ink can be supplied satisfactorily.

Although the tip of the pipe 26 has a hemispherical shape, the shape is not limited to this. Any shape such as a conical shape may be used as long as the cross-sectional area decreases toward the tip.

Next, an ink jet recording apparatus according to a second embodiment of the present invention will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, the sealing ball 100 and the spring 1 are provided inside the enlarged diameter portion 78 of the sealing member 66.
02 is provided. That is, the ball 100 is in contact with the wall surface of the enlarged diameter portion 78 by the elastic force of the spring 102 to prevent the ink from leaking (see FIG. 9A).

When the pipe 26 enters through the seal portion 76 of the seal member 66, the pipe 26 is pressed by the pipe 26 to separate from the enlarged diameter portion 78 and release the sealed state (FIG. 9 (B)). )reference).

By adopting such a configuration, the sealing property of the ink tank 20 is further improved, and it is possible to more reliably prevent the ink from leaking during the pipe entering operation.

In the first and second embodiments, the port 2
Although the pipe 26 is provided on the side of the recording head 18 (recording head 18) and the seal member 66 is provided on the side of the ink tank 20, it may be reversed. That is, a seal member (valve element) is provided on the recording head 18 side.
And a pipe may be provided on the ink tank 20 side.

[0061]

As described above, in the ink jet recording apparatus of the present invention, the ink tank and the recording head can be connected by using a pipe member having a large diameter while maintaining the sealing property. Ink can be supplied satisfactorily.

[Brief description of the drawings]

FIG. 1 is an exploded cross-sectional view illustrating an ink tank and a port (hereinafter, referred to as a connection structure) according to a first embodiment of the present invention.

FIG. 2 is a perspective view illustrating the inkjet recording apparatus according to the first embodiment of the present invention.

FIG. 3 is a partial cross-sectional perspective view of the seal member according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a connection operation in the connection structure according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a force acting on a spring and a displacement in the connection structure according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a connection operation in the connection structure according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating a connection operation in the connection structure according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a connection operation in the connection structure according to the first embodiment of the present invention.

FIGS. 9A and 9B are diagrams illustrating a connection operation in a connection structure according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ink jet recording apparatus 18 Recording head 20 Ink tank 22 Port 26 Pipe (Pipe member) 30 Protective cover (Release means) 66 Seal member (Valve element) 68 Urging member (Pressing means) 70 Spring (Pressing means) 72 Hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Oda 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. In-house (72) Inventor Jun Isozaki 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Office (72) Inventor Yumiko Namba 2274, Hongo, Ebina-shi, Kanagawa Prefecture 2C056 EA26 KC05 KC13 KC24

Claims (6)

[Claims] 1. An ink jet recording apparatus for supplying ink from an ink tank to a recording head and discharging ink droplets from the recording head onto recording paper to perform recording, comprising: an ink tank in which ink is stored; An elastically deformable valve body that seals the opening from the outside, a hole that penetrates the valve body and is expandable, a pressing unit that closes the hole by pressing the valve body, and a recording head. A communicating flow path is formed therein, and a pipe member that can be inserted into the hole, and when the ink tank is loaded in the recording head, the pressing action of the pressing means against the valve body is released to remove the hole. An ink-jet recording apparatus, comprising: a releasing unit for restoring the pipe member so that the pipe member can be inserted into the hole. 2. The pressure means is mounted on an outer peripheral portion of a valve body, and is provided with a compression holder for moving in an axial direction to expand and contract a hole, and a biasing means for urging the compression holder in a direction for closing the hole. The release means is provided on the pipe member side and moves the compression holder in a direction to restore the hole by pressing the compression holder, and the ink tank and the pipe member are brought closer to each other. 2. The ink jet recording apparatus according to claim 1, wherein said release member is pressed against said compression holder. 3. A protective cover for shielding a communication port of the flow path from the outside, and an exposing member for moving the protective cover in an axial direction of the pipe member when the pipe member enters a hole of the valve element. The ink jet recording apparatus according to claim 1 or 2, wherein: 4. An ink tank, comprising: a first ink chamber provided with a capillary member impregnated with ink and provided with an air communication hole; and an ink tank communicating with the first ink chamber and communicating with a recording head. 4. The ink jet printer according to claim 1, further comprising: a second ink chamber having a liquid surface; and a meniscus forming member disposed at a communication portion between the first ink chamber and the second ink chamber. 5. The inkjet recording apparatus according to any one of the preceding claims. 5. A guide portion having a funnel shape is formed on the pipe member side of the hole portion even when the hole portion is closed by a pressing means. The inkjet recording apparatus according to any one of claims 1 to 4, wherein 6. The ink jet recording apparatus according to claim 1, wherein the tip of the pipe member has a tapered shape whose cross-sectional area decreases toward the tip.