JPS6229750Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a pipe joint for connecting a glass tube and a metal tube, and particularly to a pipe joint suitable for connecting a glass tube and a metal tube in a chromatograph.

Conventionally, in chromatography, for example,
The glass tube in the column section and the metal tube in the detection section are connected, and the sealing means is graphite ferrule (a seal made of graphite molded under high pressure into a cylindrical shape) in consideration of heat resistance and the effect on the sample inside the tube. members) are used.

However, this conventional connection structure has the following drawbacks. FIG. 1 is a sectional view illustrating the main parts of a conventional glass tube-metal tube joint, showing a metal tube 1 and a glass tube 3 whose tip is inserted into its open end 2.
This explains the measures to airtightly connect the
4 is a sealing member made of graphite ferrule, and 5 is a second cylindrical body that can move along the glass tube 3 within the first cylindrical body 6 made of a metal material and covering the outer periphery of the sealing member 4 over almost the entire length thereof. It is.

When connecting the metal tube 1 and the glass tube 3,
Although not shown, as is well known, a cap nut that is fitted from the left side of the glass tube 3 in the figure is inserted into the metal tube 1.
By screwing and tightening the screw formed on the outer periphery, the sealing member 4 is pressed toward the open end of the metal tube 1 via the second cylindrical body 5, thereby airtightly connecting the two. That is, when the second cylindrical body 5 is pushed in the direction of arrow a in the figure by tightening the cap nut,
The tip of the seal member 4 pushes the glass tube 3 from the radial direction by the action of the inner recessed surface 7 provided on the open end surface of the metal tube 1, and the inner recessed surface 7 and this glass tube 3
The glass tube 3 and the metal tube 1 are hermetically connected by the sealing effect between them. In this case, since the second cylindrical body 5 and the first cylindrical body 6 are configured separately, when the second cylindrical body 5 is pushed in to apply a predetermined pressing force to the sealing member 4, the first cylindrical body 6
prevents buckling of the sealing member 4 pressed by the second cylindrical body 5, but since its shape is cylindrical with a uniform inner diameter, a gap 8 is likely to occur between it and the open end of the metal tube 1. For this reason, the force within the seal member 4 directed toward the glass tube 3 may escape, reducing the sealing effect on the glass tube 3. Furthermore, there is a gap in the seal member 4 that is not covered on the outer circumferential surface, and the seal member is removed from the gap. It will protrude outside and cause damage. Furthermore, if the pressure on the second cylindrical body 5 is increased to compensate for the decrease in the sealing effect, an extreme force is applied to the glass tube 3, and in extreme cases, the glass tube 3 may be damaged. Furthermore, each time this joint part is attached or detached for column replacement, etc., the seal member 4 wears out faster and a new seal member 4 is required within a short period of time, resulting in poor economic efficiency. .

Furthermore, although not shown, as a modification of the conventional connection structure shown in FIG. There is also a structure in which the sealing member 4 is pressed toward the open end 2 of the metal tube 1 through the second cylindrical body 5 by tightening the screwed cap nut, thereby airtightly connecting the two. In this case, the sealing member 4 is fixed to the metal tube (first cylindrical body) 1, and not only is it difficult to remove the sealing member 4, but also when the glass tube 3 is removed or reinstalled, the sealing member 4 is fall into disrepair. Further, the pressure on the inner recessed surface 7 of the metal tube 1 is not effectively applied, and the sealing effect is also poor.

In this invention, in order to eliminate the above-mentioned disadvantages, when tightening the sealing member with the second cylindrical body, the first cylindrical body separates from the open end of the metal tube, so that the inner surface of the first cylindrical body does not create a gap. The shape has been modified so that the pressure from the sealing member also pushes the first cylindrical body toward the open end of the metal tube.

Next, one embodiment of this invention will be described.

FIG. 2 is an explanatory cross-sectional view of the main parts of a glass tube-metal tube joint according to an embodiment of the invention, and parts common to those in FIG. 1 are given the same reference numerals. In the figure, 6' is the first cylindrical body, and the inner wall 9 on the open end 2 side of the metal tube
The diameter of the part is slightly smaller than that of the other parts. As a result, when the sealing member 4 is pushed toward the open end 2 of the metal tube 1 by the second cylindrical body 5, the first cylindrical body 6' is also pushed in the axial direction, that is, toward the open end 2 of the metal tube 1. There is no gap between the tip of the first cylindrical body 6' and the open end 2. Therefore, the outer periphery of the glass tube 3 is uniformly pressed from the radial direction by the sealing member 4 to complete the seal. Further, the entire outer circumference of the sealing member 4 is covered by the first cylindrical body 6'.
As described above, it is possible to prevent the seal member 4 from protruding outside from the gap, and there is no risk of damage to the seal member 4.

As described above, this device has the first cylindrical body 6′.
By adding a clever twist to this, the seal member is pressed against the outer periphery of the glass tube with a uniform radial force, ensuring a perfect seal and preventing damage to the seal member. Therefore, it is expected that the wear and tear of the sealing member will be reduced even when attaching and detaching work such as column replacement is performed, and the sealing member that has been used once can be removed from the glass tube and reused as a sealing member for other glass tubes. Furthermore, since the tightening force of the sealing member is increased, the finishing accuracy of the outer diameter of the glass tube can be lower than that of conventional ones.

That is, in addition to changing the shape of the first cylindrical body as in this invention, since the second cylindrical body and the first cylindrical body are separated, the sealing member does not stick to the metal pipe and can be easily removed. Not only that, but the amount of pushing of the second cylindrical body, in other words, the pressing force on the sealing member, can be adjusted more freely than before, and the shape of the sealing member, especially when reused, can be adjusted more freely. Even if there are variations in shape, the pressing force on the sealing member can be maintained at a predetermined value by adjusting the pushing amount of the second cylindrical body, and since the sealing member does not protrude to the outside, damage to the sealing member can be prevented. This makes it possible to reuse the sealing member, and furthermore, there is no need to increase the finishing accuracy of the outer diameter of the glass tube as described above.

Furthermore, although the first cylindrical body in the above embodiment has been described as having a smaller inner diameter at a portion on the open end side of the metal tube, the inner diameter is gradually reduced from the second cylindrical body side toward the open end side of the metal tube. Exactly the same effect can be obtained by using a first cylindrical body having a so-called tapered inner surface. Furthermore, in this case, the force that presses the sealing member against the outer periphery of the glass tube is obtained from the first cylindrical body, so even if the inner recess in the end surface of the metal tube shown in the above embodiment is omitted, a sufficient sealing effect can be obtained in the same manner as above. You can expect it.

As detailed above, the effects of this invention are that it eliminates all the disadvantages of conventional glass tube-to-metal tube joints, such as incomplete sealing, damage to the glass tube, and wear and tear on the sealing members, making it easier to handle. Therefore, it is possible to realize a glass tube-metal tube joint with excellent functionality and less wear and tear on the sealing member.

[Brief explanation of the drawing]

FIG. 1 is a sectional view illustrating a main part of a conventional glass tube-metal pipe joint, and FIG. 2 is a sectional view illustrating a main part of a glass tube-metal pipe joint according to an embodiment of the present invention. 1: Metal tube, 2: Open tube, 3: Glass tube, 4:
Seal member, 5: second cylindrical body, 6, 6': first cylindrical body, 7: inner recessed surface, 8: between.

Claims (1)

[Scope of utility model registration request] Fitting a cylindrical sealing member around the outer periphery of a glass tube whose tip end is inserted into the open end of the metal tube, further covering the outer periphery of this sealing member with a first cylindrical body made of a metal material,
Pressing the end surface of the sealing member against the open end surface of the metal tube using a suitable tightening means via a second cylindrical body that can move along the glass tube within the first cylindrical body,
A glass tube-metal tube joint that seals between a glass tube and a metal tube, characterized in that the inner diameter of the open end side of the metal tube of the first cylindrical body is smaller than that of the other side. Glass tube-metal pipe joint.