Quenching tool and method for deep blind inner hole of workpiece

Abstract

The application discloses a quenching tool and method for a deep blind inner hole of a workpiece, and belongs to the field of process manufacturing. The quenching tool comprises a plug, a positioning ring and a liquid storage tank. The plug is used for being inserted into the deep blind inner hole of the workpiece, so that the bottom of the plug is located at the bottom of the deep blind inner hole. The plug movably sleeves with the positioning ring. The positioning ring is arranged opposite to the deep blind inner hole. The outer peripheral wall of the positioning ring is provided with a plurality of spaced arms. The inner cavity of the liquid storage tank contains cooling liquid. The bottom and the top of the liquid storage tank are respectively provided with a discharge port and an air inlet. The discharge port is communicated with the top of the plug. A stop valve is arranged on the discharge port. The air inlet is used for being communicated with compressed air. The quenching tool for the deep blind inner hole of the workpiece can not only rapidly discharge the gas existing in the deep blind inner hole, improve the feeding rate of the cooling liquid, but also accelerate the cooling rate in the deep blind inner hole, and further ensure the quenching hardness in the deep blind inner hole.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of process manufacturing, and particularly relates to a quenching tool and method for deep blind inner hole of a workpiece. BACKGROUND

[0002] Quenching is one of the metal heat treatment processes, specifically, metal parts are heated to a certain temperature and then rapidly cooled in water, oil or air to improve the hardness and strength of the metal. Therefore, in order to obtain high-precision parts with ultra-high strength and ultra-high hardness, quenching treatment is needed after the size is processed in place.

[0003] However, some existing workpieces often have deep blind inner holes (length-diameter ratio not less than 1:7), and when quenching, there will be gas in the deep blind inner hole, which makes the cooling liquid enter slowly. In addition, the cooling medium in the deep blind inner hole has very poor flowability, and the cooling rate of the deep blind inner hole is low, which all leads to the hardness of the deep blind inner hole of the workpiece after quenching treatment not meeting the factory requirements. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the present application provides a quenching tool and method for deep blind inner hole of a workpiece, which aims to not only quickly discharge the gas existing in the deep blind inner hole, improve the feeding rate of the cooling liquid, but also accelerate the cooling rate in the deep blind inner hole, further ensuring the quenching hardness in the deep blind inner hole.

[0005] In a first aspect, the present application provides a quenching tool for deep blind inner hole of a workpiece, the quenching tool comprising a plug tube, a positioning ring and a liquid storage tank;

[0006] The plug tube is used for inserting into the deep blind inner hole of the workpiece, so that the bottom of the plug tube is located at the bottom of the deep blind inner hole, the positioning ring is movably sleeved on the plug tube, the positioning ring is arranged opposite to the deep blind inner hole, and the outer peripheral wall of the positioning ring has a plurality of spaced apart supporting arms to support on the end face of the workpiece.

[0007] The inner cavity of the liquid storage tank contains cooling liquid, the bottom and the top of the liquid storage tank have a discharge port and an air inlet respectively, the discharge port is communicated with the top of the plug tube, a stop valve is arranged on the discharge port, and the air inlet is used for communicating with compressed air.

[0008] Optionally, one end of each supporting arm extends radially along the positioning ring, each supporting arm has a strip-shaped hole, a positioning bolt is movably inserted in each strip-shaped hole, each positioning bolt abuts against the inner wall of the deep blind inner hole, and a locking nut is sleeved on the positioning bolt to clamp the corresponding supporting arm.

[0009] Optionally, one side of the positioning ring towards the deep blind inner hole has a reinforcing convex ring, and the reinforcing convex ring is located in the deep blind inner hole.

[0010] Optionally, the number of the arms is three, and the included angle between any two adjacent arms is 120°.

[0011] Optionally, the bottom of the cannula has a plurality of through holes, and the plurality of through holes are uniformly arranged along the circumference of the cannula.

[0012] Optionally, the top of the liquid storage tank is detachably inserted with a sealing cover, and the air inlet is located on the sealing cover.

[0013] Optionally, the first hose is inserted in the air inlet, one end of the first hose communicates with the inner cavity of the liquid storage tank, and the other end of the first hose is used for communicating with compressed air.

[0014] Optionally, the sealing cover and the top of the liquid storage tank are threadedly connected.

[0015] Optionally, the second hose is used for communicating between the stop valve and the cannula.

[0016] In a second aspect, the present application provides a quenching method for a deep blind hole of a workpiece, the quenching method is based on the quenching tool for a deep blind hole of a workpiece, and the quenching method comprises the following steps:

[0017] According to the length of the deep blind hole of the workpiece, the positioning ring is sleeved at the corresponding position of the outer periphery of the cannula, and the cooling liquid is added into the inner cavity of the liquid storage tank.

[0018] The cannula is inserted into the deep blind hole, and the plurality of arms are placed on the end face of the workpiece.

[0019] The stop valve is opened, and the compressed air is filled through the air inlet, so that the cooling liquid in the liquid storage tank is pressed into the bottom of the deep blind hole and fills the deep blind hole.

[0020] The compressed air is continuously filled, so that the cooling liquid vibrates in the deep blind hole.

[0021] Overall, compared with the prior art, the above technical scheme conceived by the present application has the following beneficial effects:

[0022] For the quenching tool for a deep blind hole of a workpiece provided by the embodiment of the present application, when the deep blind hole of the workpiece is cooled during the quenching process, first, the positioning ring is sleeved at the corresponding position of the outer periphery of the cannula according to the length of the deep blind hole of the workpiece, so that the positioning ring is sleeved at the appropriate position of the cannula, which can adapt to deep blind holes of different lengths and increase the application range of the tool. In addition, the cooling liquid is added into the inner cavity of the liquid storage tank, so that the deep blind hole is completely immersed in the cooling liquid, and the rapid cooling of the deep blind hole is ensured.

[0023] Then, the cannula is inserted into the deep blind hole, the plurality of arms rest on the end face of the workpiece, at this time the bottom of the cannula is inserted into the bottom of the deep blind hole, and the arms support the positioning ring and the cannula, avoiding the direct contact of the bottom of the cannula with the deep blind hole and damaging the deep blind hole. Then, the stop valve is opened, and compressed air is filled through the air inlet, so that the cooling liquid in the liquid storage tank is quickly pressed into the bottom of the deep blind hole and fills the deep blind hole, thereby quickly discharging the gas existing in the deep blind hole, improving the feeding rate of the cooling liquid, and ensuring the quenching hardness in the deep blind hole. Finally, continue to fill compressed air, so that the cooling liquid vibrates in the deep blind hole. By using the vibration mode, the steam film in the cooling liquid is quickly broken, and the cooling environment in the deep blind hole is improved. Since the time for forming a steam film between the cooling medium and the hot workpiece is greatly shortened, the strong convection stage is entered in advance, the cooling rate in the deep blind hole is accelerated, the quenching hardness in the deep blind hole is further ensured, and the hardness of the deep blind hole of the workpiece after quenching treatment reaches the factory requirement.

[0024] That is, the quenching tool for the deep blind hole of the workpiece provided by the embodiment of the present application not only can quickly discharge the gas existing in the deep blind hole, improve the feeding rate of the cooling liquid, but also can accelerate the cooling rate in the deep blind hole, and further ensure the quenching hardness in the deep blind hole. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic view of a quenching tool for a deep blind hole of a workpiece provided by the embodiment of the present application;

[0026] Figure 2 is a sectional view of the cannula in a use state provided by the embodiment of the present application;

[0027] Figure 3 is a top view of the positioning ring provided by the embodiment of the present application;

[0028] Figure 4 is a flow chart of a quenching method for a deep blind hole of a workpiece provided by the embodiment of the present application.

[0029] In all the drawings, the same reference signs represent the same technical features, specifically:

[0030] 1, cannula; 11, through hole; 2, positioning ring; 21, arm; 211, strip-shaped hole; 212, positioning bolt; 213, locking nut; 22, reinforcing convex ring; 3, liquid storage tank; 31, cooling liquid; 32, discharge port; 33, air inlet; 34, stop valve; 35, sealing cover; 4, first hose; 5, second hose; 100, workpiece; 110, deep blind hole. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, the following further describes the present application with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present application and not to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0032] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0033] In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0034] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0036] Embodiment:

[0037] Figure 1 is a structural schematic view of a quenching tool for a deep blind hole of a workpiece provided by an embodiment of the present application, as shown in the figure, the quenching tool comprises a pipe 1, a positioning ring 2 and a liquid storage tank 3. Figure 1 The pipe 1 is used to be inserted into the deep blind hole 110 of the workpiece 100, so that the bottom of the pipe 1 is located at the bottom of the deep blind hole 110, the positioning ring 2 is movably sleeved on the pipe 1, the positioning ring 2 is arranged opposite to the deep blind hole 110, the outer peripheral wall of the positioning ring 2 has a plurality of spaced arms 21 to support on the end face of the workpiece 100.

[0038] Figure 2 is a sectional view of the pipe in use, as shown in the figure, the pipe 1 is used to be inserted into the deep blind hole 110 of the workpiece 100, so that the bottom of the pipe 1 is located at the bottom of the deep blind hole 110, the positioning ring 2 is movably sleeved on the pipe 1, the positioning ring 2 is arranged opposite to the deep blind hole 110, the outer peripheral wall of the positioning ring 2 has a plurality of spaced arms 21 to support on the end face of the workpiece 100. Figure 2

[0039] The inner cavity of the liquid storage tank 3 contains cooling liquid 31, the bottom and the top of the liquid storage tank 3 have discharge port 32 and air inlet 33 respectively, the discharge port 32 is communicated with the top of the pipe 1, and the discharge port 32 is provided with a stop valve 34, and the air inlet 33 is used to communicate with compressed air.

[0040] For the quenching tool for the deep blind hole of the workpiece provided by the embodiment of the present application, when the deep blind hole 110 of the workpiece 100 is cooled in the quenching process, first, the positioning ring 2 is sleeved on the corresponding position of the outer periphery of the pipe 1 according to the length of the deep blind hole 110 of the workpiece 100, so that the positioning ring 2 is sleeved on the appropriate position of the outer periphery of the pipe 1, which can adapt to deep blind holes 110 of different lengths and increase the application range of the tool. In addition, cooling liquid 31 is added to the inner cavity of the liquid storage tank 3, so that the deep blind hole 110 is fully immersed in the cooling liquid 31, and the rapid cooling of the deep blind hole 110 is ensured.

[0041] ​Then, the insertion tube 1 is inserted into the deep blind hole 110, and the plurality of supporting arms 21 rest on the end face of the workpiece 100, at this time, the bottom of the insertion tube 1 is inserted into the bottom of the deep blind hole 110, and the supporting arms 21 play the role of supporting and positioning the ring 2 and the insertion tube 1, avoiding the direct contact of the bottom of the insertion tube 1 with the deep blind hole 110 to damage the deep blind hole 110. Then, the stop valve 34 is opened, and the compressed air is filled through the air inlet 33, so that the cooling liquid 31 in the liquid storage tank 3 is quickly pressed into the bottom of the deep blind hole 110 and fills the deep blind hole 110, thereby quickly discharging the gas existing in the deep blind hole 110, improving the feeding rate of the cooling liquid 31, and ensuring the quenching hardness in the deep blind hole 110. Finally, the compressed air is continuously filled, so that the cooling liquid 31 vibrates in the deep blind hole 110. By using the vibration mode, the steam film in the cooling liquid 31 is quickly broken, and the cooling environment in the deep blind hole 110 is improved. Since the time for forming the steam film between the cooling medium and the hot workpiece 100 is greatly shortened, the strong convection stage is advanced, the cooling rate in the deep blind hole 110 is accelerated, the quenching hardness in the deep blind hole 110 is further ensured, and the hardness of the deep blind hole 110 of the workpiece 100 after quenching treatment reaches the factory requirement.

[0042] That is, the quenching tool for the deep blind hole of the workpiece provided by the embodiment of the present application not only can quickly discharge the gas existing in the deep blind hole 110, improve the feeding rate of the cooling liquid 31, but also can accelerate the cooling rate in the deep blind hole 110, and further ensure the quenching hardness in the deep blind hole 110.

[0043] It should be noted that the air inlet 33 can also play the role of adding the cooling liquid 31 to the liquid storage tank 3.

[0044] Exemplarily, the insertion tube 1 can be a stainless steel structure. The compressed air pressure can be 0.3MPa-0.5MPa.

[0045] Figure 3 is a top view of the positioning ring provided by the embodiment of the present application, which is combined with Figure 2 and Figure 3 It is shown that one end of each supporting arm 21 extends radially along the positioning ring 2, and each supporting arm 21 has a strip-shaped hole 211, a positioning bolt 212 is movably inserted in each strip-shaped hole 211, each positioning bolt 212 abuts against the inner wall of the deep blind hole 110, and a locking nut 213 is sleeved on the positioning bolt 212 to clamp the corresponding supporting arm 21.

[0046] In the above embodiment, the position of the positioning bolts 212 can be conveniently adjusted through the slotted hole 211 and locked by the locking nut 213. At this time, the multiple positioning bolts 212 are exactly abutting against the inner wall of the deep blind inner hole 110, thereby achieving the positioning of the positioning ring 2 and the insertion tube 1, and avoiding lateral displacement or vibration of the insertion tube 1 when coolant 31 or compressed air is filled into the insertion tube 1, which would lead to uneven feeding. In addition, since the positioning bolts 212 can be adjusted radially along the positioning ring 2, they can adapt to deep blind inner holes 110 with different inner diameters, further increasing the applicability of this tooling.

[0047] Furthermore, the positioning ring 2 has a reinforcing protrusion 22 on the side facing the deep blind inner hole 110, and the reinforcing protrusion 22 is located inside the deep blind inner hole 110.

[0048] In the above embodiments, the reinforcing convex ring 22 can not only increase the structural strength of the positioning ring 2, but also increase the mass of the positioning ring 2, thus preventing the positioning ring 2 from moving during use.

[0049] For example, there are three support arms 21, and the included angle between any two adjacent support arms 21 is 120°. The support of three support arms 21 is highly reliable and more stable, and is easier to manufacture.

[0050] In this embodiment, the bottom of the insertion tube 1 has multiple through holes 11, which are evenly spaced along the circumference of the insertion tube 1. The multiple through holes 11 can further increase the feeding rate of the coolant 31, while avoiding the material from generating a reaction force with the bottom of the deep blind inner hole 110 when the material is discharged from the bottom of the insertion tube 1, which would cause the insertion tube 1 to move upward.

[0051] See you again Figure 1 The top of the liquid storage tank 3 is detachably fitted with a sealing cap 35, and the air inlet 33 is located on the sealing cap 35.

[0052] In the above embodiment, before the sealing cap 35 is put on, coolant 31 can be conveniently added to the liquid storage tank 3 through the opening corresponding to the sealing cap 35, and after the sealing cap 35 is put on, it plays the role of sealing the opening.

[0053] In this embodiment, a first flexible hose 4 is inserted into the air inlet 33. One end of the first flexible hose 4 is connected to the inner cavity of the liquid storage tank 3, and the other end of the first flexible hose 4 is used to connect to compressed air.

[0054] In the above embodiment, the first hose 4 can conveniently connect the inner cavity of the liquid storage tank 3 and the function of the air filling device, thereby conveniently filling the inner cavity of the liquid storage tank 3 with compressed air.

[0055] Furthermore, the sealing cap 35 and the top of the liquid storage tank 3 are threaded together, thereby improving the sealing performance of the liquid storage tank 3 and avoiding leakage when adding material to the insertion tube 1.

[0056] In addition, the second hose 5 is connected between the stop valve 34 and the cannula 1, facilitating reliable connection of the stop valve 34 and the cannula 1 and being not easy to be damaged.

[0057] Exemplarily, the second hose 5 is connected with the joint at both ends.

[0058] It should be noted that for a certain type of workpiece 100 with a deep blind hole 110 made of 35CrMo, the surface hardness is required to be greater than or equal to 50HRC, and the hardness of the deep blind hole 110 is required to be greater than or equal to 42.5HRC. In the quenching process, the cooling liquid 31 is directly injected into the deep blind hole 110 in the conventional manner, and the quenching hardness of the deep blind hole 110 is less than or equal to 40HRC, and the hardness is uneven, resulting in insufficient strength and wear resistance of the internal thread, which does not meet the use requirements. After quenching by using the quenching device, the hardness of the deep blind hole 110 of the workpiece 100 is 45HRC, the service life is increased by 2 times, and the customer requirements are met.

[0059] The present application is suitable for workpieces 100 with deep blind holes 110 (length-diameter ratio is not less than 1:7), especially for high-quality carbon structural steel, low (medium) carbon alloy steel, and part of tool steel and other structural steel parts with moderate hardenability.

[0060] Figure 4 is a flow chart of a quenching method for a deep blind hole of a workpiece provided by an embodiment of the present application, as shown in the figure, the quenching method is based on the above-mentioned quenching device for a deep blind hole of a workpiece, and the quenching method comprises the following steps: Figure 4

[0061] S1, according to the length of the deep blind hole 110 of the workpiece 100, the positioning ring 2 is sleeved at the position corresponding to the outer periphery of the cannula 1, and the cooling liquid 31 is added to the inner cavity of the liquid storage tank 3.

[0062] It should be noted that the volume of the cooling liquid 31 in the inner cavity of the liquid storage tank 3 is not less than the volume of the deep blind hole 110, so as to ensure that the air in the deep blind hole 110 is completely discharged.

[0063] S2, the cannula 1 is inserted into the deep blind hole 110, and the plurality of supporting arms 21 are placed on the end face of the workpiece 100.

[0064] S3, the stop valve 34 is opened, and the compressed air is filled through the air inlet 33, so that the cooling liquid 31 in the liquid storage tank 3 is pressed into the bottom of the deep blind hole 110 and fills the deep blind hole 110.

[0065] S4, continue to fill the compressed air, so that the cooling liquid 31 vibrates in the deep blind hole 110.

[0066] ​It should be noted that the outer periphery of the workpiece 100 is also immersed in the cooling liquid during quenching. When the cooling liquid in the liquid storage tank 3 is exhausted, the cooling liquid 31 overflows in the deep blind hole 110 during vibration, and the external cooling liquid is continuously supplied to the deep blind hole 110, forming a convection and accelerating the cooling rate in the deep blind hole.

[0067] The quenching method for the deep blind hole of the workpiece provided by the embodiment of the present application can not only quickly discharge the gas existing in the deep blind hole 110 and improve the feeding rate of the cooling liquid 31, but also accelerate the cooling rate in the deep blind hole 110, and further ensure the quenching hardness in the deep blind hole 110.

[0068] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A quenching fixture for a deep blind inner hole of a workpiece, characterized in that, The quenching fixture includes a tube (1), a positioning ring (2), and a liquid storage tank (3). The insertion tube (1) is used to insert into the deep blind inner hole (110) of the workpiece (100) so that the bottom of the insertion tube (1) is located at the bottom of the deep blind inner hole (110). A positioning ring (2) is movably sleeved on the insertion tube (1). The positioning ring (2) is arranged opposite to the deep blind inner hole (110). The outer peripheral wall of the positioning ring (2) has a plurality of spaced support arms (21) to support the end face of the workpiece (100). The inner cavity of the liquid storage tank (3) contains coolant (31). The bottom and top of the liquid storage tank (3) are respectively provided with a discharge port (32) and an air inlet (33). The discharge port (32) is connected to the top of the insertion tube (1), and a shut-off valve (34) is provided on the discharge port (32). The air inlet (33) is used to connect compressed air. A quenching method for a deep blind inner hole of a workpiece, the quenching method being based on the aforementioned quenching fixture for a deep blind inner hole of a workpiece, the quenching method comprising: The positioning ring (2) is fitted onto the corresponding position on the outer periphery of the insertion tube (1) according to the length of the deep blind inner hole (110) of the workpiece (100), and the coolant (31) is added into the inner cavity of the liquid storage tank (3). The cannula (1) is inserted into the deep blind bore (110), and the plurality of the arms (21) rest on the end face of the workpiece (100); Open the shut-off valve (34) and fill the air inlet (33) with compressed air, so that the coolant (31) in the liquid storage tank (3) is pressed into the bottom of the deep blind inner hole (110) and fills the deep blind inner hole (110). Continue to fill with compressed air, causing the coolant (31) to vibrate within the deep blind bore (110).

2. The quenching fixture for a deep blind inner hole of a workpiece according to claim 1, characterized in that, One end of each of the support arms (21) extends radially along the positioning ring (2), and each of the support arms (21) has a strip hole (211). A positioning bolt (212) is movably inserted into each of the strip holes (211). Each positioning bolt (212) abuts against the inner wall of the deep blind inner hole (110). A locking nut (213) is fitted on the positioning bolt (212) to clamp the corresponding support arm (21).

3. A quenching fixture for a deep blind inner hole of a workpiece according to claim 2, characterized in that, The positioning ring (2) has a reinforcing protrusion (22) on the side facing the deep blind inner hole (110), and the reinforcing protrusion (22) is located inside the deep blind inner hole (110).

4. A quenching fixture for a deep blind inner hole of a workpiece according to claim 2, characterized in that, The number of the support arms (21) is 3, and the included angle between any two adjacent support arms (21) is 120°.

5. A quenching fixture for a deep blind inner hole of a workpiece according to any one of claims 1-4, characterized in that, The bottom of the cannula (1) has a plurality of through holes (11), which are evenly spaced along the circumference of the cannula (1).

6. A quenching fixture for a deep blind inner hole of a workpiece according to any one of claims 1-4, characterized in that, The top of the liquid storage tank (3) is detachably fitted with a sealing cap (35), and the air inlet (33) is located on the sealing cap (35).

7. A quenching fixture for a deep blind inner hole of a workpiece according to claim 6, characterized in that, A first flexible tube (4) is inserted into the air inlet (33). One end of the first flexible tube (4) is connected to the inner cavity of the liquid storage tank (3), and the other end of the first flexible tube (4) is used to connect to compressed air.

8. A quenching fixture for a deep blind inner hole of a workpiece according to claim 6, characterized in that, The sealing cap (35) and the top of the liquid storage tank (3) are threaded together.

9. A quenching fixture for a deep blind inner hole of a workpiece according to any one of claims 1-4, characterized in that, The shut-off valve (34) and the cannula (1) are connected by a second flexible tube (5).

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