CN112595605A

CN112595605A - Material tensile testing machine under oil bath environment

Info

Publication number: CN112595605A
Application number: CN202011317105.1A
Authority: CN
Inventors: 马骏; 蔡磊; 徐文杰
Original assignee: Zhejiang Institute Of Medical Device Testing
Current assignee: Zhejiang Institute Of Medical Device Testing
Priority date: 2020-11-20
Filing date: 2020-11-20
Publication date: 2021-04-02
Anticipated expiration: 2040-11-20
Also published as: CN112595605B

Abstract

The material tensile testing machine under the oil bath environment comprises a base, wherein an oil containing box body is installed on the base, an oil bath groove is formed in the oil containing box body, a vertical stand column is installed on the rear side of the oil containing box body, a first motor is arranged at the upper end of the stand column, an output shaft of the first motor is connected with a lead screw, a nut is installed on the lead screw in a matched mode, a horizontally arranged mounting plate is installed on the nut, a second motor is installed on the mounting plate, an output shaft of the second motor is connected with a vertical moving rod, the vertical moving rod penetrates out of the bottom of the mounting plate and is fixedly connected with a sieve plate, a plurality of through holes are formed in the sieve plate, guide rods are further arranged at two ends of the sieve plate, guide sleeves matched with the guide rods are respectively installed at two ends of the mounting plate, a plurality of groups of testing devices are arranged at the front end of the mounting plate, each, a through groove is formed in the mounting plate, and a second stretching rod is installed in the through groove in a matched mode.

Description

Material tensile testing machine under oil bath environment

Technical Field

The invention relates to the technical field of material tensile tests, in particular to a material tensile testing machine in an oil bath environment.

Background

The tensile test is a test method for measuring the material characteristics under the condition of bearing axial tensile load, the data obtained by the tensile test can be used for determining the elastic limit, the elongation, the elastic modulus, the proportion limit, the area reduction, the tensile strength, the yield point, the yield strength and other tensile performance indexes of the material, the creep data can be obtained from the tensile test carried out at high temperature, oil bath heating is a means frequently used for carrying out the high-temperature tensile test at present, but because of the particularity of a heating medium, the potential safety hazard of operation often exists, and the normal running of the tensile test is not facilitated.

Disclosure of Invention

The invention aims to provide a material tensile testing machine in an oil bath environment, when a material moves downwards into heating oil, a follow-up shade device can cover a shade on an oil bath groove, so that the heating oil is prevented from splashing and the like, and potential safety hazards in operation are eliminated.

The technical scheme adopted by the invention for solving the technical problems is as follows: the invention relates to a material tensile testing machine in an oil bath environment, which comprises a base, wherein an oil containing box body is arranged on the base, an oil bath groove is formed in the oil containing box body, a vertical column is arranged at the rear side of the oil containing box body, a first motor is arranged at the upper end of the vertical column, an output shaft of the first motor is connected with a screw rod, a nut is arranged on the screw rod in a matching manner, a horizontally arranged mounting plate is arranged on the nut, a second motor is arranged on the mounting plate, an output shaft of the second motor is connected with a vertical moving rod, the vertical moving rod penetrates out of the bottom of the mounting plate and is fixedly connected with a sieve plate, a plurality of through holes are formed in the sieve plate, guide rods are further arranged at two ends of the sieve plate, guide sleeves matched with the guide rods are respectively arranged at two ends of the mounting plate, a plurality of groups of testing devices are arranged at the, a through groove is arranged on the mounting plate corresponding to the position of the first stretching rod, a second stretching rod is arranged in the through groove in a matching way, the second stretching rod is longer than the first stretching rod and corresponds to the upper position of the second stretching rod extending out of the mounting plate, a proximity switch is arranged on the mounting plate, two first clamping blocks which are symmetrically arranged are arranged at the bottom position of the first stretching rod, a Y-shaped groove is formed between the first clamping blocks, second clamping blocks which are symmetrically arranged are arranged at the bottom position of the second stretching rod, an inverted Y-shaped groove is formed between the second clamping blocks, the second clamping blocks are positioned at the bottom of the first stretching rod, a hook is further arranged at the bottom end of the second stretching rod, placing platforms are arranged on the oil tank bodies at the two ends of the oil bath groove, two groups of follow-up shade devices which are symmetrically arranged are arranged in the oil tank bodies, each group of follow-up shade devices comprises a vertical groove arranged in the vertical wall of the oil tank bodies, erect the groove and arrange along the length direction in oil bath groove, erect the inslot cooperation and install the shade, the bottom of shade is equipped with a plurality of bracing pieces, place all set up on the inside wall of platform with erect the cross slot of groove looks UNICOM, place and install first sprocket and second sprocket in the platform, equal cooperation is installed with the first sprocket and the second sprocket of one end to two sets of follow-up shade devices and same chain, the both ends and the bracing piece fixed connection of chain and shade, the both ends of chain are located and erect inslot and fixed mounting has the balancing weight, correspond to the intermediate position of chain, set up the upright groove with cross slot looks UNICOM on placing the inboard wall of platform, all be equipped with the follower rod at the both ends of mounting panel, and when the follower rod moves down the in-process and passes upright groove and drive the chain and enter into flourishing oil tank, shade and bracing piece can enter into the cross slot and seal the oil bath groove. The vertical moving rod, the guide rod and the stretching rod are all located in the middle of the oil bath groove, the butt joint plate is installed at the upper end of the shade, the avoidance groove matched with the vertical moving rod, the guide rod and the stretching rod is formed in the butt joint plate on one side, the hollow rubber strip is installed on the butt joint plate on the other side, and the hollow rubber strip can be tightly connected with the butt joint plate. The outer side of the placing table is provided with a chain wheel synchronizing device, the chain wheel synchronizing device comprises two gears which are symmetrically arranged, the gears and the first chain wheels are coaxially arranged, the two gears are mutually meshed, and the chain wheel synchronizing device can enable the two first chain wheels at the same end of the follow-up shade device to synchronously and reversely rotate. The front end of mounting panel is equipped with the sign board, is equipped with a plurality of labels along the length direction of sign board, and the label corresponds with every testing arrangement one-to-one. And a heat radiation fan is arranged on the placing table. An oil discharge pipeline is arranged at one end of the bottom of the oil containing box body, and adjustable support legs are arranged at the four corners of the base. Corresponding to the both ends position of oil bath groove, gas blowing device is all installed at the both ends of flourishing oil tank body upper wall, gas blowing device is including a plurality of nozzle, and every nozzle all through pipeline and series connection pipe looks UNICOM, installs the air supply pipe on the series connection pipe, and flourishing oil tank body is worn out and is connected with the air pump to the one end of air supply pipe.

The invention has the positive effects that: according to the material tensile testing machine in the oil bath environment, when the material is moved downwards to enter the heating oil, the cover can be synchronously covered on the oil bath groove by the following cover device, so that not only can the heat of the heating oil be effectively prevented from being rapidly dissipated, but also the oil can be prevented from being sputtered when the material is moved downwards to enter the oil, the personal safety of operators is ensured, the potential safety hazard in the operation process is greatly reduced, the cover can be synchronously opened in the material moving upwards process after the tensile test is finished, and the normal operation of the whole experiment process cannot be influenced.

Drawings

FIG. 1 is a schematic three-dimensional structure of the present invention;

FIG. 2 is a front view of the present invention;

FIG. 3 is an enlarged view of the cross-sectional view taken along line A-A of FIG. 2;

FIG. 4 is a schematic diagram of the structure of the set of test devices;

FIG. 5 is a sectional view taken along line B-B of FIG. 2;

FIG. 6 is a schematic view of the structure of the mask moving up into the horizontal slot;

FIG. 7 is an enlarged partial view of I of FIG. 6;

FIG. 8 is an enlarged partial view of II of FIG. 6;

FIG. 9 is a schematic view showing a state where the oil bath is closed by the shroud of the present invention;

FIG. 10 is a schematic structural view of the sprocket synchronizing device;

fig. 11 is a schematic view of a structure in which a test material is installed between a first stretching rod and a second stretching rod.

Detailed Description

The material tensile testing machine in the oil bath environment comprises a base 1, wherein an oil containing box body 2 is installed on the base 1, heating oil is contained in the oil containing box body 2, and an oil bath groove 3 is formed in the oil containing box body 2, so that a material to be tested can enter the oil containing box body 2 through the oil bath groove 3 to be subjected to oil bath heating.

Install the stand 4 of vertical setting at the rear side of flourishing oil tank body 2, the stand 4 upper end is equipped with first motor 5, as shown in fig. 3, the output shaft of first motor 5 links to each other with lead screw 6, and the cooperation is installed nut 7 on lead screw 6, install the mounting panel 8 that the level set up on the nut 7, install second motor 9 on the mounting panel 8, the output shaft of second motor 9 passes through the switching-over device and erects to move pole 10 and link to each other, erects to move the bottom fixedly connected with sieve 11 that pole 10 wore out mounting panel 8, has seted up a plurality of thru holes 12 on the sieve 11 to resistance when reducing sieve 11 and getting into the heating oil, and when carrying out oil bath 3 with sieve 11, be convenient for the heating oil on it to fall back into flourishing oil tank body 2. In order to make the vertical movement of the sieve plate 11 more stable, guide rods 13 are further arranged at the two ends of the sieve plate 11, and guide sleeves 14 matched with the guide rods 13 are respectively arranged at the two ends of the mounting plate 8.

A plurality of groups of test devices are arranged at the front end of the mounting plate 8, as shown in fig. 4, each group of test devices comprises a first stretching rod 15 fixed at the bottom of the mounting plate 8, a through groove 16 is formed in the mounting plate 8 corresponding to the position of the first stretching rod 15, a second stretching rod 17 is arranged in the through groove 16 in a matching manner, the second stretching rod 17 can freely fall in the through groove 16, and the second stretching rod 17 is longer than the first stretching rod 15. A proximity switch 18 is provided on the mounting plate 8 corresponding to the upper position where the second stretching rod 17 protrudes out of the mounting plate 8, and the proximity switch 18 can detect the upper end position of the second stretching rod 17. Two first clamping blocks 19 which are symmetrically arranged are arranged at the bottom of the first stretching rod 15, a Y-shaped groove is formed between the first clamping blocks 19, second clamping blocks 20 which are symmetrically arranged are arranged at the bottom of the second stretching rod 17, an inverted Y-shaped groove is formed between the second clamping blocks 20, the second clamping blocks 20 are arranged at the bottom of the first stretching rod 15, as shown in figure 11, the material to be tested is placed between the first clamping block 19 and the second clamping block 20, both ends of the material are bulges matched with the Y-shaped groove, after the material is arranged between the first clamping block 19 and the second clamping block 20, the second stretching rod 17 and the first stretching rod 15 can be connected together, a hook 21 is further installed on the bottom end of the second stretching rod 17, and a metering object such as a weight 43 can be installed on the hook 21 to apply a pulling force to the second stretching rod 17 and the material to be tested, so as to achieve the purpose of deformation.

When the material tensile testing machine in the oil bath environment is used, firstly, a material to be tested is arranged between the first clamping block 19 and the second clamping block 20, the height position of the sieve plate 11 is adjusted, when the weight 43 is hung on the hook 21, the weight 43 falls onto the sieve plate 11 and has no tensile force on the second tensile rod 17, namely, the distance between the first clamping block 19 and the second clamping block 20 is the length distance of the material to be tested in a normal state when the material to be tested is not stretched, wherein the weights 43 of each group of test units are different in weight, and the purpose is to test the influence of different tensile forces on the material to be tested under the same test environment. After the adjustment is finished, the first motor 5 controls the mounting plate 8 to move downwards integrally until the material to be tested completely enters the oil containing box body 2, namely the upper end position of the first clamping block 19 enters the oil bath groove 3, when the material to be tested completely enters the oil containing box body 2 and is heated for a period of time, the second motor 9 controls the sieve plate 11 to move downwards independently until the sieve plate is separated from the weight 43, at the moment, the gravity of the weight 43 exerts a tensile force on the second stretching rod 17, so that the material is stretched and deformed, because the first stretching rod 15 is fixed on the mounting plate 8, when the material is stretched, the second stretching rod 17 moves downwards synchronously, the sieve plate 11 starts to time when the weight 43 is separated, after the proximity switch 18 cannot detect the second stretching rod 17, the alarm timing is finished, the distances of the upper ends of each group of testing devices stretching out of the mounting plate 8 are the same, and under the condition of different tensile forces, different tensile forces can be obtained by comparing the used time on the premise of the same stretching length The influence of (c).

In order to avoid the situations of splashing and the like when the sieve plate 11 and the testing device pass in and out heating oil and reduce potential safety hazards to a certain extent, the oil containing box bodies 2 at two ends of the oil bath groove 3 are respectively provided with the placing table 22, the placing table 22 and the oil containing box bodies 2 are internally provided with two groups of symmetrically arranged follow-up shade devices, the follow-up shade devices can seal the oil bath groove 3 after the sieve plate 11 and the testing device enter the oil containing box bodies 2, and can also be opened from the upper end of the oil bath groove 3 when the sieve plate 11 and the testing device lift out the oil containing box bodies 2, and the normal operation of a tensile test cannot be influenced. As shown in fig. 5 and 7, each set of the following-up shade devices comprises a vertical groove 23 formed in the vertical wall of the oil tank body 2, the vertical groove 23 is arranged along the length direction of the oil bath groove 3, a shade 24 is fittingly installed in the vertical groove 23, the shade 24 can be made of elastic materials so as to be conveniently stretched, covered and shrunk and contained, and a plurality of support rods 25 are arranged at the bottom of the shade 24, and the support rods 25 can support when the shade 24 is unfolded. The inner side wall of the placing table 22 is provided with transverse grooves 26 communicated with the vertical grooves 23, the placing table 22 is internally provided with a first chain wheel 27 and a second chain wheel 28, the first chain wheel 27 and the second chain wheel 28 at the same end of the two groups of follow-up shade devices are respectively provided with a same chain 29 in a matched manner, the chains 29 are fixedly connected with the two ends of the shade 24 and the supporting rod 25, the two ends of the chains 29 are positioned in the vertical grooves 23 and are fixedly provided with balancing weights 30, the inner side wall of the placing table 22 is provided with vertical grooves 32 communicated with the transverse grooves 26 corresponding to the middle positions of the chains 29, the two ends of the mounting plate 8 are respectively provided with a follow-up rod 31, and when the follow-up rod 31 moves downwards to pass through the vertical grooves 32 and drive the chains 29 to enter the oil containing box body 2, the shade 24 and the supporting rod 25 can enter the transverse grooves 26 to seal.

When the sieve plate 11 and the testing device do not enter the oil tank body 2, the chain 29 is in a tensioned state and is matched on the first chain wheel 27 and the second chain wheel 28 under the action of the gravity of the balancing weight 30, and the shade 24 is positioned in the vertical groove 23 at the moment, so that the sieve plate 11 and the testing device are not influenced to move downwards to enter the oil bath groove 3, as shown in fig. 5. When the first motor 5 controls the sieve plate 11 on the mounting plate 8 and the testing device to move down integrally, the follower rod 31 enters the vertical groove 32 in the descending process, the middle position of the chain 29 is driven to move down synchronously by overcoming the tension of the counter weights 30 at the two ends of the chain 29, after the material to be tested completely enters the heating oil, the mounting plate 8 and the follower rod 31 stop moving down, at the moment, the masks 24 on the two sets of the follower mask devices enter the transverse groove 26 along with the chain 29, as shown in fig. 6, namely, the masks move to the upper part of the oil bath groove 3 to seal the oil bath groove, as shown in fig. 9, the follower mask devices seal the oil bath groove 3 when the testing device completely enters the oil containing box body 2. The position of the shade 24 cannot be influenced by the downward movement of the sieve plate 11 in the test process, and after the test is finished, the upward moving follower rod 31 gradually loses the pressing on the middle position of the chain 29, the chain 29 is tensioned again under the action of the gravity of the counterweight block 30, the shade 24 returns to the vertical groove 23, and the sieve plate 11 and the test device can be smoothly lifted out of the oil bath groove 3.

In order to ensure that the follow-up shade devices at the two sides can be smoothly butted at the middle position of the oil bath 3 and ensure the sealing property of the oil bath 3 covered after the butting, the vertical moving rod 10, the guide rod 13 and the stretching rod are all positioned in the middle of the oil bath groove 3, the upper end of the shade 24 is provided with a butt joint plate 33, wherein, the butt joint plate 33 on one side is provided with an avoidance groove 34 respectively matched with the vertical moving rod 10, the guide rod 13 and the stretching rod, the butt joint plate 33 on the other side is provided with a hollow rubber strip 37, the hollow rubber strip 37 can be tightly jointed with the butt joint plate 33, wherein the hollow rubber strip 37 has certain elastic deformation in the process of contacting the butt-joint plate 33, a margin range in the process of moving down the follower rod 31 is reserved, namely, when the distance of downward movement of the follower rod 31 exceeds the expected set value, the butt joint plate 33 can also compress the hollow rubber strip 37 to ensure the butt joint sealing performance, and the covering sealing performance of the follower shade devices on the two sides on the oil bath 3 is effectively ensured.

Further, in order to enable the first chain wheel 27 and the second chain wheel 28 in the two side driven shade devices to synchronously and reversely rotate, a chain wheel synchronizing device is installed on the outer side of the placing table 22, as shown in fig. 10, the chain wheel synchronizing device comprises two gears 35 which are symmetrically arranged, the gears 35 are coaxially arranged with the first chain wheel 27, the two gears 35 are meshed with each other, and the chain wheel synchronizing device can ensure that the two first chain wheels 27 at the same end of the driven shade devices synchronously and reversely rotate.

Furthermore, in order to facilitate recording and distinguishing of the testing devices using weights 43 with different weights, the front end of the mounting plate 8 is provided with an identification plate 38, a plurality of labels 39 are arranged along the length direction of the identification plate 38, the labels 39 correspond to each testing device one by one, and parameter data such as the types of materials to be tested, the weight quality and the like can be filled in the labels 39 in advance so as to facilitate distinguishing and recording.

Because in the test process, the vertical moving rod 10 and the guide rod 13 both have one end extending into the heating oil, in order to facilitate the heat dissipation of the device, the placing table 22 is provided with a heat dissipation fan 40. In order to effectively drain the heating oil after the test is finished, an oil drainage pipeline 41 is arranged at one end of the bottom of the oil containing box body 2, and adjustable support legs 42 are arranged at four corners of the base 1, so that the heights of the base 1 and the whole device can be adjusted as required.

In the process of lifting the test device after the test, the opening of the shade 24 can cause the heat enclosed in the oil containing box body 2 to be suddenly released, in order to avoid the safety risk to the operator caused by the above situation, corresponding to the positions of the two ends of the oil bath groove 3, air blowing devices are arranged at the two ends of the upper side wall of the oil containing box body 2, each air blowing device comprises a plurality of nozzles 44, each nozzle 44 is communicated with a serial pipe 45 through a pipeline, an air supply pipe 46 is arranged on the serial pipe 45, and one end of the air supply pipe 46 penetrates out of the oil containing box body 2 and is connected with an air pump 36. Wherein nozzle 44 is located above the liquid level of the heating oil, the gas blowing device is started when the testing device is lifted, the gas blowing device does not work in the testing process, when the first motor 5 drives the testing device to move upwards, the gas pump 36 starts gas supply, the blown gas can form an air curtain on the oil bath groove 3, the heat in the oil containing box body 2 can be effectively prevented from being suddenly diffused, the testing device passing through the air curtain and the sieve plate 11 can be swept, the heating oil on the gas blowing device falls back into the oil containing box body 2, and the direct contact with the heating oil due to misoperation of workers is avoided.

The technical solution of the present invention is not limited to the scope of the embodiments of the present invention. The technical contents not described in detail in the present invention are all known techniques.

Claims

1. The utility model provides a material tensile test machine under oil bath environment which characterized in that: comprises a base (1), an oil containing box body (2) is arranged on the base (1), an oil bath groove (3) is arranged on the oil containing box body (2), a vertical upright post (4) is arranged at the rear side of the oil containing box body (2), a first motor (5) is arranged at the upper end of the upright post (4), the output shaft of the first motor (5) is connected with a lead screw (6), a nut (7) is arranged on the lead screw (6) in a matching way, a horizontally arranged mounting plate (8) is arranged on the nut (7), a second motor (9) is arranged on the mounting plate (8), the output shaft of the second motor (9) is connected with a vertical moving rod (10), the vertical moving rod (10) penetrates out of the bottom of the mounting plate (8) and is fixedly connected with a sieve plate (11), a plurality of through holes (12) are arranged on the sieve plate (11), guide rods (13) are further arranged at the two ends of the sieve plate (11), guide sleeves (14) matched with the guide rods (13, the front end of the mounting plate (8) is provided with a plurality of groups of testing devices, each group of testing devices comprises a first stretching rod (15) fixed at the bottom of the mounting plate (8), a through groove (16) is formed in the mounting plate (8) corresponding to the position of the first stretching rod (15), a second stretching rod (17) is installed in the through groove (16) in a matched mode, the second stretching rod (17) is longer than the first stretching rod (15), the upper position of the mounting plate (8) extends out corresponding to the second stretching rod (17), a proximity switch (18) is arranged on the mounting plate (8), two first clamping blocks (19) symmetrically arranged are installed at the bottom position of the first stretching rod (15), a Y-shaped groove is formed between the first clamping blocks (19), second clamping blocks (20) symmetrically arranged are installed at the bottom position of the second stretching rod (17), an inverted Y-shaped groove is formed between the second clamping blocks (20), the second clamping block (20) is located at the bottom of the first stretching rod (15), a hook (21) is further mounted at the bottom end of the second stretching rod (17), oil containing boxes (2) at two ends of the oil bath groove (3) are provided with placing platforms (22), two groups of symmetrically-arranged follow-up shade devices are mounted in the placing platforms (22) and the oil containing boxes (2), each group of follow-up shade devices comprises vertical grooves (23) formed in vertical walls of the oil containing boxes (2), the vertical grooves (23) are arranged along the length direction of the oil bath groove (3), shades (24) are mounted in the vertical grooves (23) in a matched mode, the bottom of the shades (24) is provided with a plurality of support rods (25), transverse grooves (26) communicated with the vertical grooves (23) are formed in the inner side wall of the placing platforms (22), first chain wheels (27) and second chain wheels (28) are mounted in the placing platforms (22), and first chain wheels (27) and second chain wheels (28) at the same ends of the two groups of follow-up shade devices are mounted in a matched mode There is same chain (29), both ends and bracing piece (25) fixed connection of chain (29) and shade (24), the both ends of chain (29) are located and erect groove (23) and fixed mounting has balancing weight (30), corresponding to the intermediate position of chain (29), set up on putting platform (22) inside wall with vertical groove (32) of cross slot (26) looks UNICOM, all be equipped with follower rod (31) at the both ends of mounting panel (8), when follower rod (31) move down the in-process and pass vertical groove (32) and drive chain (29) and enter into oil containing box body (2), shade (24) and bracing piece (25) can enter into cross slot (26) in seal oil bath groove (3).

2. The material tensile testing machine in oil bath environment according to claim 1, characterized in that: erect and move pole (10), guide bar (13) and tensile pole and all be located the intermediate position department of oil bath groove (3), butt plate (33) are installed to the upper end of shade (24), wherein offer on butt plate (33) of one side respectively with erect move pole (10), guide bar (13) and tensile pole matched with dodge groove (34), install hollow adhesive tape (37) on opposite side butt plate (33), hollow adhesive tape (37) can with butt plate (33) close joint.

3. The material tensile testing machine in oil bath environment according to claim 1, characterized in that: place the platform (22) outside and install sprocket synchronizer, sprocket synchronizer is including two gears (35) that the symmetry set up, and gear (35) and first sprocket (27) coaxial setting, two gears (35) intermeshing, and sprocket synchronizer enables two synchronous antiport of first sprocket (27) of follow-up shade device with one end.

4. The material tensile testing machine in oil bath environment according to claim 1, characterized in that: the front end of mounting panel (8) is equipped with identification panel (38), is equipped with a plurality of labels (39) along the length direction of identification panel (38), and label (39) and every testing arrangement one-to-one.

5. The material tensile testing machine in oil bath environment according to claim 1, characterized in that: the placing table (22) is provided with a cooling fan (40).

6. The material tensile testing machine in oil bath environment according to claim 1, characterized in that: an oil discharge pipeline (41) is arranged at one end of the bottom of the oil containing box body (2), and adjustable support legs (42) are arranged at four corners of the base (1).

7. The material tensile testing machine in oil bath environment according to claim 1, characterized in that: corresponding to the both ends position of oil bath (3), gas blowing device is all installed at the both ends of flourishing oil tank body (2) upper side wall, gas blowing device is including a plurality of nozzle (44), and every nozzle (44) all through pipeline and series connection pipe (45) UNICOM, installs air supply pipe (46) on series connection pipe (45), and flourishing oil tank body (2) are worn out and air pump (36) are connected to the one end of air supply pipe (46).