JP7795366B2 - Penetration rod uncoupling device - Google Patents

Description

The present invention relates to a penetration rod disconnecting tool for disconnecting a rod used in penetration tests, in which a penetration rod equipped with a penetration body at the tip of the rod is inserted into the ground while the rod is being sequentially added.

One example of a conventional penetration testing machine is shown in Patent Document 1. This penetration testing machine is designed to perform a Swedish sounding test, which is one type of penetration test, and is configured to rotate a penetration rod, which is equipped with a screw point, an example of a penetrator, at the tip of the rod, into the ground. The penetration rod is engaged and held in a chuck attached to a lifting platform that can be raised and lowered by a motor, and the screw point at the tip penetrates into the ground as the lifting platform descends. When the lifting platform reaches its lowest point, the operator attaches the next rod to the rear end of the rod by screwing it into place. Then, the operator disengages the penetration rod from the chuck, raises the lifting platform, and lowers the platform again with the rod attached to the chuck still engaged, thereby penetrating the screw point to an even greater depth. By repeating this rod connection process, the screw point can be penetrated to a predetermined depth.

After the test is completed, the lifting platform is raised while the penetration rod and chuck are still engaged, allowing the rod to be pulled out of the ground, and the worker then disconnects the rod. The rod's connection is tightly secured with a screw, so the worker uses a pipe wrench to disconnect it.

Japanese Patent Application Laid-Open No. 2004-92202

However, using a pipe wrench is difficult for beginners and requires skill. As such, the process of disconnecting the rod posed problems in terms of workability.

The objective of the present invention is to provide a penetration rod disconnection tool that can easily disconnect the rod used in a penetration testing machine.

The above problem can be solved by a penetration rod disconnecting device used in a penetration testing machine that has a chuck that can rotatably hold a penetration rod as the motor is driven, and is configured to rotate and penetrate the ground while sequentially extending and extending extension rods via a screw connection.The penetration rod disconnecting device includes a device main body that can hold the extended extension rod, and a fixing means that is fixed to the penetration testing machine and restricts the rotation of the device main body.The penetration rod disconnecting device is configured to drive the chuck's motor to rotate the penetration rod, thereby releasing the screw connection between these rods.

The tool body preferably comprises a hollow chuck shaft with an inner hole through which the extension rod can be inserted, a sleeve that is movable back and forth along the chuck shaft and is constantly biased toward the end of the chuck shaft, a sleeve retainer that restricts movement of the sleeve toward the end of the chuck shaft, and a steel ball that is disposed on the chuck shaft and is constantly supported by the sleeve in a state where it protrudes into the inner hole of the chuck shaft. The steel ball is fitted into engagement grooves formed on the outer circumferential surfaces of both ends of the extension rod, and the engagement between the steel ball and the engagement groove is released by pushing down the sleeve, allowing the tool to be attached and detached from the extension rod.

The penetration rod disconnection device of the present invention can be easily attached to a penetration testing machine, allowing the operator to easily disconnect the penetration rod without having to use their hands.

FIG. 1 is a perspective view of an automatic penetration testing machine. FIG. 1 is a side view of an automatic penetration testing machine. 3 is an enlarged, partially cutaway cross-sectional view taken along line AA of FIG. 2. FIG. 2 is an enlarged, partially cutaway cross-sectional view of a main part showing the configuration of a chuck of an automatic penetration testing machine. FIG. 2 is a diagram illustrating a configuration of a load sensor. 1A and 1B are diagrams showing the configuration of a penetration rod uncoupling device of the present invention.

First, a penetration testing machine in which the penetration rod disconnecting device 100 of the present invention is used will be described with reference to the drawings. In Figure 1, reference numeral 1 denotes an automatic penetration testing machine, which has a lifting platform 3 that can be raised and lowered along a support 2. This lifting platform 3 is loaded with a weight 3a of a predetermined weight, a rotation motor 6, a chuck 5 that can be rotated by the drive of this rotation motor 6, a penetration rod 4 that is held by this chuck 5 and can rotate integrally with it, and a lifting motor 8 that operates to raise and lower the lifting platform 3.

The penetration rod 4 consists of a rod 4a and a screw point 4b connected to its tip (lower end). The rod 4a has three engagement grooves 4c at its upper end, dividing the circumference into thirds, and three engagement grooves 4d at its lower end, dividing the circumference into thirds.

As shown in Figure 2, the lifting platform 3 has a sprocket 7 that rotates along a guide chain 2a that is arranged vertically along the support 2, and is configured to rise and fall as the sprocket 7 rotates along the guide chain 2a. The lifting platform 3 and the total weight loaded on the lifting platform 3 are configured so that a load of 1 kN can be applied to the penetration rod 4.

As shown in Figure 3, the sprocket 7 is connected to a transmission shaft 12 via a planetary gear mechanism 11 so as to rotate integrally with the transmission shaft 12. A drive gear 13 is attached to the tip of the drive shaft 8a of the lift motor 8, which can rotate forward and backward, so as to rotate integrally with the shaft. Furthermore, an intermediate gear 14 and a transmission gear 15 mesh with the drive gear 13 in sequence, so that the drive force of the lift motor 8 is transmitted to the transmission shaft 12.

The transmission gear 15 is a hollow cylinder with external teeth on its outer periphery. A one-way clutch 16 is press-fitted into the interior of the transmission gear 15 so that it rotates integrally with the transmission gear 15, and is rotatably supported on the transmission shaft 12. This first one-way clutch 16 is configured to transmit the drive of the lifting motor 8 when the lifting motor 8 is driven to rotate the sprocket 7 in the direction in which the lifting platform 3 attempts to rise (for convenience, this drive is referred to as forward drive). With this configuration, a load determined by (load based on the total gravity of the lifting platform) minus (lifting force corresponding to the output torque of the lifting motor 8) is applied to the penetration rod 4 as the test load.

On the other hand, when the lifting motor 8 is driven (for convenience, this drive is referred to as reverse drive), the one-way clutch 16 spins freely. This creates a state in which the drive of the lifting motor 8 is not transmitted to the transmission shaft 12, and the penetration rod 4 can be loaded with 1 kN (maximum test load) based on the mass of the lifting platform.

A rotary encoder 17 is attached to the transmission shaft 12 and outputs a pulse signal in response to the rotation of the sprocket 7. The control unit 50, described in detail below, processes this pulse signal and calculates the penetration amount and penetration speed of the penetration rod 4 based on the amount and speed of elevation of the lifting platform 3.

The lift motor 8 is an induction motor, and is drive-controlled by the inverter control unit 53. A drive pulley 18 is attached to the rear end of the drive shaft 8a of the lift motor 8 so that the drive pulley 18 can rotate integrally with the lift motor. A driven pulley 19 is positioned a predetermined distance from the drive pulley 18, and an endless belt 20 is wound around these pulleys 18, 19. A rotary encoder 21 is attached to the driven pulley 19 as an acceleration detection means for the lift motor 8, and is configured to detect pulse signals associated with the rotation of the drive shaft 8a of the lift motor 8. The pulse signals from the rotary encoder 21 are sent to the inverter control unit 53 and calculation processing unit 51 of the lift motor 8.

However, equivalent functionality can be achieved by using an AC servo motor instead of an induction motor and providing a drive control unit that conforms to this.

As shown in Figure 4, the chuck 5 is composed of a hollow chuck shaft 31 rotatably supported by bearings 45, 46, 47, and 48, and a flange-type sleeve 32 inserted into the chuck shaft 31 via a machine key (not shown). The sleeve 32 is constantly biased upward by a spring 33 and is configured to move while sliding on the outer periphery of the chuck shaft 31. Meanwhile, it is configured to rotate circumferentially together with the chuck shaft 31. The chuck shaft 31 is also provided with storage holes at positions dividing its outer periphery into three equal parts, capable of storing steel balls 34. The steel balls 34 fit into the engagement grooves 4c of the penetration rod 4, holding it in place. The inner diameter of the upper part of the sleeve 32 is larger than the inner diameter of the chuck shaft 31. Manually pushing the sleeve 32 down against the bias of the spring 33 disengages the steel balls 34 from the engagement grooves 4c of the penetration rod 4. Furthermore, if the chuck shaft 31 is rotated together with the sleeve 32 in this state and the steel ball 34 is moved to a position where the engagement groove 4c of the penetration rod 4 is not formed, the penetration rod 4 and chuck shaft 31 will no longer be engaged even if you release your hand from the sleeve 32.

An annular retaining member 32a is inserted into and fixed to the chuck shaft 31. This retaining member 32a is molded to the same inner diameter as the sleeve 32 and is configured to press down on the sleeve 32 from above to prevent it from coming loose. The retaining member 32a is also positioned so that it protrudes from the upper end of the chuck shaft 31, the reason for which will be explained later.

A rotary motor 6 is also mounted on the lifting platform 3. The rotary motor 6 is an induction motor, and is drive-controlled by the inverter control unit 54. A drive sprocket 36 is attached to the drive shaft 6a of the rotary motor 6 via a one-way clutch 35. A driven sprocket 37 is attached to the lower end of the chuck shaft 31, and an endless chain 38 is wound around these sprockets 36, 37 to transmit the rotational drive of the rotary motor 6 to the chuck shaft 31.

Here, the screw point 4b at the tip of the penetration rod 4 has a drill shape with one twist per 200 mm of length, as specified in Japanese Industrial Standard A1221. Therefore, the one-way clutch 35 transmits the drive to the drive sprocket 35 when the rotation motor 6 drives in the direction that screws the penetration rod 4 into the ground in accordance with the twist of the screw point 4b (hereinafter, for convenience, this drive will be referred to as forward drive). On the other hand, when the rotation motor 6 drives in the opposite direction (hereinafter, for convenience, this drive will be referred to as reverse drive), it spins freely and is configured not to transmit the drive to the penetration rod 4.

A washer-type load cell 39, an example of a load sensor, is inserted into the chuck shaft 31. As shown in FIG. 5, this washer-type load cell 39 is composed of pressure-receiving portions 41 molded at equal intervals in the circumferential direction on the underside of the sensor body 40, support portions 42 molded at equal intervals in the circumferential direction on the upper surface of the sensor body 40, and a strain gauge 43 affixed to the sensor body 40. With this configuration, the thrust load actually applied to the penetration rod 4 is transmitted to the pressure-receiving portion 41 via the angular ball bearings 45, 46 and cylindrical roller bearing 47 that support the chuck shaft 31. In response, the support portion 42 acts as a fulcrum for the pressure-receiving plate 44, causing distortion in the sensor body 40. This distortion is detected by the strain gauge 43, allowing the load applied to the penetration rod 4 to be detected with high accuracy.

As shown in Figure 2, the control unit 50, which controls the operation and load of the automatic penetration testing machine 1 of the present invention, includes a calculation processing unit 51, an inverter control unit 53 that controls the drive of the lifting motor 8, an inverter control unit 54 that controls the drive of the rotation motor, a memory unit 55, and an input unit 56.

The memory unit 55 stores a torque command value corresponding to the test load, and the calculation processing unit 51 selects that torque command value when a specific test load is set. This torque command value is then output to the inverter control unit 53, and the lifting motor 8 exerts an upward force corresponding to the torque command value, thereby applying the specific test load to the penetration rod 4.

The inverter control unit 53 controls the drive of the lift motor 8 so that it is driven by the torque command value output from the calculation processing unit 51. Specifically, the inverter control unit 53 controls the rotation speed and output torque of the lift motor 8 through vector control based on the pulse signal from the rotary encoder 21.

The calculation processing unit 51 calculates the rotational acceleration of the drive shaft 8a of the lift motor 8 based on the pulse signal from the rotary encoder 21 of the lift motor 8.

Next, the operation of the automatic penetration testing machine 1 will be explained. In the automatic penetration testing machine 1, the load applied to the penetration rod 4 is set to six levels: 50N, 150N, 250N, 500N, 750N, and 1KN, in accordance with the Swedish sounding test. For example, if the penetration speed slows down at a 250N load, the load applied to the penetration rod 4 is increased. On the other hand, if the penetration speed increases, the load applied to the penetration rod 4 is decreased. In this way, as the penetration speed slows during the penetration stage, the command value is changed so that the load increases in the order 500N, 750N, and 1KN. Then, when a 1KN load is applied and the penetration speed slows, the rotation motor 6 is driven to rotate the chuck 5 and penetration rod 4 together, and rotational penetration is performed with the load applied.

Furthermore, during the penetration test, when the lifting platform 3 reaches the ground surface and the entire length of the penetration rod 4 penetrates into the ground, an extension rod 104a is attached to the rear end of the penetration rod 4.

The extension rod 104a has a similar configuration to the rod 4a of the penetration rod 4. Both the rod 4a of the penetration rod 4 and the extension rod 104a have female threads at their tips and male threads at their rear ends. This configuration allows the female threads of the extension rod 104a to be threaded onto the male threads at the rear end of the penetration rod 4. The penetration rod 4 and chuck 5 are then disengaged, the lifting platform 3 is raised, and the steel ball 34 of the chuck 5 is fitted into the engagement groove 104c of the extension rod, completing the extension. The lifting platform 3 is then lowered again, penetrating the screw point 4b to an even greater depth. By repeating this rod connection process, the screw point 4b can be penetrated to the desired depth.

After the test is completed, the extension rod 104a is pulled out of the ground by raising the lifting platform 3 while the extension rod 104a and chuck 5 are still engaged. The extension rod 104a is then disengaged from the chuck 5, and the lifting platform 3 is lowered to the position of the lower penetration rod 4, and the steel ball 34 of the chuck 5 is engaged with the engagement groove 4c of the rod 4a of the penetration rod 4 (or the engagement groove 104c of the extension rod 104a). The penetration rod disconnecting tool 100 of the present invention is then attached to the upper extension rod 104a.

As shown in Figure 6, the penetration rod disconnection device 100 of the present invention is composed of a device body 110 and a fixing means 120 for fixing the device body 110 to the automatic penetration testing machine 1.

The tool body 110 has the same configuration as the chuck 5, and is composed of a hollow chuck shaft 131 with a through-hole through which the extension rod 104a can be inserted, and a sleeve 132 fitted onto the chuck shaft 131. The sleeve 132 is constantly biased upward by a spring 133, and is configured to be able to move while sliding on the outer circumferential surface of the chuck shaft 131. Meanwhile, it is configured to rotate integrally with the chuck shaft 131 in the circumferential direction.

The chuck shaft 131 of the instrument body 110 has storage holes drilled into it at positions dividing its outer circumference into thirds, capable of storing steel balls 134. These steel balls 134 fit into engagement grooves 104d formed on the outer surface of the lower end of the extension rod 104a, holding the extension rod 104a in place. The inner diameter of the upper part of the sleeve 132 is larger than the inner diameter of the chuck shaft 131, and when the sleeve 132 is manually pushed down against the bias of the spring 133, the steel balls 134 are disengaged from the engagement grooves 104d of the extension rod 104a.

The fixing means 120 is a block member connected to the lower part of the instrument body 110, and has a communication hole 121 that communicates with the through hole of the chuck shaft 131 of the instrument body 110. The fixing means 120 also has a holding groove 122 that can be fitted into the frame 101 provided on the lifting platform 3. For convenience, the frame 101 is not shown in any drawings other than Figure 6.

The fixing means 120 also has a spigot portion 123 at the opening of the communication hole 121, and is configured to be positionable at the upper end of the chuck shaft 31.

As described above, the method of using the penetration rod disconnecting device 1 involves performing the specified withdrawal operation using the automatic penetration testing machine 1 after the penetration test is completed, then attaching the device body 110 of the penetration rod disconnecting device 100 to the engagement groove 104d of the upper extension rod 104a, and securing the fixing means 120 to the frame 101 of the lifting platform 3.

In this state, driving the rotation motor 6 to rotate the chuck 5 rotates the lower penetration rod 4. Meanwhile, the rotation direction of the upper extension rod 104a is fixed by the penetration rod disconnection tool 100, so the threaded portion connecting these rods is unscrewed.

After the threads are released, manually pushing down the sleeve 132 against the force of the spring 133 disengages the steel ball 134 from the engagement groove 104d of the extension rod 104a. In this state, manually rotating the extension rod 104a and rotating the engagement groove 104d of the extension rod 104a to a position where the steel ball 134 is no longer present disengages the extension rod 104a from the chuck shaft 131, allowing the extension rod 104a to be removed from the device body even if the sleeve 132 is released. The penetration rod disconnecting tool 1 can be removed from the automatic penetration testing machine 1, and the specified pulling operation of the automatic penetration testing machine 1 can be repeated, using the penetration rod disconnecting tool 100 each time, to sequentially disconnect the extension rod 104a.

1 Automatic penetration test machine 2 Support 2a Guide chain 3 Lifting platform 3a Weight 4 Penetration rod 4b Screw point 4c Engagement groove 5 Chuck 6 Rotation motor 6a Drive shaft 8 Lifting motor 8a Drive shaft 11 Planetary gear mechanism 12 Transmission shaft 13 Drive gear 14 Intermediate gear 15 Transmission gear 16 One-way clutch 17 Rotary encoder 18 Drive pulley 19 Driven pulley 20 Endless belt 21 Rotary encoder 31 Chuck shaft 32 Sleeve 32a Presser member 33 Spring 34 Steel ball 35 One-way clutch 36 Drive sprocket 37 Driven sprocket 38 Endless chain 39 Washer type load cell 40 Load cell body 41 Pressure receiving part 42 Support part 43 Strain gauge 44 Pressure receiving plate 45, 46 Angular ball bearing 47, 48 Cylindrical roller bearing 50 Control unit 51 Arithmetic processing unit 53 Inverter control unit 54 Inverter control unit 55 Memory unit 56 Input unit 100 Penetration rod connection release device 101 Frame 104a Extension rods 104c, 104d Engagement groove
110 Tool body 120 Fixing means 121 Communication hole 122 Holding groove 123 Spigot portion 131 Chuck shaft 132 Sleeve 133 Spring 134 Steel ball

Claims (1)

A penetration rod disconnection tool used in a penetration testing machine that is equipped with a chuck that can rotatably hold a penetration rod as the motor is driven, and is configured to rotate and penetrate into the ground while sequentially extending and connecting extension rods by screw connection.
a tool body capable of holding an extension rod;
A penetration rod disconnection device comprising: a fixing means provided in a penetration testing machine and fixing the device body ;
The instrument body includes:
a hollow chuck shaft having an inner hole through which the extension rod can be inserted;
a sleeve that is reciprocally movable along the chuck shaft and is always biased toward the end of the chuck shaft;
a sleeve holder that restricts movement of the sleeve toward the chuck shaft end;
a steel ball disposed on the chuck shaft and always supported by the sleeve in a state of protruding into an inner hole of the chuck shaft,
A penetration rod disconnection device characterized in that when the steel balls of the device body are fitted into the engagement grooves formed on the outer peripheral surfaces of both ends of the extension rod and the chuck motor is driven to rotate the penetration rod, the device body holds the extension rod without rotating it, thereby releasing the threaded connection of these rods.