Drill bit expanding device for casing protection wall rotary drilling bored pile

Abstract

The utility model belongs to the technical field of constructional engineering, and relates to a drill bit expanding device for a casing protection wall rotary excavating drilling pile, which is an expanding drill bit applied to a casing protection wall rotary excavating drilling pile process of pile foundation engineering, and the diameter of a hole-forming pile and smooth lowering of a casing pipe are guaranteed through the expanding device additionally arranged on the rotary excavating drill bit. According to the telescopic expanding drilling tool, a conventional rotary excavating double-bottom drill bit is modified, the telescopic expanding drilling tool has the expanding capacity by additionally installing components and optimizing a mechanical structure, and the arranged thrust block can achieve the expanding and closing functions of the telescopic expanding drilling tool according to the drilling state; the efficiency of casing running while drilling and the stability of casing running can be improved in an easily collapsed loose filling soil (stone) layer, and meanwhile, the pile diameter of a non-casing section subjected to reaming by adopting the device is kept consistent with the pile diameter of a casing section, so that a steel retaining casing with the same size can be prepared according to the requirement of the designed pile diameter; and the drilling cost can be effectively controlled, and the cost of over-pouring concrete in a sleeve section is saved.

Description

Technical Field

[0001] The utility model belongs to the technical field of construction engineering, and relates to a drill bit diameter expansion device for casing wall rotary drilling piles. The utility model is a diameter expansion drill bit used in the casing wall rotary drilling pile process of pile foundation engineering. The diameter expansion device installed on the rotary drilling drill bit ensures the smooth lowering of the bored pile diameter and the casing. Background Art

[0002] In pile foundation projects using rotary drilling rigs, steel casing is normally used for wall protection in loose fill (rock) layers prone to hole collapse and soil formations prone to necking. The casing wall protection process is normally to advance the casing and then lower the drill bit to dig out the soil. However, for fill (rock) layers with a high hardness content, lowering the casing is often difficult. In this case, it is necessary to first use a rotary drilling rig to pre-select a hole along the casing lowering path before lowering the steel casing. When lowering the casing in this way, it is normally necessary to replace it with a large-diameter ordinary drill bit or a large-sized reaming drill bit to pre-drill the hole and then rotate and press the steel casing in. One drilling rig is required to reciprocate to dig the soil and lower the casing, or two drilling rigs are used to alternately dig the soil and lower the casing. Conventional reaming drill bits have a complex structure and are not very convenient and practical to operate, resulting in low drilling efficiency and a long hole-making time.

[0003] When drilling through loose fill (rock) layers and easily collapsible clay and sandy soil layers, mud walling or dry drilling can be used for relatively stable strata, eliminating the need to lower steel casing wall. However, to ensure that the pile diameter meets the design requirements, the design pile diameter is usually based on the pile foundation of the non-cased section. To ensure that the rotary drilling drill bit can be lowered smoothly, the casing diameter of the casing section will be larger than the designed pile diameter. As a result, the pile diameter of the casing section will be larger than the designed pile diameter, resulting in increased drilling costs and waste of concrete due to over-pouring of the casing section.

[0004] Therefore, it is necessary to modify the conventional rotary bored pile drill bit and design a hole-reaming drill bit suitable for the casing wall protection process. By adding a hole-reaming device, the rotary bored pile can be assisted in realizing casing while drilling in the formation prone to hole collapse. At the same time, the pile diameter after hole expansion in the non-casing section is consistent with the pile diameter in the casing section. The same size steel casing can be equipped according to the requirements of the designed pile diameter, saving the cost of hole making and a certain amount of concrete while ensuring the pile diameter. Utility Model Content

[0005] In order to solve the problem that the above-mentioned rotary drilling rig has difficulty in lowering casing in the backfill (stone) layer with high hardness content, and the requirement for diameter expansion in the non-casing section, the utility model proposes a rotary drilling pile drill bit diameter expansion device that can be applied to the casing wall protection process. The rotary drilling drill bit with the diameter expansion device can be used in the whole process of hole forming. The main purpose is to realize the smooth lowering of the wall protection casing after the drill bit pre-drills a hole in the backfill (stone) layer with high hardness content by adding a retractable diameter expansion drill bit. At the same time, the retractable diameter expansion drill has a hole expansion effect in the non-casing wall protection section, and the pile diameter after the hole expansion in the non-casing section is consistent with the pile diameter of the casing section. Specifically, a thrust block is welded to the base plate of a conventional double-bottomed rotary drilling rig. When the drill bit rotates forward to extract soil, the base plate is extended, and the forward thrust block welded to the base plate rotates with it. After the end of the thrust block contacts the connecting rod of the telescopic expansion drill bit, the telescopic expansion drill bit assembly opens to a certain angle, and the drill teeth expand the hole wall, thereby increasing the soil cutting range. The expanded hole profile can cover the hole diameter range of the lowered steel casing. When the drill is lifted to drain soil, the base plate is closed. Without the action of the thrust block, the expanded hole drill bit assembly is retracted into the barrel, without affecting the lifting and lowering of the drill bit in the casing section. The telescopic expansion drill bit effectively cuts and breaks the soil layer between the drill barrel and the expanded hole profile, thereby achieving the dual functions of pre-drilling the casing section drill bit to assist in casing running and expanding the diameter of the non-casing section.

[0006] The retractable expanding diameter drill tool is symmetrically arranged on the outside of the rotary drilling bit barrel. A reinforcement block is set on the outside of the expanding diameter drill tool to ensure the strength of the drill tool during rotation to extract soil. The curved thrust block connected to the base plate switches the working state and recovery state of the retractable expanding diameter drill tool according to the expanded and closed states of the drill base plate during the soil extraction and discharge process. Through mechanical modification, the expansion function of the conventional drill bit is expanded while ensuring the normal use of the drill bit.

[0007] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A drill bit expansion device for casing-walled rotary bored piles, mainly consisting of an expansion drill tool reinforcement block 7, a thrust block 9 and a retractable expansion drill tool 8 mounted on a rotary double-bottom sand bailing drill bit;

[0009] The retractable expanding drill 8 is composed of an expanding drill tooth 81, a cutter head support 82, and a connecting rod 83. The front end of the connecting rod 83 is fixedly connected to the cutter head support 82, and the expanding drill tooth 81 is mounted on the cutter head support 82. The rear end of the connecting rod 83 is connected to the outer wall of the drill barrel 2 via a rotating pin 84 to achieve the telescopic function. The number of the retractable expanding drill 8 is greater than or equal to two, and they are symmetrically mounted on the outer wall of the drill barrel 2. Each retractable expanding drill 8 is equipped with two expanding drill reinforcement blocks 7 and a thrust block 9.

[0010] The expanded diameter drill tool reinforcement block 7 is fixed to the outer wall of the drill bit barrel 2. Two expanded diameter drill tool reinforcement blocks 7 are symmetrically installed on both sides of the telescopic expanded diameter drill tool 8. The bottom of the expanded diameter drill tool reinforcement block 7 is flush with the bottom of the connecting rod 83. The expanded diameter drill tool reinforcement block 7 limits the swing range of the telescopic expanded diameter drill tool 8 and ensures the rigidity of the drill teeth 81 during the drill bit rotation and soil cutting operation.

[0011] The thrust block 9 is fixed on the lower base plate 4 of the drill bit and is located on the side of the telescopic expanding diameter drilling tool 8. The front end of the thrust block 9 is a wedge-shaped structure. When the telescopic expanding diameter drilling tool 8 is in the recovered state, the connecting rod 83 contacts the edge of the front end of the thrust block 9; the drill bit drives the telescopic expanding diameter drilling tool 8 to expand and retract during the rotary soil excavation process, thereby realizing the expansion of the pile hole.

[0012] When the rotary drilling rig is rotating and drilling, the lower base plate 4 of the rotary drilling double-bottom sand bailing drill bit is opened, and the thrust block 9 connected to the lower base plate 4 rotates accordingly. The front end of the thrust block 9 contacts the connecting rod 83 of the telescopic expanding diameter drill tool 8 and then expands it to a certain angle. The drill teeth 81 of the telescopic expanding diameter drill tool 8 are opened to a certain angle and cut the rock and soil between the drill bit barrel 2 and the reaming profile 11 as the drill bit rotates forward. In the casing wall protection section, it can ensure that the steel wall protection casing 6 pressed in while drilling can be smoothly lowered between the rotary drill bit barrel 2 and the hole expansion profile 11, thereby improving the lowering efficiency and stability of the steel wall protection casing 6; in the non-casing wall protection section, in addition to the normal excavation of the soil within the range of the drill bit barrel 2, the rock and soil between the rotary drill bit barrel 2 and the hole expansion profile 11 can also be effectively cut by the retractable expanding diameter drill tool 8, and the original soil after cutting is discharged through the drill bit through mud circulation or after falling to the bottom of the hole, thereby achieving the hole expansion effect of the non-casing wall protection section.

[0013] After the rock and soil cut by the rotary drill bit fills the drill bucket, the rotary drill bit is reversed and the drill is lifted. At this time, the lower base plate 4 is reversed and closed, and the thrust block 9 welded to the lower base plate 4 rotates to the gap position. The front end of the thrust block 9 is out of contact with the telescopic expanding drill tool 8. Under the action of its own weight, the telescopic expanding drill tool 8 will be recovered into the range of the barrel, which will not affect the lifting and lowering of the casing section of the drill bit during the soil discharge process, thereby ensuring that the drill barrel 2 carrying the rock and soil can be smoothly lifted out of the borehole for slag discharge.

[0014] Beneficial effects of the utility model:

[0015] This utility model proposes a drill expansion device for casing-walled, drilled piles. It incorporates a thrust mechanism integrated with the drill base plate. This mechanism provides driving force through the opening and closing of the lower base plate during forward and reverse rotation, driving the expansion drill tool's deployment and retraction, thus achieving the desired hole expansion process. The mechanical expansion drill tool boasts a relatively simple structure, is durable and reliable, and requires no additional driving force. The entire expansion mechanism is adaptable to meet varying expansion requirements, and the expansion device can be disassembled to function as a conventional drill bit.

[0016] 2. The drill expansion device proposed in this utility model creates a larger crushing surface than the drill barrel within the lowering range of the drill bit's outer casing. This pre-drilling method effectively solves the difficulty of lowering casing in hard fill (rock) layers. The retractable expansion drill tool can switch between operating and retractable states without affecting the normal raising and lowering of the casing section during the soil removal process.

[0017] 3. When drilling in the non-casing wall section, in addition to the normal excavation of soil within the range of the drill bit barrel, the rotary drill bit will effectively cut the soil within the scope of the hole expansion contour formed by the expanding drill bit. The original soil after cutting will be discharged through mud circulation or bottom cleaning, thereby achieving the hole expansion effect of the non-casing wall section. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a bottom plan view of a rotary double-bottom sand bailing drill bit with a drill bit expansion device for casing-walled rotary bored piles according to the present invention (the drill bit expansion device is in an expanded state);

[0019] Figure 2 It is a cross-sectional schematic diagram of a rotary double-bottom sand bailing drill bit with a drill bit expansion device for casing-walled rotary bored piles according to the utility model (the drill bit expansion device is in an expanded state);

[0020] Figure 3 This is a schematic structural plan view of a drill bit diameter expansion device for casing-walled rotary bored piles ( Figure 1 (enlarged view of point A in the middle);

[0021] Figure 4 This is a tangential diagram of the structure of the drill bit expansion device used for casing wall rotary bored piles ( Figure 2 (enlarged view of point B in the middle);

[0022] In the figure: 1 connecting square head; 2 drill bit barrel; 3 upper base plate; 4 lower base plate; 5 cutting teeth and tooth plates; 6 steel wall casing; 7 expansion drill tool reinforcement block; 8 telescopic expansion drill tool; 81 expansion drill tool drill teeth; 82 cutter head support; 83 connecting rod; 84 rotating pin; 9 thrust block; 10 alloy wear-resistant block; 11 expansion hole profile. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0024] The structure of the drill bit diameter expansion device for casing wall rotary drilling bored pile of the utility model is as follows Figure 3 and Figure 4 As shown, the structure of the rotary drilling double bottom sand bailing drill bit with the drill bit diameter expansion device for casing wall rotary drilling bored pile of the utility model is as follows Figure 1 and Figure 2 shown.

[0025] When the rotary drilling rig is drilling for soil normally, the rotary drilling bit is connected to the drill rod driven by the upper drive through the connecting square head 1, and the upper base plate 3 and the lower base plate 4 of the rotary drilling double-bottom sand bailing drill bit can be staggered and opened. When the rotary drilling double-bottom sand bailing drill bit is rotating, the lower base plate 4 of the rotary drilling double-bottom sand bailing drill bit is opened, and the thrust blocks 9 symmetrically arranged on the lower base plate 4 of the double-bottom drill bit play a role. When the front end of the thrust block 9 is rotating, it contacts the connecting rod 83 of the telescopic expanding diameter drilling tool 8, and the cutter head support 82 connected to the connecting rod 83 and the drill teeth 81 of the expanding diameter drilling tool are rotated around the rotating pin 84 and spread out a certain distance outside the drill bit barrel 2. The expanded angle of the drill teeth 81 in the telescopic expanding drill 8 forms a reaming profile 11 that can effectively cut the rock and soil between the rotary drill bit barrel 2 and the reaming profile 11. Due to the large resistance when the drill bit rotates to cut the soil, in order to ensure the rigidity of the drill teeth during the drill bit rotation and to secure the rotating pin 84 of the telescopic expanding drill 8, expansion drill reinforcement blocks 7 are symmetrically arranged on both sides of the connection between the telescopic expanding drill 8 and the drill bit barrel 2. At the same time, alloy wear-resistant blocks 10 are placed in other positions of the drill bit barrel 2 to enhance the rigidity of the drill bit barrel 2 and its stability during drilling. When the drill bit is drilling beyond the steel retaining wall casing 6 in the casing retaining wall drilling section, the rotary drilling rig can press the steel retaining wall casing 6 into the rock and soil between the drill bit barrel 2 and the reaming profile 11 relatively smoothly after the reaming drill bit pre-drills the formation. For the drilling section without casing protection, the process of hole enlarging and soil excavation by the rotary drill bit is basically the same as that of the casing section. The soil within the range of the drill bit barrel 2 and the rock and soil between the drill bit barrel 2 and the hole enlarging profile 11 are effectively cut. The original soil after cutting is circulated through the mud in the hole or is dug out by the drill bit barrel 2 after gathering at the bottom of the hole, thereby achieving the hole enlarging effect of the non-casing protection section.

[0026] After the rotary drill bit cuts the rock and soil and fills the drill barrel 2, the rotary drill bit is reversed to close the lower base plate 4 and lift the drill. At this time, the thrust block 9 welded to the base plate rotates in the opposite direction with the lower base plate 4 of the drill bit. When the front end of the thrust block 9 rotates in the opposite direction, it disengages from the connecting rod 83 of the telescopic expanding drill tool 8. After rotating with the drill, under the action of its own weight, the cutter head support 82 connected to the connecting rod 83 and the drill teeth 81 of the expanding drill tool rotate around the rotating pin 84 and rotate into the reaming tooth groove on the inside of the drill barrel 2, and the telescopic expanding drill tool 8 is recovered to the normal range of the drill barrel 2, thereby ensuring that the drill bucket carrying the rock and soil can smoothly lift out the steel wall casing section for soil discharge.

[0027] The working process of this utility model is as follows:

[0028] 1. When a foundation pile hole for a loose fill (stone) layer that is prone to collapse needs to be drilled with a steel retaining wall casing, a rotary drilling rig equipped with a rotary drill bit having an expansion device of the present invention is aligned with the hole position for drilling. The diameter of the steel retaining wall casing can be consistent with the designed pile diameter.

[0029] 2. The rotary drilling bit equipped with the expansion device of the utility model provides driving force through the forward and reverse rotation of the lower base plate in the double-bottom sand drill bit. The thrust block connected to the lower base plate drives the telescopic expansion drill tool to pre-drill the lowering path of the steel wall casing while performing normal drilling, ensuring the smooth lowering of the steel wall casing;

[0030] 3. After drilling to a certain depth and entering a relatively stable original soil layer, there is no need to press in the steel retaining wall casing. The hole can be continued by using mud retaining wall or dry operation. At this time, the telescopic expanding drill can continue to play a role, cutting and destroying the soil within the hole expansion contour. The cut soil can be discharged through mud circulation or bottom cleaning drill bit, thereby achieving the hole expansion effect of the non-casing retaining wall section, forming a rotary pile hole with the same outer diameter of the non-casing retaining wall section and the casing;

[0031] 4. When drilling in the casing section and the non-casing section, after the soil excavated by the rotary drill bit fills the drill bucket, the drill bit is reversed and the drill is lifted. At this time, the thrust block connected to the lower base plate is disengaged from the contact with the retractable expanding drill tool, and the retractable expanding drill tool is switched to the recovery state. During the soil discharge process, the drill bit expansion device can be normally lifted and lowered in the casing section; it will not affect the soil discharge.

[0032] 5. Repeat the above steps until the designed hole depth is reached and the hole is completed.

[0033] The utility model discloses a drill diameter expansion device for casing wall protection rotary drilling piles. The utility model is a modification of a conventional rotary drilling double-bottom sand bailing drill bit. The device has the hole expansion capability by adding components and optimizing the mechanical structure. The provided thrust block can realize telescopic diameter expansion of the drill tool according to the drilling state. The hole expansion device has the expansion and closing functions. In loose fill (stone) layers that are prone to collapse, the efficiency of casing running while drilling and the stability of casing lowering can be improved. At the same time, the pile diameter after hole expansion in the non-casing section is consistent with the pile diameter of the casing section. Therefore, the steel wall protection casing of the same size can be equipped according to the requirements of the designed pile diameter, which can effectively control the drilling cost and save the cost of over-pouring concrete in the casing section.

Claims

1. A drill bit diameter expansion device for casing wall drilling bored piles, characterized in that: The drill bit diameter expansion device for casing wall-protected rotary bored piles is composed of an expanded drill tool reinforcement block (7), a thrust block (9) and a telescopic expanded drill tool (8) mounted on a rotary double-bottom sand bailing drill bit; The telescopic expanding diameter drill tool (8) is composed of an expanding diameter drill tool tooth (81), a cutter head support (82) and a connecting rod (83). The front end of the connecting rod (83) is fixedly connected to the cutter head support (82). The cutting head support (82) is provided with the expanding diameter drill tool tooth (81). The rear end of the connecting rod (83) is connected to the outer wall of the drill bit barrel (2) through a rotating pin (84) to realize the telescopic function. The number of the telescopic expanding diameter drill tools (8) is greater than or equal to 2, and they are symmetrically installed on the outer wall of the drill bit barrel (2). Each telescopic expanding diameter drill tool (8) is equipped with two expanding diameter drill tool reinforcement blocks (7) and a thrust block (9). The expanded diameter drill tool reinforcement block (7) is fixed to the outer wall of the drill bit barrel (2), and two expanded diameter drill tool reinforcement blocks (7) are symmetrically installed on both sides of the telescopic expanded diameter drill tool (8). The bottom of the expanded diameter drill tool reinforcement block (7) is flush with the bottom of the connecting rod (83). The expanded diameter drill tool reinforcement block (7) limits the swing range of the telescopic expanded diameter drill tool (8) and ensures the rigidity of the drill teeth (81) when the drill bit rotates and cuts the soil; The thrust block (9) is fixed on the lower base plate (4) of the drill bit and is located on the side of the telescopic expanding diameter drilling tool (8). The front end of the thrust block (9) is a wedge-shaped structure. When the telescopic expanding diameter drilling tool (8) is in a retracted state, the connecting rod (83) contacts the edge of the front end of the thrust block (9); the drill bit drives the telescopic expanding diameter drilling tool (8) to expand and retract during the rotary soil excavation process, thereby realizing the expansion of the pile hole.

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