Efficient drilling rig for geotechnical engineering

Abstract

The invention relates to the technical field of rock-soil drilling, and particularly discloses an efficient drilling device for geotechnical engineering, which comprises a mounting mechanism, the mounting mechanism comprises a base and two longitudinal moving rail plates fixedly mounted on the upper surface of the base, one surface of each longitudinal moving rail plate is provided with an open slot, and the other surface of each longitudinal moving rail plate is provided with an open slot; the two open grooves are oppositely formed, movable protruding blocks are arranged in the open grooves, the movable protruding blocks are in sliding fit with the open grooves, the two movable protruding blocks are both connected with connecting rods and a drilling mechanism, the drilling mechanism comprises a driving bin and a vibrating bin which are fixedly connected to the two connecting rods, the vibrating bin is fixedly connected to one end of the driving bin, and a connecting shaft is arranged in the vibrating bin; according to the device, the base with the longitudinal moving rail plate is arranged, the spiral drill column can conduct longitudinal reciprocating impact while rotating, then the acting force of high-frequency vibration impact can be applied to hard rock, and the drilling efficiency can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of rock and soil drilling, and in particular relates to a high-efficiency drilling device for rock and soil engineering. Background Art

[0002] Geotechnical drilling is an important geological exploration technology used to find and evaluate mineral resources such as oil, natural gas, coal, metal and non-metallic minerals. Through drilling, samples of underground rocks and ores can be obtained, their composition and reserves can be analyzed, and a scientific basis can be provided for resource development. Drilling technology is used to monitor groundwater levels, water quality and soil pollution, assess environmental risks, and carry out geological environmental governance and restoration. In civil engineering construction, such as bridges, dams, high-rise buildings, etc., geotechnical drilling is used to determine the bearing capacity of the foundation, groundwater levels, soil layer structure and soil properties to ensure the safety and stability of the project. Geotechnical drilling helps to identify and assess geological disaster risks, such as landslides, mudslides, earthquakes, etc., and to formulate prevention and mitigation measures by obtaining underground structure information. In the agricultural field, geotechnical drilling can be used to assess soil fertility and moisture conditions, guide reasonable fertilization and irrigation, and improve agricultural production efficiency. The development and utilization of urban underground space, such as subways, underground pipelines, underground warehouses, etc., all require geotechnical drilling to understand the underground conditions in order to plan and design safe and reasonable urban underground projects.

[0003] According to a drilling device for geotechnical engineering construction proposed by publication number CN 115012836 A, the device comprises a base plate, a support plate, a driving motor, a transmission device, and a drill rod structure. Two vertical plates are arranged above the base plate, and the support plate is slidably arranged between the two vertical plates; the output end of the driving motor is connected to a rotating shaft, and the rotating shaft passes through the support plate and extends to the bottom of the support plate; the input end of the transmission device is connected to the rotating shaft, and the output end is connected to the support plate, so as to transmit the power to move the support plate downward; the drill rod structure comprises a drill rod, the upper end of the drill rod is connected to the rotating shaft through a clamping structure, and the lower end of the drill rod is connected to a drill bit through the clamping structure, and a first avoidance hole is opened on the support plate. The present invention is used to connect the drill rod and the drill bit by arranging a first clamping part and a second clamping part, and the drill rod is further added between the rotating shaft and the drill rod through the clamping structure, thereby increasing the length of the overall drill rod structure. At the same time, the transmission device only needs to move a distance equal to the length of one section of the drill rod, so that the drilling device is more portable.

[0004] Traditional geotechnical drilling equipment can only provide a single excavation-type drilling operation. When encountering some difficult-to-break rock formations, the effect of continuous rotary drilling on the surface is poor, resulting in low drilling efficiency.

[0005] Therefore, those skilled in the art have proposed an efficient drilling device for geotechnical engineering to solve the problems raised by the background technology.

[0006] The above information disclosed in this background technology is only used to increase the understanding of the background technology of the present invention and therefore, it may include information that does not constitute the prior art known to ordinary technicians in this field. Summary of the invention

[0007] The object of the present invention is to provide a high-efficiency drilling device for geotechnical engineering to solve the problems raised in the above-mentioned background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] An efficient drilling device for geotechnical engineering, comprising:

[0010] The mounting mechanism comprises a base and a longitudinal movable rail plate fixedly mounted on the upper surface of the base, the number of the longitudinal movable rail plates is two, one surface of the two longitudinal movable rail plates is provided with a groove, the two grooves are arranged opposite to each other, a movable protrusion is arranged in the groove, the movable protrusion is slidably matched with the groove, and the two movable protrusions are connected with a connecting rod;

[0011] A drilling mechanism, the drilling mechanism includes a driving chamber and a vibration chamber fixedly connected to the two connecting rods, the vibration chamber is fixedly connected to one end of the driving chamber, a connecting shaft is arranged inside the vibration chamber, one end of the connecting shaft is connected to a spiral drill column, one end of the spiral drill column is fixedly connected to an eccentric drill bit, a lifting cylinder is arranged on the upper surface of the vibration chamber, a lifting hole is opened in the lifting cylinder, a stretching rod is arranged in the lifting hole, the stretching rod is slidably matched with the lifting cylinder through the lifting hole, the other end of the connecting shaft is connected to a follower gear, the follower gear is located in the vibration chamber, and one end of the stretching rod is connected to the follower gear.

[0012] Preferably, a bearing is provided at the connection between the follower gear and the stretching rod, and the stretching rod is movably matched with the follower gear through the bearing.

[0013] Preferably, a driving motor is fixedly mounted on the lower surface of the driving bin, an output end of the driving motor is connected to a driving shaft, and a driving gear and a first bevel gear are fixedly mounted on the peripheral side of the driving shaft.

[0014] Preferably, the driving gear is located in the driving compartment, the first bevel gear is located above the driving compartment, and the driving gear is meshed with the driven gear.

[0015] Preferably, a bracket is fixedly mounted on the upper surface of the driving bin, a positioning shaft is inserted into the bracket, one end of the positioning shaft is fixedly connected to a second bevel gear, and the second bevel gear is meshed with the first bevel gear.

[0016] Preferably, one end of the positioning shaft away from the second bevel gear is connected to a rotating plate, the rotating plate is a circular plate structure, one surface of the rotating plate is fixedly connected to an extension shaft, and one end of the extension shaft is movably connected to a movable crank.

[0017] Preferably, one end of the movable crank is movably connected to a movable shaft, a sleeve is sleeved on a circumferential side of the movable shaft, and the sleeve is connected to the stretching rod.

[0018] Preferably, a reciprocating motor is fixedly mounted on the upper surface of the longitudinal movable rail plate, a threaded rod is arranged in the slot, the threaded rod is threadably matched with the movable protrusion, and the threaded rod is connected to the output end of the reciprocating motor.

[0019] Preferably, a storage plate is fixedly mounted on one side of the longitudinal movable rail plate, a water tank is fixedly mounted on the storage plate, a delivery pipe is connected to one end of the water tank, a pump is fixedly mounted on the upper surface of the base, and the delivery pipe is connected to the pump.

[0020] Preferably, a drilling groove is provided on the base, the drilling groove is located below the spiral drill column, a water outlet hole is provided on the inner peripheral side of the drilling groove, a nozzle is connected to the pump, and the nozzle is communicated with the water outlet hole.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention is provided with a base with a longitudinally movable rail plate. When rock drilling operations are required, the device can be placed at the drilling site to be drilled, and the driving motor is started to drive the active gear to mesh with the follower gear, thereby driving the spiral drill string to rotate. The longitudinal movement of the longitudinally movable rail plate can realize the effect of automatic excavation. In addition, the present device is provided with a first bevel gear and a rotating plate with a movable crank on the driving shaft. When the driving shaft rotates, it can drive the second bevel gear to mesh with the first bevel gear. At this time, the second bevel gear drives the rotating plate on the positioning shaft to rotate, and the outer shaft on the rotating plate drives the movable crank to rotate. A rectangular sliding groove is provided on the movable crank. The movable shaft will slide along the sliding groove and will also generate longitudinal movement as the position of the outer shaft changes. Then, the movable shaft will drive the stretching rod to slide and cooperate in the lifting cylinder, and the stretching rod will reciprocate the spiral drill string in the rotating state. Therefore, the spiral drill string can perform longitudinal reciprocating impact while rotating, thereby exerting a high-frequency vibration impact force on the hard rock, thereby improving the drilling efficiency.

[0023] (2) The present invention provides two longitudinal moving rail plates with reciprocating motors and threaded rods. The reciprocating motor can be started to drive the threaded rods to cooperate with the moving protrusions, thereby driving the moving protrusions to slide longitudinally in the slots, thereby driving the entire drilling equipment to gradually advance downwards. A water outlet and a water tank are provided on the base. The pump can be started to discharge the water in the water tank through the water outlet. The friction heat generated during drilling will increase the temperature of the drill bit and the cuttings. Sprinkling water can reduce the temperature of the cuttings, reduce equipment wear and drill bit loss caused by high temperature, and thus improve drilling efficiency. Water is used as a flushing medium and can also help remove the cuttings generated during the drilling process to prevent the accumulation of cuttings from affecting the drilling progress. Effective cuttings removal can reduce the frequency of drill bit replacement and improve drilling efficiency. In some formations, cuttings may clog the drilling equipment. Using water flushing can reduce such clogs, keep the drilling equipment unobstructed, and improve drilling efficiency.

[0024] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a front perspective structural schematic diagram of the present invention;

[0026] Figure 2 It is a bottom-up three-dimensional structural schematic diagram of the present invention;

[0027] Figure 3 It is a schematic diagram of the specific structure of the drive compartment of the present invention;

[0028] Figure 4 It is a front view of the present invention;

[0029] Figure 5 A top view of the present invention;

[0030] Figure 6 It is a schematic diagram of the internal structure of the drive compartment of the present invention.

[0031] In the figure: 1. base; 2. longitudinal movable rail plate; 3. slot; 4. reciprocating motor; 5. threaded rod; 6. movable protrusion; 7. connecting rod; 8. driving chamber; 9. connecting shaft; 10. spiral drill column; 11. eccentric drill bit; 12. drilling groove; 13. water outlet; 14. storage plate; 15. water tank; 16. pump; 17. delivery pipe; 18. driving motor; 19. vibration chamber; 20. driving shaft; 21. first bevel gear; 22. bracket; 23. positioning shaft; 24. second bevel gear; 25. rotating plate; 26. extension shaft; 27. movable crank; 28. movable shaft; 29. ​​sleeve; 30. stretching rod; 31. lifting hole; 32. lifting cylinder; 33. driving gear; 34. follower gear. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Embodiment 1:

[0034] See also Figure 1-Figure 6 As shown, a high-efficiency drilling device for geotechnical engineering comprises:

[0035] The mounting mechanism includes a base 1 and a longitudinal movable rail plate 2 fixedly mounted on the upper surface of the base 1. The number of the longitudinal movable rail plates 2 is two. A groove 3 is provided on one surface of the two longitudinal movable rail plates 2. The two grooves 3 are arranged opposite to each other. A movable protrusion 6 is provided in the groove 3. The movable protrusion 6 is slidably matched with the groove 3. The two movable protrusions 6 are connected with a connecting rod 7;

[0036] The drilling mechanism includes a driving bin 8 and a vibration bin 19 fixedly connected to two connecting rods 7. The vibration bin 19 is fixedly connected to one end of the driving bin 8. A connecting shaft 9 is arranged inside the vibration bin 19. One end of the connecting shaft 9 is connected to a spiral drill column 10. One end of the spiral drill column 10 is fixedly connected to an eccentric drill bit 11. A lifting cylinder 32 is arranged on the upper surface of the vibration bin 19. A lifting hole 31 is opened in the lifting cylinder 32. A stretching rod 30 is arranged in the lifting hole 31. The stretching rod 30 is slidably matched with the lifting cylinder 32 through the lifting hole 31. The other end of the connecting shaft 9 is connected to a follower gear 34. The follower gear 34 is located in the vibration bin 19. One end of the stretching rod 30 is connected to the follower gear 34.

[0037] Specifically, a bearing is provided at the connection between the follower gear 34 and the stretching rod 30 , and the stretching rod 30 is movably matched with the follower gear 34 through the bearing.

[0038] Specifically, a driving motor 18 is fixedly mounted on the lower surface of the driving compartment 8 , an output end of the driving motor 18 is connected to a driving shaft 20 , and a driving gear 33 and a first bevel gear 21 are fixedly mounted on the side surface of the driving shaft 20 .

[0039] Specifically, the driving gear 33 is located in the driving compartment 8 , the first bevel gear 21 is located above the driving compartment 8 , and the driving gear 33 is meshed with the driven gear 34 .

[0040] Specifically, a bracket 22 is fixedly installed on the upper surface of the driving chamber 8 , a positioning shaft 23 is inserted into the bracket 22 , one end of the positioning shaft 23 is fixedly connected to a second bevel gear 24 , and the second bevel gear 24 is meshed with the first bevel gear 21 .

[0041] Specifically, one end of the positioning shaft 23 away from the second bevel gear 24 is connected to a rotating plate 25 . The rotating plate 25 is a circular plate structure. An extension shaft 26 is fixedly connected to one surface of the rotating plate 25 . One end of the extension shaft 26 is movably connected to a movable crank 27 .

[0042] Specifically, one end of the movable crank 27 is movably connected to a movable shaft 28 , a sleeve 29 is sleeved on a side surface of the movable shaft 28 , and the sleeve 29 is connected to a stretching rod 30 .

[0043] As can be seen from the above, the device is provided with a base 1 with a longitudinally movable rail plate 2. When a rock drilling operation is required, the device can be placed at the location to be drilled, and the drive motor 18 is started to drive the active gear 33 to mesh with the follower gear 34, thereby driving the spiral drill column 10 to rotate, and then the longitudinal movement of the longitudinally movable rail plate 2 can achieve the effect of automatic excavation, and the device is provided with a first bevel gear 21 and a rotating plate 25 with a movable crank 27 on the drive shaft 20. When the drive shaft 20 rotates, it can drive the second bevel gear 24 to mesh with the first bevel gear 21. At this time, the second bevel gear 24 drives The rotating plate 25 on the positioning shaft 23 rotates, and the extension shaft 26 on the rotating plate 25 drives the movable crank 27 to rotate. A rectangular slide groove is provided on the movable crank 27, and the movable shaft 28 will slide along the slide groove. At the same time, it will also produce longitudinal movement as the position of the extension shaft 26 changes, and then the movable shaft 28 will drive the stretching rod 30 to slide and cooperate in the lifting cylinder 32, and the stretching rod 30 will reciprocate the spiral drill string 10 in the rotating state, thereby allowing the spiral drill string 10 to perform longitudinal reciprocating impact while rotating, and then can exert high-frequency vibration impact force on the hard rock, which can improve the drilling efficiency.

[0044] Embodiment 2:

[0045] See also Figure 1-Figure 6As shown, a reciprocating motor 4 is fixedly mounted on the upper surface of the longitudinal movable rail plate 2 , a threaded rod 5 is arranged in the slot 3 , the threaded rod 5 is threadably matched with the movable protrusion 6 , and the threaded rod 5 is connected to the output end of the reciprocating motor 4 .

[0046] Specifically, a storage plate 14 is fixedly installed on one side of the longitudinal movable rail plate 2, a water tank 15 is fixedly installed on the storage plate 14, a delivery pipe 17 is connected to one end of the water tank 15, a pump 16 is fixedly installed on the upper surface of the base 1, and the delivery pipe 17 is connected to the pump 16.

[0047] Specifically, a drilling groove 12 is provided on the base 1 , and the drilling groove 12 is located below the spiral drill string 10 . A water outlet 13 is provided on the inner peripheral side of the drilling groove 12 . A nozzle is connected to the pump 16 , and the nozzle is communicated with the water outlet 13 .

[0048] As can be seen from the above, the device is provided with two longitudinal moving rail plates 2 with a reciprocating motor 4 and a threaded rod 5. The reciprocating motor 4 can be started to drive the threaded rod 5 to engage with the moving protrusion 6, thereby driving the moving protrusion 6 to slide longitudinally in the slot 3, so as to drive the entire drilling equipment to gradually dig downward, and a water outlet 13 and a water tank 15 are provided on the base 1. The pump 16 can be started to discharge the water in the water tank 15 along the water outlet 13. The friction heat generated during drilling will increase the temperature of the drill bit and the cuttings. Sprinkling water can reduce the temperature of the cuttings, reduce equipment wear and drill bit loss caused by high temperature, thereby improving the drilling efficiency. Water is used as a flushing medium, and can also help remove the cuttings generated during the drilling process to avoid the accumulation of cuttings affecting the drilling progress. Effective cuttings removal can reduce the frequency of drill bit replacement and improve drilling efficiency. In some formations, cuttings may block the drilling equipment. Using water flushing can reduce such blockage, keep the drilling equipment unobstructed, and improve drilling efficiency.

[0049] The standard parts used in the present invention can all be purchased from the market, and the special-shaped parts can be customized according to the description and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the prior art. The machinery, parts and equipment all adopt conventional models in the prior art, and the circuit connection adopts the conventional connection method in the prior art, which will not be described in detail here. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0050] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0051] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean 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, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0053] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0054] In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An efficient drilling device for geotechnical engineering, characterized in that: include: The mounting mechanism comprises a base (1) and a longitudinal movable rail plate (2) fixedly mounted on the upper surface of the base (1), the number of the longitudinal movable rail plates (2) being two, a groove (3) being provided on one surface of the two longitudinal movable rail plates (2), the two grooves (3) being arranged opposite to each other, a movable protrusion (6) being provided in the groove (3), the movable protrusion (6) being slidably matched with the groove (3), and a connecting rod (7) being connected to the two movable protrusions (6); A drilling mechanism, the drilling mechanism comprising a driving chamber (8) and a vibration chamber (19) fixedly connected to the two connecting rods (7), the vibration chamber (19) being fixedly connected to one end of the driving chamber (8), a connecting shaft (9) being arranged inside the vibration chamber (19), one end of the connecting shaft (9) being connected to a spiral drill column (10), one end of the spiral drill column (10) being fixedly connected to an eccentric drill bit (11), a lifting cylinder (32) being arranged on the upper surface of the vibration chamber (19), a lifting hole (31) being arranged inside the lifting cylinder (32), a stretching rod (30) being arranged inside the lifting hole (31), the stretching rod (30) being slidably matched with the lifting cylinder (32) through the lifting hole (31), the other end of the connecting shaft (9) being connected to a follower gear (34), the follower gear (34) being located inside the vibration chamber (19), and one end of the stretching rod (30) being connected to the follower gear (34).

2. The high-efficiency drilling device for geotechnical engineering according to claim 1, characterized in that: A bearing is provided at the connection between the follower gear (34) and the stretching rod (30), and the stretching rod (30) is movably matched with the follower gear (34) via the bearing.

3. The high-efficiency drilling device for geotechnical engineering according to claim 1, characterized in that: A driving motor (18) is fixedly mounted on the lower surface of the driving bin (8); an output end of the driving motor (18) is connected to a driving shaft (20); and a driving gear (33) and a first bevel gear (21) are fixedly mounted on the peripheral side of the driving shaft (20).

4. The high-efficiency drilling device for geotechnical engineering according to claim 3, characterized in that: The driving gear (33) is located in the driving bin (8), the first bevel gear (21) is located above the driving bin (8), and the driving gear (33) is meshed with the follower gear (34).

5. The high-efficiency drilling device for geotechnical engineering according to claim 4, characterized in that: A bracket (22) is fixedly mounted on the upper surface of the driving bin (8), a positioning shaft (23) is plugged into the bracket (22), one end of the positioning shaft (23) is fixedly connected to a second bevel gear (24), and the second bevel gear (24) is meshed with the first bevel gear (21).

6. The high-efficiency drilling device for geotechnical engineering according to claim 5, characterized in that: One end of the positioning shaft (23) away from the second bevel gear (24) is connected to a rotating plate (25), the rotating plate (25) is a circular plate structure, one surface of the rotating plate (25) is fixedly connected to an extension shaft (26), and one end of the extension shaft (26) is movably connected to a movable crank (27).

7. The high-efficiency drilling device for geotechnical engineering according to claim 6, characterized in that: One end of the movable crank (27) is movably connected to a movable shaft (28), a sleeve (29) is sleeved on the peripheral side of the movable shaft (28), and the sleeve (29) is connected to a stretching rod (30).

8. The high-efficiency drilling device for geotechnical engineering according to claim 1, characterized in that: A reciprocating motor (4) is fixedly mounted on the upper surface of the longitudinal moving rail plate (2), a threaded rod (5) is arranged in the slot (3), the threaded rod (5) is threadably matched with the moving protrusion (6), and the threaded rod (5) is connected to the output end of the reciprocating motor (4).

9. The high-efficiency drilling device for geotechnical engineering according to claim 1, characterized in that: A storage plate (14) is fixedly mounted on one side of the longitudinal movable rail plate (2), a water tank (15) is fixedly mounted on the storage plate (14), one end of the water tank (15) is connected to a delivery pipe (17), a pump (16) is fixedly mounted on the upper surface of the base (1), and the delivery pipe (17) is connected to the pump (16).

10. The high-efficiency drilling device for geotechnical engineering according to claim 9, characterized in that: The base (1) is provided with a drilling groove (12), the drilling groove (12) is located below the spiral drill column (10), a water outlet hole (13) is provided on the inner peripheral side surface of the drilling groove (12), and a nozzle is connected to the pump (16), and the nozzle is communicated with the water outlet hole (13).

Images