CN116692323A - Auxiliary cargo handling robot for logistics and application method thereof - Google Patents

Abstract

The invention relates to the technical field of cargo handling robots, in particular to an auxiliary cargo handling robot for logistics and a using method thereof, comprising the following steps: the automatic control device comprises a transfer robot main body, wherein one side of the transfer robot main body is fixedly provided with a rear carrying and carrying frame through screws, displacement driving rollers are arranged at the positions of the two sides of the bottom of the rear carrying and carrying frame and the transfer robot main body, an automatic control action module is arranged at the top of the transfer robot main body, and a sensor module is arranged at the position of the surface of the automatic control action module, which is close to the rear carrying and carrying frame. According to the invention, the front and back carrying and placing frame and the clamping jaw machine assembly are matched with each other, so that a plurality of cargoes can be transported at a time by utilizing the front and back carrying and placing frame and the clamping jaw machine assembly of the carrying robot body in the whole carrying process, the times of back and forth moving and carrying can be effectively reduced, and the carrying efficiency is improved.

Description

Auxiliary cargo handling robot for logistics and application method thereof

Technical Field

The invention relates to the technical field of cargo handling robots, in particular to an auxiliary cargo handling robot for logistics and a using method thereof.

Background

The warehouse logistics is to utilize a self-built or leased warehouse, a site, storage, safekeeping, loading and unloading, carrying and delivering goods, the traditional warehouse definition is given from the aspect of storing goods, the modern warehouse is not the warehouse in the traditional sense and warehouse management, but the warehouse in the environment of economic globalization and supply chain integration, is the warehouse in the modern logistics system, and the goods are required to be moved when the warehouse logistics is operated.

With the increase of industrial automation demands, more and more use cargo handling robots to realize automatic handling of materials in logistics warehouse, in the related art, in the cargo handling process of logistics, different cargoes, such as various accessories, materials or finished products, are often required to be handled, generally people utilize lifting carts to carry cargoes, heavy cargoes are required to be handled by forklift trucks, the lifting carts need workers to put cargoes on the carts, and then move and carry back and forth in many times, so that the handling operation is time-consuming and labor-consuming, and the cargoes can be easily forked by forklift and tray, but the cargoes need to be orderly stacked on the tray in advance manually, so that the shaking is easy to occur in the transportation process, and even the cargo can slide occasionally, therefore, the auxiliary cargo handling robot for logistics and the use method thereof are provided to solve the problems.

Disclosure of Invention

The invention aims to provide an auxiliary cargo handling robot for logistics and a use method thereof, which are used for solving the problems that in the prior art, a worker is required to put cargoes on a trolley in an existing lifting type trolley, and then the cargoes are moved and carried back and forth for a plurality of times, so that the carrying operation is time-consuming and labor-consuming, and the cargoes are easy to shake in the transportation process, so that the cargoes slide and even drop occasionally.

In order to achieve the above purpose, the present invention provides the following technical solutions:

an auxiliary cargo handling robot for logistics and a use method thereof, comprising: the automatic control device comprises a carrying robot main body, wherein one side of the carrying robot main body is fixedly provided with a rear carrying and carrying frame through screws, displacement driving rollers are arranged at the positions of the rear carrying and carrying frame and the two sides of the bottom of the carrying robot main body, an automatic control action module is arranged at the top of the carrying robot main body, and a sensor module is arranged at the position of the surface of the automatic control action module, which is close to the rear carrying and carrying frame;

clamping jaw machine subassembly, clamping jaw machine subassembly is installed to the opposite side of transfer robot main part, and clamping jaw machine subassembly is close to transfer robot main part's position department and installs arm master control module, clamping jaw machine subassembly is including accepting mounting bracket and second arm, and accept the mounting bracket and erect in arm master control module top position department to accept mounting bracket and transfer robot main part fixed surface connection, accept the surface of mounting bracket and install the main half gear through the bearing, and the input and the arm master control module output electrical connection of main half gear, the bearing mounting bracket surface of main half gear one side is installed the vice half gear through the bearing, and the meshing is connected between vice half gear and the main half gear, the one end that main half gear and then vice half gear kept away from each other is connected with first clamping jaw through the pivot, the intermediate position department of first clamping bracket is articulated with accepting the clamping jaw through the pivot and is connected.

Preferably, the transfer robot main body comprises an automatic control action module, a sensor module and a mechanical arm main control module, wherein the automatic control action module is connected with the mechanical arm main control module through a serial port, a first control signal output end of the automatic control action module is connected with a control signal input end of the mechanical arm main control module, a second control signal output end of the automatic control action module is connected with a control signal input end of the sensor module, and a signal output end of the sensor module is connected with a signal input end of the mechanical arm main control module.

Preferably, the top both sides of frame are placed in back bearing transport have set up the fender protection frame respectively, and the inside of fender protection frame is installed the guide pulley through the bearing.

Preferably, the bottom of the rear carrying and carrying placing frame is inclined, and at least four groups of guide pulleys are arranged.

Preferably, the second clamping jaw is installed at the surface position of the main body of the transfer robot below the first clamping jaw through a bearing, and the middle section and the top end of the second clamping jaw are respectively connected with the first clamping jaw through a bearing shaft rod.

Preferably, the first clamping jaw, the second mechanical arm and the second clamping jaw are arranged in two groups, and the first clamping jaw, the second mechanical arm and the second clamping jaw are symmetrically distributed.

Preferably, the outer end positions of the first clamping jaw and the second clamping jaw are arranged in a bent hook shape.

The application method of the auxiliary cargo handling robot for logistics comprises the following steps:

step one: starting a power supply of a transfer robot main body, enabling the transfer robot main body to be in a power-on state, and initializing each module and corresponding parameters;

step two: the control of the transfer robot main body is started, the transfer robot main body is controlled through signal connection, the transfer robot main body is started, meanwhile, a path is preset in advance to enable the transfer robot main body to move, and the detection result of the sensor module is fed back to the mechanical arm main control module;

step three: the mechanical arm main control module judges the movement route of the transfer robot main body according to the detection result and sends the information to the automatic control action module through the serial port, and the automatic control action module sends a movement direction instruction to the displacement driving roller to control the movement state of the transfer robot main body, so that the transfer robot main body walks along the route;

step four: the transfer robot main body performs grabbing operation, and after stopping, the mechanical arm main control module controls the steering engine to control the clamping jaw machine assembly to perform grabbing operation;

step five: after the grabbing operation is finished, the mechanical arm main control module sends an action completion instruction to the automatic control action module through the serial port, and the automatic control action module controls the transfer robot main body to rotate left until the sensor module detects that a preset path is stopped, so that the transfer robot main body is moved;

step six: after the sensor module detects the starting line, the automatic control action module receives an instruction of the mechanical arm main control module to control the robot to stop, and sends a placing operation command to the mechanical arm main control module through the serial port, the mechanical arm main control module controls the main half gear and the auxiliary half gear to move in a meshing mode, and the first clamping jaw and the second clamping jaw at the tail end are opened to finish the placing operation.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, through the matched use of the front and back carrying and placing frame and the clamping jaw machine assembly of the carrying robot main body, in the whole carrying process, the front and back carrying and placing frame and the clamping jaw machine assembly of the carrying robot main body are utilized, so that a plurality of cargoes can be transported at a time, the times of back and forth movement carrying can be effectively reduced, the carrying efficiency is improved, the carrying operation is time-saving and labor-saving, and meanwhile, the two side baffle protection frames and the sliding guide pulleys on the carrying and placing frame are matched, so that the two side guide pulleys can save time and labor in the cargo loading process, and can also block the cargoes due to shaking in the moving process, and the problem of falling or damage of the cargoes can be effectively avoided;

and through the design of clamping jaw machine assembly, make it adopt arm master control module to drive the mode of gear engagement motion between main half gear and the pair half gear to control the open size of first clamping jaw and second clamping jaw and carry out the centre gripping fixedly, its first clamping jaw and second clamping jaw outer end crotch form can tightly clamp the goods, guarantee the stable transport to the goods, make it ensure to shipment the goods steadily, and whole automatic operation, make it convenient to carry out swift transfer and transport to the goods, reduce the intensity of labour of goods transport.

Description of the drawings:

in order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic perspective view of the rear view of the present invention;

FIG. 2 is a schematic partial perspective view of a post-receiving, carrying and placing frame according to the present invention;

FIG. 3 is a schematic perspective view of the front view of the present invention;

fig. 4 is a partial perspective view showing the structure of a transfer robot body according to the present invention;

fig. 5 is a partial perspective view of the jaw machine assembly of the present invention.

In the figure: 1. a transfer robot body; 2. carrying and placing the frame at the rear; 3. a displacement driving roller; 4. a side shield protection frame; 5. a guide pulley; 6. an automatic control action module; 7. a sensor module; 8. a mechanical arm main control module; 9. a jaw machine assembly; 91. a bearing mounting frame; 92. a main half gear; 93. a secondary half gear; 94. a first mechanical arm; 95. a first clamping jaw; 96. a second mechanical arm; 97. a receiving shaft lever; 98. a second clamping jaw.

The specific embodiment is as follows:

the following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 1-5, an embodiment of the present invention is provided:

embodiment one:

an auxiliary cargo handling robot for logistics and a use method thereof, comprising: the robot comprises a transfer robot body 1, wherein a rear carrying and carrying placing frame 2 is fixedly arranged on one side of the transfer robot body 1 through screws, displacement driving rollers 3 are arranged at the positions of the two sides of the bottom of the rear carrying and carrying placing frame 2 and the transfer robot body 1, an automatic control action module 6 is arranged at the top position of the transfer robot body 1, and a sensor module 7 is arranged at the position, close to the surface of the rear carrying and carrying placing frame 2, of the automatic control action module 6;

the transfer robot body 1 comprises an automatic control action module 6, a sensor module 7 and a mechanical arm main control module 8, wherein the automatic control action module 6 is connected with the mechanical arm main control module 8 through a serial port, a first control signal output end of the automatic control action module 6 is connected with a control signal input end of the mechanical arm main control module 8, a second control signal output end of the automatic control action module 6 is connected with a control signal input end of the sensor module 7, a signal output end of the sensor module 7 is connected with a signal input end of the mechanical arm main control module 8, and according to the attached drawings 1 and 4, a preset path can be detected by using the sensor module 7, and the pressure between a cargo and a rear receiving transfer placing frame 2 can be detected, so that whether the cargo moves in place or not is determined. For example: the first clamping jaw 95 and the second clamping jaw 98 have a sensor for clamping the goods or a sensor for sensing that the rear carrying and carrying placing frame 2 cannot load the goods due to the too heavy goods, and the like;

further, the two sides of the top of the back carrying and carrying frame 2 are respectively provided with a side guard frame 4, the inside of the side guard frame 4 is provided with guide pulleys 5 through bearings, the bottom of the back carrying and carrying frame 2 is provided with at least four groups of guide pulleys 5, according to the design of the side guard frame 4 and the guide pulleys 5 erected on the back carrying and carrying frame 2 on one side of the carrying robot main body 1, the back carrying and carrying frame 2 can be moved to the back carrying and carrying frame 2, so that the back carrying and carrying frame 2 can move inwards under the action of gravity, and meanwhile, the back carrying and carrying frame is pushed to be more smooth by being matched with the pushing of the four groups of guide pulleys 5 on the two sides, the goods loading operation is convenient, the time and labor are saved by being matched with the side guard frames 4 on the back carrying frame, and the problem that the goods fall or damage caused by shaking in the moving process can be effectively avoided;

the clamping jaw machine assembly 9 is arranged on the other side of the transfer robot main body 1, the mechanical arm main control module 8 is arranged at the position, close to the transfer robot main body 1, of the clamping jaw machine assembly 9, the clamping jaw machine assembly 9 comprises a bearing mounting frame 91 and a second mechanical arm 96, the bearing mounting frame 91 is arranged at the position above the mechanical arm main control module 8, the bearing mounting frame 91 is fixedly connected with the surface of the transfer robot main body 1, a main half gear 92 is arranged on the surface of the bearing mounting frame 91 through a bearing, the input end of the main half gear 92 is electrically connected with the output end of the mechanical arm main control module 8, a secondary half gear 93 is arranged on the surface of the bearing mounting frame 91 on one side of the main half gear 92 through a bearing, the secondary half gear 93 is in meshed connection with the main half gear 92, one end, far away from each other, of the main half gear 92 and the secondary half gear 93 is connected with a first mechanical arm 94 through a rotating shaft, the other end of the first mechanical arm 94 is connected with a first clamping jaw 95 through the rotating shaft, and the middle position of the first clamping jaw 95 is hinged with the top of the bearing mounting frame 91 through the second mechanical arm 96;

the second clamping jaw 98 is arranged at the surface position of the transfer robot main body 1 below the first clamping jaw 95 through a bearing, the middle section and the top end of the second clamping jaw 98 are respectively connected with the first clamping jaw 95 through a bearing shaft rod 97, the first clamping jaw 95, the second mechanical arm 96 and the second clamping jaw 98 are arranged in two groups, the two groups of the first clamping jaw 95, the second mechanical arm 96 and the second clamping jaw 98 are symmetrically distributed, and according to the figures 4 and 5, the output end of the mechanical arm main control module 8 drives the main half gear 92 to move and drives the auxiliary half gear 93 meshed with the main half gear to move reversely, so that the two groups of the first mechanical arms 94 are driven to open, the opening sizes of the first clamping jaw 95 and the second clamping jaw 98 are controlled through the linkage of the second mechanical arm 96 and the bearing shaft rod 97, the goods can be clamped and fixed, the whole-process automatic operation can be realized, the goods can be conveniently transferred and conveyed, and the labor intensity of the goods is reduced;

further, the outer end positions of the first clamping jaw 95 and the second clamping jaw 98 are set to be bent hooks, and according to the design of the bent hooks shown in fig. 5, the friction force of the first clamping jaw 95 and the second clamping jaw 98 when clamping goods can be increased, so that the problem of slipping in the moving process is avoided, the goods can be tightly clamped by the bent hooks at the outer ends of the first clamping jaw 95 and the second clamping jaw 98, stable carrying of the goods is guaranteed, and the goods can be stably transported.

Embodiment two:

the application method of the auxiliary cargo handling robot for logistics comprises the following steps:

step one: starting a power supply of the transfer robot main body 1, enabling the transfer robot main body 1 to be in a power-on state, and initializing each module and corresponding parameters;

step two: the control of the transfer robot body 1 is started, the transfer robot body 1 is controlled through signal connection, the transfer robot body 1 is started, meanwhile, a path is preset in advance to move, and the detection result of the sensor module 7 is fed back to the mechanical arm main control module 8;

step three: the mechanical arm main control module 8 judges the movement route of the transfer robot main body 1 according to the detection result and sends the information to the automatic control action module 6 through the serial port, the automatic control action module 6 sends a movement direction instruction to the displacement driving roller 3 to control the movement state of the transfer robot main body 1, and the transfer robot main body 1 walks along the route;

step four: the transfer robot main body 1 performs grabbing operation, and after the transfer robot main body 1 stops, the mechanical arm main control module 8 controls the steering engine to control the clamping jaw machine assembly 9 to perform grabbing operation;

step five: after the grabbing operation is finished, the mechanical arm main control module 8 sends an action completion instruction to the automatic control action module 6 through a serial port, and the automatic control action module 6 controls the carrying robot main body 1 to rotate left until the sensor module 7 detects that a preset path is stopped, so that a moving step of the carrying robot main body 1 is performed;

step six: after the sensor module 7 detects the starting line, the automatic control action module 6 receives the instruction of the mechanical arm main control module 8 to control the robot to stop, and sends a placing operation command to the mechanical arm main control module 8 through a serial port, the mechanical arm main control module 8 controls the main half gear 92 and the auxiliary half gear 93 to move in a meshing mode, and the first clamping jaw 95 and the second clamping jaw 98 at the tail end are opened to finish the placing operation.

Working principle: the invention is a auxiliary cargo handling robot for logistics and its method of use, its structure and principle are that the technicians can all know through the technical manual or know through the routine experimental method, in the idle place of this apparatus, all electric devices of above-mentioned, it refers to power component, electric device and adaptive supervisory computer and power supply are connected through the wire, the concrete connection means, should consult in the following working principle, the electric connection of each electric device is finished sequentially, its detailed connection means, it is the well-known technology in the field, the following mainly introduces working principle and course, do not explain the electric control, its structure and principle are that the technicians can know through the technical manual or know through the routine experimental method;

starting a power supply of the transfer robot main body 1, initializing all modules and corresponding parameters, judging a movement route of the transfer robot main body 1 by a mechanical arm main control module 8 according to a detection result, sending the information to an automatic control action module 6 through a serial port, enabling the automatic control action module 6 to send a movement direction instruction to a displacement driving roller 3 to control the movement state of the transfer robot main body 1 according to the information, enabling the transfer robot main body 1 to move to a position ready for transfer along the route, enabling the transfer robot main body 1 to stop, enabling a first clamping jaw 95 and a second clamping jaw 98 to be located at two sides of goods at the moment, enabling an output end of the mechanical arm main control module 8 to drive a main half gear 92 to start rotating when the mechanical arm main control module 8 controls a steering engine control clamping jaw machine assembly 9 to start rotating, enabling the main half gear 92 to drive a secondary half gear 93 meshed with the main half gear 92 to start synchronously reversely rotating, enabling a second mechanical arm 96 to synchronously push the first clamping jaw 95 and the second clamping jaw 98 to start synchronously, enabling the second clamping jaw 98 to start synchronously push the first clamping jaw 95 and the second clamping jaw 98 to synchronously open under the connection effect of the first clamping jaw 98 and the second clamping jaw 98;

meanwhile, the operator can also move lighter goods onto the rear carrying and placing frame 2, so that the lighter goods can roll and push along the inclined rear carrying and placing frame 2 and the guide pulleys 5 at two sides under the action of gravity, slide into the rear carrying and placing frame 2, finally, the carrying robot main body 1 filled with the goods is moved back, the mechanical arm main control module 8 sends an action completion instruction to the automatic control action module 6 through a serial port, the automatic control action module 6 controls the carrying robot main body 1 to rotate left until the sensor module 7 detects a preset path stop, and finally, the automatic control action module 6 receives the instruction of the mechanical arm main control module 8 to control the robot to stop and sends a placing operation command to the mechanical arm main control module 8 through the serial port, and the operation is performed, so that the mechanical arm main control module 8 controls the main half gear 92 and the auxiliary half gear 93 to move in a meshed mode, the first clamping jaw 95 and the second clamping jaw 98 at the tail end are opened, and meanwhile, the goods carrying and placing on the rear carrying and placing frame 2 are put down.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims (8)

1. An auxiliary cargo handling robot for logistics, comprising: the automatic control device comprises a carrying robot main body (1), wherein a rear carrying and carrying placing frame (2) is fixedly arranged on one side of the carrying robot main body (1) through screws, displacement driving rollers (3) are arranged at the positions of the two sides of the bottoms of the rear carrying and carrying placing frame (2) and the carrying robot main body (1), an automatic control action module (6) is arranged at the top position of the carrying robot main body (1), and a sensor module (7) is arranged at the position, close to the surface of the rear carrying and carrying placing frame (2), of the automatic control action module (6);

clamping jaw machine subassembly (9), clamping jaw machine subassembly (9) are installed to the opposite side of transfer robot main part (1), and clamping jaw machine subassembly (9) are close to the position department of transfer robot main part (1) and install arm master control module (8), clamping jaw machine subassembly (9) are including accepting mounting bracket (91) and second arm (96), and accept mounting bracket (91) and erect in arm master control module (8) top position department to accept mounting bracket (91) and transfer robot main part (1) fixed surface connection, accept the surface of mounting bracket (91) and install main half gear (92) through the bearing, and the input and the arm master control module (8) output electrical connection of main half gear (92), the mounting bracket (91) surface of main half gear (92) one side is installed auxiliary half gear (93) through the bearing, and be connected between auxiliary half gear (93) and the main half gear (92) meshing, the one end that main half gear (93) and then auxiliary half gear (93) kept away from each other is connected with first arm (94) through being connected with pivot (95) through pivot, the middle position of the first clamping jaw (95) is hinged with the top of the bearing mounting frame (91) through a second mechanical arm (96).

2. An auxiliary cargo handling robot for logistics according to claim 1, wherein: the transfer robot main body (1) comprises an automatic control action module (6), a sensor module (7) and a mechanical arm main control module (8), wherein the automatic control action module (6) is connected with the mechanical arm main control module (8) through a serial port, a first control signal output end of the automatic control action module (6) is connected with a control signal input end of the mechanical arm main control module (8), a second control signal output end of the automatic control action module (6) is connected with a control signal input end of the sensor module (7), and a signal output end of the sensor module (7) is connected with a signal input end of the mechanical arm main control module (8).

3. An auxiliary cargo handling robot for logistics according to claim 1, wherein: the two sides of the top of the rear carrying and placing frame (2) are respectively provided with a side guard protection frame (4), and the inside of the side guard protection frame (4) is provided with a guide pulley (5) through a bearing.

4. A logistical auxiliary cargo handling robot according to claim 3, characterized in that: the bottom of the rear carrying and placing frame (2) is arranged to be inclined, and at least four groups of guide pulleys (5) are arranged.

5. An auxiliary cargo handling robot for logistics according to claim 1, wherein: the second clamping jaw (98) is installed at the surface position of the transfer robot main body (1) below the first clamping jaw (95) through a bearing, and the middle section and the top end of the second clamping jaw (98) are connected with the first clamping jaw (95) through a bearing shaft rod (97) respectively.

6. A logistical auxiliary cargo handling robot according to claim 1 or 5, characterized in that: the first clamping jaw (95), the second mechanical arm (96) and the second clamping jaw (98) are arranged in two groups, and the first clamping jaw (95), the second mechanical arm (96) and the second clamping jaw (98) are symmetrically distributed.

7. A logistical auxiliary cargo handling robot according to claim 1 or 5, characterized in that: the outer end positions of the first clamping jaw (95) and the second clamping jaw (98) are arranged in a bent hook shape.

8. The invention also discloses a using method of the auxiliary cargo handling robot for logistics, which comprises the following steps of:

step one: starting a power supply of the transfer robot main body (1), enabling the transfer robot main body (1) to be in a power-on state, and initializing each module and corresponding parameters;

step two: the control of the transfer robot main body (1) is started, the transfer robot main body (1) is controlled through signal connection, the transfer robot main body (1) is started, meanwhile, a preset path is moved in advance, and the detection result of the sensor module (7) is fed back to the mechanical arm main control module (8);

step three: the mechanical arm main control module (8) judges the movement route of the transfer robot main body (1) according to the detection result and sends the information to the automatic control action module (6) through the serial port, the automatic control action module (6) sends a movement direction instruction to the displacement driving roller (3) to control the movement state of the transfer robot main body (1), and the transfer robot main body (1) walks along the route;

step four: the transfer robot main body (1) performs grabbing operation, and after the transfer robot main body (1) stops, the mechanical arm main control module (8) controls the steering engine to control the clamping jaw machine assembly (9) to perform grabbing operation;

step five: after the returning movement of the transfer robot main body (1) is finished, the mechanical arm main control module (8) sends an action completion instruction to the automatic control action module (6) through a serial port, and the automatic control action module (6) controls the transfer robot main body (1) to rotate left until a sensor module (7) detects that a preset path is stopped, so that the transfer robot main body (1) is moved;

step six: after the sensor module (7) detects a starting line, the automatic control action module (6) receives an instruction of the mechanical arm main control module (8) to control the robot to stop, and sends a placing operation command to the mechanical arm main control module (8) through a serial port, the mechanical arm main control module (8) controls the main half gear (92) and the auxiliary half gear (93) to move in a meshing mode, and the first clamping jaw (95) and the second clamping jaw (98) at the tail end are opened to finish the placing operation.