CN218201781U

CN218201781U - Automatic unhooking device suitable for submersible sewage pump

Info

Publication number: CN218201781U
Application number: CN202222165579.XU
Authority: CN
Inventors: 刘兴让; 代亚东; 王鹏; 郑继红; 祁辉; 陈薇薇; 赵雪君; 张伟; 张君; 李少博; 李薛萌; 张鹏飞
Original assignee: Zhengzhou Municipal Engineering Management Office
Current assignee: Zhengzhou Municipal Engineering Management Office
Priority date: 2022-08-17
Filing date: 2022-08-17
Publication date: 2023-01-03
Anticipated expiration: 2032-08-17

Abstract

The utility model discloses an automatic device of hanging that takes off suitable for stealthily dirty pump relates to rain sewage pump station technical field. The device comprises an L-shaped positioning frame which sinks to the water and is attached to one side of a lifting lug of the pump machine, two positioning ropes with the bottom ends symmetrically tied and fixed to the left side and the right side of the L-shaped positioning frame, and positioning ropes with the upper ends wound on automatic recovery wheels of the positioning ropes on the corresponding sides respectively, a hook assembly which is sleeved on the two positioning ropes and lifted up and down along the positioning ropes under the driving of an external lifting steel wire rope, a locking rod with an h-shaped groove at the top and vertically arranged on the L-shaped positioning frame, a hook tightening mechanism which is horizontally arranged on the L-shaped positioning frame, two unhooking tension springs and two hook trigger rods which are fixed to the left side and the right side of the hook assembly. Utilize the utility model discloses can realize the automatic couple or the unhook of lifting hook and pump machine lug fast safely, swiftly safely with the stealthily dirty pump that has a fault or treat to maintain from hanging out under water and overhauls or maintain, in time will overhaul effectively or maintain stealthily dirty pump and reserve pump reset again.

Description

Automatic unhooking device suitable for submersible sewage pump

Technical Field

The utility model relates to a technical field of city rain sewage pump station, more specifically say and be an automatic device of hanging that takes off suitable for stealthily dirty pump.

Background

The submersible sewage pump is a submersible pump which is relatively high in proportion in use of an urban rainwater and sewage pump station. Because the operation environment of the submersible sewage pump is under invisible sewage, the submersible sewage pump is difficult to smoothly hook or unhook when the submersible sewage pump needs to be lifted out for daily maintenance or reset after maintenance. The mode that adopts at present lets lifting hook and pump machine lug combine through the artifical blind world all around left and right sides swing electric block wire rope, sometimes even need the manual work go to the pump pond below with the help of apparatus such as flashlight to monitor the combination condition of lifting hook and lug, lifts by crane inefficiency, extension maintenance time, intensity of labour is big, the human cost is high. Particularly, a secondary hoisting device is adopted in an individual pump station, so that repeated hooking operation is carried out by manually climbing to a cover plate hole, great unsafe factors exist, and hoisting risk is high; in addition, the speed of putting down the iron ring needs to be manually controlled by a plurality of people, and the labor cost and the labor intensity are increased. In addition, more importantly, when heavy rain or heavy rain attacks a city, if a submersible sewage pump in a working state in an urban overpass pump station fails and cannot be lifted out along a slide way for maintenance in time, and meanwhile, a standby pump cannot be lifted down along the slide way, the overpass can be seriously accumulated with water or submerged, the urban overpass can be switched on and off quickly, and even serious consequences endangering the safety of pedestrians can occur. Therefore, how to effectively and safely lift the submersible sewage pump with fault or to be maintained out of the water in time for overhauling or maintaining and reset the standby pump or the well maintained submersible sewage pump becomes a technical problem to be solved urgently in actual work.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing an automatic unhooking device suitable for stealthily dirty pump aiming at the weak point that exists among the above-mentioned prior art. Utilize the utility model discloses can realize the automatic couple or the unhook of lifting hook and pump machine lug fast safely, and then swiftly safely will have a fault or wait to maintain stealthily dirty pump to hang out from under water and overhaul or maintain, in time will overhaul or maintain stealthily dirty pump and reserve pump that good effectively and reset again, the artifical couple that exists in the use of traditional city rain sewage pump station has been solved, the manual work resets, technical problem such as unable replacement reserve pump, have the convenience and hang off, it is efficient to lift by crane, be convenient for reset, shorten the maintenance time, reduce intensity of labour, time saving and labor saving, safe and reliable's advantage.

The purpose of the utility model can be realized by the following technical measures:

<xnotran> L ( ; , ; ), L , ( , ), , ( ), L , h ( , ), L ( , L , h , , , , ), </xnotran> The lifting hook is characterized by comprising two unhooking tension springs and two hook trigger rods which are fixed on the left side and the right side of a lifting hook assembly (in the automatic hooking process, the hook trigger rods move downwards along with a lifting hook to touch a cross hanging rod on an L-shaped positioning frame, and the hook trigger rods push a hook tightening mechanism to move downwards to be separated from an h-shaped groove in a locking rod; the lifting hook assembly comprises two positioning rope guide pipes (the positioning rope guide pipes are matched with the positioning ropes to ensure that the lifting hook assembly can be accurately lifted) for sleeving the positioning ropes on the corresponding sides, a lifting hook pulley (serving as an installation base of the lifting hook and transmitting the tension of the positioning ropes) which is arranged between the two positioning rope guide pipes and is tied and hung at the bottom end of an external lifting steel wire rope, and a lifting hook (used for hanging a pump lifting lug of the submersible sewage pump and transmitting the tension at the same time) which is arranged below the lifting hook pulley; the hook tightening mechanism is matched with the h-shaped groove through a transverse hanging rod which is embedded in the h-shaped groove and two hook tension spring transverse hanging rods which are respectively and vertically connected to two ends of the transverse hanging rod, the hook tension springs are locked or elastically reset in an auxiliary mode as required, and the other ends of the two hook tension springs are respectively fixed to the left side and the right side of the L-shaped positioning frame.

The utility model discloses in two automatic recovery wheel of location rope is installed on the lateral wall of pump crane thing hole through recovery wheel support symmetry (the automatic recovery wheel of location rope is used for automatic positioning rope of receiving and releasing; the recovery wheel support is used for supporting and installs the automatic recovery wheel of positioning rope).

The L-shaped positioning frame in the utility model is an integral bracket which is formed by connecting a left group of vertical rods and a right group of vertical rods which are respectively arranged along the Z-axis direction of the height, and a bottom longitudinal rod which is arranged along the Y-axis direction of the front and the back in sequence and then forming an L-shaped bracket structure, and connecting a transverse connecting rod along the X-axis direction of the left and the right groups of vertical rods to the outer ends of the two bottom longitudinal rods; the locking rod is vertically fixed on the transverse connecting rod (the transverse connecting rod is an installation base of the locking rod); one end of each of the two hook tension springs is fixed on a vertical rod on the corresponding side in the L-shaped positioning frame (the vertical rod is a mounting base of the hook tension spring).

The utility model discloses in the opening end in h type groove is down (be convenient for horizontal peg pressurized roll-off h type groove downwards, realize the separation of couple tightening mechanism and locking lever), and the notch width direction in h type groove is along around Y axle direction extend to pump machine lug place side (be convenient for couple tightening mechanism or unhook tension spring accessible kick-back reset smoothly), and the notch width in h type groove is greater than the diameter of horizontal peg (make things convenient for inlay horizontal peg).

The utility model discloses in unhook tension spring's non-fixed end is bent into spring hanger (be convenient for the hook hang on horizontal peg).

The design principle of the utility model is as follows:

the L-shaped positioning frame designed by the utility model is matched with the positioning rope, so that the moving track of the lifting hook component is limited, and the lifting hook can be ensured to be in a range to be hoisted, which is close to and just opposite to the lifting lug of the pump machine, before falling in place or being hoisted; the utility model discloses two couple trigger bars are designed to the design in the hook subassembly left and right sides, there is couple tightening mechanism at the left and right sides horizontal installation of L type locating rack, vertically install two locking levers that the top has h type groove on the cross-connecting rod of L type locating rack, like this in the accurate decline process of hook subassembly along the locating rope, when the couple trigger bar on the hook subassembly touches the cross-connecting rod on the L type locating rack, couple tightening mechanism moves down and breaks away from h type groove in the locking lever, couple tension spring contracts under the horizontal resilience force effect and resets, couple tightening mechanism drives the lifting hook and moves horizontally to the treating hoist and mount within range that is close to pump machine lug, realize the automatic couple of lifting hook and pump machine lug fast safely, and then fast safely hang out the stealthy dirty pump that has a fault or treat to maintain from under water and overhaul or maintain; the utility model discloses it has two unhook tension spring to design in the lifting hook subassembly left and right sides, before automatic unhook, unhook tension spring hooks and hangs port on h type groove and be in tensile state, and horizontal peg card is put in the locking lever in the port under h type groove, because in the decline in-process because the horizontal resilience force that the lifting hook receives is greater than unhook tension spring far away from, the lifting hook can not lateral deviation, but after the pump machine falls to the coupling position down, the lifting hook does not receive vertical hoisting power, the horizontal resilience force effect at unhook tension spring stimulates the lifting hook to the direction removal of keeping away from the pump machine lug down, open outside electric block reversal after the lifting hook breaks away from the pump machine lug completely, go upward withdraw the lifting hook, realize the automatic unhook of lifting hook and pump machine lug fast safely, and then in time effectively with the stealthily dirty pump after overhaul or having maintained reset or install the reserve pump smoothly under water again.

The utility model has the advantages of as follows:

utilize the utility model discloses can realize the automatic couple or the unhook of lifting hook and pump machine lug fast safely, and then swiftly safely will have a fault or wait to maintain stealthily dirty pump to hang out from under water and overhaul or maintain, in time will overhaul or maintain stealthily dirty pump and reserve pump that good effectively and reset again, the artifical couple that exists in the use of traditional city rain sewage pump station has been solved, the manual work resets, technical problem such as unable replacement reserve pump, have the convenience and hang off, it is efficient to lift by crane, be convenient for reset, shorten the maintenance time, reduce intensity of labour, time saving and labor saving, safe and reliable's advantage.

Drawings

Fig. 1 is a schematic structural diagram of the present invention.

Fig. 2 is a schematic structural view of the hook assembly.

Fig. 3 is a schematic structural diagram of a combined part of the L-shaped positioning frame, the hook tightening mechanism and the locking rod.

Part number in the figures illustrates: 1. the automatic positioning rope recovery device comprises a positioning rope automatic recovery wheel, 2, a recovery wheel support, 3, a positioning rope, 4, a hook assembly, 4-1, a positioning rope guide pipe, 4-2, a hook pulley, 4-3, a hook, 5, a hook trigger rod, 6, a unhooking tension spring, 6-1, a spring hook, 7, an external hoisting steel wire rope, 8, an L-shaped positioning frame, 8-1, a vertical rod, 8-2, a bottom longitudinal rod, 8-3, a transverse connecting rod, 9, a locking rod, 9-1, an h-shaped groove, 10, a hook tightening mechanism, 10-1, a transverse connecting rod, 10-2, a hook tension spring, 11, a side wall of a pump lifting hole, 12 and a pump lifting lug.

Detailed Description

The utility model is further described with the following figures:

as shown in fig. 1 to 3, the automatic unhooking device for submersible sewage pump of the present invention comprises an L-shaped positioning frame 8 (as an installation base for a hook tightening mechanism 10 and a locking rod 9 on one hand; on the other hand, the lifting hook assembly is used for tying the bottom end of a positioning rope 3, limiting the moving track of the lifting hook assembly 4 after being matched with the positioning rope 3, ensuring that the lifting hook 4-3 falls in place or is positioned in a range close to and opposite to a lifting lug 12 of a pump after being lifted by lifting, wherein the two bottom ends are symmetrically tied on the left side and the right side of an L-shaped positioning frame, the upper ends of the two positioning ropes 3 are respectively wound on the automatic recovery wheel 1 of the positioning rope on the corresponding side (the positioning ropes 3 are used as lifting guide rails of a positioning rope guide pipe 4-1 and the lifting hook assembly 4, the lifting hook assembly 4 can realize accurate lifting under the driving action of an external electric hoist, the driving action of an external lifting steel wire rope 7 and the guiding action of the positioning ropes 3), the lifting hook assembly 4 is sleeved on the two positioning ropes 4 (used for hanging a submersible pump) which is lifted up and down along the positioning ropes under the driving of the external lifting steel wire rope 7, the two lifting hook assemblies 9 (used for hanging) which are vertically arranged on the L-shaped positioning frame and are provided with h-shaped grooves 9-1 at the top (used for clamping a transverse hanging rod 10-1 and further locking the transverse hanging rod 10-3), a tightening mechanism 10 horizontally arranged on the L-shaped positioning frame (when the lifting hook assembly 4 retracts along the lifting hook assembly 4 and the transverse locking rod 10 in the lifting hook assembly 4, when the transverse locking rod 10 is in the transverse locking rod triggering mechanism 2, and the transverse hook assembly 4 is moved back to the locking rod 10, when the locking rod 10, the locking rod 10 is moved to the locking rod 10, the locking rod 10 is moved horizontally arranged on the locking rod 10 in the locking rod 2, the hook tightening mechanism 10 drives the lifting hook 4-3 to horizontally move towards a to-be-hoisted range close to the pump lifting lug 12, automatic hooking of the lifting hook 4-3 and the pump lifting lug 12 is quickly and safely achieved, and then a submersible sewage pump which is in fault or to-be-maintained is quickly and safely hoisted out of water for maintenance or repair, the two unhooking tension springs 6 and the two hook trigger rods 5 are fixed to the left side and the right side of the hook assembly (in the automatic hooking process, when the hook trigger rods 5 move downwards along with the lifting hook 4-3 and touch the transverse hanging rods 10-1 on the L-shaped positioning frame 8, the hook trigger rods 5 push the hook tightening mechanism 10 to move downwards to be separated from h 9-1 in the locking rod 9). Before automatic unhooking, the unhooking tension spring 6 is hooked on the upper port of the h-shaped groove 9-1 and is in a stretching state, the transverse hanging rod 10-1 is clamped in the lower port of the h-shaped groove 9-1 in the locking rod 9, and the lifting hook 4-3 cannot transversely deviate due to the fact that the vertical lifting force borne by the lifting hook 4-3 is far greater than the transverse resilience force of the unhooking tension spring 6 in the descending process; when the pump falls to the coupling position, the lifting hook 4-3 is free from vertical lifting force, the lifting hook 4-3 is pulled to move towards the direction far away from the pump lifting lug 12 under the action of the transverse resilience force of the unhooking tension spring 6, the external electric block is opened to reversely rotate after the lifting hook 4-3 is completely separated from the pump lifting lug 12, the lifting hook 4-3 is upwards retracted, automatic unhooking of the lifting hook 4-3 and the pump lifting lug 12 is quickly and safely realized, and then the submerged sewage pump after overhauling or maintenance is timely and effectively reset or a standby pump is smoothly installed underwater), and the height of the hook trigger rod 5 is lower than that of the unhooking tension spring 6 (the hook trigger rod 5 is ensured to firstly touch the cross hanging rod 10-1 in the automatic hooking process); the lifting hook assembly 4 comprises two positioning rope guide pipes 4-1 (the positioning rope guide pipes 4-1 are matched with the positioning ropes 3 to ensure that the lifting hook assembly 4 is accurately lifted) for sleeving the positioning ropes on the corresponding sides, a lifting hook pulley 4-2 (serving as an installation base of the lifting hook 4-3 and transmitting the tension of the positioning rope 3) which is installed between the two positioning rope guide pipes 4-1 and is tied and hung at the bottom end of an external lifting steel wire rope 7, and a lifting hook 4-3 (used for hanging a pump lifting lug 12 of the submersible sewage pump and transmitting the tension at the same time) which is installed below the lifting hook pulley; the hook tightening mechanism 10 comprises a transverse hanging rod 10-1 embedded in the h-shaped groove 9-1 and two hook tension springs 10-2 respectively and vertically connected to two ends of the transverse hanging rod (the transverse hanging rod 10-1 is matched with the h-shaped groove 9-1, and the hook tension springs 10-2 are locked in position or elastically restored in an auxiliary mode as required), and the other ends of the two hook tension springs 10-2 are respectively fixed to the left side and the right side of the L-shaped positioning frame 8.

The utility model discloses in two automatic take-up pulley 1 of location rope is installed on the lateral wall 11 of pump crane thing hole through the take-up pulley support 2 symmetry (the automatic take-up pulley 1 of location rope is used for automatic receive and release location rope 3; take-up pulley support 2 is used for supporting and installs the automatic take-up pulley 1 of location rope).

The L-shaped positioning frame 8 in the utility model is an integral support which is composed of a left group and a right group of vertical rods 8-1 which are respectively arranged along the direction of a height Z axis, and a L-shaped support structure which is composed of bottom longitudinal rods 8-2 which are arranged along the directions of front and back Y axes and are sequentially connected, and a transverse connecting rod 8-3 which is arranged along the directions of left and right X axes and is connected with the outer ends of the two bottom longitudinal rods; the locking rod 9 is vertically fixed on the cross link 8-3 (the cross link 8-3 is the installation base of the locking rod 9); one end of each of the two hook tension springs 10-2 is fixed on a vertical rod 8-1 at the corresponding side in the L-shaped positioning frame 8 (the vertical rod 8-1 is a mounting base of the hook tension spring 10-2).

The utility model discloses in the open end of h type groove 9-1 is down (be convenient for horizontal peg 10-1 pressurized roll-off h type groove 9-1 downwards, realize the separation of couple tightening mechanism 10 and locking lever 9), and the notch width direction of h type groove 9-1 is along front and back Y axle direction to pump machine lug 12 place side extension (be convenient for couple tightening mechanism 10 or unhook tension spring 6 accessible resilience reset smoothly), and the notch width of h type groove 9-1 is greater than the diameter of horizontal peg 10-1 (make things convenient for inlay the horizontal peg 10-1 of card).

In the utility model, the non-fixed end of the unhooking tension spring 6 is bent into a spring hook 6-1 (convenient to hook on the transverse hanging rod 10-1).

The utility model discloses a concrete in service behavior as follows:

before the utility model is used, the utility model is assembled according to the relative position relationship shown in the structural description and the attached drawings.

The submersible sewage pump breaks down and needs to be lifted out of water for maintenance or needs to be lifted out for maintenance:

firstly, the bottom ends of two positioning ropes 3 are symmetrically tied and fixed at the left side and the right side of an L-shaped positioning frame 8, the two positioning rope automatic recovery wheels 1 are synchronously started, and the positioning ropes 3 and the L-shaped positioning frame 8 are driven to sink to the water and are attached to one side of a pump lifting lug 12. Then, the hook assembly 4 descends accurately under the driving action of the external electric hoist, the driving action of the external hoisting steel wire rope 7 and the guiding action of the positioning rope 3. Subsequently, when the hook trigger rod 5 on the hook assembly 4 touches the cross hanging rod 10-1 on the L-shaped positioning frame 8 in the descending process, the hook tightening mechanism 10 moves downwards, so that the cross hanging rod 10-1 embedded in the h-shaped groove 9-1 in the locking rod 9 slides downwards and is separated from the lower port of the h-shaped groove 9-1, and at the moment, the hook tension spring 10-2 retracts and resets under the action of horizontal resilience force, drives the cross hanging rod 10-1, and simultaneously pushes the hook 4-3 to move together in the direction close to the pump lifting lug 12. And then, when the pump lifting lug 12 is within the working range of the lifting hook 4-3, starting an external electric hoist and an external hoisting steel wire rope 7 to drive the lifting hook 4-3 to move upwards, quickly and safely realizing the automatic hooking of the lifting hook 4-3 and the pump lifting lug 12, and further quickly and safely lifting the submersible sewage pump with a fault or to be maintained out of the water for overhauling or maintaining. And finally, synchronously starting the two automatic positioning rope recovery wheels 1 to reversely rotate, driving the positioning ropes 3 and the underwater L-shaped positioning frame 8 to move upwards until the L-shaped positioning frame 8 is completely moved out of the pump hoisting hole for later use.

And (II) resetting or smoothly installing a standby pump underwater after the submersible sewage pump is overhauled or maintained:

firstly, an external electric hoist is opened to drive an external hoisting steel wire rope 7 to move and bear force, and a pump lifting lug 12 of the submersible sewage pump is lifted by using a lifting hook 4-3. Then, before the pump is taken down, a transverse hanging rod 10-1 in a hook tightening mechanism 10 is clamped in a lower port of an h-shaped groove 9-1 of a locking rod 9, two unhooking tension springs 6 are hung in an upper port of the h-shaped groove 9-1, the two unhooking tension springs 6 are in a stretching state, and at the moment, as the vertical hoisting force borne by a lifting hook 4-3 is far larger than the transverse resilience force of the unhooking tension spring 6, the lifting hook 4-3 cannot transversely shift. Then, an external electric hoist is controlled to rotate to drive an external hoisting steel wire rope 7, a lifting hook 4-3 and the submersible sewage pump to move downwards until the pump is coupled in place. At the moment, the lifting hook 4-3 is free from vertical hoisting force, the lifting hook 4-3 is pulled to move towards the direction far away from the pump lifting lug 12 under the action of the transverse resilience force of the unhooking tension spring 6, after the lifting hook 4-3 is completely separated from the pump lifting lug 12, the external electric hoist is opened to reversely rotate, the lifting hook 4-3 is upwards retracted, automatic unhooking of the lifting hook 4-3 and the pump lifting lug 12 is rapidly and safely realized, and the submerged sewage pump after overhauling or maintenance is timely and effectively reset or the standby pump is smoothly installed underwater.

Claims

1. The utility model provides an automatic device of hanging that takes off suitable for stealthily dirty pump which characterized in that: the automatic unhooking device comprises an L-shaped positioning frame (8) which sinks into water and is attached to one side of a pump lifting lug (12), two positioning ropes (3) with bottom ends symmetrically tied and fixed to the left side and the right side of the L-shaped positioning frame, and upper ends respectively wound on positioning rope automatic recovery wheels (1) on the corresponding sides, a hook assembly (4) which is sleeved on the two positioning ropes and is driven by an external hoisting steel wire rope (7) to lift up and down along the positioning ropes, two locking rods (9) which are vertically arranged on the L-shaped positioning frame and provided with h-shaped grooves (9-1) at the tops, a hook tightening mechanism (10) which is horizontally arranged on the L-shaped positioning frame, two unhooking tension springs (6) and two hook trigger rods (5) which are fixed to the left side and the right side of the hook assembly, wherein the height of each hook trigger rod (5) is lower than that of the unhooking tension spring (6); the lifting hook assembly (4) comprises two positioning rope guide pipes (4-1) for sleeving positioning ropes on corresponding sides, a lifting hook pulley (4-2) which is arranged between the two positioning rope guide pipes (4-1) and is tied and hung at the bottom end of an external lifting steel wire rope (7), and a lifting hook (4-3) arranged below the lifting hook pulley; the hook tightening mechanism (10) comprises a transverse hanging rod (10-1) embedded in the h-shaped groove (9-1) in a clamping mode and two hook tension springs (10-2) vertically connected to two ends of the transverse hanging rod respectively, and the other ends of the two hook tension springs (10-2) are fixed to the left side and the right side of the L-shaped positioning frame (8) respectively.

2. The automatic unhooking device suitable for the submersible sewage pump as recited in claim 1, wherein: the two automatic positioning rope recovery wheels (1) are symmetrically arranged on the side wall (11) of the object hanging hole of the pump machine through the recovery wheel support (2).

3. The automatic unhooking device suitable for the submersible sewage pump as recited in claim 1, wherein: the L-shaped positioning frame (8) is an integral support which is formed by connecting a left group of vertical rods (8-1) and a right group of vertical rods (8-1) which are respectively arranged along the Z-axis direction of the height and a front group of bottom longitudinal rods (8-2) which are arranged along the Y-axis direction and a rear group of bottom longitudinal rods (8-2) in sequence and then connecting the L-shaped support structure with the outer ends of the two bottom longitudinal rods by using a transverse connecting rod (8-3) along the left-and-right X-axis direction; the locking rod (9) is vertically fixed on the transverse connecting rod (8-3); one end of each of the two hook tension springs (10-2) is fixed on the vertical rod (8-1) on the corresponding side in the L-shaped positioning frame (8).

4. The automatic unhooking device suitable for the submersible sewage pump as recited in claim 1, wherein: the opening end of the h-shaped groove (9-1) faces downwards, the width direction of the notch of the h-shaped groove (9-1) extends towards the side where the pump lifting lug (12) is located along the front-back Y-axis direction, and the width of the notch of the h-shaped groove (9-1) is larger than the diameter of the cross hanging rod (10-1).

5. The automatic unhooking device suitable for the submersible sewage pump as recited in claim 1, characterized in that: the non-fixed end of the unhooking tension spring (6) is bent into a spring hook (6-1).