KR102683964B1 - Manhole fall protection with safety signage - Google Patents

Abstract

The present invention relates to a manhole fall prevention member installed with a safety sign, which involves drilling an installation hole on the inner peripheral surface of the manhole entrance side, installing a locking holder by fastening an insert pin into the installation hole, and inserting a locker of the fall prevention net. The structure has been improved to fasten, and includes an installation hole (10), a locking holder (20), a locker (30), and a stop pin (40) so that a fall prevention net can be easily applied inside an existing manhole at minimal cost. This is the main composition.

Description

Manhole fall protection member with safety sign installed {Manhole fall protection with safety signage}

The present invention relates to a manhole fall prevention member with a safety sign installed. More specifically, the locker of the fall prevention net is installed by drilling an installation hole on the inner peripheral surface of the manhole entrance side and installing a locking holder by fastening an insert pin into the installation hole. This relates to a manhole fall prevention member equipped with a safety sign that has been structurally improved to be fastened by a fitting method, allowing a fall prevention net to be easily applied inside an existing manhole at minimal cost.

Typically, manholes are holes made to allow people to enter and exit from the road surface to the underground. Depending on their use, manholes are classified into water supply, sewerage, rainwater, sewage, and telecommunications, and are installed at regular intervals on the road.

In addition, manholes are commonly seen anywhere, including roadways, sidewalks, and residential areas, but when the manhole cover is opened for manhole work, a pedestrian who does not realize that work is in progress may fall into a sewer pipe and fall, causing serious injury to the pedestrian. In addition, safety accidents that injure workers working on sewer pipes occur frequently.

In addition, due to heavy rain, rainwater flows back to the conventionally installed manhole covers, causing frequent deaths due to falls when the manhole covers come off. Therefore, the Occupational Safety and Health Act, Ministry of Employment and Labor Ordinance No. 308, January 19, 2021, partially revised, Chapter 4, Harmful, According to the risk prevention measures, the law stipulates that new products must be equipped with fall prevention nets with fall prevention and danger phrases engraved on them.

Accordingly, in the previously disclosed registered utility No. 20-0497164, an opening of a predetermined radius is formed by covering the opening in the upper part of the manhole, and a locking protrusion is provided in a concentric circle in the middle of the inner circumferential surface of the opening so that the upper cover is caught on the upper inner circumferential surface of the opening. a body supported by jaws; A plurality of joints are provided at predetermined intervals along the inner circumferential surface of the opening at the lower part of the locking jaw of the body, and a coupling groove that protrudes toward the inner center and opens toward the internal space is formed in the horizontal direction and penetrates the locking jaw in the vertical and vertical directions. a fixing frame in which an inlet groove is formed in connection with one end of the coupling groove, and an insertion hole is formed in one of the coupling grooves and passes vertically through the middle portion, so that a fixing pin is inserted into the insertion hole; Protrusions that are inserted into the coupling groove through the inlet groove of the fixing frame and mounted to move laterally are provided to protrude on the outer edge, and the middle cover is formed in the shape of a circular grill. In the fixing frame, the middle of the upper surface catches the body. It is formed with a space between the jaws, and an insertion hole through which a fixing pin penetrates is formed in the upper and lower direction on the upper surface where the space is located, and a locking jaw at the upper position of the insertion hole is cut so that the fixing pin can be moved up and down, A technology has previously been proposed in which the lower end of the fixing pin, which is formed to be bent in the middle, is inserted into the insertion hole, and the bent upper end is inserted into the space between the locking jaw and the upper surface.

However, the prior art is intended to easily fix the protrusion of the middle cover used for fall prevention with a fixing pin, but due to the structural characteristics of the fixing frame being formed integrally with the body, the fixing frame must be damaged due to impact and the entire body must be replaced. Additionally, in order to apply an intermediate cover to an existing manhole, there was the inconvenient problem of having to replace the body.

KR 20-0497164 Y1 (2023.08.10.)

Accordingly, the present invention was conceived to solve the above problems. An installation hole is drilled on the inner peripheral surface of the manhole entrance, and a locking holder is installed by fastening an insert pin into the installation hole. A locking method is used to insert a fall prevention net locker. The purpose is to provide a manhole fall prevention member equipped with a safety sign that can be easily applied to a fall prevention net inside an existing manhole at a minimum cost by improving the structure to bind to it.

In order to achieve this purpose, the present invention features an installation hole (10) formed by drilling in the transverse direction on the inner peripheral surface of the entrance side of the manhole (1); A locking holder (20) in which an insert pin (21) protrudes at one end to be inserted into the installation hole (10), and the other end protrudes toward the inner peripheral surface of the entrance to the manhole (1) to form an 'L' shaped locking rail (22); A locker (30) installed on the outer peripheral surface of the fall prevention net (2) installed to close the entrance to the manhole (1) and inserted into the 'L' shaped locking rail (22) of the locking holder (20); And a stop pin 40 provided to restrain the locker 30 inserted into the locking rail 22.

At this time, the locking holder 20 is placed at three locations at equal intervals of 120° on the inner peripheral surface of the entrance side of the manhole (1), and the locker 30 is placed at three locations at equal intervals of 120° on the outer peripheral surface of the fall prevention net (2). It is characterized in that it is provided to be inserted into each locking holder (20).

In addition, the locking rail 22 has one end connected to the lower end of the vertical rail 22a and a vertical rail 22a that opens to the upper part of the locking holder 20 to allow entry and exit of the locker 30, and the other end is connected to the lower end of the vertical rail 22a. It includes a horizontal rail (22b) that extends in the transverse direction and restrains the locker (30), and the locker (30) enters the upper part of the vertical rail (22a) in a downward direction and attaches the fall prevention net (2) in the circumferential direction. When rotated, the locker 30 is provided to be restrained within the horizontal rail 22b.

In addition, a pinhole 23 is formed through the locking holder 20 corresponding to the horizontal rail 22b in the longitudinal direction, and a stop pin 40 is fastened to the pinhole 23 to accommodate the locking holder 20 in the horizontal rail 22b. It is provided to restrain the locker 30, and the stop pin 40 has a 'C' shaped ring 41 formed at one end, and the ring 41 is bound to the locking holder 20 via the pinhole 23. It is characterized by being provided as much as possible.

In addition, the insert pin 21 is formed in a conical shape whose diameter decreases in the direction away from the locking holder 20, and is characterized by having a concave-convex portion 21a on the outer peripheral surface.

In addition, the insert pin 21 is provided to be bound by the water expansion module 50 while inserted into the installation hole 10, and the water expansion module 50 is formed on the outer peripheral surface of the insert pin 21. A belt groove 51, a water expansion index material ring 52 installed in the band groove 51, installed in the band groove 51, installed to surround the water expansion index material ring 52, and a plurality of gripping blades on one side ( 53) includes a holding band 54 formed, and when the water expansion module 50 is exposed to moisture while the insert pin 21 is inserted into the installation hole 10, the water expansion index material ring 52 As this expands, the plurality of gripping blades 53 are expanded, and the gripping blades 53 are provided to be held and locked on the inner peripheral surface of the installation hole 10 with the end of the gripping band 53 accommodated in the belt groove 51. It is characterized by

In addition, the locker 30 is provided so that its expansion and contraction length can be adjusted by the variable module 60, and the variable module 60 includes a center shaft hole 61 penetrating through the center of the fall prevention net 2, and a center shaft hole ( 61), a variable shaft bar 62 having a plurality of link pins 62a radially arranged at the lower end and an angle bar 62b formed at the upper end, and a non-slip washer fitted into the upper part of the variable shaft rod 62. (63) and a lock nut (64) that is screwed to the upper end of the variable shaft rod (62) to press the non-slip washer (63) toward the fall prevention net (2) and to bind the variable shaft rod (62) to the fall prevention net (2). One end is connected to the link pin (62a), the other end extends to the outer peripheral surface of the fall prevention net (2), and the link bar (65) at which the locker (30) is installed at the end, and the longitudinal direction of the link bar (65) It includes a guide hole (66) cut into the guide hole (66) and a guide pin (67) that penetrates the guide hole (66) and is fastened to the fall prevention net (2), thereby restraining the link bar (65) on the fall prevention net (2). , while fastening a tool to the angle bar (62b) to restrain the variable shaft rod (62), fasten another tool to the lock nut (64) to rotate it in the loosening direction, and then use the tool fastened to the angle bar (62b). When the variable shaft bar 62 is rotated at a predetermined angle, the link bar 65 is transported in a straight line by the circular motion of the link pin 62a, and the locker 30 protrudes corresponding to the size of the inner peripheral surface of the entrance side of the manhole 1. When the length is adjusted and the lock nut 64 is tightened, the non-slip washer 63 is pressed toward the fall prevention net 2 and the variable shaft rod 62 is fixed.

In addition, a stop groove 24 is formed on the side wall of the horizontal rail 22b of the locking rail 22, and the locker 30 is accommodated in the horizontal rail 22b and is connected to the link bar using the variable module 60. When (65) is stretched and transferred, the locker (30) is provided to engage and lock with the stop groove (24).

According to the above configuration and operation, the present invention has been improved in structure to drill an installation hole on the inner peripheral surface of the manhole entrance side, install a locking holder by fastening an insert pin to the installation hole, and fasten the locker of the fall prevention net by fitting. , it has the effect of being able to simply apply a fall prevention net inside an existing manhole at minimal cost.

Figure 1 is a schematic diagram showing the overall configuration of a manhole fall prevention member equipped with a safety sign according to an embodiment of the present invention.
Figure 2 is a configuration diagram showing a manhole fall prevention member with a safety sign installed in a plan view according to an embodiment of the present invention.
Figure 3 is a configuration diagram showing the locker fastening state of a manhole fall prevention member with a safety sign installed according to an embodiment of the present invention.
Figure 4 is a configuration diagram showing a water expansion module of a manhole fall prevention member with a safety sign installed according to an embodiment of the present invention.
Figure 5 is a configuration diagram showing a variable module of a manhole fall prevention member equipped with a safety sign according to an embodiment of the present invention.
Figure 6 is a configuration diagram showing the operating state of the variable module of the manhole fall prevention member with a safety sign installed according to an embodiment of the present invention.
Figure 7 is a configuration diagram showing a stop groove of a manhole fall prevention member equipped with a safety sign according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Also, in describing the present invention, if it is determined that related known functions may unnecessarily obscure the gist of the present invention as they are obvious to those skilled in the art, the detailed description thereof will be omitted.

Figure 1 is a diagram showing the overall configuration of a manhole fall prevention member installed with a safety sign according to an embodiment of the present invention, and Figure 2 is a configuration showing a manhole fall prevention member installed with a safety sign according to an embodiment of the present invention in a plan view. Figure 3 is a configuration diagram showing the locker fastening state of the manhole fall prevention member equipped with a safety sign according to an embodiment of the present invention, and Figure 4 is a diagram showing the locker fastening state of the manhole fall prevention member installed with a safety sign according to an embodiment of the present invention. It is a configuration diagram showing the water expansion module of the member, and Figure 5 is a configuration diagram showing the variable module of the manhole fall prevention member installed with a safety sign according to an embodiment of the present invention, and Figure 6 is a configuration diagram showing the variable module according to an embodiment of the present invention. It is a configuration diagram showing the operating state of the variable module of the manhole fall prevention member with the safety sign installed, and Figure 7 is a configuration diagram showing the stop groove of the manhole fall prevention member with the safety sign installed according to an embodiment of the present invention.

The present invention relates to a manhole fall prevention member installed with a safety sign, which involves drilling an installation hole on the inner peripheral surface of the manhole entrance side, installing a locking holder by fastening an insert pin into the installation hole, and inserting a locker of the fall prevention net. The structure has been improved to fasten, and includes an installation hole (10), a locking holder (20), a locker (30), and a stop pin (40) so that a fall prevention net can be easily applied inside an existing manhole at minimal cost. This is the main composition.

The installation hole 10 according to the present invention is formed by drilling laterally on the inner peripheral surface of the entrance side of the manhole 1.

The installation hole 10 is a configuration for installing the locking holder 20, which will be described later, and is drilled in the transverse direction on the concrete wall on the inner peripheral surface of the entrance side of the manhole 1 or on the cover frame supporting the cover of the manhole 1.

In addition, the installation holes 10 are formed at predetermined equal intervals in consideration of the number of installation locking holders 20. As an example, the installation holes 10 are angled at 120° to support three locking holders 20 as shown in FIG. 2. It shows the state formed at intervals.

In addition, the locking holder 20 according to the present invention has an insert pin 21 protruding at one end to be inserted into the installation hole 10, and the other end protrudes toward the inner peripheral surface of the entrance to the manhole 1 to form an 'ㄴ' shaped locking rail. (22) is formed.

In Figure 2, the locking holder 20 is shown arranged at three locations at equal intervals of 120° on the inner peripheral surface of the entrance side of the manhole 1.

In the enlarged view of FIG. 2, the locking rail 22 has a vertical rail 22a that opens to the upper part of the locking holder 20 to allow entry and exit of the locker 30, and one end is connected to the lower end of the vertical rail 22a. And the other end includes a horizontal rail (22b) that extends in the transverse direction and restrains the locker (30).

In addition, as shown in FIG. 3 (a), when the locker 30, which will be described later, enters the upper part of the vertical rail 22a in a downward direction and rotates the fall prevention net 2 in the circumferential direction, the locker 30 as shown in FIG. 3 (b) (30) is restrained within the horizontal rail (22b).

In addition, a pinhole 23 is formed through the locking holder 20 corresponding to the horizontal rail 22b in the longitudinal direction, and a stop pin 40 is fastened to the pinhole 23 to accommodate the locking holder 20 in the horizontal rail 22b. It is provided to restrain the locker (30).

Here, the stop pin 40 is provided to restrain the locker 30 inserted into the locking rail 22.

At this time, the stop pin 40 has a 'C' shaped ring 41 formed at one end, and the ring 41 is provided to be fastened to the locking holder 20 via the pinhole 23, thereby protecting against vibration and shock. escape is prevented.

In addition, the insert pin 21 is formed in a conical shape whose diameter decreases in the direction away from the locking holder 20, and is provided with a concavo-convex portion 21a on the outer peripheral surface.

Accordingly, the uneven portion 21a of the insert pin 21 engages with the inner peripheral surface of the installation hole 10, and the fixing force is firmly maintained.

In addition, the insert pin 21 is provided to be bound by the water expansion module 50 while inserted into the installation hole 10.

In FIG. 4, the water expansion module 50 includes a strip groove 51 formed on the outer peripheral surface of the insert pin 21, a water expansion index material ring 52 installed in the strip groove 51, and a strip groove 51 installed in the strip groove 51. It is installed to surround the water expansion index material ring 52 and includes a gripping band 54 on one side of which a plurality of gripping blades 53 are formed.

At this time, the gripping band 54 has a plurality of gripping blades 53 spaced apart from each other as shown in the enlarged view of FIG. 4, and the gripping band 54 is cut to a predetermined length to surround the water expansion index material ring 52. It is installed by wrapping it in a circular shape.

Accordingly, when the water expansion module 50 is exposed to moisture with the insert pin 21 inserted into the installation hole 10 as shown in Figure 4 (a), the water expansion index material ring 52 as shown in Figure 4 (b) As this expands, the plurality of gripping blades 53 are expanded, and the gripping blades 53 are held and locked on the inner peripheral surface of the installation hole 10 with the end of the gripping band 53 accommodated in the band groove 51.

In addition, the locker 30 according to the present invention is installed on the outer peripheral surface of the fall prevention net (2) installed to close the entrance to the manhole (1), and is inserted into the 'L' shaped locking rail (22) of the locking holder (20). It is provided.

The lockers (30) are arranged at three locations on the outer peripheral surface of the fall prevention net (2) at equal intervals of 120° and are inserted into the locking holders (20).

In this way, an installation hole (10) is drilled on the inner peripheral surface of the entrance side of the manhole (1), and the locking holder (20) is installed by fastening the insert pin (21) to the installation hole (10) to secure the locker of the fall prevention net (2). The structure has been improved to bind (30) by a fitting method, which has the advantage of being able to simply apply the fall prevention net (2) inside the existing manhole (1) at minimal cost.

At this time, the locker 30 is formed integrally with the outer peripheral surface of the fall prevention net 2, as shown in Figure 2, or is separated from the fall prevention net 2 as shown in Figures 5 and 6, and the length is adjusted by the variable module 60, which will be described later. Possibly provided.

Meanwhile, the fall prevention net (2) has a grid-shaped bar installed inside the circular border, and includes safety accident prevention phrases such as 'suffocation risk', 'fall risk', and 'be sure to check before inspection' on one side of the upper surface. Signs are installed.

In FIG. 5, the locker 30 is provided so that its expansion and contraction length can be adjusted by the variable module 60.

The variable module 60 is installed by inserting into the center shaft hole 61 penetrating the center of the fall prevention net 2, and a plurality of link pins 62a are arranged radially at the lower end, and at the upper end. The variable shaft bar 62 on which the angle bar 62b is formed, the non-slip washer 63 fitted to the upper end of the variable shaft rod 62, and the non-slip washer 63 screwed to the upper end of the variable shaft rod 62 are connected to the fall prevention net. (2) side, one end is connected to the locking nut (64) that binds the variable shaft rod (62) to the fall prevention net (2), and the link pin (62a), and the other end is connected to the outer peripheral surface of the fall prevention net (2). A link bar 65 that extends and has a locker 30 installed at the end, a guide hole 66 cut longitudinally in the link bar 65, and a fall prevention net (2) penetrating the guide hole 66. It is fastened to and includes a guide pin 67 that restrains the link bar 65 on the fall prevention net (2).

In operation, a tool is fastened to the angle bar 62b to restrain the variable shaft rod 62, and another tool is fastened to the lock nut 64 to rotate in the loosening direction, and then fastened to the angle bar 62b. When the variable shaft bar 62 is rotated at a predetermined angle using a tool, the link bar 65 is transported in a straight line by the circular motion of the link pin 62a, and the locker 30 is opened in the manhole ( 1) The protrusion length is adjusted according to the size of the inner peripheral surface of the inlet side, and then when the lock nut 64 is tightened, the non-slip washer 63 is pressed toward the fall prevention net 2 to fix the variable shaft rod 62.

As an example, Figure 6 (a) shows the state in which the locker 30 is contracted and transported when the size of the inner peripheral surface on the entrance side of the manhole 1 is relatively small (L1), and Figure 6 (b) shows the state in which the locker 30 is transported at the entrance to the manhole 1. When the side inner circumferential surface size is relatively large (L2), the locker 30 is shown in an expanded state.

As the protrusion length of the locker 30 is easily varied by the variable module 60, the protrusion length of the locker 30 is adjusted in consideration of the size of the inner peripheral surface of the entrance side of the manhole 1 at the site, thereby installing the fall prevention net 2. Versatility is provided that can be applied to manholes (1) of various (different) specifications.

In Figure 7, a stop groove 24 is formed on the side wall of the horizontal rail 22b of the locking rail 22.

When the link bar 65 is stretched and transferred using the variable module 60 while the locker 30 is accommodated in the horizontal rail 22b, the locker 30 is in the stop groove 24 as shown in the enlarged view of FIG. 7. As it is provided to be interlocked and locked, the locker 30 is prevented from being separated due to vibration and impact, and the fall prevention net 2 is separated only when the variable module 60 is unlocked, which has the advantage of being safely managed by a designated manager. there is.

As described above, the most preferred embodiments of the present invention have been described in the detailed description of the present invention, but various modifications may be made without departing from the technical scope of the present invention. Therefore, the scope of protection of the present invention should not be limited to the above-mentioned embodiments, but should be recognized to the technologies in the patent claims described later and to equivalent technical means from these technologies.

10: Installation hole 20: Locking holder
30: locker 40: stop pin

Claims (8)

An installation hole (10) formed by drilling laterally on the inner peripheral surface of the entrance side of the manhole (1); A locking holder (20) in which an insert pin (21) protrudes at one end to be inserted into the installation hole (10), and the other end protrudes toward the inner peripheral surface of the entrance to the manhole (1) to form an 'L' shaped locking rail (22); A locker (30) installed on the outer peripheral surface of the fall prevention net (2) installed to close the entrance to the manhole (1) and inserted into the 'L' shaped locking rail (22) of the locking holder (20); And a stop pin 40 provided to restrain the locker 30 inserted into the locking rail 22,
The locking rail (22) is,
A vertical rail (22a) opens to the upper part of the locking holder (20) to allow entry and exit of the locker (30), one end is connected to the lower end of the vertical rail (22a), and the other end extends laterally to secure the locker (30). It includes a horizontal rail (22b) for restraining,
The locker 30 is provided so that when the fall prevention net 2 is rotated in the circumferential direction while entering the upper part of the vertical rail 22a in a downward direction, the locker 30 is restrained within the horizontal rail 22b,
The locker 30 is provided so that its expansion and contraction length can be adjusted by the variable module 60,
The variable module 60 is,
A center shaft hole (61) passing through the center of the fall prevention net (2),
A variable shaft rod 62 that is inserted into the center shaft hole 61, has a plurality of link pins 62a radially arranged at the lower end, and has an angle rod 62b formed at the upper end,
A non-slip washer (63) fitted to the upper part of the variable shaft rod (62),
A lock nut (64) that is screwed to the upper part of the variable shaft bar (62) to press the non-slip washer (63) toward the fall prevention net (2) and to bind the variable shaft bar (62) to the fall prevention net (2),
A link bar (65) with one end connected to the link pin (62a) and the other end extending toward the outer peripheral surface of the fall prevention net (2) and a locker (30) installed at the end,
A guide hole (66) cut longitudinally in the link bar (65),
It includes a guide pin (67) that penetrates the guide hole (66) and is fastened to the fall prevention net (2), thereby restraining the link bar (65) on the fall prevention net (2),
After fastening a tool to the angle bar (62b) to restrain the variable shaft rod (62), fastening another tool to the lock nut (64) and rotating it in the loosening direction, using the tool fastened to the angle bar (62b) When the variable shaft bar 62 is rotated at a predetermined angle, the link bar 65 is transported in a straight line by the circular motion of the link pin 62a, so that the locker 30 has a protruding length corresponding to the size of the inner peripheral surface of the entrance side of the manhole 1. is adjusted, and then when the lock nut 64 is tightened, the non-slip washer 63 is pressed toward the fall prevention net 2 and the variable shaft rod 62 is fixed,
The protruding length of the locker 30 is varied by the variable module 60, and the protruding length of the locker 30 is adjusted in consideration of the size of the inner peripheral surface of the entrance side of the manhole 1, thereby installing the fall prevention net 2 of different specifications. It is provided so that it can be applied to the manhole (1),
A stop groove 24 is formed on the side wall of the horizontal rail 22b of the locking rail 22,
When the link bar 65 is stretched and transferred using the variable module 60 while the locker 30 is accommodated in the horizontal rail 22b, the locker 30 is provided to engage and lock with the stop groove 24. A manhole fall prevention member equipped with a safety sign, characterized in that.
According to clause 1,
The locking holder (20) is placed at three locations at equal intervals of 120° on the inner peripheral surface of the entrance side of the manhole (1), and the locker (30) is placed at three locations at equal intervals of 120° on the outer peripheral surface of the fall prevention net (2) for locking. A manhole fall prevention member equipped with a safety sign, characterized in that it is provided to be inserted into each holder (20).
delete According to clause 1,
A pinhole 23 is formed in the longitudinal direction through the locking holder 20 corresponding to the horizontal rail 22b,
It is provided to fasten a stop pin (40) to the pinhole (23) to restrain the locker (30) accommodated in the horizontal rail (22b),
The stop pin (40) has a 'C' shaped ring (41) formed at one end, and the ring (41) is a safety sign characterized in that it is provided to be fastened to the locking holder (20) via the pinhole (23). Installed manhole fall prevention member.
According to clause 1,
The insert pin (21) is formed in a cone shape whose diameter decreases in the direction away from the locking holder (20), and is provided with an uneven portion (21a) on the outer peripheral surface. A manhole fall prevention member with a safety sign installed.
According to clause 1,
The insert pin 21 is provided to be bound by the water expansion module 50 while inserted into the installation hole 10,
The water expansion module 50 is,
A strip groove (51) formed on the outer peripheral surface of the insert pin (21),
A water expansion index material ring (52) installed in the strip groove (51),
It is installed in the belt groove 51 and is installed to surround the water expansion index material ring 52, and includes a gripping band 54 on one side of which a plurality of gripping blades 53 are formed,
When the water expansion module 50 is exposed to moisture while the insert pin 21 is inserted into the installation hole 10, the water expansion index material ring 52 expands and the plurality of gripping blades 53 expand, A manhole fall prevention member equipped with a safety sign, characterized in that the end of the grip band (53) is received in the strip groove (51) and the grip blade (53) is gripped and locked on the inner peripheral surface of the installation hole (10). delete delete