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(11) | EP 0 931 904 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Ladder |
| (57) A ladder capable of preventing an accident from being caused due to the weakened
combining force between beams and hinges while a user uses the ladder to perform work,
and capable of preventing the beams and the steps from being released from each other.
The ladder includes two pairs of beams (1,1' and 2,2')engaged with each other by hinge
means (H,H' ) , and a plurality of steps(S) disposed between the beams (1,1',2,2')
at the same distance interval. Both ends of the steps(S) are inserted into holes (100)
which are formed at one side surfaces of the beams (1,1',2,2')and have the same cross
sectional shape with that of the steps(S) and a predetermined size adapted to receive
the ends of the steps (1,1',2,2'). Both ends of the steps(S) are enlarged due to the
striking force applied by a punch (102) and are engaged with the beams (1,1',2,2')under
the state that rounded ends of the steps(S) are formed from the outer side surfaces
of the beams (1,1',2,2')to inner side surfaces of the beams (1,1',2,2') due to the
striking force applied by the punch (102) and the rounded ends are brought into contact
with the ends of the steps(S). |
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a ladder, and more particularly to a ladder consisted of a plurality of beams having a plurality of steps disposed between the beams and being engaged with each other by hinges which allow the beams to pivot.
2. Description of the Prior Art
[0002] Generally, a ladder allows a worker for going up a high working place, and is made of wood. Recently, the ladder is made of aluminum so that the durability of the ladder is highly enhanced and the distortion of the ladder is reduced. As a result, the worker can safely use the ladder.
[0003] Since the ladder of aluminum is consisted of two pairs of beams and of a plurality of steps disposed between the beams, it is not necessary to have supporting members in order to assemble the ladder.
[0004] FIG. 1 is a perspective view of a ladder according to a prior art. Referring to FIG. 1, both ends of a plurality of steps(S) are inserted into holes formed at inner sides of the beams 1,1',2,2' adjacent to positions at which the steps(S) are disposed. Combining pins(P) are inserted into holes formed at outer sides of the beams. That is, the combining pins(P) combine both ends of the steps(S) with the steps(S). Consequently, two pairs of beams 1,1' and 2,2' are combined with each other by the plurality of steps(S).
[0005] Two pairs of beams 1,1' and 2,2' are connected to each other by a pair of hinges H,H'at their one ends so that the beams 1,1' are hinged together with the beams 2,2', respectively.
[0006] Korean Patent Application Laid-Open No. 89-10840 discloses a hinge which has been used with a ladder. FIGs. 2 to 4 show the hinge as described above. Referring to FIGs. 2 to 4, the hinge includes a pair of discs 3,3' and an auxiliary disc 3'' disposed between the discs 3,3'. A ring-shaped stage 11' is formed at an outer periphery of the auxiliary disc 3''. Between the disc 3 and the auxiliary disc 3'', a rotating disc 11 is fitted onto the ring-shaped stage 11'. The discs 3,3', the rotating disc 11 and the auxiliary disc 3''are combined together by a bush 5 passing through center holes 4',4'',4'''. Thereby, the pair of discs 3,3' and the auxiliary disc 3'' can rotate around the bush 5.
[0007] Locking stages A,B are formed at a one side of the ring-shaped stage 11' and a gap 12 is created between the locking stages A,B. An operation piece 13 of the rotating disc 11 is positioned Into the gap 12. One end of a tension spring 14 is inserted into a hole 13' formed at the operation piece 13. If a user deploys the rotating disc 11, the rotating disc 11 rotates toward the locking stage B formed at the gap 12. At this time, combining protrusions 8,8' of a combining portion 7 are inserted through insertion holes 15,16 and combining holes 9,9' by a spring 17 mounted to an axle 6 of a compress portion 18. In other words, if the pair of discs 3,3' and the auxiliary disc 3'' rotate at a predetermined position, the insertion holes 15,16 and combining holes 9,9' stand in line. At this time, the user inserts the combining protrusions 8,8' into the insertion holes 15,16 and combining holes 9,9', and thereby the pair of discs 3,3' and the auxiliary disc 3'' are fixed to the predetermined position.
[0008] If the user presses the compress portion 18, the combining protrusions 8,8' are released from the insertion holes 15,16 and combining holes 9,9'. At this time, the rotating disc 11 rotates toward the locking stage A, and thereby the combining protrusions 8,8' are smoothly inserted into the insertion hole 16 along a slant portion 16' formed at a periphery of the insertion hole 16.
[0009] Korean Patent Application Laid-Open No. 95-9197 discloses another hinge which has been used with a ladder. FIGs. 5 to 7 show the hinge as described above. Referring to FIGs. 5 to 7, a user can control an angle of the ladder by rotating a support of the hinge. Two discs 40 are disposed at a one end of the hinge. An opening 41 is created between the discs 40. The other end of the hinge is provided with a first support connector 20A at which an opening 200A is formed.
[0010] The hinge includes a second support connector 20B of which one end is provided with a hollow auxiliary disc 40A and the other end is provided with an opening 200B formed through it. Further, the hinge includes a front end portion 82 of which a distal end is cut at an acute angle, and includes a combining portion 80 having a packing 83 allowing the combining portion 80 for smoothly being combined with the discs 40.
[0011] However, in the ladder having the hinge as described above, combining portions of the beams 1,1',2,2' extending toward the discs 3,3' and the auxiliary disc 3''(40A) of the hinge H,H' are formed as a plate shape(referred to FIGs. 2 to 8). Accordingly, the combining force between the beams 1,1',2,2' and the hinge H,H' can be weakened, and thereby an accident can be caused.
[0012] In addition, since the pluralities of steps(S) are coupled to the beams 1,1',2,2' by the combining pin(P) passing through the holes formed at the outer surface of the beams 1,1',2,2' under the state that the pluralities of steps(S) are inserted into the holes formed at the Inner surface of the beams 1,1',2,2', the combining pin(P) can be released from the beams 1,1',2,2'with easy.
SUMMARY OF THE INVENTION
[0013] The present invention is contrived to solve the foregoing problems. It is an object of the present invention to provide a ladder having a plurality of beams, a plurality of steps disposed between the beams, and hinges being tightly engaged with one ends of the beams, capable of preventing any accident from being caused due to the weakened combining force between the beams and the hinges while a user uses the ladder to perform a work, and capable of preventing the beams and the steps from being released from each other.
[0014] In order to achieve the above object, the present invention provides a ladder including two pairs of beams engaged with each other by hinge means, and a plurality of steps disposed between the beams at the same distance interval, the improvement comprising:
both ends of the steps being inserted into holes which are formed at one side surfaces of the beams and have the same cross sectional shapes with that of the steps and a predetermined size adapted to receive the ends of the steps, both ends of the steps being enlarged due to the striking force applied by a punch and being engaged with the beams under the state that rounded ends of the steps are formed from outer side surfaces of the beams to inner side surfaces of the beams due to the striking force applied by the punch and the rounded ends are brought into contact with the ends of the steps.
[0015] The hinge means includes outer hinge members having combining portions and a pair of outer hinge plates, the combining portions being inserted into the ends of the beams, the outer hinge plates symmetrically extending from both sides of the combining portions in order to form a reinforcing rib and being rounded under the state that the center of the outer hinge plates is positioned at an outer periphery of one side surface crossing with both sides of the combining portions;
inner hinge members having combining portions and a pair of inner hinge plates, the combining portions being inserted into the ends of the beams, the inner hinge plates symmetrically extending from both sides of the combining portions in order to form a reinforcing rib and being rounded under the state that the center of the outer hinge plates is positioned at an outer periphery of one side surface crossing with both sides of the combining portions;
a center rivet for rotatably riveting the outer hinge plates of the outer hinge members and the inner hinge plates of the inner hinge members; and a fixing means for fixing the hinge outer members and the hinge inner members at a predetermined pivot position.
[0016] The outer hinge plates of the outer hinge members are symmetrically uneven so that the outer hinge plates have a reinforcing force.
[0017] The inner hinge plates of the inner hinge members are brought into tightly contact with each other and are engaged with the outer hinge plates of the outer hinge members, and the inner hinge plates are symmetrically uneven so that the inner hinge plates have a reinforcing force.
[0018] The combining ends of the inner hinge members and the outer hinge members have the same cross sectional shape with that of the beam and a predetermined size adapted to receive the ends of the beams, the combining ends of the inner hinge members and the outer hinge members are inserted into combining holes formed at outer side surfaces of the beams under the state that the combining ends are brought into contact with outer side surfaces of the beams and thereafter a user strikes outer side surfaces of the beams by using a punch, and inner side surfaces of the beams are provided with step holes for receiving the ends of the steps.
[0019] The fixing means includes an U-shaped fixing key having a center portion passing through first holes formed through the outer hinge members, a fixing portion passing through the first holes, second holes formed through the outer hinge plates at a predetermined position, and third holes formed through the inner hinge plates at positions corresponding to the second holes;
a push cover being engaged with the end of the center portion; and a spring being fitted onto the center portion of the fixing key and being disposed between the push cover and one side surfaces of the outer hinge members.
[0020] Further, the present invention provides a ladder including two pairs of beams engaged with each other by a hinge means, and a plurality of steps disposed between the beams at the same distance interval, the improvement comprising:
the hinge means including outer hinge members and inner hinge members, and one side surfaces of combining ends of the outer hinge members and the inner hinge members being cut and provided with a combining hole and a step hole so that the combining ends are elastically engaged with the beams.
[0021] In addition, the present invention provides a ladder including two pairs of beams engaged with each other by center rivets, and a plurality of steps disposed between the beams at the same distance interval, the improvement comprising:
the hinge means including outer hinge members and inner hinge members, and combining ends of the outer hinge members and the inner hinge members being cut and provided with first holes and second holes, the first holes being formed at inner side surfaces of the combining ends and having the same cross sectional shape with that of the beam and a predetermined size adapted to receive the ends of the beams, the second holes being formed at outer side surfaces of the combining ends, and protrusions, which are formed from the outer side surfaces of the beams to inner side surfaces of the beams due to the striking force applied by a punch, being inserted into the second holes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The above object and other characteristics and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings, in which:
FIG. 1 is a perspective view of a ladder according to a prior art;
FIGs. 2 to 4 show a hinge means of the ladder according to the prior art:
FIGs. 5 to 8 show other hinge means of the ladder according to the prior art:
FIGs. 9 and 10 are partially sectional views of a ladder according to a preferred embodiment of a present invention, showing the combining state of a step and a beam:
FIG. 11 is a partially exploded perspective view of the ladder according to the preferred embodiment of the present invention, showing a hinge means of the ladder:
FIG. 12 is a partially exploded sectional view of the ladder according to the preferred embodiment of the present invention, showing the hinge means of the ladder:
FIG. 13 is an assembled view corresponding to Figure 12;
FIG. 14 is a sectional view through FIG. 13;
FIG. 15 is a partially exploded perspective view of a ladder according to another preferred embodiment of the present invention, showing a hinge means of the ladder; and
FIGs. 16 and 17 are sectional views of the ladder according to the preferred embodiment of the present invention, showing a fixing means of the ladder.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Hereinafter, preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings.
[0024] A ladder according to a preferred first embodiment of the present invention includes two pairs of beams 2,4 and 6,8 which are combined with each other by the hinge as illustrated in FIG. 1, a plurality of steps(S) which are disposed between the beams 2,4 and are disposed between the beams 6,8 at the same distance interval.
[0025] FIGs. 9 and 10 are partially sectional views of a ladder according to the preferred embodiment of the present invention, showing the state that a step and a beam are combined with each other. Referring to FIGs. 9 and 10, combining holes 100 are formed at an inner side surface of beams 1,1',2,2'. The combining hole 100 has the same cross sectional shape with the steps(S). Both ends of the plurality of steps(S) are inserted into the combining holes 100.
[0026] If a user wants to combine both ends of the steps(S) with the beams 1,1'2,2', the user inserts the ends of the steps(S) into the combining holes 100. Then, the user pushes both ends of the steps(S) until the ends of the steps(S) are brought into contact with inner surfaces of the beams 1,1',2,2'. Under this state, the user strikes the outer side surface of the beams 1,1'2,2', which is adjacent to the inner surface of the beams 1,1'2,2', by using a punch 102.
[0027] A hole 104 is formed through the outer side surface of the beams 1,1'2,2' at the position that the user gives a shock by using the punch 102. Therefore, when the user hits the outer side surface by using the punch 102, a rounded end 106, which is formed toward the inner side surface from the outer side surface of the beams 1,1',2,2', can be easily transformed. The rounded end 106 is tightly combined with the ends of the steps(S) so that the ends of the steps(S) are combined with the beams 1,1,2,2', respectively.
[0028] A predetermined portion of the punch 102 has the same cross sectional area with that of the steps(S). The predetermined portion of the punch 102 is tapering toward a head portion of the punch 102. Therefore, when the user hits the outer side surface by using the punch 102, the ends of the steps(S) are plastically deformed so that the ends of the steps(S) are enlarged.
[0029] Thereby, the ends of the step(S) disposed between the beams 1,1',2,2', are tightly engaged with the beams 1,1',2,2' so that the ends of the step(S) are not released from the interior of the beams 1,1',2,2'.
[0030] Since the hinges H,H' allowing the beams 1,1'and 2,2' to pivot are combined with both upper ends of the beams 1,1',2,2', two pairs of the beams 1,1'and 2,2' are rotatably engaged with each other so that the beams 1,1',2,2' can be folded or deployed.
[0031] FIG. 11 is a partially exploded perspective view of the ladder according to the preferred embodiment of the present invention, showing a hinge means of the ladder and FIG. 12 is a partially exploded sectional view of the ladder according to the preferred embodiment of the present invention, showing a hinge means of the ladder.
[0032] Referring to FIGs. 11 and 12, the hinge H,H' includes a pair of outer hinge members 110,112 and a pair of inner hinge members 114,116. The outer hinge members 110,112 are engaged with the beams 1,1'. The inner hinge members 114,116 are engaged with the inner hinge members 114,116 and the beams 2,2'.
[0033] The outer hinge members 110,112 includes a combining portion 120 being inserted into the ends of the beams 1,1' and a pair of outer hinge plates 122 extending from the combining portion 120. The inner hinge members 114,116 Includes a pair of inner hinge plates 124 being hinged with the outer hinge plates 122 and a combining portion 126 extending from the inner hinge plates 124.
[0034] FIG. 15 is a partially exploded sectional view of the ladder according to the preferred embodiment of the present invention, showing a fixing means of the ladder.
[0035] The outer hinge plates 122 of the outer hinge members 110,112 symmetrically extend from both sides of the combining portions 120 under the state reinforcing ribs are created at both sides of the combining portions 120. Further, the outer hinge plates 122 are rounded so that the center of the outer hinge plates 122 is located at an outer periphery of one side crossing with both sides of the combining portions 120. Since the outer hinge plates 122 are symmetrically rugged, they can exert the reinforcing force.
[0036] Further, the inner hinge plates 124 of the inner hinge members 114,116 symmetrically extend from both sides of the combining portions 126 inserted into the ends of the beams 1,1',2,2' under the state that reinforcing ribs are created at both sides of the combining portions 126. The inner hinge plates 124 are rounded so that the center of the inner hinge plates 124 is located at an outer periphery of one side crossing with both sides of the combining portions 126. Since the inner hinge plates 124 are symmetrically rugged, they can exert the reinforcing force.
[0037] Referring to FIG. 11, rivet holes(R) are formed through the centers of the outer hinge plate 122 of the outer hinge members 110,112 and the inner hinge plates 124 of the inner hinge members 114,116. The outer hinge plates 122 and the inner hinge plates 124 are rotatably engaged with each other by passing a center rivet 130 through the rivet holes(R).
[0038] There is a fixing member for fixing the outer hinge members 110,112 and the inner hinge members 114,116 which rotate around the center rivet 130 at a predetermined position.
[0039] Lower ends of the combining portions 126,120 of the outer hinge members 110,112 and the inner hinge members 114,116 are cut off so that the lower ends of the combining portions 126,120 are pursed during the insertion of the combining portions 126,120 into the ends of beams 1,1',2,2'. Holes 100 are formed at one side surfaces of the combining portions 126,120 on which the ends of the steps(S) are located.
[0041] Referring to FIG. 13, the ends of the step(S) being positioned on the uppermost portion of the beams 1,1',2,2' are inserted into the holes 100 under the state that the combining portions 126,120 of the outer hinge members 110,112 and the inner hinge members 114,116 are inserted into the beams 1,1',2,2'.
[0042] Holes 101 are formed at a position adjacent to the holes 100 at the one side surfaces of the combining portions 126,120 of the inner hinge members 114,116 and the outer hinge members 110,112. Protrusions 103 formed at the beams 1,1',2,2' are inserted into the holes 101 by striking portions of the other side surfaces opposite to the holes 101.
[0043] FIG. 14 is a partially exploded perspective view of a ladder according to other preferred embodiment of the present invention, showing a hinge means of the ladder.
[0044] Referring to FIG. 14, the hinge H,H' according to the other preferred embodiment includes a pair of outer hinge members 110,112 and a pair of inner hinge members 114,116.
[0045] The outer hinge members 110,112 are engaged with the beams 1,1'. The inner hinge members 114,116 are simultaneously engaged with the inner hinge members 114,116 and the beams 2,2'.
[0046] Further, the hinge H,H' are provided with combining portions 120, a pair of outer hinge plates 122 extending from the combining portions 120, a pair of inner hinge plates 124 and combining portions 126.
[0047] In addition, the hinge H,H' are provided with a fixing key 134, a push cover 136, a spring 138 for elastically supporting the fixing key 134 and the push cover 136. As shown in FIGs. 15 and 16, the fixing key 134 combines the outer hinge plates 122 to the inner hinge plates 124 so that it restricts the movement of the outer hinge plates 122 and the inner hinge plates 124. The push cover 136 allows the fixing key 134 for moving at the longitudinal direction.
[0048] The fixing key 134 has a U shape and includes a center portion and a fixing portion. The center portion of the fixing key 134 passes through the hole 140 formed through the outer hinge members 110,112. The fixing portion of the fixing key 134 passes through the hole 140, a hole 142 formed at a predetermined position of the outer hinge plate 122 and a hole 131 formed through the inner hinge plate 124.
[0049] The push cover 136 is engaged with the end of the center portion of the fixing key 134. The spring 138 is fitted onto the center portion of the fixing key 134 and is disposed between the push cover 136 and one side surfaces of the outer hinge members 110,112,
[0050] Therefore, both ends of the steps(S) are inserted into the hole 100 formed through the beams 1,1',2,2'.
[0051] Under this state, the user hits the outer side surfaces of the beams 1,1',2,2' with which both ends of the step(S) are brought into contacted, by using the punch 102. As a result, the outer side surfaces of the beams 1,1',2,2' are partially deformed and thereby the cross sectional area of the ends of the step(S) is enlarged.
[0052] Therefore, after combining the steps(S) to the beams 1,1',2,2', the user inserts the hinge into the upper ends of the beams 1,1' and 2,2' and combines the step(S) to the beams 1,1' and 2,2' by using riveting.
[0053] By riveting the hinge to the inner hinge members 114,116 and the outer hinge members 110,112, two pairs of the beams 1,1',2,2' can be folded or deployed.
[0054] In the ladder according to the present invention as described above, the beams and the hinges are tightly engaged with each other, and thereby it is possible to prevent the connection between the beams and the hinges from being broken down due to the weakness of the combining force. As a result, it is possible to prevent any accident from being caused and to prevent the connection between the beams and the steps from being broken down.
[0055] While the present invention has been particularly shown and described with reference to a particular embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims.
both ends of the steps being inserted into holes which are formed at one side surfaces of the beams and have the same cross sectional shapes with that of the steps and a predetermined size adapted to receive the ends of the steps, both ends of the steps being enlarged due to the striking force applied by a punch and being engaged with the beams under the state that rounded ends of the steps are formed from outer side surfaces of the beams to inner side surfaces of the beams due to the striking force applied by the punch and the rounded ends are brought into contact with the ends of the steps.
inner hinge members having combining portions and a pair of inner hinge plates, the combining portions being inserted into the ends of the beams, the inner hinge plates symmetrically extending from both sides of the combining portions in order to form a reinforcing rib and being rounded under the state that the center of the outer hinge plates is positioned at an outer periphery of one side surface crossing with both sides of the combining portions;
a center rivet for rotatably riveting the outer hinge plates of the outer hinge members and the inner hinge plates of the inner hinge members; and
a fixing means for fixing the hinge outer members and the hinge inner members at a predetermined pivot position.
a push cover being engaged with the end of the center portion;and
a spring being fitted onto the center portion of the fixing key and being disposed between the push cover and one side surfaces of the outer hinge members.
the hinge means including outer hinge members and inner hinge members, and one side surfaces of combining ends of the outer hinge members and the inner hinge members being cut and provided with a combining hole and a step hole so that the combining ends are elastically engaged with the beams.
the hinge means including outer hinge members and inner hinge members, and combining ends of the outer hinge members and the inner hinge members being cut and provided with first holes and second holes, the first holes being formed at inner side surfaces of the combining ends and having the same cross sectional shape with that of the beam and a predetermined size adapted to receive the ends of the beams, the second holes being formed at outer side surfaces of the combining ends, and protrusions, which are formed from the outer side surfaces of the beams to inner side surfaces of the beams due to the striking force applied by a punch, being inserted into the second holes.