Sheet feeding apparatus for a corrugated fiberboard container making machine

The present invention provides a sheet feeding apparatus for a corrugated fiberboard box making machine, which has front stops disposed at two locations spaced in the width direction (transverse direction) to true up the front edges of stacked corrugated fiberboard sheets and is constructed so as to feed a lowermost corrugated fiberboard sheet successively from the front end side of the front stop, characterized in that the front stops at the two locations are constructed so as to be movable in the longitudinal direction in such a manner as to be capable of supporting the corrugated fiberboard sheets while tilting the front edges thereof obliquely in the longitudinal direction.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
 1. Field of the Invention
 The present invention relates to a sheet feeding apparatus for a corrugated
 fiberboard container making machine for feeding stacked corrugated
 fiberboard sheets one after another.
 2. Description of Related Art
 FIGS. 8 and 9 are explanatory views showing outlines of conventional sheet
 feeding apparatuses for a corrugated fiberboard container. In FIG. 8,
 frames 1 are erected on both sides, right and left, of a table 2, and a
 beam 3 is installed between the frames 1. A hopper 6 is defined by front
 stops 4 attached to the beam 3 and side guides 5, and corrugated
 fiberboard sheets 7 are stacked on the table in this hopper 6. A lowermost
 sheet 7a of the stacked corrugated fiberboard sheets 7 is kicked from one
 end side by a kicker 8 and reaches feed rolls 9 on the other end side as
 indicated by the chain line. Then, the sheet 7a is pulled by the feed
 rolls 9 and is sent to the following process (for example, a printing
 section 10).
 FIG. 9 shows an outline of a sheet feeding apparatus of another type. In
 this sheet feeding apparatus, delivery rolls 11 are provided under the
 front stops 4 in place of the kicker 8, and the vacuum pressure in a
 vacuum box (suction box) 12 attracts the lowermost sheet 7a to the surface
 of the delivery rolls 11, so that the sheet 7a is delivered by a
 frictional force.
 The above-described conventional sheet feeding apparatuses for a corrugated
 fiberboard box making machine have problems as described below. For
 example, if the feed roll 9 wears eccentrically, the feeding force becomes
 nonuniform in the transverse direction. Also, in the case shown in FIG. 9,
 if the corrugated fiberboard sheet 7 is warped, the contact pressure
 between the delivery roll 11 and the lowermost sheet 7a of the corrugated
 fiberboard sheets 7 becomes nonuniform in the transverse direction even
 with the aid of the suction pressure of the vacuum box 12. Particularly
 for a corrugated fiberboard sheet with high flexural rigidity such as a
 double-sided sheet, such tendency is remarkable.
 Thus, when a feeding force that is nonuniform in the transverse direction
 is applied to the corrugated fiberboard sheet 7 under the mechanical
 condition of eccentric wear of the feed roll 9 or under the condition of
 warped sheet 7, the sheet 7 is fed while being turned obliquely at a
 predetermined angle as shown in FIG. 10. The sheet 7 fed in this manner
 decreases the accuracy of box made in the subsequent process. Therefore,
 the accuracy is kept by a correction, for example, by decreasing the sheet
 feed speed or by purposely installing the kicker 8 slantwise.
 Since such a tendency for oblique turning is often developed by the
 eccentric wear of the feed roll 9, the warping of the corrugated
 fiberboard sheet 7, and the like as described above, the oblique turning
 does not occur at random for each corrugated fiberboard sheet 7, but there
 is a tendency for all corrugated fiberboard sheets 7 of a certain
 production lot to be turned obliquely in the same manner.
 OBJECT AND SUMMARY OF THE INVENTION
 The present invention has been made in view of the above situation, and
 accordingly an object thereof is to provide a sheet feeding apparatus for
 a corrugated fiberboard box making machine in which even if corrugated
 fiberboard sheets have a tendency for oblique turning, the tendency for
 oblique turning can be adjusted easily.
 To solve the problem with the above-described prior art, according to the
 invention defined in claim 1, there is provided a sheet feeding apparatus
 for a corrugated fiberboard box making machine, which has front stops
 disposed at two locations spaced in the width direction to true up the
 front edges of stacked corrugated fiberboard sheets and is constructed so
 as to feed a lowermost corrugated fiberboard sheet successively from the
 front end side of the front stop, characterized in that the front stops at
 the two locations are constructed so as to be movable in the longitudinal
 direction in such a manner as to be capable of supporting the corrugated
 fiberboard sheets while tilting the front edges thereof obliquely in the
 longitudinal direction.
 According to the invention defined in claim 2, in the invention according
 to claim 1, the front stops are disposed at two locations on a beam which
 extends in the width direction and can be tilted slantwise in the
 longitudinal direction with one end thereof in the width direction being a
 fulcrum, and are constructed so as to support the corrugated fiberboard
 sheets while tilting the front edges thereof obliquely in the longitudinal
 direction by moving together with the beam.
 According to the invention defined in claim 3, in the invention according
 to claim 1, the front stops are disposed at two locations on a beam
 extending in the width direction, and are constructed so as to support the
 corrugated fiberboard sheets while tilting the front edges thereof
 obliquely in the longitudinal direction by moving individually in the
 longitudinal direction with respect to the beam.
 As described above, in the invention defined in claim 1, the two front
 stops are constructed so as to be movable in the longitudinal direction in
 such a manner as to be capable of supporting the corrugated fiberboard
 sheets while tilting the front edges thereof obliquely in the longitudinal
 direction. Therefore, even if corrugated fiberboard sheets have a tendency
 for oblique turning, the tendency for oblique turning can be adjusted
 easily to a straight state, for example.
 Also, in the invention defined in claim 2, since the two front stops are
 disposed on a beam which can be tilted slantwise in the longitudinal
 direction, the positions and directions of the two front stops can be
 changed at the same time merely by changing the tilt of the beam.
 Therefore, the direction of the corrugated fiberboard sheet 7 can be
 corrected quickly. In addition, the same effect as that of the invention
 defined in claim 1 can be achieved.
 Further, in the invention defined in claim 3, since the two front stops are
 moved individually in the longitudinal direction with respect to the beam,
 the direction of the corrugated fiberboard sheet can easily be adjusted
 finely.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
 Embodiments of the present invention will be described below with reference
 to FIGS. 1 to 7. FIGS. 1 to 4 show a first embodiment, and FIGS. 5 to 7
 show a second embodiment.
 First, the first embodiment of the present invention will be described with
 reference to FIGS. 1 to 4. In these figures, the same reference numerals
 are applied to elements common to those of the conventional example, and
 the duplicated explanation of those elements is simplified. The sheet
 feeding apparatus for a corrugated fiberboard container making machine has
 front stops 27, which are disposed at two locations a predetermined
 distance away from each other in the transverse direction (the width
 direction), for truing up the front edges of the sheets 7 so that a
 lowermost corrugated fiberboard sheet 7 is fed successively from the front
 end side. The front stops 27 at the aforesaid two locations are
 constructed movably in the longitudinal direction so as to be capable of
 supporting the corrugated fiberboard sheets 7 while tilting them obliquely
 in the longitudinal direction. The front stops 27 are mounted at two
 predetermined locations of a beam 22 which extends in the transverse
 direction and is capable of being tilted obliquely in the longitudinal
 direction with one end in the transverse direction being a fulcrum, and
 are constructed so as to support the corrugated fiberboard sheets 7 while
 tilting the front edges thereof obliquely in the longitudinal direction by
 moving together with the beam 22.
 Next, the above-described construction will be described in more detail. Of
 the frames 1 disposed at right and left, the frame 1 located on the right
 side in FIGS. 1 and 2 is fitted with a mounting base 21 by welding or
 other means. On this mounting base 21, one end of the beam 22 is supported
 via a fulcrum pin 23 so as to be rotatable in the longitudinal direction
 with respect to the sheet advance direction. The other end of the beam 22
 is slidably supported via a groove portion formed so as to hold a support
 base 24 fixed to the frame 1 on the opposite side (left side).
 As shown in FIG. 3, the beam 22 is fitted with a bracket 25 having a U
 shape in cross section and a keep plate 26 which are slidable in the axial
 direction (transverse direction). The bracket 25 and the keep plate 26
 enclose the beam 22. A face of the bracket 25 on the side opposite to the
 beam 22 is formed with a dovetail groove 25a, and the front stop 27 is
 fitted in this dovetail groove 25a so as to be slidable in the vertical
 direction. On a mounting base 28 fixed to the upper part of the front stop
 27 is mounted a motor 29. A screw shaft 30, which is fixed to the shaft of
 the motor 29, engages with a screw hole 25b in the bracket 25. Therefore,
 when the motor 29 is rotated, the screw shaft 30 goes into and out of the
 bracket 25, and accordingly the front stop 27 moves vertically, so that a
 gap between the lower edge of the front stop 27 and the table 2 can be
 changed according to the thickness of the corrugated fiber board 7 being
 worked.
 A motor 31 is mounted above the support base 24 of the frame 1 on the
 sliding side of the beam 22, that is, on the left side. On the shaft of
 this motor 31 is fixed an eccentric ring (eccentric cam) 32, which fits in
 an oval-shaped groove 22a in the beam 22. Therefore, when the motor 31 is
 rotated, the beam 22 sways in the longitudinal direction (sheet advance
 direction) with the fulcrum pin 23 being a fulcrum.
 In the sheet feeding apparatus for a corrugated fiberboard box making
 machine constructed as described above, by rotating the motor 31, the beam
 22 is tilted obliquely in the longitudinal direction with the fulcrum pin
 23 being a fulcrum, so that the two front stops 27 provided on the beam 22
 also move in the longitudinal direction in a tilted manner. That is to
 say, a hopper 6 can be tilted as shown in FIG. 4. Therefore, if the
 corrugated fiberboard sheet 7 is turned obliquely, for example, at an
 angle of a when the sheet 7 is fed from the normal position of the hopper
 6, at which position the sheet 7 is not tilted (the front edges of the
 corrugated fiberboard sheets 7 are arranged perpendicularly to the sheet
 advance direction), the two front stops 27 are tilted at the turning angle
 .alpha. of the corrugated fiberboard sheet 7 in the reverse direction in
 advance, whereby the posture of the corrugated fiberboard sheet 7 can be
 corrected. Therefore, the corrugated fiberboard sheet 7 takes a correct
 posture when being fed and reaching the downstream process such as a
 printing section, that is, the corrugated fiberboard sheet 7 can be fed
 straight from the table 2 to the next process.
 Thereupon, unlike the conventional sheet feeding apparatus, there is no
 need for decreasing the sheet feed speed or for correcting the attachment
 of a kicker, and the feed direction of the corrugated fiberboard sheet 7
 can be adjusted easily. Further, merely by changing the tilt of the beam
 22, the positions and directions of the two front stops 27 can be change
 at the same time, so that the direction of the corrugated fiberboard sheet
 7 can be corrected quickly.
 Next, the second embodiment of the present invention will be described with
 reference to FIGS. 5 to 7. In these figures, the same reference numerals
 are applied to elements common to those of the conventional example and
 the first embodiment, and the duplicated explanation of those elements is
 simplified.
 In the above-described first embodiment, the beam 22 fitted with the front
 stops 27 is tiltable, by which the direction in which the corrugated
 fiberboard sheets 7 are held by the two front stops 27 can be changed
 easily. In the second embodiment, contrarily, the beam 3 is fixed to the
 frames 1 as before, and the two front stops 27 themselves can be made
 movable in the longitudinal direction with respect to the beam 3, by which
 the direction in which the corrugated fiberboard sheets 7 are held by the
 two front stops 27 can be changed easily.
 Specifically, the beam 3 fixed to the frames 1 is fitted with an inside
 bracket 40 by using a keep plate 41, and the inside bracket 40 is
 configured so as to be slidable on the beam 3 in the axial direction
 (lengthwise direction). Also, on the outside of the inside bracket 40, an
 outside bracket 42 is installed by being guided by a key member 44 so as
 to be slidable to the right and left in FIG. 5 (longitudinally with
 respect to the sheet advance direction). A keep plate 43 is installed on
 the opening side of the outside bracket 42 to prevent the outside bracket
 42 from coming off from the inside bracket 40. A face of the outside
 bracket 42 on the side opposite to the beam 3 is formed with a dovetail
 groove 42a, and the front stop 27 is fitted in this dovetail groove 42a so
 as to be slidable in the vertical direction and can be moved vertically by
 the motor 29 as in the case of the first embodiment.
 A motor 45 is mounted above the outside bracket 42, and the shaft thereof
 passes through the outside bracket 42 and projects toward an oval-shaped
 groove 40a in the inside bracket 40. On the shaft of the motor 45 is fixed
 an eccentric ring (eccentric cam) 46, which fits in the oval-shaped groove
 40a. Therefore, when the motor 45 is rotated, the outside bracket 42 is
 moved in the direction indicated by an arrow 47 in FIG. 5 (longitudinally
 with respect to the sheet advance direction) with respect to the inside
 bracket 40, and therefore with respect to the beam 3 according to the
 rotational angle of the eccentric ring 46.
 That is to say, the two front stops 27 are independently moved
 longitudinally with respect to the sheet advance direction, whereby the
 direction of the front edge of the corrugated fiberboard sheet 7 can be
 changed easily.
 Of two sets of the front stops, one set may be fixed to the beam 3 as
 before and one set may be adjustable longitudinally as described in the
 second embodiment. Alternatively, both of the two sets may be adjustable.
 The sheet feeding apparatus for a corrugated fiberboard box making machine
 constructed as described above is suitable for fine adjustment of
 direction of the corrugated fiberboard sheet 7 because the front stops 27
 can independently be moved in the longitudinal direction. In addition,
 this sheet feeding apparatus achieves the same operation and effect as in
 the case of the first embodiment, except that although the side guides 5
 fixed to the beam 22 are tilted in the same way as the front stops 27 in
 the first embodiment, the side guides 5 are fixed in the second
 embodiment. However, since the quantity of tilt is very small (several
 millimeters at the position of the eccentric ring 32 in the first
 embodiment), whether the side guides 5 tilt or not has no effect on the
 performance of the sheet feeding mechanism.