Pulp crushing apparatus

An absorbent product manufacturing apparatus including a pulp feed mechanism (2) for feeding a pulp sheet along a lower surface of a pulp guide part (2411) and a pulp crushing mechanism (3) for crushing the pulp sheet from the pulp feed mechanism (2). The pulp crushing mechanism (3) crushes the pulp sheet with a first crushing cylinder (312) and a second crushing cylinder (322). The crushing cylinders are disposed so as to be inclined with respect to a direction of feeding the pulp sheet. This reduces the force necessary to draw the pulp sheet in the feeding direction and suppresses an increase in the movement speed of the pulp sheet in crushing a rear end portion of the pulp sheet. As a result, it is possible to increase the amount of crushed pulp to be generated in a unit time and to maintain uniformity in the quality thereof.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a pulp crushing apparatus for crushing a pulp sheet for absorbent product.

2. Description of the Related Art

In manufacturing absorbent products used for hygiene products such as a disposal diaper, conventionally, a crushing apparatus for crushing a pulp sheet is used. Japanese Patent Application Laid Open Gazette No. 2001-309945, for example, discloses a technique to form an absorbent layer of an absorbent product, where a pulp sheet wound on a drum is unreeled and crushed by a crushing apparatus and the crushed pulp is blown on nonwoven fabrics to be layered. In such a crushing apparatus, for crushing pulp sheets, usually, a feed mechanism such as a feed roller feeds the pulp sheets at a constant speed to a crushing cutter which rotates about a rotation axis where the rotation axis is provided in parallel to the pulp sheets and it is orthogonal to a direction of feeding the pulp sheets.

In such a crushing apparatus, however, there is a possibility that a piece of pulp after passing the feed roller might be pulled by and get entangled in the crushing cutter in crushing a rear end portion of the fed pulp sheet, to go in a crushing chamber provided with the crushing cutter, without being crushed. Even if no piece of pulp gets entangled, the movement speed of pulp sheets increases with torque of the crushing cutter and this makes the amount of crushed pulp to be generated in a unit time larger than the regular amount and makes the crushed pulp coarser. Further, since the distance between a rear end portion of a preceding pulp sheet and a following pulp sheet becomes larger for a certain interval and no crushed pulp is generated for the interval, there arises variation in the amount of crushed pulp to be generated in a unit time and quality thereof, and therefore the uniformity in quality of an absorbent product to be formed is disadvantageously degraded.

For this reason, an operation of stopping the apparatus before entangling the rear end portion of the pulp sheet to remove it from the feed roller is needed and this decreases the efficiency of crushing operation and makes improvement in yield difficult. With two pulp feed mechanisms alternately working, a decrease in efficiency of the crushing operation can be prevented but the apparatus disadvantageously becomes larger.

The coarsely crushed pulp is repeatedly crushed until it becomes smaller than a predetermined size by providing a screen with a lot of very small openings at an outlet of the crushing chamber for discharging the crushed pulp and another crushing mechanism in the crushing chamber, or a full stop of generation of the crushed pulp is prevented by parallelly using a crushing apparatus for crushing a pulp sheet coarsely and another crushing apparatus for crushing a pulp sheet finely. These methods, however, can not keep a constant amount of crushed pulp to be generated in a unit time and thereby need measurement for the amount of crushed pulp before formation of an absorbent product.

SUMMARY OF THE INVENTION

The present invention is intended for a pulp crushing apparatus for crushing a pulp sheet for absorbent product, and it is an object of the present invention to increase in the amount of crushed pulp to be generated in a unit time and uniformity of quality thereof by suppressing an increase in movement speed of a pulp sheet in crushing a near-rearend portion of the pulp sheet after passing a pulp feed mechanism.

According to the present invention, the pulp crushing apparatus comprises a pulp feed mechanism for feeding a pulp sheet along a predetermined feed line, and a first crushing mechanism and a second crushing mechanism for crushing one end and the other end of the pulp sheet, respectively, with respect to a width direction of the pulp sheet, the first crushing mechanism and the second crushing mechanism being arranged in parallel to the width direction in the downstream of the pulp feed mechanism, and in the pulp crushing apparatus of the present invention, each of the first crushing mechanism and the second crushing mechanism comprises an inclined rotation axis, farther end of which from a center line of the feed line is inclined toward the pulp feed mechanism, a crushing cylinder having a substantial tubular shape with the inclined rotation axis as a center and rotating about the inclined rotation axis to crush the pulp sheet which goes into an outer peripheral surface thereof, and a pulp support part having a substantial plate shape, for supporting the pulp sheet against rotation of the outer peripheral surface.

The pulp crushing apparatus of the present invention can increase the amount of crushed pulp to be generated in a unit time and uniformity of quality thereof by suppressing an increase in movement speed of the pulp sheet in crushing a near-rearend portion of the pulp sheet.

According to one preferred embodiment of the present invention, the respective crushing cylinders of the first crushing mechanism and the second crushing mechanism are provided, being approximate to each other and symmetrical with respect to the center line of the feed line, and the pulp sheet is crushed in whole in the width direction thereof by the first crushing mechanism and the second crushing mechanism. Preferably, an angle between the inclined rotation axis of the crushing cylinder and the center line of the feed line is not smaller than 30 degrees and not larger than 60 degrees.

According to another preferred embodiment of the present invention, the crushing cylinder comprises a plurality of crushing blades arranged along the inclined rotation axis, each of the plurality of crushing blades has a substantial disk shape orthogonal to the inclined rotation axis, and comprises a plurality of teeth provided in its outer periphery at a regular pitch, and teeth are arranged in a spiral fashion on the outer peripheral surface of the crushing cylinder. It is thereby possible to reduce the maximum value of a force applied to the pulp sheet by rotation of the crushing cylinder.

Preferably, the teeth of the crushing cylinder sequentially come into contact with the pulp sheet outwards from the side of the center line of the feed line and teeth of the first crushing mechanism and teeth of the second crushing mechanism are provided symmetrically with respect to the center line of the feed line.

According to still another preferred embodiment of the present invention, a near-rearend portion of a preceding pulp sheet after passing the pulp feed mechanism is fed into the first crushing mechanism and the second crushing mechanism with its end pushed by a following pulp sheet fed by the pulp feed mechanism in crushing the near-rearend portion of the preceding pulp sheet. Preferably, each of the first crushing mechanism and the second crushing mechanism further comprises a guide part which comes into contact with the pulp sheet while being opposed to the pulp support part. Since the guide part is provided, it is possible to surely crush the pulp sheet even in crushing the near-rearend portion of the pulp sheet.

According to an aspect of the present invention, the pulp crushing apparatus further comprises a control part for changing a feeding speed at which a pulp sheet is fed by the pulp feed mechanism and controlling a rotation speed of crushing cylinders of the first crushing mechanism and the second crushing mechanism on the basis of the feeding speed. With this control by the control part, it is possible to maintain uniformity in quality of the crushed pulp even if the feeding speed of the pulp sheet varies.

According to another aspect of the present invention, the pulp crushing apparatus further comprises a stopper provided near the center line of the feed line between the first crushing mechanism and the second crushing mechanism, being opposed to a front edge of the pulp sheet.

According to still another aspect of the present invention, the pulp crushing apparatus further comprises a pressing part provided near the center line of the feed line between the first crushing mechanism and the second crushing mechanism, for pressing a front end portion of the pulp sheet onto the pulp support part.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a view showing a construction of an absorbent product manufacturing apparatus in accordance with the first preferred embodiment of the present invention. The absorbent product manufacturing apparatus1serves to manufacture an absorbent product90used for a disposal diaper, a sanitary napkin or the like, and the absorbent product90is manufactured by using crushed pulp which is obtained by crushing a pulp sheet9which is pulp cut into a certain size.

The absorbent product manufacturing apparatus1comprises a pulp feed mechanism2for feeding the pulp sheet9along a predetermined feed line in the (−X) direction ofFIG. 1, a pulp crushing mechanism3for crushing the pulp sheet9fed by the pulp feed mechanism2downstream of the pulp feed mechanism2, an absorbent product forming mechanism4for forming the absorbent product90by molding the crushed pulp generated by the pulp crushing mechanism3and a control part5for controlling these mechanisms. In the absorbent product manufacturing apparatus1, the pulp feed mechanism2and the pulp crushing mechanism3serve as a pulp crushing apparatus for crushing the pulp sheet9for absorbent product.

The pulp feed mechanism2comprises a pulp mounting part21on which a plurality of layered pulp sheets9are placed, a pulp unloading mechanism22for unloading the pulp sheet9from the pulp mounting part21sheet by sheet, a conveyor23receiving the pulp sheet9from the pulp unloading mechanism22to transfer it in the (−X) direction, and a feed line24provided on the (−X) side of the conveyor23, for guiding the pulp sheet9to the pulp crushing mechanism3.

FIGS. 2 and 3are a front elevation and a plan view, respectively, enlargedly showing the feed line24and the pulp crushing mechanism3and their vicinity. For convenience of illustration, the direction of showing part of the pulp crushing mechanism (the second crushing mechanism32) is changed inFIG. 2(andFIG. 1) and the inside of part of the pulp crushing mechanism (the first crushing mechanism31and the second crushing mechanism32) is shown inFIG. 3(the same applies toFIGS. 5 and 7).

As shown inFIG. 2, the feed line24comprises an upper plate241and a lower plate242each having a substantial plate shape, which are in contact with main surfaces of the pulp sheet9on the (+Z) and (−Z) sides, respectively. The pulp feed mechanism2further comprises a first upper roller243provided on the (+X) side of the pulp crushing mechanism3, a first lower roller244provided so as to be opposed to the first upper roller243with the pulp sheet9interposed therebetween, a second upper roller245provided on the (+X) side of the first upper roller243and a second lower roller246provided so as to be opposed to the second upper roller245with the pulp sheet9interposed therebetween. The first upper roller243and the second upper roller245are in contact with the main surface of the pulp sheet9on the (+Z) side through openings2410(seeFIG. 3) provided in the upper plate241. The first lower roller244and the second lower roller246are in contact with the main surface of the pulp sheet9on the (−Z) side through openings provided in the lower plate242. The first upper roller243and the second upper roller245are pressed toward the lower rollers by a pressing mechanism.

In the pulp feed mechanism2, the first upper roller243and the second upper roller245are rotated clockwise inFIG. 2by motors247and250through timing belts2481and2482, respectively. The first lower roller244and the second lower roller246are connected to the first upper roller243and the second upper roller245through gears2491and2492and rotated counterclockwise inFIG. 2with rotation of the first upper roller243and the second upper roller245, and the pulp sheet9is thereby smoothly fed to the pulp crushing mechanism3, being guided by the upper plate241and the lower plate242, respectively. In the absorbent product manufacturing apparatus1, an operation of the pulp crushing mechanism3is controlled on the basis of the rotation speed of the motor247(i.e., the feeding speed of the pulp sheet9) which is controlled by the control part5(detailed discussion on this control will be made later). The first lower roller244and the second lower roller246may be passively rotated with the movement of the pulp sheet9.

The pulp crushing mechanism3comprises a first crushing mechanism31and a second crushing mechanism32which are arranged along the width direction of the pulp sheet9(the Y direction) as shown inFIG. 3. The first crushing mechanism31and the second crushing mechanism32crush portions on the (+Y) and (−Y) sides of the pulp sheet9on the (+Y) and (−Y) sides of the center line91of the feed line24in parallel to the direction of feeding the pulp sheet9(the X direction).

The first crushing mechanism31comprises a first crushing cylinder312having a substantial tubular shape with a first inclined rotation axis311as a center and rotating about the first inclined rotation axis311to crush the pulp sheet9which goes into an outer peripheral surface thereof, and the second crushing mechanism32comprises a second crushing cylinder322having a substantial tubular shape with a second inclined rotation axis321as a center and rotating about the second inclined rotation axis321to crush the pulp sheet9which goes into an outer peripheral surface thereof. The first inclined rotation axis311and the second inclined rotation axis321are each in parallel to the pulp sheet9, and each farther end of the inclined rotation axes from the center line91of the feed line24is inclined toward the pulp feed mechanism2, i.e., the inclined rotation axis goes toward the pulp feed mechanism2(the (+X) side) as become farther from the center line91. The first inclined rotation axis311and the second inclined rotation axis321are symmetrical with respect to the center line91of the feed line24, and an angle between each of the inclined rotation axes and the center line91is not smaller than 30 degrees and not larger than 60 degrees (45 degrees in this preferred embodiment). In other words, the first crushing cylinder312and the second crushing cylinder322are provided so as to be inclined with respect to the direction of feeding the pulp sheet9.

The first crushing cylinder312and the second crushing cylinder322are provided, being approximate to each other, symmetrically on the (+Y) and (−Y) sides of the center line91of the feed line24and are rotated clockwise inFIG. 2by a cylinder rotating mechanism, to crush the whole pulp sheet9with respect to the width direction thereof.FIGS. 1 and 2show the second crushing mechanism32from the direction in parallel to the second inclined rotation axis321(the same applies toFIG. 5).

As shown inFIGS. 2 and 3, the second crushing cylinder322comprises thirty crushing blades33arranged along the second inclined rotation axis321, and each crushing blade33has a substantial disk shape with the second inclined rotation axis321as a center. Each blade is orthogonal to the second inclined rotation axis321. Each crushing blade33comprises a plurality of teeth331(twelve in this preferred embodiment) provided in its outer periphery at a regular pitch. Similarly, the first crushing cylinder312comprises thirty crushing blades33arranged along the first inclined rotation axis311, and each crushing blade33has a substantial disk shape with the first inclined rotation axis311as a center, orthogonal to the first inclined rotation axis311.

FIG. 4is an enlarged view showing an outer peripheral surface of the second crushing cylinder322and its vicinity viewed from the direction in parallel to the second inclined rotation axis321. As shown inFIG. 4, since the thirty crushing blades33have the teeth331which are so provided as to be shifted by one degree in the rotation direction of the second crushing cylinder322(in other words, clockwise inFIG. 4) as become closer to the center line91of the feed line24(seeFIG. 3), tip portions of the teeth331are arranged in a spiral fashion with the second inclined rotation axis321as a center on the outer peripheral surface of the second crushing cylinder322as shown inFIG. 3. Similarly, in the first crushing cylinder312, tip portions of the teeth331are arranged in a spiral fashion with the first inclined rotation axis311as a center on the outer peripheral surface of the first crushing cylinder312, and the teeth331of the first crushing cylinder312and the teeth331of the second crushing cylinder322are provided symmetrically on the (+Y) and (−Y) sides of the center line91of the feed line24.

In the pulp crushing mechanism3, since the first crushing cylinder312and the second crushing cylinder322are rotated synchronously through a pulley313and a pulley323and the not-shown timing belts, respectively, the pulp sheet9is crushed sequentially by the teeth331arranged in a spiral fashion on the outer peripheral surface of these crushing cylinders. Therefore, it is possible to prevent a lot of teeth331in these crushing cylinders from coming into contact with the pulp sheet9at the same time and thereby reduce the maximum value of a force applied to the pulp sheet9in crushing. Since the teeth331of these crushing cylinders sequentially come into contact with the pulp sheet9outwards from the side of the center line91of the feed line24(in other words, in the direction of becoming farther away from the center line91) to crush the pulp sheet9, it is possible to prevent a force to push and bend the pulp sheet9toward the center line91and stably crush the pulp sheet9. Since the teeth331of these crushing cylinders come into contact with the pulp sheet9symmetrically with respect to the center line91to crush the pulp sheet9, the force applied to the pulp sheet9is made symmetrical with respect to the center line91and it is thereby possible to prevent the pulp sheet9from shifting in the Y direction (the direction orthogonal to the direction of feeding the pulp sheet9).

In the absorbent product manufacturing apparatus1, as shown inFIGS. 2 and 3, front edges of the upper plate241and the lower plate242are positioned approximately at the outer peripheral surface of the first crushing cylinder312on the (+Y) side of the center line91of the feed line24in parallel and approximately at the outer peripheral surface of the second crushing cylinder322on the (−Y) side of the center line91in parallel. When the first crushing cylinder312and the second crushing cylinder322are rotated to come into contact with the pulp sheet9from the (+Z) side, a tip portion2421of the lower plate242serves as a support part for supporting the pulp sheet9, which goes in these crushing cylinders from the (−Z) side, against the rotation of the outer peripheral surfaces of these crushing cylinders, and as a result, the pulp sheet9is surely crushed. Hereinafter, the tip portion2421of the lower plate242is referred to as “a pulp support part2421”.

A tip portion2411of the upper plate241, being opposed to the pulp support part2421, serves as a guide part to come into contact with the pulp sheet9from the (+Z) side. Hereinafter, the tip portion2411of the upper plate241is referred to as “a pulp guide part2411”. As the pulp support part2421, two support parts may be provided correspondingly to the first crushing cylinder312and the second crushing cylinder322, and as the pulp guide part2411, two guide parts may be provided correspondingly to these crushing cylinders.

When crushing of the pulp sheet9goes ahead and a rear end portion of the pulp sheet9(the edge on the (+X) side) passes the first upper roller243and the first lower roller244and is released from the pulp feed mechanism2, the pulp sheet9is automatically moved in the feeding direction by a force applied to the pulp sheet9(a force to pull the pulp sheet9toward the (−X) direction) with rotation of the first crushing cylinder312and the second crushing cylinder322.

In the pulp crushing mechanism3, as discussed above, since the first crushing cylinder312and the second crushing cylinder322are provided so as to be inclined with respect to the direction of feeding the pulp sheet9, a force applied to the pulp sheet9in the feeding direction (or the movement speed in the feeding direction) is a component of the force (or the movement speed) applied to the pulp sheet9with rotation of these crushing cylinders in the feeding direction. As a result, it is possible to reduce the force required to pull the pulp sheet9in the feeding direction (or the movement speed) as compared with the case where the rotation axis of the crushing cylinder is provided orthogonally to the feeding direction, and it is further possible to suppress an increase in movement speed of the pulp sheet9in crushing a near-rearend portion of the pulp sheet9. This suppresses variation in the amount of pulp sheet9to be fed to the pulp crushing mechanism3in a unit time also at the near-rearend portion of the pulp sheet9, and it is thereby possible to increase the amount of crushed pulp to be generated in a unit time and uniformity in quality thereof.

Since the pulp sheets9are sequentially crushed by the teeth331arranged in a spiral fashion on the outer peripheral surfaces of the first crushing cylinder312and the second crushing cylinder322, it is possible to further reduce the force required to pull the pulp sheet9in the feeding direction (in other words, prevent a large force from discontinuously applying to the pulp sheet9) and more efficiently suppress an increase in feeding speed of the pulp sheet9in crushing the near-rearend portion of the pulp sheet9.

The movement speed of the pulp sheet9after passing the first upper roller243and the first lower roller244varies with the kind or thickness of the pulp sheet9, the arrangement of the first crushing cylinder312and the second crushing cylinder322or the like. In the pulp crushing mechanism3, by setting an angle of the first inclined rotation axis311and the second inclined rotation axis321to the center line91to an appropriate one (45 degrees in this preferred embodiment), the movement speed of the pulp sheet9after passing the pulp feed mechanism2is made lower than the feeding speed of the pulp sheet9by the pulp feed mechanism2. Therefore, in crushing a near-rearend portion of a preceding pulp sheet9after passing the pulp feed mechanism2(exactly, the first upper roller243and the first lower roller244), the preceding pulp sheet9is fed into the pulp crushing mechanism3with its rear end portion pushed by a following pulp sheet9fed by the pulp feed mechanism2. In other words, the rear end portion of the preceding pulp sheet9after passing the pulp feed mechanism2is fed into the pulp crushing mechanism3at the same speed as the one before passing the pulp feed mechanism2and crushed therein. As a result, the pulp sheets9can be always fed at a constant speed by sequentially feeding a plurality of pulp sheets9into the pulp crushing mechanism3, and it is thereby possible to always maintain a uniform amount of crushed pulp to be generated in a unit time.

Since the pulp guide part2411and the pulp support part2421which come into contact with the pulp sheet9from the (+Z) and (−Z) sides are provided closely to the outer peripheral surfaces of these crushing cylinders, even in crushing the rear end portion of the pulp sheet9, it is possible to prevent the pulp sheet9, which is separated from the first upper roller243and the first lower roller244, from being drawn into the pulp crushing mechanism3without being crushed because of a bend or the like, and each pulp sheet9can be surely crushed completely. As a result, it is possible to improve a yield of crushed pulp.

In the pulp crushing mechanism3, as shown inFIG. 3, since the first crushing cylinder312and the second crushing cylinder322are provided so as to be inclined with respect to the direction of feeding the pulp sheet9, a stopper34opposed to the front edge of the pulp sheet9, which is being fed along the feed line24and crushed, can be provided between the first crushing mechanism31and the second crushing mechanism32near the center line91of the feed line24. If the feeding speed of the near-rearend portion of the pulp sheet9increases due to some abnormality, the stopper34comes into contact with the front edge of the pulp sheet9to forcedly reduce the feeding speed. As a result, even if the feeding speed of the pulp sheet9varies, it is possible to prevent the crushed pulp generated by the pulp crushing mechanism3from becoming too fine and maintaining the uniformity in the quality of the crushed pulp.

In the absorbent product manufacturing apparatus1, for example, if the supply of the pulp sheets9to the pulp mounting part21is delayed by some cause, in order to prevent the feed of the pulp sheets9into the pulp crushing mechanism3from being stopped for a long time, the feeding speed of the pulp sheet9may be made slower by reducing the rotation speed of the motors247and250of the pulp feed mechanism2. In this case, on the basis of the rotation speed of the motor247(in other words, the feeding speed of the pulp sheet9), the first crushing cylinder312of the first crushing mechanism31and the second crushing cylinder322of the second crushing mechanism32are controlled by the control part5, to reduce the rotation speed of these crushing cylinders. As a result, even if the feeding speed of the pulp sheet9varies, without stopping the operation of the absorbent product manufacturing apparatus1, it is possible to prevent the crushed pulp being generated by the pulp crushing mechanism3from becoming too fine and maintaining the uniformity in the quality of the crushed pulp. If the feed of the pulp sheet9is delayed, by making the rotation speed of the motor250higher than that of the motor247, the newly fed pulp sheet9can catch up with the preceding pulp sheet9and therefore the yield of the crushed pulp is improved.

Next, the construction of the absorbent product manufacturing apparatus1downstream of the pulp crushing mechanism3will be discussed. The crushed pulp generated by the pulp crushing mechanism3is transferred to the absorbent product forming mechanism4through a duct41by a blowing mechanism (not shown) and mixed with a water-absorbent polymer (e.g., SAP (Super Absorbent Polymer)) fed by a polymer feed part421to be blown on a tubular adsorption drum42. The adsorption drum42is rotated clockwise inFIG. 1and absorbs the crushed pulp and the water-absorbent polymer with a suction mechanism (not shown) connected to its inside onto its outer peripheral surface in which very small vacuum holes are provided up to a predetermined level. Depending on the absorbing power required for the absorbent product90, mixture of the water-absorbent polymer may be omitted.

The crushed pulp and the water-absorbent polymer absorbed on the outer peripheral surface of the adsorption drum42are moved toward the (−Z) side of the adsorption drum42by rotation of the adsorption drum42and then transferred on tissue paper92which is unreeled from a roll43and conveyed by a conveyor401toward the (−X) direction. An adhesive (e.g., hot melt) is applied in advance onto an upper surface of the tissue paper92by an adhesive supply part431and the crushed pulp and the water-absorbent polymer are bonded on the tissue paper92to form a pulp layer900.

While the pulp layer900is transferred by the conveyor401toward the (−X) direction, an adhesive is applied onto one side of tissue paper93unreeled from another roll44by an adhesive supply part441and the tissue paper93is bonded on the pulp layer900and the tissue paper92with its one side with adhesive facing the pulp layer900. The pulp layer900wrapped by the tissue paper92and93from the (−Z) and (+Z) sides, respectively, is cut into pieces901(hereinafter, referred to as “absorbent cores901” since these pieces serve as core parts of the absorbent product90) each having a predetermined length by a cutting part471and a plurality of absorbent cores901are transferred by a conveyor402toward the (−X) direction at a predetermined pitch.

A top sheet94and a back sheet95unreeled from rolls45and46, with an adhesive from adhesive supply parts451and461applied to their respective one side, are bonded on the tissue paper92and93wrapping the absorbent cores901and cut by a cutting part472at a gap between the adjacent absorbent cores901, to form the absorbent product90. The absorbent product90manufactured is unloaded from the absorbent product manufacturing apparatus1by a conveyor403.

In the absorbent product manufacturing apparatus1, as discussed above, since the amount of crushed pulp to be generated in a unit time and its quality can be increased by the pulp crushing mechanism3, it is possible to improve the uniformity in quality of the absorbent product90. If such a control is made as to reduce the feeding speed of the pulp sheet9and the rotation speed of the crushing cylinders, an operation speed of the downstream constituents is controlled to decrease in proportion.

Next, a pulp crushing apparatus (a pulp feed mechanism and a pulp crushing mechanism) in accordance with the second preferred embodiment will be discussed.FIGS. 5 and 6are a front elevation and a plan view, respectively, enlargedly showing part of the feed line24and the pulp crushing mechanism3in the pulp crushing apparatus in accordance with the second preferred embodiment. In the pulp crushing apparatus of the second preferred embodiment, a pulp pressing mechanism26serving as a pressing part for pressing the front end portion of the pulp sheet9onto the pulp support part2421is provided on the (−X) side of the feed line24. Constituent elements other than the above are identical to those shown inFIGS. 1 to 4and are represented by the same reference signs.

As shown inFIGS. 5 and 6, the pulp pressing mechanism26is provided between the first crushing mechanism31and the second crushing mechanism32, near the center line91of the feed line24(on the center line91in this preferred embodiment). The pulp pressing mechanism26comprises a pressing member261having a substantial cylindrical shape and conical ends, and the pressing member261is attached to a frame263, which is rotatable about a rotation axis262. In the pulp crushing apparatus of the second preferred embodiment, a notch2412extending from the end on the (−X) side toward the (+X) side is provided at the pulp guide part2411of the upper plate241and a tip portion of the pressing member261on the (−X) side is inserted into the notch2412of the pulp guide part2411so as to be opposed to the pulp support part2421of the lower plate242.

In the pulp pressing mechanism26, torsion springs264are attached to the outer periphery of the rotation axis262both on the (+Y) and (−Y) sides of the pressing member261and the frame263, and an end portion of each torsion spring264protrudes from its coil part toward almost the (+Z) direction and the other end portion protrudes toward almost the (−X) direction. The end portion protruding toward the (+Z) direction is in contact with the (−X) side of an axis265protruding from the frame263toward the (+Y) and (−Y) directions and the other end portion protruding toward the (−X) direction is in contact with the (+Z) side of an axis266protruding from the pressing member261toward the (+Y) and (−Y) directions.

Since the torsion springs264are compressed in a direction where the end portion in contact with the axis266should approximate clockwise inFIG. 5to the other end portion in contact with the axis265, the axis266is pressed down toward the (−Z) direction by the repulsion of the torsion springs264. As a result, a force to rotate the pressing member261counterclockwise inFIG. 5about the rotation axis262works and front end portion of the pulp sheet9(the end portion on the (−X) side) is thereby pressed onto the pulp support part2421by the pressing member261between the tip portion of the pressing member261on the (−X) side and the pulp support part2421.

Two pins267extending in the Z direction are provided on the frame263and a tip of the pin267on the (−Z) side is placed with a slight gap between itself and the axis266on the (+Z) side of the axis266(for example, at a distance almost equal to the diameter of a metal wire forming the torsion spring264). In the pulp crushing apparatus of the second preferred embodiment, even if the tip portion of the pressing member261on the (−X) side is bounced up clockwise ofFIG. 5by the impact applied to the pulp sheet9in crushing it, the movement of the axis266toward the (+Z) side is controlled by the pins267.

In the pulp crushing apparatus of the second preferred embodiment, like in the first preferred embodiment, the pulp crushing mechanism3comprises the first crushing mechanism31and the second crushing mechanism32arranged in parallel to the width direction of the pulp sheet9(the Y direction), and the first crushing mechanism31and the second crushing mechanism32comprise the first crushing cylinder312and the second crushing cylinder322, respectively, for crushing the pulp sheet9which goes into the outer peripheral surface. The first crushing cylinder312and the second crushing cylinder322are provided, being approximate to each other, symmetrically on the (+Y) and (−Y) sides of the center line91of the feed line24and with rotation of the first crushing cylinder312and the second crushing cylinder322, portions of the pulp sheet9on the (+Y) and (−Y) sides are crushed and then the pulp sheet9is crushed in whole of the width direction.

The first inclined rotation axis311and the second inclined rotation axis321are the respective rotation axes of the first crushing cylinder312and the second crushing cylinder322, and each farther end of the inclined rotation axes from the center line91is inclined toward the pulp feed mechanism2. The first inclined rotation axis311and the second inclined rotation axis321(seeFIG. 3) are symmetrical with respect to the center line91of the feed line24, and an angle between each of the inclined rotation axes and the center line91is not smaller than 30 degrees and not larger than 60 degrees (45 degrees in this preferred embodiment).

In the pulp crushing apparatus of the second preferred embodiment, like in the first preferred embodiment, when crushing of the pulp sheet9goes ahead and the rear end portion of the pulp sheet9(the edge on the (+X) side) passes the first upper roller243and the first lower roller244in the pulp feed mechanism2(seeFIG. 2), the pulp sheet9is automatically moved in the (−X) direction by rotation of the first crushing cylinder312and the second crushing cylinder322.

In the pulp crushing mechanism3, like in that of the first preferred embodiment, since the first crushing cylinder312and the second crushing cylinder322are provided so as to be inclined with respect to the direction of feeding the pulp sheet9, it is possible to reduce the force to pull the pulp sheet9in the feeding direction (or the movement speed) as compared with the case where the rotation axis of the crushing cylinder is provided orthogonally to the feeding direction, and it is further possible to suppress an increase in movement speed of the pulp sheet9in crushing the near-rearend portion of the pulp sheet9. This suppresses variation in the amount of pulp sheet9to be fed to the pulp crushing mechanism3in a unit time also at the near-rearend portion of the pulp sheet9, and it is thereby possible to increase the amount of crushed pulp to be generated in a unit time and uniformity in quality thereof.

Like in the first preferred embodiment, since the movement speed of the pulp sheet9pulled by the first crushing cylinder312and the second crushing cylinder322is slower than the feeding speed by the pulp feed mechanism2(seeFIG. 2), the preceding pulp sheet9after passing the first upper roller243and the first lower roller244is fed to the pulp crushing mechanism3at the same speed as one before passing these rollers with its rear end portion pushed by the following pulp sheet9and crushed therein. Therefore, the pulp sheets9can be always fed into the pulp crushing mechanism3at a constant speed, and it is thereby possible to always maintain a uniform amount of crushed pulp to be generated in a unit time.

Since the pulp guide part2411and the pulp support part2421which come into contact with the pulp sheet9from the (+Z) and (−Z) sides are provided near the outer peripheral surfaces of the first crushing cylinder312and the second crushing cylinder322, even in crushing the near-rearend portion of the pulp sheet9, it is possible to prevent the pulp sheet9which becomes apart from the first upper roller243and the first lower roller244from being drawn into the pulp crushing mechanism3without being crushed and surely crush the pulp sheet9completely.

In the pulp crushing apparatus of the second preferred embodiment, especially, the pulp sheet9is pressed onto the pulp support part2421by the pulp pressing mechanism26very near the first crushing cylinder312and the second crushing cylinder322which are farthest away from the pulp feed mechanism2(in other words, portions to which the near-rearend portion of one pulp sheet9is fed last). Therefore, the near-rearend portion of the pulp sheet9is held between the pulp pressing mechanism26and the pulp support part2421until immediately before being fed into the pulp crushing mechanism3and it is thereby possible to surely prevent the near-rearend portion of the pulp sheet9from being drawn into the pulp crushing mechanism3without being crushed. As a result, in the pulp crushing apparatus of the second preferred embodiment, it is possible to surely crush the pulp sheet9completely.

In the pulp crushing apparatus of the second preferred embodiment, the pressing member261does not necessarily have to have a substantial cylindrical shape but, for example, a polygonal column-like member may be used as the pressing member. In this case, from the viewpoint that the near-rearend portion of the pulp sheet9should be surely and completely pressed very near the first crushing cylinder312and the second crushing cylinder322, it is preferable that the tip portion of the pressing member on the (−X) side should have a pointed shape like a polygonal pyramid.

Though the preferred embodiments of the present invention have been discussed above, the present invention is not limited to the above-discussed preferred embodiments, but allows various variations.

For example, the angle between each of the first inclined rotation axis311and the second inclined rotation axis321and the center line91may be an appropriate one which is larger than 0 and smaller than 90 degrees in accordance with the kind and the feeding speed of the pulp sheet9to be crushed, the required uniformity in quality of the crushed pulp or the like. From the viewpoint, however, to suppress upsizing of the width of pulp crushing mechanism3in the Y direction and increase the feeding speed of the pulp sheet9in crushing the near-rearend portion of the pulp sheet9, it is preferable that the angle should be not smaller than 30 degrees and not larger than 60 degrees.

The first crushing cylinder312and the second crushing cylinder322do not necessarily have to be arranged symmetrically with respect to the center line91of the feed line24but, for example, in order to surely crush a portion of the pulp sheet9near the center line91of the feed line24, such an arrangement may be adopted so as to shift the positions of these crushing cylinders in the X direction (the feeding direction) and place one (or both) of the crushing cylinders across the center line91.

In the pulp crushing mechanism3, though the pulp sheet9can be stably crushed by the first crushing cylinder312and the second crushing cylinder322provided being approximate to each other, symmetrically with respect to the center line91of the feed line24, an additional crushing cylinder may be provided. As shown inFIG. 7, for example, a third crushing cylinder35is provided between the first crushing cylinder312and the second crushing cylinder322on the center line91of the feed line24, to crush the whole pulp sheet9with respect to its width direction by the three crushing cylinders.

In the pulp crushing apparatus, for example, a roll-like pulp sheet wound on the drum may be unreeled and fed into the pulp crushing mechanism3.