DE19734205A1 - Arrangement for positioning and holding down sheets formed into stack - Google Patents

Abstract

Free end (30) of first arm (19) projects above the aligned edge of the top sheet (14) and contacts it along a line (B-B), which moves from the free end of the arm towards its bearing position (17) as the stack increases in height. The centre of gravity (24) of the lever (18) lies along a line (25) which forms an angle ( delta opt) optimised according to a given equation. The weight (22) is preferably in the form of as cylinder.

Description

The invention relates to a device for guiding and holding down by means of a Conveyor individually fed a sheet stack formed in a storage container guided leaves, consisting of a two-armed one around the leaf conveyor track bearing pivoted lever, with a first arm that is designed as a hold-down arm and at an acute angle β to the surface of the Sheet stack runs and with a free end, on the aligned edge of a top sheet of the sheet stack rests, and with a second arm, the one Carries weight, and by an angle γ formed by both arms, which the bearing job includes.

English patent number 789,015 discloses a detent device piling cards. The cards ejected from a machine are turned into one square box. To distract the cards into the box is a distraction element provided that the incoming cards to the bottom of the box distracts to achieve safe storage. The deflector is with a End attached to a freely rotatable axis, which is provided with a counterweight is. The counterweight serves that regardless of the stack height in the Box the one exerted by the deflecting element on the running cards Braking is almost constant.

Another such device is for example from the international patent Application WO 89106633 known. In a sheet stacking and aligning device is after a sheet conveyor a two-armed lever pivotally arranged with  his one arm rests on the sheet stack to keep the sheets aligned in theirs Able to calm down and prevent the leaf ends from rolling up, and that at his other arm carries a weight to balance the lever. This device has the defect that the bearing force of the lying on the sheet stack Armes with changing sheet stack height also changed significantly. This leads to unacceptable operating conditions, because in today's with a leaf sequence of up to 90 sheets per minute such a Leit- and Niederhal The device does not function reliably when the stacks of sheets are formed guaranteed.

The German patent application DE-A-44 44 488.5 discloses an apparatus for Guiding and holding one in a tray by means of a conveyor container-formed stack of sheets. The device consists of a two-armed order a bearing located above the sheet conveyor track pivotally mounted Lever. A first arm lies at an acute angle with its free end on the Sheet stack surface on. The second arm carries a weight that is adjustable in such a way that the contact force of the first arm is optimized.

The invention is therefore based on the object of a device at the outset to create mentioned type, the contact force on the sheet stack regardless of the height of which is substantially constant, and the device must be arranged in this way be that an optimal stack structure can be achieved.

Another object of the invention is that the mass moment of inertia of the front direction should be as small as possible in order to ensure that the sequence of sheets is largely independent number per minute of the contact force of the hold-down arm.

This is achieved according to the invention in that the free arm, with its free end, projects beyond the aligned edge of the top stack sheet regardless of the stack height and touches the aligned edge of the top stack sheet ( 14 ) along a line, that the line along increases with the height of the stack of sheets of the first arm moves from its free end in the direction of the bearing point, and that the center of gravity of the lever lies on a line which forms an angle δ _{opt which} is optimized in accordance with equation 5 with the top sheet of the sheet stack.

With a device designed in this way, a uniform contact force is achieved at every sheet stack height by arranging the center of gravity of the device on the line running at the angle δ. With an optimized angle δ _opt , the change in the contact force depends on the distance from the bearing point to the contact point of the arm. This shift in the center of gravity on the line running at the angle δ is achieved by changing the distance of the weight from the bearing point on the lever arm arranged at the angle γ.

In particular, the invention is such that the weight in the form of a cylinder formed and is arranged on the second arm to be longitudinally displaceable. Through the The choice of the cylinder shape for the weight of its mass moment of inertia is only linear depending on its length, so that the moment of inertia of the device is kept extremely small and the same for determining the value moderate exposure is largely free. That means at one certain dimensioning of the diameter of the weight, the angle and the Distance of the weight from the bearing point is the contact force in a wide range adjustable to an even value.

In such a guide and hold-down device is independent of its installation an even contact force on the sheet stack was adjustable.

In a further embodiment of the device, the arms of the lever have a fla chen rectangular cross-section, and the bearing is in a simple manner a wall arranged on one side between the arms.

To balance the only bearing of the lever and to avoid friction effects is the weight on the second arm opposite the center position towards the Bearing position offset. The weight can also be in the direction of the axis The bearing point can be arranged to be displaceable and lockable.  

The further features and advantages are the description of an exemplary embodiment the invention and the further subclaims.

The drawing shows in the

Fig. 1, the device according to the invention in perspective view,

Fig. 2 is a side view of an embodiment of the apparatus,

Fig. 3 is a diagram of the course of the change in the contact force of the device on the sheet stack over the height of the sheet stack and

Fig. 4 is a three-dimensional representation of the embodiment of the device shown in Fig. 2.

In FIG. 1, the device according to the invention is illustrated and all not contributing to the invention, components have been omitted for the sake of clarity.

A stack of sheets 15 is located in a storage container 11 with a front wall 12 and a side wall 13 for the edge-accurate storage of sheets 14 fed in the direction of arrow A. It is also conceivable that a corresponding front and / or side wall (not shown) is provided on the corner of the storage container 11 which bears the front wall 12 and the side wall 13 . In order to calm the incoming sheets 14 on the stack 15 from their movement and to keep them in the exact position, a device 16 is provided, which consists of a two-armed lever 18 pivotably mounted about a bearing point 17 .

The lever 18 has a first arm 19, the constricting on the anlie on the front wall 12 edge of the stack top sheet 14 lies, in order to calm the incoming sheets from their movement and hold down. The first arm 19 contacts the sta pelobere sheet 14 along a line BB. The lever 18 has a second arm 20 which is bent at an angle γ enclosing the bearing point 17 in the same plane as the first arm 19 . The device 16 is arranged such that line BB moves along the first arm 19 depending on the stack height. If there are few to no sheets in the storage container 11 , the line BB is located at or near the front end 30 of the first arm 19 . As the stack height increases, line BB moves along the first arm 19 in the direction of the bearing 17 .

In the embodiment shown in FIG. 1, the two arms 19 and 20 have a flat rectangular cross section (other cross sections are within the ability of a person skilled in the art) and at the same time enclose a vertically angled wall 21 in which the bearing point 17 is at a distance b from hen first arm 19 is provided.

A weight 22 is arranged on the second arm 20 , the arm 20 projecting through a slot 23 in the weight 22 . The slot 23 is dimensioned so that the weight 22 moves on the arm 20 in the longitudinal and transverse directions and determined who can. Due to the movability of the weight, the entire device 16 is balanced so that no tilting occurs in the bearing point. A tilting of the device around the bearing 17 would lead to increased friction, which affects the functioning of the entire device.

The weight 22 consists of a cylindrical rod of a certain diameter d and a selectable length c, and it is at a certain variable distance l from the bearing 17 .

Depending on the distance l and the angle γ, the device 16 has a specific position of its center of gravity 24 which lies on a line 25 which lies at an angle 8 to a plane formed by the first arm 19 . The position of the center of gravity 24 on the line 25 can be influenced by changing the distance l of the weight 22 from the bearing 17 .

In the very simple lever 18 , the bearing 17 is arranged laterally to the lever center. In order to avoid friction effects, the weight 22 can be shifted by the dimension a depending on the dimensioning of the lever on the arm 20 in the direction of the wall 21 . So that the lever 18 is balanced in its central position. The slot 23 is dimensioned accordingly in length.

With an optimized assignment of the parameters, the distance l of the weight 22 from the bearing 17 , the angle δ and the diameter d of the weight 22 , there is a certain angle δ and thus a defined position of the center of gravity 24 , which results in a uniform contact force F of the first Arms 19 leads over the entire height of the sheet stack 15 from the first to the last sheet. The usual maximum stack height is around 15 to 25 millimeters. The angle δ at which the condition of a contact force F which is independent of the stack height is fulfilled is referred to as the optimal angle δ _opt .

The device 16 can be used for both horizontal and inclined storage containers. Fig. 2 shows an embodiment with an inclined arranged storage container 11. Furthermore, the designations of the quantities required for the various calculations are entered in FIG. 2.

The optimal position of the center of gravity 24 of the device 16 can be calculated using the formulas below. All the quantities required for the calculation can be seen in FIG. 2.

The force F _p , which the device 16 exerts perpendicular to the sheet stack 15 , should be as constant as possible and thereby regardless of the height h of a sheet stack 15 which grows up to a _maximum height h _max . For this purpose, it is necessary that the center of gravity 24 of the device 16 lies on a line 25 which forms the optimal angle δ _opt with the first arm 19 of the device 16 . The optimal angle δ _opt depends on the bearing 17 of the device 16 , which is determined by a distance L _x from an imaginary extension 32 a of a front contact edge 32 and by the distance L _y from an imaginary extension 33 a of the storage container 11 , from which Location of the first arm 19 of the device 16 , which is determined by the distance d _{h of} an imaginary extension 34 a of the first arm 19 and from the inclination α of the sheet stack 15 or of the storage container 11 to the horizontal 35 .

Since, as already mentioned above, it must be ensured for an optimal layering of the sheet stack 15 that the first arm 19 of the device 16 protrudes beyond the front edge 32 . This condition makes it difficult to determine the optimal position of the center of gravity 24 , since the effective length of the first arm 19 now shortens as the height of the sheet stack 15 increases. With the horizontal position of the center of gravity 24 , which at first glance is obvious, the force F _p would decrease with increasing h _p .

In the following, a calculation method is presented which determines the optimal angle δ _opt , the contact force F _{p being} approximately independent of the height of the sheet stack 15 . The following dimensions of the device 16 are used . These dimensions are valid for one embodiment and it is self-evident that other dimensions can be chosen by the person skilled in the art depending on the design conditions.

The dimensions of the device 16 are:

α = 45 ° The inclination of the storage compartment 11 to the horizontal 35 .
L _x = 100 mm distance of the bearing point 17 from the imaginary extension 32 a of the front contact edge 32 .
L _y = 75 mm distance of the bearing point 17 from the imaginary extension 33 a of the storage container 11 .
D _h = 25 mm distance of the bearing point 17 from the imaginary extension 34 a of the first arm 19 of the device 16 .
h _pmax = 15 mm is the maximum height of the _{sheet stack} 15 .

As auxiliary variables for the calculation

h _p the height of the sheet stack 15 ,
β the angle of the first arm 19 of the device 16 to the surface of the sheet stack 15 ,
s = 15 mm the distance of the center of gravity 24 from the bearing 17 and
δ the angle between the line 25 through the center of gravity 24 and the bearing 17 and the first arm 19 of the device 16 ver used.

The ruling powers can join in

G = 0.981 N of the weight of the total mass of the device 16 in the center of gravity 24 and
F _{p of} the contact force of the device 16 perpendicular to the sheet stack 15

to be discribed.

The angle β as a function of the height of the sheet stack 15 in the storage compartment 11 can be described with equation 1.

Equation 1

Equation 2 describes the contact force of the device 16 as a function of the height of the sheet stack 15 and the angle δ.

Equation 2

In the construction of the device 16 , the aim is that the optimal angle δ _{opt is} as independent as possible of the height h _{p of} the sheet stack 15 . This is fulfilled if the contact force F _{p of} the device 16 at the height 0 of the sheet stack 15 is equal to the contact force F _p at the maximum height h _{max of} the sheet stack. This relationship can be expressed in Equation 3:

Equation 3

F _p (h _{pmax, δopt} ) - F _p (0, δ _opt ) = 0.

From equation 1 it follows that the angle β of the first arm 19 of the device 16 assumes the size β ₀ = 25.333 ° at the height 0 of the sheet stack 15 . At the maximum height of the _{sheet stack} (h _pmax = 15 mm), the angle β of the first arm 19 of the device 16 has a size β _hmax = 18.585 °. The condition disclosed in equation 4 then results from equation 2.

Equation 4

This results in the condition shown in equation 5 for the optimum angle δ _opt .

Equation 5

The optimal angle δ _opt is therefore only dependent on the arrangement of the device 16 with respect to the position of the bearing 17 , the distance of the bearing 17 from the imaginary extension of the first arm 19 , the inclination of the storage compartment 11 , etc. The weight G of the device 16 in the center of gravity 24 and the distance of the center of gravity 24 from the bearing point 17 has no influence on the optimal angle δ _opt .

The independence of the contact force F _{p of} the device 16 on the sheet stack 15 is impressively shown in FIG. 3. On the abscissa is the height h _{p of} the sheet stack 15 and on the ordinate is the contact force F _{p of} the device on the front contact edge 32 , or along the line BB, with which the first arm 19 touches the top sheet of the stack. The above values were used to calculate the contact force F _p . It is clearly evident that the contact force F _{p is} almost independent of the height h _{p of} the sheet stack 15 .

Fig. 4 shows the device 16 of Fig. 2 in perspective, and for reasons of clarity, the individual names of the sizes are omitted. The storage compartment 11 is designed in this embodiment such that the front contact edge 32 is not formed continuously over the entire width of the sheets to be aligned. The front contact edge 32 has an interruption 41 , which is arranged and designed such that the front end of the first arm 19 extends through the interruption 41 .

As already mentioned, the lever 18 consists of the first arm 19 and the second arm 20 . On the second arm 20 , the weight 22 is arranged, which is cylindrical and, after optimal balancing, is fastened to the second arm 20 by soldering, welding, gluing, etc. It is important that in the manufacture of the device 16 the weight 22 is attached to the second arm 20 of the device 16 in such a way that there is no lateral tilting in the bearing 17 about an axis CC which is parallel to the support 11 of the sheet stack.

If the device 16 remains unchanged, only the weight G and / or the center of gravity have to be varied accordingly in the case of a specific support force. The optimal angle δ _opt is retained. It should also apply that h _p = h _pmax . The positional force F _p is determined by equation 6. The weight force required for the weight 22 can then be determined by equation 7.

Equation 6

Equation 7

The mass of the additional weight can be calculated in a known manner from the weight force determined with equation 7. If the shape of the weight 22 is fixed, it must be placed in such a way that the common center of gravity 24, together with the device 16, takes the calculated target position (s, δ _opt ). This can be done iteratively in CAD or with common calculation methods.

In addition, if the moment of inertia of the device 16 around the bearing 17 is minimal, a cylindrical weight 22 is optimal, the position of which is varied at a constant radius. A cylinder is advantageous because the mass moment of inertia of a cylinder around the longitudinal axis of all solid bodies, which undergoes the slightest change when the mass is increased by changing the length of the cylinder. The mass of the weight can thus be varied with the least possible influence on the moment of inertia.

In addition, the lowest possible total weight and a minimum distance from the center of gravity 24 must be sought. This can be calculated using the above equations, known calculation rules for moments of inertia and a suitable optimization program (for example, the programming language and the optimization program from ANSYS was used).

The invention has been described in terms of a preferred embodiment, however of course, within the scope of a skilled craftsman Modifications are made without sacrificing the scope of protection of the below to leave the claims.  

Reference list

11

Storage container

12th

Front wall

13

Side wall

14

leaves

15

Sheet stack

16

Hold down device

17th

Depository

18th

lever

19th

first arm

20th

second arm

21

vertically angled wall

22

Weight

23

slot

24th

main emphasis

25th

Line on which the focus is

30th

front end of the first arm

32

front contact edge

32

an imaginary extension of the front contact edge

33

an imaginary extension of the storage container

34

an imaginary extension of the first arm

35

horizontal

41

Interruption
A Direction of the fed sheets
BB Line of contact of the first arm with the top sheet
CC axis through bearing
F _p

Force of the device on the sheet stack
L _x

Distance of the bearing point to the imaginary extension of the front contact edge
L _y

Distance of the storage point to the imaginary extension of the storage container
a Weight displacement
b Distance of the bearing point to the first arm
c Length of the cylindrical weight
d diameter of the weight
_i.e.

Distance from the bearing point to the imaginary extension of the first arm
h _p

maximum stack height
s Distance of the center of gravity from the bearing
α inclination of the sheet stack
β angle of the first arm to the sheet stack surface
γ angle between the first and the second arm
δ angle between the line on which the center of gravity lies and the first arm
δ _opt

optimal angle

Claims (9)

Individually 1. An apparatus (16) for guiding and holding down by means of a conveyor to a sheet stack formed in a storage container (11) (15) of fed sheets (14), consisting of a two-arm lying at a ground above the sheet feed bearing (17) pivotably mounted Lever, with a
first arm ( 19 ), which is designed as a hold-down arm and extends at an acute angle (β) to the surface of the sheet stack ( 15 ) and has a free end ( 30 ) on the aligned edge of a top stack ( 14 ) of the sheet stack ( 15 ) lies on,
second arm ( 20 ) carrying a weight ( 22 ),
by the two arms ( 19 and 20 ) formed angle γ, which includes the bearing point ( 17 ), characterized in that
extends the first arm (19) with its free end (30) irrespective of the stack height above the aligned edge of the stack top sheet (14) and contacting along a line (BB) the aligned edge of the stack top sheet (14),
that the line (BB) moves with increasing height of the sheet stack ( 14 ) along the first arm ( 19 ) from its free end ( 30 ) in the direction of the bearing point ( 17 ),
and that the center of gravity ( 24 ) of the lever ( 18 ) lies on a line ( 25 ) which forms an angle (δ _opt ) which is optimized in accordance with equation 5 with the top sheet of the sheet stack ( 15 ). 2. Device according to claim 1, characterized in that the weight ( 22 ) has the shape of a cylinder. 3. Apparatus according to claim 2, characterized in that according to the diameter (d) of the cylindrical weight ( 22 ) and the distance (l) of the weight ( 22 ) from the bearing point ( 17 ), the position of the center of gravity ( 24 ) on the Line ( 25 ) and the contact force (F) of the first arm ( 19 ) on the sheet stack ( 15 ) can be determined. 4. Device according to claims 1 to 3, characterized in that the weight ( 22 ) on the second arm ( 20 ) is arranged to be longitudinally displaceable. 5. Device according to claims 1 to 4, characterized in that the weight on the second arm ( 20 ) is arranged transversely. 6. The device according to claim 2, characterized in that the weight ( 22 ) of the art on the second arm ( 20 ) is placed that the common center of gravity ( 24 ) together with the device ( 16 ) the calculated target position with respect to the distance from the center of gravity the imaginary extension of the first arm ( 19 ) and the optimized angle (δ _opt ). 7. The device according to claim 1, characterized in that the arms ( 19 and 20 ) of the lever ( 18 ) have a flat, rectangular cross section, and that the bearing point ( 17 ) is provided in a wall ( 21 ) arranged on one side between the arms. 8. Device according to one of claims 1 to 7, characterized in that the weight ( 22 ) relative to the central position on the second arm ( 20 ) in the direction of the bearing point ( 17 ) is arranged offset so that a tilting of the device ( 16 ) around the bearing ( 17 ) can be prevented. 9. Device according to one of claims 1 to 7, characterized in that in an optimized embodiment, the angle (γ) between the first and the second arm ( 19 , 20 ) is approximately 122 degrees,
the optimized angle (δ _opt ) between the first arm ( 19 ) and the line ( 25 ) of the center of gravity ( 24 ) is approximately 112 degrees,
the distance (s) between the bearing point ( 17 ) and the center of gravity ( 24 ) is approximately 15 millimeters,
the distance (D _h ) between the bearing point ( 17 ) and the imaginary extension of the first arm ( 19 ) is approximately 25 millimeters,
the distance (L _x ) between the bearing point ( 17 ) and the imaginary extension of the contact edge is approximately 100 millimeters,
the distance (L _y ) between the bearing point ( 17 ) and the imaginary extension of the storage compartment about 75 millimeters, and
the angle of inclination (α) of the storage compartment ( 11 ) to the horizontal is approximately 45 degrees.