JP7524042B2 - Wrapping Machine - Google Patents

Description

The present invention relates to a wrapping machine that wraps wrap film around roll bales made from rolled (cylindrical) pieces of grass or other materials.

Until now, wrapping machines have been known that use lift arms to assist when placing a wrapped roll bale, which has been completely wrapped in wrapping film, in a field, as in Patent Document 1. Also, wrapped roll bales have been placed upright, as in Patent Document 1.

Patent No. 4730756

A lift arm with a pair of rollers protruding from both sides of the tip of the arm was developed (Fig. 53) as described in Patent Document 1. However, the lift arm was originally intended for loading unwrapped roll bales placed in a farm field into a wrapping machine, and it was difficult to say that the structure was optimal for placing wrapped roll bales upright in the farm field.
SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a wrapping machine equipped with a lift arm that smoothly assists the movement of a wrapped roll bale when the wrapped roll bale is placed vertically.

The present invention solves the problem by providing a wrapping machine that includes a lift arm and a rotating roller, the lift arm being rotated around the base of the lift arm by a lift arm drive unit to hold the roll bale, the tip of the lift arm having an attachment portion that protrudes to the left and right in the direction of rotation, and the rotating rollers being provided in pairs on the left and right of the attachment portion from the tip of the lift arm to the tip, and being freely rotatable.

When placing the wrapped roll bale vertically, the rollers rotate around the outer surface of the wrapped roll bale, helping to place it vertically smoothly.

Explanatory diagram of a wrapping machine: (A) perspective view, (B) front view, (C) side view FIG. 2 is a partial perspective view of the perspective view of FIG. 1 and a cross-sectional perspective view of a vertical arm; Close-up of the tip of the lift arm FIG. 2 is an explanatory diagram of the vertical placement start process; (A) a side view of the wrapping machine at the end of wrapping; (B) a side view of the wrapping machine at the start of the loading/unloading process; (C) a perspective view of the wrapping machine at the start of the loading/unloading process. An explanatory diagram of the loading and unloading process. (A) A side view of the wrapping machine during loading and unloading. (B) A side view of the wrapping machine after unloading the roll bale in the field. (A) An explanatory diagram of the process from the end of the unloading process to the vertical placement process (vertical placement on the right side) (A) An explanatory diagram at the end of the unloading process (A-1) A front view of the wrapping machine at the end of the unloading process (A-2) A bottom view of the unloaded roll bale (A-3) A perspective view of the unloaded roll bale (wrapping machine not shown) (B) A perspective view of the vertical placement process in which the bale is placed vertically on the right An explanatory diagram of the process from the end of the unloading process to the vertical placement process (vertical placement on the left) (A-1) A front view of the wrapping machine at the end of the unloading process (A-2) A bottom view of the unloaded roll bale (A-3) A perspective view of the unloaded roll bale (wrapping machine not shown) (B) A perspective view of the vertical placement process in which the bale is placed vertically on the left (C) A conventional example Illustration of the movement of roll bales during the vertical placement process (A) Process diagram for vertical placement on the right (B) Process diagram for vertical placement on the left An explanatory diagram of wrapping work at a collection point using the wrapping machine of the embodiment. Side view of the bale gripper (A) A side view of the bale gripper gripping a roll bale with its bottom facing sideways (B) A side view of the bale gripper gripping a roll bale that is vertically placed An explanatory diagram of wrapping work at a collection point using a conventional wrapping machine that cannot store roll bales vertically.

(wrapping machine)
The wrapping machine 1 in the present invention includes any type, such as a self-propelled type, a type directly mounted on a towing vehicle (such as a tractor), or a type that is towed by a towing vehicle.

(Roll bale)
The roll bale R in this invention is a product obtained by compressing and molding crops into a cylindrical shape using a roll bale molding device such as a roll baler, and wrapping (rolling) it in film. Unless otherwise specified, such as "roll bale R before wrapping", when simply referring to a "roll bale R", it refers to a product in a state where it is wrapped (rolled) in film.

(Crops that are rolled into bales)
Here, crops include forage crops such as sorghum, dent corn, and pasture grass.

(Roll bales placed in position)
The roll bale R before wrapping is formed by a roll baler and released into the field. At this time, the roll bale R is placed in the field with the central axis of the cylindrical roll bale R parallel to the field surface. When there is no mention of the state in which it is placed, or when it says "a roll bale before wrapping placed in the field," it means that the central axis of the cylindrical roll bale R is placed parallel to the field surface.
In contrast, the state in which the roll bale R is placed vertically refers to a state in which the central axis of the roll bale R is vertical to the field surface and the round bottom surface is placed on the ground. In the present invention, the roll bale R is placed in the field in the vertical state by the wrapping machine 1.

The various drive units referred to in this invention may be hydraulic, electric, or any other type, and are not limited to the examples.

Example 1
The bottom surface of the roll bale R is thicker and has more overlapping wrap films than the peripheral surface R6, so holes are less likely to form in the bottom surface due to protrusions such as crop stems piercing the bottom surface. The wrapping machine 1 of the first embodiment places the roll bale R vertically with the bottom surface, which is less likely to form holes, facing down.

(Outline of the main equipment of the wrapping machine)
An outline of the main devices mounted on the wrapping machine 1 of the embodiment 1 will be described. The wrapping machine 1 has a wrap film winding-related device and a roll bale loading/unloading-related device. However, some devices (members) are related to both.
Fig. 1 is an explanatory diagram of a wrapping machine 1. Fig. 1(A) is a perspective view, Fig. 1(B) is a front view, and Fig. 1(C) is a side view.
(wrapping film winding equipment)
The roll bale support 21 is used to place a roll bale R placed in the field before wrapping. The roll bale R before wrapping is placed on the endless belt 212 so that the peripheral surface R6 of the roll bale R abuts against the endless belt 212. The endless belt 212 is rotated by a pair of rolling rollers 213 provided at the front and rear, and rotates the roll bale R before wrapping around its central axis (horizontal axis).
1(C) 的带状体轴2支持线 ...
The end of the film discharged from the wrap film winding device 7 is secured to the roll bale support 21, so that the roll bale support 21 rotates about the support rotation shaft 216 to unwind the film and wrap it around the outer surface of the roll bale R before wrapping placed on the roll bale support 21. At this time, the roll bale R before wrapping is rotated in two directions, vertically and horizontally, simultaneously by rotation in the vertical direction by the support rotation shaft 216 and in the horizontal direction by the endless belt 212. The peripheral surface R6 and bottom surface R7 (see FIG. 8) of the roll bale R before wrapping are wrapped with wrap film without any gaps. The cylindrical shape of the roll bale R has a smaller bottom area than the peripheral area, and the bottom surface R7 is wrapped thicker with wrap film.

(Roll bale loading and unloading equipment)
The roll bale support unit base 2, shown hatched in Figure 1 (C), is tilted backwards by a dump cylinder (not shown) around the tilting shaft 22. The detailed operation will be described later, but the roll bale support unit base 2 tilts rearward toward the field. As the roll bale support unit base 2 tilts, the roll bale support unit 21 rotates close to the field and functions to load the roll bale R, which has been placed in the field and is not yet wrapped, into the wrapping machine 1. It also functions when placing the roll bale R vertically.
The lift arm 4 has a mounting portion 42 protruding to the left and right on the tip side. A pair of rotating rollers 43 are provided on the left and right of the mounting portion 42, respectively, and are provided in a direction approaching each other toward the tip. In addition, the rotating rollers 43 are freely rotatable.
The lift arm 4 is attached to the roll bale support base 2 shown by hatching in Figure 1 (C), and when the roll bale support base 2 tilts, the lift arm 4 also tilts. The lift arm 4 rotates up and down relative to the roll bale support base 2 by a lift arm drive unit 41 (lift arm cylinder) about a lift arm rotation shaft 45. When the lift arm 4 rotates and presses down on the roll bale R, the roll bale R is held by the roll bale support unit 21.
As described above, the lift arm 4 has the function of sandwiching and holding the roll bale R before wrapping between the lift arm 4 and the roll bale support part 21, and loading it into the wrapping machine 1. When loading and unloading, the lift arm 4 holds the roll bale R firmly between the roll bale support part 21 and the roll bale support part 21 so that it does not roll off.

1(B) and 2, the vertical placement arm 5 is attached to a vertical placement arm pivot shaft 52 provided at the rear end 23 of the roll bale support machine base 2. The vertical placement arm pivot shaft 52 may be located anywhere at the rear end 23 of the roll bale support machine base 2, but in the first embodiment, it is located on the right side of the rear end 23 as shown in FIG.
The vertical arm 5, which plays an important role in placing the roll bale R vertically, has a vertical arm drive unit 51 (vertical arm cylinder) at its base end and is designed to rotate around the vertical arm rotation axis 52.
Figure 2 is a partial perspective view of Figure 1, illustrating the movement of the vertical placement arm 5. An imaginary rotation plane 59 indicates the rotation plane of the vertical placement arm 5, and the vertical placement arm 5 can be stopped at any position within the imaginary rotation plane 59. The vertical placement arm 5 shown in dotted lines is in a state where it is stored along the rear end 23 of the roll bale support base 2. In contrast, the vertical placement arm 5 shown in solid lines is in a state where it is in the vertical placement process, which will be described in detail later.
2 shows the cross-sectional structure of the vertical placement arm 5. The rod-shaped portion of the vertical placement arm 5 has a structure in which a hollow cylindrical roller material 55 is fitted into a cylindrical core material 54. The roller material 55 is configured to freely rotate around the core material 54, so that even if the vertical placement arm 5 comes into contact with the peripheral surface R6 of the roll bale R and slips when the roll bale R is placed vertically, the roller material 55 rotates, preventing damage to the wrap film wrapped around the roll bale R.

(Detailed explanation of lift arm)
3 is an enlarged view of the tip of the lift arm 4. The tip of the lift arm 4 is provided with an attachment portion 42 that protrudes to the left and right. A pair of rotating roller shafts 431 are firmly fixed to the left and right of the attachment portion 42. The rotating roller 43 has a cylindrical shape with a hole in the center, and is attached by passing the rotating roller shaft 431 through the hole of the rotating roller 43 and fastening a stopper 46 to the rotating roller shaft 431. The rotating roller 43 is attached so as to be freely rotatable around the rotating roller shaft 431.
The pair of rotating rollers 43 are preferably attached in a direction approaching each other toward the tip end. That is, the pair of rotating rollers 43 are attached such that the attachment side interval S1 is wide and the tip side interval S2 is narrow.

(Vertical placement start process)
4A is an explanatory diagram of the vertical placement start process. Fig. 4A is a side view of the wrapping machine 1 at the end of wrapping. The lift arm 4 and the vertical placement arm 5 are placed in a position retracted from the roll bale R while the film is being wound.
Next, the loading and unloading process begins. Fig. 4(B) is a side view of the wrapping machine 1 at the start of the loading and unloading process, and Fig. 4(C) is a perspective view of the wrapping machine 1 at the start of the loading and unloading process. The lift arm 4 is lowered, and the roll bale R is firmly held by the rotating roller 43. The vertical arm 5 is raised by the vertical arm drive unit 51 to a predetermined angle, which varies depending on whether the roll bale is vertically placed on the right side or the left side of the wrapping machine 1. In Fig. 4(C), a dotted line is added exactly halfway between the left and right end faces of the roll bale R, indicating the midline R2 of the roll bale R. The base side of the vertical arm 5 is on the right side of the roll bale R, and the tip end 53 of the vertical arm is on the left side beyond the midline R2.

(When placing the roll bale vertically on the right side of the wrapping machine)
5A and 5B are explanatory views of the loading and unloading process. Fig. 5A is a side view of the wrapping machine 1 during unloading, and Fig. 5B is a side view of the wrapping machine 1 after the roll bale R has been unloaded in the field.
The roll bale support machine base 2 is gradually tilted toward the field by a dump cylinder (not shown) around the tilting shaft 22. The roll bale R is sandwiched between the rotating roller 43 of the lift arm 4 and the roll bale support 21 and does not roll off during the loading and unloading process. Eventually, the roll bale R touches the ground on the field, the tilting of the roll bale support machine base 2 stops, and the loading and unloading process ends. When the loading and unloading process is finished, the upright arm 5 is sandwiched between the field and the roll bale R.

Fig. 6 is an explanatory diagram of the process from the end of the unloading process to the vertical placement process (vertical placement on the right side). Fig. 6 (A-1) is a front view of the wrapping machine 1 at the end of the unloading process. Fig. 6 (A-1) is a front view of the wrapping machine 1 in Fig. 5 (B), with the vertical placement arm tip 53 located to the left of the midline R2 of the roll bale R. Fig. 6 (A-2) is a bottom view of the unloaded roll bale R. Since the unloaded roll bale R is unloaded like a fallen cylinder, the part where the roll bale R touches the ground forms a line as shown by the grounding line R1. However, since the roll bale R is soft and is slightly crushed by its own weight, even if it is said to be linear, the line will be quite wide.
The tip 53 of the vertical placement arm exceeds this ground line R1, and the intersection R4 of the vertical placement arm 5 and the ground line R1 is to the left of the midline R2 of the roll bale R. It can be seen from the perspective view of the roll bale R in Figure 6 (A-3) that the only place where the fallen cylindrical roll bale R comes into contact with the vertical placement arm 5 is the intersection R4 with the ground line R1.

In this state, the process moves to the vertical placement process, in which the roll bale support base 2 is tilted again toward the wrapping machine 1. The roll bale support 21 and vertical placement arm 5 are raised up toward the wrapping machine 1 together with the roll bale support base 2. The vertical placement arm 5 comes into contact with the roll bale R at intersection R4, and eventually lifts up this intersection R4. As the position of the center of gravity R5 is to the right of intersection R4, the roll bale R begins to rotate clockwise around the rotation fulcrum R3 at the lower right end of the fallen cylindrical roll bale R. Figure 6(B) illustrates this state.
If the roll bale R moves in a direction away from the roll bale support part 21, the vertical placement arm 5 will no longer be in contact with the roll bale R, making it impossible to place it vertically. At this time, the rotating rollers 43 of the lift arm 4 rotate in the same direction while in contact with the peripheral surface R6 of the roll bale R, gently assisting the roll bale R so that it does not move too far away from the roll bale support part 21 and so as not to interfere with the rotation of the roll bale R while it is being placed vertically. The rotating rollers 43 of the lift arm 4 function to prevent the roll bale R from moving in a direction away from the roll bale support part 21, so they need only be controlled so as to lightly come into contact with the roll bale R, and do not press the roll bale strongly.
Once the roll bale R is lifted to a certain extent, the center of gravity of the roll bale R also shifts and it eventually autonomously ends up vertically on the right side. If the farm field slopes downward on the right side, there is a concern that the roll bale R will roll to the right with force and fall over again. The lift arm 4 also serves to prevent the roll bale R from falling to the right at an unnecessarily high speed.
After completing this function, the lift arm 4 is lifted by the lift arm drive unit 41 at a predetermined timing and moves away from the roll bale R.
Then, the roll bale R is gently placed upright in the field with the bottom surface R7, which is wrapped with a thicker film than the peripheral surface R6, facing down.

The rotating roller 43 assists in placing the roll bale R vertically while in contact with the peripheral surface R6 of the roll bale R. Because the rotating roller 43 rotates, excessive strain is not placed on the film wrapped around the roll bale R during the vertical placement process.

(When placing the roll bale vertically on the left side of the wrapping machine)
Figure 7 is an explanatory diagram of the process from the end of the unloading process to the vertical placement process (vertical placement on the left). Figure 7 (A-1) is a front view of the wrapping machine 1 at the end of the unloading process. At this time, the tip 53 of the vertical placement arm is to the right of the midline R2 of the roll bale R, and Figure 7 (A-2) is a bottom view of the unloaded roll bale R. Since the unloaded roll bale R is unloaded like a fallen cylinder, the part where the roll bale R touches the ground forms a line, as shown by the grounding line R1.

The tip 53 of the vertical arm exceeds this ground line R1, and the intersection R4 of the vertical arm 5 and the ground line R1 is to the right of the midline R2 of the roll bale R. It can be seen from the perspective view of the roll bale R in Figure 7 (A-3) that the only place where the fallen cylindrical roll bale R comes into contact with the vertical arm 5 is the intersection R4 with the ground line R1.

In this state, the process moves to the vertical placement process. The roll bale support 21 and vertical placement arm 5, together with the roll bale support base 2, are raised towards the wrapping machine 1. The vertical placement arm 5 comes into contact with the roll bale R at intersection R4, and lifts the roll bale R. Because the center of gravity R5 is located to the left of intersection R4, the roll bale R begins to rotate around rotation fulcrum R3 at the lower left end of the fallen cylindrical roll bale R. Figure 7(B) shows this state.
At this time, the lift arm 4 presses against the roll bale R, and the rotating rollers 43 of the lift arm 4 rotate smoothly in the same direction while in contact with the peripheral surface R6 of the roll bale R, helping to place it upright. As the rotating rollers 43 rotate, they prevent the film on the peripheral surface R6 of the roll bale R from being torn. In addition, as the rotating rollers 43 press the roll bale R against the roll bale support part 21, they prevent the roll bale R from moving in a direction away from the roll bale support part 21.
As the roll bale R is lifted to a certain extent, the position of its center of gravity R5 shifts and it eventually autonomously places itself upright on the left side.The roll bale R is then gently placed upright in the field with its bottom surface R7, which is wrapped with a thicker film than the periphery R6, facing down.

Figure 7 (C) shows a conventional example. The roll bale R is being placed vertically on the left side. At this time, the roll bale R rotates in the direction of the arrow around the pivot point R3. The rotation axis of the conventional rotating roller 9 is horizontal, and the conventional rotating roller 9 cannot rotate smoothly. As a result, it moves along the peripheral surface R6 of the roll bale R in a dragging manner. The peripheral surface R6 of the roll bale R, which has a thinner film than the bottom surface, is more likely to be damaged by the conventional rotating roller 9.

Figure 8 is an explanatory diagram of the movement of the roll bale R during the vertical placement process, with Figure 8(A) being a process diagram for vertical placement on the right, and Figure 8(B) being a process diagram for vertical placement on the left. The roll bale R rotates in the direction of the arrow shown in a semicircular shape with the rotation fulcrum R3 as the fulcrum. R7 is the bottom surface of the roll bale R. The dotted line in the figure indicates the position of the roll bale R before the vertical placement process.
The pair of rotating rollers 43 are attached in such a manner that they approach each other toward the tip so that the roll bale R can rotate smoothly whether it is placed vertically on the right side or the left side.

(Effect of being able to choose left or right side and place vertically)
There are two main ways to wrap roll bales R before wrapping them with a wrapping machine. One is to wrap the roll bales R on the spot after they are discharged into the field by the roll baler. The wrapped roll bales R are eventually collected by a bale gripper or the like, and then transported outside the field by truck or the like. In order to transport the roll bales R in the field as efficiently as possible, placing them vertically on the side closest to the road or the side closest to the roll bale R collection point can shorten the transport distance and increase the work efficiency of collecting the roll bales R.

The other is a case where roll bales R before wrapping are collected at a predetermined location in a farm field as a collection point, and wrapping is performed all at once. Figure 9 is an explanatory diagram of wrapping work at a collection point using the wrapping machine of the embodiment. In this case, the wrapping machine 1 does not move, and a bale gripper 8 as shown in Figure 10 is often used to place the roll bale R before wrapping on the wrapping machine 1. Figure 10 is a side view of the bale gripper 8, and Figure 10(A) is a side view of the bale gripper 8 in a state where the roll bale R with the bottom surface R7 facing horizontally is being gripped. As can be seen from Figure 10(A), in order to grip a roll bale R with the bottom surface R7 facing horizontally, the support arm 81 of the bale gripper 8 needs to pinch the peripheral surface R6 of the roll bale R. Therefore, in order to grip a roll bale R with the bottom surface R7 facing horizontally, the bale gripper 8 needs to approach from the bottom surface R7 or the top surface of the roll bale R.
Also, Figure 10(B) is a side view of the bale gripper 8 gripping a vertically placed roll bale R. The support arm of the bale gripper 8 is configured so that the head can rotate so that it can grip either a roll bale R with its bottom surface R7 facing horizontally or a vertically placed roll bale R. As can be seen from Figure 10(B), the support arm 81 of the bale gripper 8 grips the peripheral surface R6 of the vertically placed roll bale R. A vertically placed roll bale R has the same shape when viewed from any of the four directions, so when the bale gripper 8 grips a vertically placed roll bale R, it can approach it from any of the four directions.

Returning to the explanation of Figure 9, the hatched roll bale R indicates a roll bale R that has already been wrapped, and two already wrapped roll bales R have been gathered in front. In (Step 1), the roll bale R before wrapping is placed on the wrapping machine 1 by a bale gripper 8 (not shown), as indicated by the arrow, and the wrapping operation is carried out.
(Step 2) shows the state immediately after the roll bale R is lowered into the field and placed upright.
(Step 3) is a step in which the vertically placed roll bale R is transported by the bale gripper 8 (not shown). As described above, the vertically placed roll bale R is cylindrical, and its shape does not change when viewed from any direction. The bale gripper 8 can grip the vertically placed roll bale R no matter what direction it approaches. The bale gripper 8 approaches the vertically placed roll bale R from the direction that provides the best work efficiency, and moves the wrapped roll bale R to the collection location.
The worker can take into consideration the movement of the bale gripper 8 and operate the wrapping machine 1 to vertically place the roll bale R in either the right or left direction, whichever is more efficient for work.

FIG. 11 is an explanatory diagram of a wrapping operation at a collection point using a conventional wrapping machine 1 that cannot be placed upright.
(Conventional process 1) is the same as (process 1) in the embodiment of FIG. 9. In (conventional process 2), the roll bale R is lowered so that the bottom surface R7 faces horizontally and the peripheral surface R6 touches the field, since the conventional wrapping machine 1 cannot vertically place the roll bale R. Therefore, (conventional process 3), which did not exist in the embodiment of FIG. 9, is added. (Conventional process 3) is the work of vertically placing the roll bale R. At this time, as described above, in order for the bale gripper 8 to grip the roll bale R placed with the bottom surface R7 facing horizontally, it is necessary to approach from the bottom surface R7 or the top surface of the roll bale R. Unlike (process 3) in FIG. 9, the bale gripper 8 cannot approach from any direction, which greatly reduces the work efficiency. After that, in (conventional process 4), the roll bale R that has been vertically placed and the wrapped roll bale R are moved to the accumulation location by the bale gripper 8.
In this way, in the conventional wrapping machine 1 which cannot be placed vertically, the work efficiency is reduced in the cooperation with the bale gripper 8.

The effects of the embodiment of the present invention have been explained in the section (effect of being able to select the left or right side and place vertically). The wrapping machine 1 of the embodiment prevents holes from being made in the roll bale R by placing the roll bale R, which has a thick wrap film, vertically with its bottom surface R7 facing down. If a hole is made, more wrap film will be consumed to plug the hole, so the wrapping machine 1 of the embodiment contributes to reducing the environmental load. And in addition to the effects of the wrapping machine 1, it contributes to the overall work efficiency of agricultural work such as collecting and transporting the roll bale R, and can save fuel and resources. The wrapping machine 1 of the embodiment can contribute to the United Nations-led sustainable development goal of "promoting sustainable agriculture."

The wrapping machine 1 according to the embodiment of the present invention has been described in detail above with reference to the drawings, but the specific structure and configuration are not limited to these embodiments, and the present invention includes design changes that do not deviate from the gist of the present invention.

Furthermore, the above-mentioned examples and embodiments can be combined by reusing each other's technologies, so long as there are no particular contradictions or problems in their purpose and configuration.

R Roll bale R1 Ground line R2 Midline R3 Pivot fulcrum R4 Intersection R5 Center of gravity R6 Circumferential surface R7 Bottom surface 1 Wrapping machine 2 Roll bale support machine base 21 Roll bale support 212 Endless belt 213 Rolling roller 22 Tilting shaft 23 Rear end 4 Lift arm 41 Lift arm drive unit 42 Mounting unit 43 Rotating roller 431 Rotating roller shaft 45 Lift arm rotating shaft 46 Stopper S1 Mounting unit side spacing S2 Tip side spacing 5 Vertically placed arm 51 Vertically placed arm drive unit 52 Vertically placed arm rotating shaft 53 Vertically placed arm tip 54 Core material 55 Roller material 59 Virtual rotation surface 8 Bale gripper 81 Support arm 9 Conventional rotating roller

Claims (2)

Equipped with lift arms and rotating rollers,
The lift arm is rotated around the base of the lift arm by a lift arm drive unit to hold the roll bale, and the tip of the lift arm has mounting parts protruding to the left and right,
The rotating rollers are provided in pairs on the left and right sides of the mounting portion from the tip of the lift arm toward the tip, and are freely rotatable.
Wrapping machine.
The wrapping machine according to claim 1, characterized in that the pair of rotating rollers are mounted in a direction such that they approach each other as they approach the tips.

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