INTERNAL FOLDING APPARATUS WITH PRE-FORMATION TRANSFER ROLLER BACKGROUND The present invention relates to internal folding apparatuses and, more specifically, to the transfer of sheets in internal folding rollers of internal folding apparatuses. Various combinations and types of rollers may be present in the internal folding apparatuses. A typical internal folding apparatus includes at least two internal folding rollers, at least one knife or blade roller, and at least one feed roller for pulling the streams of weft material into the internal folding apparatus. The weft material is generally cut in the vicinity of the knife rollers and is eventually transferred to a clamping point between the internal folding rollers. The succession of sheets entering the fastening point is such that a middle portion of a reference sheet in a first internal folding roller enters the fastening point at the same time as the rear and front edges of the sheets downstream and current above, respectively, are placed in a second internal folding roller. The front and rear edges are positioned adjacent to the folder of the second internal folding roller. The folder pushes or bends the middle portion of the reference sheet in a clamp (either mechanical or vacuum) of the first internal folding roller when the folder and clamp pass through the clamping point. The clip receives the middle portion and the posterior and anterior edges from the folder, folds the middle portion capturing the anterior and posterior edges to the inside of the fold, and transports and releases the fold to an adjacent side of a stack of internal folding sheets being built under the
Internal folding rollers. As the internal folding rollers continue to rotate, a clamp of the second internal folding roller receives a middle portion of the sheet stream and the associated leading and trailing edges from a folder of the first internal folding roller, doubles the middle portion capturing the associated anterior and posterior edges, and transports and releases the fold to the adjacent side of the stack of folded inward sheets. This process is repeated in an alternative mode between the first and second internal folding rollers. To ensure that the associated anterior and posterior edges are properly bent into the middle portion of the folded sheet, it is important to control the position of the leading and trailing edges on the internal folding rollers, and more particularly with respect to the Folder of the internal folding roller. Well-known internal folders intend to maintain the position of the leading and trailing edges during internal folding by providing vacuum ports on the internal folding rollers. However, as described above, during internal folding, a folder forces a middle portion of a sheet into a recess of an opposing clip. The length of the forced sheet within the clip must be compensated for by a stretching or breaking of the sheet or by a movement, or both, of the leading and trailing edges of the sheet being folded. In some cases, this will alter the position of the leading edge (that is, direct it closer to the nearest middle portion), so that the leading edge is pulled from the downstream clamp, which performs the previous bending. In other cases, this will alter the position of the trailing edge, so that the trailing edge is detached from its respective vacuum port. In some extreme cases, the folding of a middle portion of a sheet into a
The opposite clamp will cause the trailing edge of the bending sheet to be released from the clamp or from the leading or leading edge to become released from the vacuum port. Where an edge is new or becomes released, the edge does not bend strongly inside the fold and a visible discontinuity in the pile would result. In the case of a freed edge, the interruption of the internal folding could occur. COMPENDIUM Some embodiments of the invention provide an internal folding apparatus and an internal folding method of sheets of a sheet material which improves the control of the position of the sheets on the internal folding rolls during internal folding. In one embodiment, the invention provides an internal folding apparatus that includes a knife roller, a first internal folding roller, a second internal folding roller, and a transfer roller. The knife roller is rotatable about an axis operable to cut sheets of a stream of weft material that is emitted from a source in a downstream direction. The first internal folding roller is positioned downstream of the knife roller and is adapted to receive the sheets. The first internal folding roller is rotatable in a first direction. The second internal folding roller is rotatable in a second direction and is positioned adjacent to the first internal folding roller to define a clamping point therebetween. The first and second internal folding rollers are rotatable to internally fold the sheets with additional sheets received by means of the second internal folding roller. A transfer roller is placed between the blade roller and the first internal folding roller. He
Transfer roller has a non-uniform surface configuration and rotates in the second direction. The transfer roller is operable to receive the sheets from the knife roller, to form a bend in each of the sheets received from the knife roller, and to transfer the formed sheets to the first internal folding roller. In another embodiment, the invention provides a method of internal folding of sheets of the weft material. The method includes sending weft material in a downward direction of a source, cutting with a blade roller the flow of the sheet material, transferring each sheet to a transfer roll, with the transfer roll forming a fold in the portion one half of each sheet, transfer each formed sheet to an internal folding roll, and internally fold the formed sheet in an internal folding roll with at least one other sheet of an adjacent internal folding roll. Other aspects of the invention will become apparent in consideration of the detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side view illustrating an internal folding apparatus of one embodiment of the present invention. Figure 2 is an enlarged side view of a portion of the internal folding apparatus shown in Figure 1, illustrating a blade on a blade roller. Figure 3 is a view similar to Figure 2, illustrating an anterior or leading edge of the sheets being transferred to a transfer roller from the knife roller. Figure 4 is a view similar to Figure 2, illustrating a portion
half of the sheet being formed in a fold between the knife roller and the transfer roller. Figure 5 is a view similar to Figure 2, illustrating the leading edge of the sheets that is transferred to an internal folding roll from the transfer roll. Figure 6 is a view similar to Figure 2, illustrating the middle portion of the formed sheet that is being transferred on a folding roller clamp from the transfer roll. Figure 7 is a side view of a portion of the internal folding apparatus shown in Figure 1, illustrating the sheet being folded inwardly between the internal folding roller and an adjacent internal folding roller. DETAILED DESCRIPTION Before any of the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangements of the components disclosed in the following description or illustrated in the following drawings. . The invention is susceptible to other modalities and to be practiced or to be carried out in various ways. Also, it should be understood that the wording and terminology used here are for description purposes and should not be viewed as limiting. The use here of "including", "comprising", or "having" and variations thereof, means to accompany the items listed below and their equivalents also as additional items. Unless specified or otherwise limited, the terms "assembled", "connected", "supported", and "coupled" and variations of these are widely used and accompany both
mounts, connections, brackets, and couplings, direct and indirect. In addition, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings. In Figure 1 there is illustrated an internal folder, or internal folding apparatus 10, of one embodiment of the present invention. The internal folding apparatus 10 includes a set of rear removal rollers 12a, 12b, which are mounted for rotation on the axes 14a, 14b. A set of internal extraction rollers 16a, 16b are adjacent to the rear rollers 12a, 12b which are mounted for rotation on the axes 18a, 18b. The knife rollers 20a, 20b are mounted for rotation on the axes 22a, 22b. The knife rollers 20a, 20b contain blades 24a, 24b which are in respective contact with the stationary anvil bars 26a, 26b. The transfer rollers 28a, 28b are located adjacent the knife rollers 20a, 20b to form the points 30a, 30b, respectively. The transfer rollers 28a, 28b are mounted for rotation on the axes 32a, 32b. The internal folding rollers 34a, 34b are positioned antecedent to the knife rollers 28a, 28b to form the attachment points 36a, 36b, respectively. The internal folding rollers 34a, 34b are mounted for rotation on the axes 38a, 38b. The internal folding rollers 34a, 34b are mutually adjacent to form a holding point 40. The internal folding apparatus 10 is enabled for internal folding of streams of continuously flowing weft material 42a, 42b. The internal folding apparatus 10 can be divided into two sides which are mirror images between them. Therefore, only one side "b" will be described in detail, with the understanding that the other "a" side performs the same functions,
only that the movement is opposite to that of the "b" side. For example, the clockwise rotation of a roller on the "b" side would mean that the complementary roller on the "a" side would have a counterclockwise rotation. As more clearly shown in Figure 2, the blade roller 20b includes a vacuum port 44b adjacent to each individual blade 24b. In the embodiment illustrated in Figures 1-7, the blade roller 20b includes four blades 24b with four corresponding vacuum ports 44b. The distance between the blades 24b corresponds to the length of a blade 48 cut from the stream of weft material 42b. In other words, the blade 48 extends through a circumferential length that is equal to 1/4 of the circumference of the blade roller 20b. A circumferential length is defined as the length of the portion of the circumference of the roll between the leading and trailing edges of the sheet, assuming that the radius of the roll is continuous and without taking into account any deformity of the roller surface, such as protuberances or grooves. The knife roller 20b also includes four slots 50b positioned between adjacent knife assemblies 24b. The forming blades 52b of the transfer roller 28b protrude or protrude from the periphery of the transfer roller 28b and terminates at a fastening point 54b. The vacuum ports 56b are located on opposite sides of the forming blade 52b. The transfer roller 28b also includes slots 58b positioned between adjacent sets of forming blades 52b. The vacuum ports 60b are located on either side of each respective slot 58b. The folders 64b of the internal folding roller 34b are
similar to the forming blades 52b of the transfer roller 28b in which the folders 64b protrude from the periphery of the internal folding roller 34b and end at a fastening point 66b. The vacuum ports 68b are located on both sides of the folder 64b. As shown in Figure 7, the internal folding roller 34b also includes clips 70b placed between adjacent sets of folders 64b. The tweezers 70b may include their own vacuum ports 74b, located adjacent to the tweezers 70b. The folder 64b of the internal folding roller 34b is received into the slots 58b of the transfer roller 28b, and the folder 64b is received into the clip 70a during the rotation of the transfer roller 28b and of the internal folding rollers 34a, 34b. The forming blades 52b are received into the slots 50b to pre-form the sheet 48 with an anterior fold to fold the sheet 48 with a gripper 70b. In some embodiments, the preforming operation of the forming sheets 52b and the grooves 50b do not leave a bending mark on the sheet 48 if the sheet 48 were to come off the internal folding apparatus 10 after being pre-formed by means of the forming sheets 52b and the slots 50b. In these embodiments, a fold is formed in the middle portion 72 of the sheet 48 when the gripper 70b of the internal folding roller 34b pinches the folded portion of the sheet 48, as discussed in more detail below. In other embodiments, a fold can be formed by means of the transfer roller 28b. As shown in Figure 1, in operation, the weft material streams 42a, 42b are stocked with separate paper feeders (not shown). As shown in Figure 1, the streams of weft material 42b, 42a are transferred to subsequent take-up rollers 12b, 12a,
respectively. Referring now to the "b" side of the internal folding apparatus, a rear external roller 12b is rotating clockwise about the axis 14b to direct the stream of weft material 42b toward the rear inner roller 16b. The rear inner roller 16b is rotating in the counterclockwise direction on the shaft 18b, so that the first stream of weft material 42b can be transferred to blade roller 20b. Other methods and arrangements are available to transfer streams of weft material to the blade rolls, as is well known to those of ordinary skill in the art. As shown in Figure 2, when a blade 48 is transferred to the blade roller 20b, the blade 48 is cut from the first stream of weft material 42b when the blade 24b comes into contact with the anvil 26b. Other methods and arrangements are available to cut streams of sheet material on a blade roller, as is well known to those of ordinary skill in the art. For purposes of clarity, only one sheet 48 is shown. In general, for the illustrated embodiment, the adjacent sheets of the weft material cut by means of the knife roller 20b would be present on the upstream and downstream sides of the sheet 48. The knife roller 20b successfully cuts the leaves of the first stream of weft material 42b with the blade 24b. The vacuum port 44b is operable to hold the leading edge 46 of the blade 48 on the blade roller 20b. Figure 2 illustrates a leading edge 46 of the blade 48 aligned with the blade 24b and held against the periphery of the blade roller 20b by means of the vacuum port 44b. The trailing edge 62 of the blade 48 is aligned with a cutting edge of the blade 24b. Initially, sheet 48 is not received inside
of the slot 50b in the blade roller 20b. However, on rotation of the blade roller, the slot 50b receives a forming blade 52b from the adjacent transfer roller 28b. Figure 3 illustrates the sheet 48 downstream of the first position shown in Figure 2. As the knife roller 20b rotates clockwise, and the transfer roller 28b rotates counterclockwise , the blade 48 begins to transfer from the blade roller 20b to the transfer roller 28b. More specifically, the leading edge 46 of the sheet 48 is pulled by the vacuum port 60b, adjacent the slot 58b of the transfer roller 28b. The vacuum ports 60b support the leading and trailing edges 46, 62 of the blade 48 against the transfer roller 28b and partially over the groove 58b. The suction force of the vacuum port 60b is stronger than the suction force of the vacuum port 44b at that point of rotation of the transfer roller 28b and the knife roller 20b, so that the sheet 48 is released from the port of vacuum 44b and held by vacuum port 60b. As illustrated in Figure 4, the blade roller 20b and the transfer roller 28b have progressed in rotation, so that the forming blade 52b of the transfer roller 28b is inserted into the slot 50b of the blade roller 20b , and the blade 48 is in a downstream position from the position shown in Figure 3. The insertion of the forming sheet 52b into the slot 50b of the blade roller 20b forms a fold in the blade 48 in the middle portion 72. , so that the sheet 48 becomes pre-formed. The bend in the sheet 48 is held against the periphery of the transfer roller 28a due to the vacuum force and the positioning of the vacuum ports 56b in the transfer roller 28b. The blade 48 changes: of having a first peripheral length in the
blade roller 20b to have a second peripheral length in transfer roller 28b, which is shorter than the first peripheral length. The second peripheral length of the blade 48 in the transfer roller 28b is shorter than the first peripheral length of the blade 48 in the blade roller 20b because the forming blade 52b is inserted into the slot 50b, the blade 48 is transferred through the projecting surface of the forming blade 52b. As the forming blade 52b protrudes past the uniform radial surface of the roller, the peripheral length of the blade 48 is shortened by the added distance required to cover the forming blade 52b. The circumference of the transfer roller 28b is less than 3/4 of the circumference of the blade roller 20b. In other embodiments, the circumference of the transfer roller 28b is not equally divisible by the length of the sheet. For example, the circumference of the blade roller 20b is equal to four blade lengths, but the circumference of the transfer roller 28b is not equally divisible by three blades. Instead, the circumference of the transfer roller 28b is equal to a number between 2 and 3 sheet lengths. Figure 5 illustrates the sheet 48 downstream of the position of the sheet 48 shown in Figure 4. As the transfer roller 28b rotates in an anti-clockwise direction, the slot 58b of the transfer roller 28b now partially receives. the folder 64b of the internal folding roller 34b. The vacuum force of the vacuum port 74b of the internal folding roller 34b is greater than the suction force of the vacuum port 56b of the transfer roller 28b, so that the leading edge 46 of the sheet 48 which is supported in the groove adjacent 58b of transfer roller 28b is released from vacuum port 56b and sustained ppr vacuum port 74b. The leading edge 46 is
positioned along the folder 64b and adjacent to the fastening point 66b of the folder 64b. Figure 6 illustrates the sheet 48 downstream of the position of the sheet 48 shown in Figure 5. The transfer roller 28b and the internal folding roller 34b have rotated to a position in which the forming blade 52b of the roller transfer 28b and the folded portion of the sheet 48 are inserted into the collet 70b of the internal folding roller 34b. The suction force of the vacuum port 74b of the gripper 70b in which the rotational position of the transfer roller 28b and the internal folding roller 34b is greater than the suction of the two vacuum ports 56b surrounding the forming blade 52b of the transfer roller 28b, so that the middle portion 72 of the sheet 48 will be released from the vacuum port 56b and held against the vacuum port 74b of the internal folding roller 34b. The vacuum port 74b helps maintain the middle portion 72 of the blade 48 in a fixed position relative to the periphery of the internal folding roller 34b. The trailing edge 62 will be pressed against the periphery of the internal folding roller 34b, because the transfer clamping point 36b which defines a roller adjustment distance is operable to iron the transfer sheet 48 when rotating the transfer roller 28b and the internal folding roller 34b. The transfer roller 28b functions to pre-form sheets of the material, so that the circumferential length of the sheet along the transfer roll is the same as the circumferential length of the sheet along the internal folding roll to obtain a fold more suitable. This is accompanied by the creation of a fold in the sheet, and transfer the sheet of the transfer roller to the internal folding roller of the same size so that
the bent portion is inserted into the clip. Because the bent portion is positioned within the clip, the blade in no way moves on the internal folding roller to compensate for the amount of blade forced into the clip by the opposing folder. This allows a more adequate control of the positions of the leading and trailing edges of the sheets in the internal folding rollers. Figure 7 illustrates the sheet 48 downstream of the position of the sheet 48 shown in Figure 6. The leading edge 46 of the sheet 48 is positioned near the clip 70a and adjacent the internal folding roll 34a. If the downstream and upstream sheets had been shown on both internal folding rollers 70a, 70b, the leading edge 46 of the sheet 48 would still be received by the gripper 70a, but a preformed middle portion of a sheet downstream of the internal folding roller 70a lies between leading edge 46 of 48 and clip 70a with its preformed middle portion 72 positioned within clip 70a. When the internal folding roller 34b rotates clockwise and the internal folding roller 34a rotates counterclockwise, the gripper 70b receiving the middle portion 72 of the blade 48 is aligned to receive the folder 64a of the internal folding roller 34a. If the downstream and upstream sheets had been shown on the two rollers, the gripper 70b would also receive the trailing edge of the sheet downstream of the internal folding roller 34a and the leading edge of the upstream stream of the internal folding roller 34a when the folder 64a is inserted into the clip 70b. As the sheets continue to advance through the internal folding apparatus 10, the internal folding rollers 34a, 34b will continue
folding in the sheets of the material in the manner described.