METHOD AND DEVICE FOR SEPARATING PROFILE SECTIONS

Description

[0001] The invention relates to a method for separating profile sections in extrusion lines according to the preamble of patent claim 1 and a device according to the preamble of patent claim 7.

[0002] In particular, the invention relates to a method in which, during the ongoing extrusion process, a carriage is coupled in an upstream position to the calibrated profile strand in order to move along with the profile strand, wherein in the coupled state a knife in the carriage is moved from an initial state transversely to the extrusion direction to a final state in order to separate a profile section from the profile strand, after which the knife is moved back to the initial state, after which the carriage is uncoupled from the profile strand and moved back to the upstream state.

[0003] This is therefore a process that uses a cutter. In extrusion technology, especially in the extrusion of window profiles, a "cutter" refers to a machine for cutting profiles to length. With a knife, individual profile rods, usually 6 m long, are cut from the continuously produced profile strand without chipping. Cutters are increasingly replacing cross-cutting saws, which have always been used for cutting.

[0004] The actual cutting device, referred to below as the cutter device, comprises a stable, divided profile support with a clamping device for the profile and a knife that can be moved perpendicularly to it. The latter is clamped in the center area of ​​a vertically movable clamping frame, whereby a considerable tensile preload must be present. The cutting edge of the knife forms an angle of approximately 30° to the profile support. The cutting stroke usually occurs from top to bottom, so that the clamping frame with the knife is mounted in vertically arranged axial guides, which allow displacement relative to the profile support. During the cutting process, the inclined knife is pressed vertically through the profile by moving the clamping frame. The drive for the cutting stroke and the necessary retraction to the starting position is usually provided by a spindle or rack drive with an electric motor or by an eccentric drive.In the past, pneumatic or hydraulic cylinders were also used for this purpose.

[0005] Since the profile to be cut moves in the extrusion direction during extrusion, the cutter device described above must move synchronously with the profile during the cutting process. Therefore, the cutter device is mounted on a movable carriage, which moves synchronously with the profile in the extrusion direction during the cutting process and is then moved back to its starting or waiting position.

[0006] The length of the knife and its angle to the support surface, the geometry of the clamping frame, and the maximum cutting stroke limit the "cutting window," which defines the extreme dimensions of the profile to be cut. Narrow profiles can therefore be taller than wide ones due to the knife's inclination.

[0007] The cutting angle, i.e., the angle between the cutting edge and the direction of movement of the knife, as well as the angle between the cutting edge and the profile wall currently being cut, is particularly important with regard to the cutting force generated and the quality of the end face of the severed profile. Other important factors influencing cut quality include the geometry of the knife (length, thickness, cutting angle, etc.), the temperature of the knife, the cutting speed, the maximum permissible cycle time, etc.

[0008] A cutter performs its task better the more flexibly it can be adapted to a specific cutting task—that is, to a specific profile, its geometry, and orientation. In terms of flexibility, the cutters used to date are considered very limited. They have not yet progressed beyond electronically setting the upper standby position, limiting the downward stroke immediately after the profile has been completely cut through, and specifying a uniform feed speed for the knife in both directions (speed for the working stroke and speed for the return stroke).

[0009] The main advantages of a cutter compared to a saw are: No material loss due to the sawblade thickness; no dust generation and no sawdust sticking to the profiles; very low noise level.

[0010] The main disadvantages of a cutter compared to saws are: Limited stability of the blade – application limits for larger wall thicknesses and material accumulations; limited flexibility of the setting parameters for unusual profile cross-sections; quality of the cutting surface (flatness, burr formation, etc.) not guaranteed for all profile cross-sections.

[0011] The objective of the invention is to design the cutter so that it can be adapted to different cutting tasks with minimal effort, thus ensuring the optimal achievable cutting quality, and so that the setting parameters, once found, can be easily and reproducibly adjusted for each production batch of the respective profile. This objective is best achieved with a fully equipped cutter according to the following description. However, it should be noted that individual aspects of the invention can also be implemented with less fully equipped cutters, which, according to the patent claims, also expressly fall within the scope of this invention.

[0012] WO 2018 / 219477 A discloses a saw designed for cutting profile sections. Thus, the aforementioned disadvantages of saws are also present here.

[0013] WO 2005 / 087420 A describes a cutting device that can be used either with a knife or a saw. Due to the limited speed at which the knife can be moved through the profile, a very large displacement path is required, depending on the extrusion speed, so the extrusion line must be very long.

[0014] The object of this invention is to avoid these disadvantages and to provide a solution that is functionally reliable and requires as little space as possible in the extrusion direction.

[0015] These objects are solved by the features of patent claim 1.

[0016] For the sake of clarity, the description of the cutter from a design perspective is made using terms such as horizontal, vertical, top, bottom, etc. In a cutter according to the prior art, see above, the knife moves vertically from top to bottom during the cutting process. If this cutter is tilted about the extrusion axis, which is advantageous for a wide, flat profile, the knife then moves horizontally from back to front during the cutting process. In terms of function, the two cutters, the original and the tilted one, are identical, so tilting hardly constitutes an inventive step. In the following, the cutter according to the invention is only described in the preferred orientation. If, for whatever reason, a different orientation is chosen, this description also applies mutatis mutandis to such differently oriented cutters.

[0017] From a physical perspective, the processes involved in cutting are best described by the movement of the knife relative to the profile. For this purpose, the terms "in cutting plane," "direction of the cutting edge," "direction perpendicular to the cutting edge," "angle between the cutting edge and the direction of movement of the knife," "angle between the cutting edge and the profile wall," and others are suitable. These terms are necessary to clarify the distinction between this invention and the prior art.

[0018] The following process is typically performed when cutting with a state-of-the-art cutter: A blade, tilted at an angle of approximately 60° relative to the direction of travel, is pressed vertically through the profile at a specific speed. Initially, the cutting edge only penetrates one longitudinal edge of the profile, and the actual cutting length is very short. As the penetration depth increases, the actual cutting length becomes increasingly longer, depending on how many profile walls of a certain thickness are cut. As the penetration depth increases, the actual cutting length can also shorten if the cross-sectional shape of the profile is designed accordingly.

[0019] What is important from a physical point of view is that the speed of movement v 0 of the knife has main components relative to the profile: Movement component perpendicular to the cutting edge. This is calculated at a knife inclination of 60° as follows: v 1 = v 0 × 0,866 . Movement component in the direction of the cutting edge. This is calculated at the specified inclination as follows: v 2 = v 0 × 0,5 .

[0020] These two velocity components v 1 and v 2 cause reaction forces which place considerable stress on the knife and may cause it to break.

[0021] To illustrate this, let’s compare it to a cutting process using a kitchen knife: Cutting vegetables: The vegetables generate only low reaction forces. The force required to push the knife downward is of the same magnitude as the force required to move the knife lengthwise. The knife glides through the vegetables at an angle, and the cutting process is completed "in a short distance"—literally. This cutting motion is often referred to as a "pushing cut." Cutting bacon: The bacon resists the downward penetration of the knife with a large force, whereas the force required to move the knife lengthwise is relatively small. The knife cannot be pushed vertically or diagonally through the bacon from the wrist. The bacon is therefore pushed back and forth several times, thus cutting through the bacon with relatively little effort. This cutting motion is often referred to as a "pulling cut."

[0022] Cutting with a conventional cutter is roughly equivalent to cutting vegetables, but the profile of the blade counteracts the vertical movement of the blade with a comparatively large force. The force component perpendicular to the cutting edge is 0.866 times the driving force applied to the blade via the support frame. The force component acting in the direction of the cutting edge is smaller, amounting to 0.5 times the driving force.

[0023] These force components place varying loads on the blade and limit the range of application of cutters. Currently used cutters lack any degrees of freedom regarding the blade's movement, which could be influenced by changing various digitally adjustable parameters, with the exception of the feed rate.

[0024] The inventive and optional features of the patent claims will now be explained in more detail. The following measures within the meaning of this invention are to be considered an extension of the functionality of conventional cutters: measure A: Digitally preset end positions or waiting positions of the knife and variable cutting speed:

[0025] The knife's waiting positions are adjusted to the profile geometry to within a few millimeters, so that the cycle time is reduced due to short stroke lengths. The feed speed is adapted to the profile geometry so that optimal cut surface quality can be expected. If visible surfaces of the profile are being cut, a low cutting speed is helpful; if side surfaces of the profile are being cut, higher cutting speeds may be sufficient. The return stroke can again be performed at very high speed. The stroke path of the clamping frame in conjunction with the movement speed and the time required to push the cutter device back to its starting position determines the cycle duration, which must under no circumstances lead to limitations, even at high extrusion speeds.

[0026] To optimize and "program" the movement sequence, a "learning process" is provided. This can be carried out either directly at the cutter, where a profile piece is clamped at a short distance from the knife, or alternatively on a screen using a CAD simulation that vividly depicts the situation of the knife and profile during the cutting process. The entire travel path of the vertical feed axis is traversed step by step, and at prominent points on the knife, the desired speed for moving the previous (or subsequent) path is electronically specified. Normally, the knife is in the upper end position because it is heated here by a temperature control device. Starting from the uppermost position of the knife and continuing up to just above the profile, a high, possibly even maximum, speed is stored for controlling the feed axis.From the first contact with the profile, the travel speed is successively reduced, depending on which cutting lengths currently have to be cut at the cutting edge and which frictional forces can be expected as a result of the contact pressure of the profile on the side of the cutting edge. Other factors influencing the specification of a sensible feed speed arise from the effectiveness of the profile support in critical profile sections (e.g. rollover, = laterally protruding profile section), from the arrangement of the inner walls of the profile, etc. It takes some experience to set the speed curve so that the quality of the cutting surface is optimized and the maximum available cycle time is not exceeded. Since all parameters for controlling the feed axis are stored digitally, these can be changed in specific areas with little effort, taking into account the findings after evaluating test cuts. measure B: Changing the angle between the cutting edge and the direction of movement:

[0027] For this purpose, several mounting points and some spacers are provided in the holding frame to bridge length differences, allowing knives to be clamped at different angles ranging from approximately 30° to 60°. If this angle is more than 45° relative to the cutting direction, the cutting behavior changes to a "pulling cut," which means less stress on the knife. If this angle is less than 45° relative to the cutting direction, the cutting behavior corresponds to a "pushing cut." However, there is a close connection with the cutting window, so the limits are very tightly defined by the profile geometry and orientation of the profile. measure C: Using two knives:

[0028] The two knives are arranged approximately mirror-symmetrically to each other, so that the cutting edges are aligned in a V-shape, forming a relatively acute angle to each other. The opening of this "V" faces downward. During the cutting process, each knife is allocated only approximately half the profile cross-section, and each knife cuts only half the profile width. This allows for very small angles of inclination between the cutting edge and the direction of movement, resulting in a distinctly "pulling" cutting action. This results in minimal stress on the knife "perpendicular to the cutting edge," which minimizes the risk of breakage and virtually eliminates any chance of the cutting edge drifting. The cutting edge is self-centering. measure D: Hard coating the knife and / or applying a lubricant or release agent:

[0029] A hard coating of the cutting edge, or better yet, the entire knife, reduces wear and increases service life. At the same time, the coefficient of friction is also reduced. A hard coating made of TiN (titanium nitride) has proven effective. Periodically spraying the knife with a lubricant or release agent, similar to that used in injection molding tools, also reduces the coefficient of friction. This places less stress on the knives, thus reducing the risk of breakage. Measure E: Second feed axis:

[0030] A major leap forward in the cutter's development is the addition of a second feed axis, which enables the knife to move translationally in any direction within the cutting plane. It is therefore essential that the movement is not linear or essentially linear as with conventional solutions, but two-dimensional along a polygon or a curved curve. Any direction in which the velocity component perpendicular to the cutting edge points away from the knife toward the profile, i.e., the cutting edge penetrates deeper into the profile, is helpful for cutting. The now two feed axes can be controlled with little effort to move the knife reproducibly and smoothly in the desired direction and at the desired speed.A key advantage of such a cutter is that critical profile sections can be cut with a clearly pulling cut, whereby the speed component in the direction of the cutting edge can also change direction one or more times, similar to sawing with a handsaw or cutting bacon with a knife.

[0031] With a pulling cut, the cutting edge is subjected to significantly less stress than with conventional cutters. With a conventional cutter, the force acting perpendicular to the cutting edge is considerably higher than with a cutter according to the invention with a pulling cut. This force acting perpendicular to the cutting edge causes bending stress in the knife, which leads to high compressive stresses on the front edge of the knife. The cutting edge under compressive load tends to deviate sideways at the front edge of the knife, which triggers a chain reaction: If the cutting edge only deviates slightly in one direction, the deviation increases with each further penetration into the profile. Only in a few cases does the deviation fall below the critical level of a few millimeters, meaning the knife does not break and remains ready for use. In most cases, however, the cutting edge deviates so severely that the knife breaks suddenly.

[0032] The data required for the synchronous control of the two feed axes (especially the speed curve as a function of the current position) and the reading of the power consumption of the drive motors allow for a very accurate representation of the force curve during the working stroke. Since this data also reveals the position of the cutting edge in relation to the profile, the force curve as a function of the cutting depth can also be displayed. Load peaks on the knife can be detected. These load peaks can be eliminated by changing the knife's movement sequence with regard to feed speed and "pulling cut."

[0033] In addition, the force curve per cutting stroke and a comparison with the historical data provide valuable information about cutting edge wear. An alarm in advance of a blade breakage helps prevent a malfunction by replacing the worn blade in a timely manner. It is advisable to evaluate the force curve separately for both the components in the direction of the cutting edge and the components perpendicular to it. The component perpendicular to the cutting edge is particularly critical with regard to blade breakage. measure F: Angle adjustment:

[0034] A further leap forward in the development of the cutter is achieved by introducing an additional degree of freedom for the knife in the form of angle adjustment. A fixed, mechanically acting adjustment of the angle between the cutting edge and the support surface, as already mentioned above, significantly expands the optimization possibilities for cutting critical profiles in conjunction with the translational movement resulting from the vertical and horizontal feed axes. Pulling cuts in both directions are possible, similar to cutting bacon with a kitchen knife. measure G: Adjustable blade angle:

[0035] If the knife's inclination angle can also be adjusted during the cutting process using another electronically controlled axis, the cutting process can be adjusted to the theoretical optimum for any profile contour and any profile orientation. The limits are then determined only by the knife's stability, the spatial conditions of the cutter, and the profile's geometry.

[0036] According to the invention, the measures of patent claims 1 and 9 and optionally those of the dependent claims are provided.

[0037] From the above description it can be seen that when cutting a given profile (geometry and wall thickness as well as clamping orientation) three factors in particular have a significant influence on the cutting quality and the mechanical stress on the knife: A Direction of movement of the knife B Movement speed of the knife C Angle between the cutting edge of the knife and the profile section currently being cut

[0038] Measure A (see above) changes the speed of movement of the knife in sections.

[0039] Measure B (see above) mechanically changes the angle between the knife (specifically the cutting edge of the knife) and the profile.

[0040] Measure C (see above) reduces the angle between the direction of movement of the knife and the cutting edge of the knife (and also reduces the stroke required to separate the profile).

[0041] Measure D (see above) reduces the friction between the knife and the profile and thus the mechanical stress on the knife.

[0042] By means of measure E (see above), superimposed movement of the knife along a horizontal axis, the direction and speed of movement can be freely controlled within wide limits.

[0043] Measure F (see above) changes both the angle between the knife and the profile and the angle between the direction of movement and the knife's cutting edge equally. Due to the mechanical adjustment, the knife's orientation remains constant throughout the entire cutting process.

[0044] By means of measure G (see above), similar to measure F, but with rotational adjustment of the knife by a third axis, the orientation of the knife can be changed during the cutting process.

[0045] Measures A to G can be combined in many different ways, allowing the three factors mentioned above to be varied within a wide range, either mechanically or electrically. This allows for optimized cutting quality for difficult cutting tasks.

[0046] By combining measures A and E, a process is achieved in which the movement of the knife from the initial state to the final state is composed of a main movement and a transverse movement.

[0047] It is therefore advantageous that the movement is not linear or essentially linear as in known solutions, but two-dimensional along a polygon or a curved curve. The main movement is essentially the one that corresponds to a direct connection between the initial state and the final state, and the transverse movement is a movement inclined to it, for example a movement perpendicular to the main movement. This means in particular that in addition to the main movement, which is typically directed vertically downwards, a transverse movement perpendicular to it can be carried out, with this transverse movement being carried out selectively in individual areas. For example, such a transverse movement can improve quality if a horizontal section of the profile is not simply severed by the knife moving vertically downwards, but a horizontal movement of the knife is superimposed at the same time.Since the cutting edge of the knife is typically not positioned exactly perpendicular to the main direction of movement, i.e., not horizontally but slightly upwards, this transverse movement also influences the cutting speed. This effect can be taken into account when determining the movement speed in the main direction of movement.

[0048] To achieve high cutting quality, it is essential that the main movement and the transverse movement can be controlled reproducibly and synchronously.

[0049] A preferred embodiment of the invention provides for the transverse movement to be a reciprocating movement. It is particularly advantageous if the transverse movement occurs in the direction of a cutting edge of the knife.

[0050] The combined movement is thus zigzag or sinusoidal and roughly corresponds to a manual cutting motion. The cutting direction is not only vertically downward, but can be in almost any direction away from the cutting edge.

[0051] Another aspect of the inventive solution is that the movement of the knife from the initial state to the final state is carried out at a variable speed. The basic idea is that the knife's movement speed is critically different depending on which parts of the profile are subjected to the cutting process at any given moment. This makes it possible to shorten the duration of the cutting process without having to fear a reduction in the quality of the cut surface.

[0052] In the initial state, the knife is typically positioned a predetermined distance above the profile strand to be severed. The feed movement until the knife touches the profile strand can be performed at maximum speed without any disadvantages. It is also possible for the knife to move from the initial state until contact with the profile strand to be performed at a higher speed than the knife's movement through the profile strand.

[0053] A particularly effective reduction in cutting time can be achieved by dividing the movement of the knife through the profile strand into sections, and by moving the knife at a different speed within each section compared to neighboring sections. The choice of the respective speed, depending on the knife position, can be based on the maximum possible speed in this range at which no deterioration in cut quality occurs.

[0054] In this context, it is particularly advantageous if the blade's movement is slower in movement sections where fragile areas of the profile strand are severed than in movement sections where this is not the case. Fragile areas in the above sense are considered to be so-called extremities of the profile, i.e., projections with sealing grooves and the like, or thin-walled webs inside the profile.

[0055] The method according to the invention also includes determining the cutting speed profile. In a preferred embodiment of the invention, a learning cycle is run before the start of the extrusion process. In this learning cycle, the movement of the knife from the initial state to the final state is simulated at a reduced speed in order to be able to determine the respective speed of the knife for individual movement sections. To carry out the learning cycle, a previously produced piece of the respective profile is inserted into the otherwise stationary cutter and the knife is manually controlled at low speed and thus moved gradually downwards. By setting markers, movement sections can be defined and a corresponding speed can be specified for each movement section.The choice of this speed can be based on experience and can also be adjusted during the ongoing production process if problems arise in certain areas of the cutting surface.

[0056] The present invention also relates to a device for separating profile sections in extrusion lines, comprising a carriage which is movably guided in the longitudinal direction of the profile strand between an upstream position and a downstream position, wherein the carriage has a clamping device for temporarily connecting it to the profile strand, with a knife movably guided on the carriage.

[0057] According to the invention, the cutting time can be shortened by providing a control device that controls the movement of the knife from the initial state to the final state at a variable speed. Thus, the control device specifies the speed profile for the movement of the knife.

[0058] The input of the respective speeds can preferably be facilitated by the control device providing for the setting of a predetermined speed for individual movement sections of the knife from the initial state to the final state.

[0059] A particularly preferred embodiment of the present invention provides a first guide for the movement of the knife from the initial state to the final state and a further guide for a movement of the knife at right angles thereto. This allows for a particularly fine adjustment of the knife's movement with respect to the profile.

[0060] In particular, it is advantageous if the knife has a cutting edge that forms an acute angle with the direction of movement of the knife from the initial state to the final state.

[0061] In connection with the present invention, it is particularly advantageous if the knife has a heating device. It has been found that the effect of the heating can be increased by selectively selecting an appropriate cutting speed, since slower cutting speeds naturally increase the duration of heat exposure. Particularly good results can be achieved in this way.

[0062] A further preferred embodiment of the invention is provided when the knife is pre-tensioned in the direction of the cutting edge. This reduces the risk of the knife slipping at high cutting speeds.

[0063] The present invention will now be explained in more detail with reference to the exemplary embodiments illustrated in the figures. They show: Fig.1 is a schematic representation of a cutter system according to the invention for separating profile sections with a caterpillar take-off; Fig.2 is a cutter device in basic design, view against the extrusion direction in a section along line A - A in Fig. 1 ; Fig.3 Clamping frame and blade with inclination angle α = 60°, view against the extrusion direction; Fig.4 Clamping frame and blade with inclination angle α = 45°, view against the extrusion direction; Fig.5 Clamping frame and blade with inclination angle α = 30°, view against the extrusion direction; Fig.6 Clamping frame and blade with inclination angle α = 60° - learning process: different cutting speed in certain areas; Fig.7 Clamping frame with two blades, each with an inclination angle α = 20°, view against the extrusion direction; Fig.8 A cutter device with an additional horizontal axis, view against the extrusion direction according to cutting position A - A in Fig. 1; Fig. 9 Clamping frame with knife for use in a two-axis cutter device - learning process: different cutting speeds and different directions of movement in certain areas; Fig. 10 Vertical frame with angle-adjustable knife, view in the extrusion direction; Fig. 11 A schematic diagram explaining the cutting speed setting;

[0064] Fig. 1shows the arrangement of the device 1 for separating profile sections in extrusion lines following a caterpillar take-off device 3. The continuously manufactured profile in the form of a profile strand 10 is transported from left to right by the caterpillar take-off device in the extrusion direction E and cut to length in the device 1 into profile bars, usually 6 m long. The separation of a profile section from the profile strand 10 is carried out by a cutter device 2. At the time of separation, the cutter device 2 moves synchronously with the profile strand 10 in the extrusion direction and is then pushed back into its starting position; see the directional arrows C.

[0065] The Fig. 2 shows a cutter device 2 in basic design according to the cutting guide A - A in Fig. 1. The knife 11 with the cutting edge 12 is clamped in a vertically movable clamping frame 13. The clamping frame is provided, for example, with bars 14 which are guided in bearing bushes 15. These bearing bushes 15 as well as the drive 19 and the threaded spindle for the vertical axis are fixedly connected to the base plate 16. With this threaded spindle, the clamping frame 13 can be moved downwards in the cutting direction M via the threaded nut 20 and back upwards to its starting position. The linear drive shown here, consisting of a rotating threaded spindle and fixed nut, is only shown as an example. In principle, alternative linear drives can also be used, e.g. a rack and pinion with a gear. The profile 10 is clamped against the base plate 16 during the cutting process so that the entire cutter device 2 moves with the profile 10 in the extrusion direction E, with the bars 17 interacting with the bearing bushes 18.

[0066] The Fig. 3 to 5 each show assembly 4, with the angle of inclination α having different values. In Fig. 3This angle is 60°, which is within the range of currently known cutters. At this relatively large angle, the cutting characteristics correspond to a pressing cut. In this case, the cutting window 22, which is formed by the contours of the base plate 16, the inner surfaces of the clamping frame 13 and the cutting edge 12, is trapezoidal and comparatively large. The cutting window 22 is the area within which the profiles 10 must fit in order to be severed. The cutting force, which is made up of the force for the actual cutting of the profile at the cutting edge 12 and of frictional forces due to the lateral pressing of the profile against the knife, is always directed against the cutting direction M of the knife 11.This means that when a pressing cut is made in the knife, higher compressive stresses are created at the front edge of the knife in the area of ​​the cutting edge 12, which promote the knife's drift and therefore represent a high risk of breakage for the knife.

[0067] In Fig. 4 The angle of inclination α is 45°, whereby the cutting window 22 is now triangular and smaller than above. In order to be able to realize different angles of inclination, several attachment points 21 for the knife are now provided in the clamping frame 13 according to the invention. The use of spacers 23 is expedient for making the knives 11 shorter, which makes them more stable and reduces the risk of breakage.

[0068] In Fig. 5 the angle of inclination α is only 30°, which makes the section window 22 even smaller than in Fig. 4This acute angle changes the cutting behavior toward a "pulling cut." The cutting force is always directed against the cutting direction M of the blade 11, see above. This means that a pulling cut predominantly creates tensile stresses on the cutting edge 12 of the blade 11, which pose little risk of breakage to the blade. The cutting window 22 is comparatively small, but standard window profiles can be cut through without any problem.

[0069] Based on Fig. 6It shows how different vertical speeds of the knife 11 can be specified depending on the geometry of the profile and the position of the knife relative to the profile. This process, the learning process, can be carried out either directly on the machine, i.e., at the cutter, during the setup process of the extrusion line, or using a CAD simulation that precisely reproduces the spatial conditions of the cutter device 2, the vertical movement of the assembly 4 of the clamping frame 13 and knife 11, the geometry and position of the profile 10, and its clamping situation. If the learning process is carried out physically on the cutter, a profile piece is clamped a short distance "in front" of the knife (relative to the extrusion direction). Once the sequence of the working stroke and return stroke has been digitally recorded and saved, this process is highly reproducible and can be called up again for each production batch of the respective profile 10.

[0070] A learning process is described using a non-restrictive example. The starting situation for the learning process is Fig. 6 Shown: The clamping frame 13 is in the uppermost position relative to the base plate 16. The profile 10 rests on the base plate 16 and has a lateral clearance of 24 mm, here approximately 15 mm, from the clamping frame 13. In this position, it is firmly clamped during the cutting process. The clamping devices required for this purpose are not shown for clarity.

[0071] The relevant information is summarized in the following Table 1:

[0072] The starting position of knife 11 or cutting edge 12 refers to waypoint 0 in Table 1 at a vertical position of 0 mm. The operator / programmer can only access the input fields with a light gray background for the learning process. The others are locked to prevent operating errors. First, assembly 4, clamping frame 13 with knife, is gradually moved downward by the operator / programmer until the position of cutting edge 12 relative to profile 10 reaches a relevant vertical position, in this case, "just before impact with the profile." This vertical position is entered under waypoint 1 "at the push of a button" as "-85 mm." The operator enters 100% as the relative speed for the distance traveled. This means that the distance from 0 to -85 mm represents an idle stroke; the profile is not yet severed, and is traveled at the maximum speed of 180 mm / s.The maximum speed is the technically feasible speed that, based on the performance of the linear drive and the moving masses, represents the upper limit at which vibrations due to acceleration forces are not expected to have a negative impact on the cutting quality and service life of the cutter. The movement of the knife 12 from pathpoint 0 to pathpoint 1 is referred to as movement section b1. Assembly 4 is gradually moved further downward. The cutting edge 12 penetrates the profile (only visually during the learning process...) and has completely severed the upper visible surface of the profile 10 up to the vertical position "-128 mm". The position "-128 mm" is automatically entered under pathpoint 3, and the operator enters 40% as the relative speed for the distance traveled. This means that the distance from -85 to -128 mm should be covered at a speed of "40% of 180 mm / s, i.e., 72 mm / s".The movement of the knife 12 from pathpoint 1 to pathpoint 2 is referred to as movement section b2. In this sense, the operator defines further relevant vertical positions of the cutting edge 12 and specifies the target speeds for cutting the respective sections. Once the profile has been completely severed—here, after passing through movement section b4 at the vertical position "202 mm"—the operator specifies the starting position, i.e., "0 mm," as the next waypoint and the desired speed for the return stroke, in this example, "85% of 180 mm / s." In this example, this movement section b5 corresponds to the return stroke back to the starting position. If the time for a complete cycle is short, it is not necessary to move to waypoint 1, the uppermost position "0 mm," but rather waypoint 2, corresponding to "-85 mm," can be specified as the waiting position for the next working stroke.The cycle time is thus reduced by the duration of the two idle strokes upwards and downwards over a distance of 85 mm. The time required to cut through the profile in question can be seen from the diagram. Starting from the zero position, the working stroke takes place downwards at four different speeds up to 202 mm in 1.92 s (total 0.47 + 0.60 + 0.17 + 0.68 s), followed by the return stroke upwards at a speed of 153 mm / s to the zero position in 1.32 s, a total of 3.24 s. The learning process is now complete, and the relevant data is saved for cutting to length in extrusion mode. It is advisable to check that the cutting process is running correctly by first triggering it manually without a profile and observing whether the switchover travel points and speeds are maintained as planned and whether the profile is cut completely.

[0073] The arrows at waypoints 30 in Fig. 6 represent the direction of movement of the knife 11 and also mark the four different movement sections b1 to b4 during the downward stroke. Movement section b5, the return stroke to the starting position, is not shown.

[0074] It is advisable to measure the force required to move assembly 4, clamping frame 13 with knife, for each working stroke and store it for ongoing comparison. The force required to move the assembly consists of three components: inertial forces for accelerating and decelerating the clamping frame 13, frictional forces due to the profile pressing on both sides of knife 11 as plastic is displaced by the knife, and the actual cutting force at cutting edge 12 to separate the profile.

[0075] In the simplest case, a force-displacement diagram can be determined by evaluating the electrical data of the vertical axis 19: The displacement is calculated from the angle of rotation of the threaded spindle, and the force from the current consumption of the drive motor. Force measurement becomes more accurate if a suitable force transducer is installed in the area of ​​the nut 20 for the vertical axis or in the area of ​​the threaded spindle 19. If the force curve is compared for each working stroke over a longer period of time, conclusions can be drawn about the function of the device and the condition of the blade 11. Ideally, an impending blade breakage can be detected and replaced in a timely manner.

[0076] Fig. 7shows an assembly 4, clamping frame 13 with a knife, to which two knives 11 are attached. This arrangement has the particular advantage that comparatively small inclination angles α can be realized for each knife, thus resulting in a pronounced pulling cut. Despite the small inclination angle, neither a long knife nor a long cutting stroke are required, because each knife only has to cut through approximately half the profile cross-section. This also results in short cycle times and a low risk of breakage for the knives. It is advantageous if the visible surfaces of the profile, i.e. those surfaces that should have a particularly clean cut surface without burrs, are aligned in the direction of movement of the knife. Fig. 7Therefore, a 90° rotation of the profile 10 (or alternatively, the entire cutter device 2) would be advantageous. In this case, the two visible surfaces of the profile would be pushed "inward" by the cutting edge 12, so that no protruding edge would be disruptive on the cut profile. At the point where the two cutting edges converge, a small step could appear on the cutting surface if the two blades 11 are not precisely aligned with each other, or if they are slightly misaligned. This is not, in principle, a major problem, since window profiles almost always have to be mitered. Any disruption to the visible surface caused by this step is also avoided in the rotated position of the profile. This also eliminates complications when laminating films onto the visible surface.

[0077] The two knives can be mounted loosely next to each other in the clamping frame, as in the Fig. 7It is not practical to manufacture the knives from a single piece by first making a V-shaped notch in a rectangular blank and then providing it with two cutting edges. The two cutting edges are difficult to manufacture with high precision in the "tip area." Slight deviations in symmetry along the length of the cutting edge encourage the cutting edges to misalign, which could easily lead to bending of the knives. Even a slight bend would quickly lead to a knife breakage. A weld seam followed by flush grinding could securely join two separately manufactured knives, if necessary.

[0078] In Fig. 8a cutter device 2 is shown in which the assembly 4, clamping frame 13 and knife, can be moved vertically in the usual way, see double arrow V, and according to the invention additionally horizontally, see double arrow H. For this purpose, the vertical axis 19, drive and threaded spindle, as well as the bearing bushes 15 for the vertical axis are not fastened to the base plate 16, but to an intermediate plate 26 for the transverse movement. The linear drive for the transverse movement, i.e. for the horizontal axis, is not shown here. This is supported on the base plate 16 and moves the intermediate plate 26 in the horizontal direction according to double arrow H. The knife 11 is thus fastened to a so-called cross slide and can therefore be moved in any direction if the vertical and horizontal axes are controlled accordingly.

[0079] Based on Fig. 9It shows how different movement directions and speeds of the knife 11 can be specified depending on the geometry of the profile and the position of the knife relative to the profile. This process, the learning process, can be carried out either directly on the machine, i.e., at the cutter, during the setup process of the extrusion line, or using a CAD simulation that precisely reproduces the spatial conditions of the cutter device 2 and the vertical and horizontal movement of the assembly 4 of the clamping frame 13 and knife 11, as well as the geometry and position of the profile. If the learning process is carried out physically on the cutter, a profile piece 10 is clamped a short distance "in front" of the knife (relative to the extrusion direction). Once the sequence of the working stroke and return stroke has been digitally recorded and saved, this process is highly reproducible and can be called up again for each production batch of the respective profile.

[0080] A learning process is described below for the movements of the knife 11 in the cutting plane, i.e. in the vertical and horizontal directions, using a non-limiting example. The starting situation for the learning process is shown in Fig. 9 Shown: The clamping frame 13 is in the uppermost, "right" position relative to the base plate 16. The profile 10 rests on the base plate 16 and has a lateral clearance of 24 mm, here approximately 15 mm, from the clamping frame 13. In this position, it is firmly clamped during the cutting process. The clamping devices required for this purpose are not shown for clarity. The relevant data are summarized in Table 2 below:

[0081] The starting position of the knife 11 or the cutting edge 12 refers to waypoint 0 in Table 2: vertical position 0 mm and horizontal position 0 mm. The operator now moves assembly 4, clamping frame 13 with knife, vertically and horizontally in several steps until relevant waypoints are available. In this example, these are the coordinates 0 / -80 mm for waypoint 1, which are automatically entered into the table above "at the push of a button." The relative speed, here 100%, based on the maximum speed of 180 mm / s, is then entered. In this specific case, the movement from waypoint 0 to waypoint 1 is an idle stroke vertically downwards, until just before impacting the profile 10, which is referred to here as movement section b1. The dashed lines refer to the position of the cutting edge 12 at each waypoint, supplemented by vertical markings that indicate the lateral limitation by the clamping frame 13 orrepresent the intermediate piece 23. These markings are necessary to estimate possible collisions between the profile and the frame structure. The values ​​for the subsequent waypoints 3 and 4 are determined using the same principle. The coordinates of waypoint 5 are the same as for waypoint 0 and refer to the return stroke to the starting position. This return stroke is referred to here as movement section b4. The other columns of the table provide calculated values ​​for displacement distances, horizontal and vertical speeds, and the time required.

[0082] The arrows at waypoints 30 in Fig. 9 represent the direction of movement of the knife 11 and also mark the 4 different movement sections b1 to b4. The movement section b4 is the return stroke to the starting position

[0083] α x represents in Fig. 8the angle of inclination of the knife 11 to the direction of movement for 2-axis movement for the waypoint x. The Fig. 9 It can be seen that this angle of inclination is approximately 30° for waypoints 2 and 3 in the table above. This angle means that the two cuts correspond to a "pulling cut," which largely prevents the knife 11 from wandering and reduces the risk of breakage. Furthermore, an "outer edge" on the two cutting surfaces is prevented, which would lead to problems, especially when laminating films.

[0084] Fig. 10shows, without limitation, an assembly 5 according to the invention, a clamping frame with an angle-adjustable blade, in a view in the extrusion direction. This assembly can be used in the cutter device instead of assembly 4, a clamping frame 13 with a blade, in which the blade can be mounted "only" in structurally defined angular positions. The vertical frame 32 is used instead of the previously described vertically displaceable clamping frame 13. Two bearing segments 34, screwed to the vertical frame 32, accommodate the ring-segment clamping frame 33, in which the blade 11 is clamped. A groove on the outer circumference of the ring-segment clamping frame 33 cooperates with a web of the bearing segments 34, so that the former can be rotated in the plane. The cutting edge 12 can in principle be rotated by 360° starting from the vertical, preferably the inclination angle α covers the range from -30° to +30°, which corresponds to a rotation range of 120°.In the simplest embodiment, a desired angle is set manually, and the ring segment clamping frame 33 is fixed in this position. The locking bolt 41 prevents the ring segment clamping frame 33 from slipping out of the bearing segment 34 when the knife is aligned almost vertically.

[0085] It is advantageous if the ring-segment clamping frame 33 can be adjusted with an electric rotary drive 35, whereby a pinion of the rotary drive 35 interacts with a gear segment on the outer circumference of the ring-segment clamping frame. This rotation can also be achieved by other means, e.g., a worm drive. Desired angles β can thus be stored as parameters in the control system and thus "automatically" adjusted to the current profile 10 during each setup process of the extrusion line. In the case of an electric rotary drive 35, the angle β can also be controlled synchronously with the vertical movement V of the clamping frame and the horizontal movement H of the intermediate plate, so that even with complex profiles, there are virtually no restrictions regarding the optimal cutting path.

[0086] In the Fig. 11A frame profile 10 with the associated movement sections b1 to b8 is shown. Each movement section b1 to b8 is assigned a corresponding speed v1 to v8, with which the knife 11 is moved downward. The movement section b1 of the knife 11 concerns the movement of the knife from the starting position until contact with the profile section 10 and represents an idle stroke.

[0087] The broken lines 39 and 40 represent the initial state and the final state of the cutting edge 12 of the knife 11.

[0088] In the present case, the speed v1 will be 100%, i.e. the maximum possible speed. In the second movement section b2, the speed v2 is, for example, 55%, because in addition to thick-walled sections 36, extremities 37 and thin-walled webs 38 have to be cut. In the third movement section b3, less critical parts of the profile are affected, so that the speed v3 can be approximately 85%. In the further movement sections b4 and b6, more critical conditions exist, which result in speeds v4 and v6 of 40%. In movement section b5, fewer critical parts are affected, so that the speed v5 can be approximately 90%. The same applies to the speed v7 in movement section b7. In the last movement section b8, an average speed v8 of approximately 80% can be assumed, since only one relatively robust extremity needs to be taken into account.The movement section b9 for moving the knife from the final state to the initial state is shown in the . Fig. 11 not shown and occurs at speed v9.

[0089] The present invention makes it possible to optimize the speed of cutting profile sections. List of reference symbols

[0090] 1Cutter system for cutting profile sections in extrusion lines 2Cutter device 3Caterpillar take-off 4Clamping frame assembly with knife 5Clamping frame assembly with angle-adjustable knife 10Profile strand 11Knife 12Knife cutting edge 13Clamping frame, vertically movable 14Hole for vertical axis 15Bearing bush for vertical axis 16Base plate with support surface for the profile (= longitudinal slide) 17Hole for longitudinal movement of the cutter device 18Bearing bush for longitudinal movement of the cutter device 19Vertical axis, drive and threaded spindle 20Nut for vertical axis 21Attachment points for knives 22Cutting window 23Intermediate piece for attaching different knives 24Reference distance profile - clamping frame 25Position of cutting edge 12 for pure vertical movement 26Intermediate plate for transverse movement 27Bearing bush for transverse movement 28Hole for transverse movement 29Support for the vertical axis 30Waypoint x,for characterizing the position and direction of movement of the knife 31Position of the cutting edge 12 during 2-axis movement 32Vertical frame 33Ring segment clamping frame for the knife 34Bearing segment 35Rotary drive with pinion 36Thick-walled sections 37Extremities 38Thin-walled webs 39Broken lines (initial state) 40Broken lines (final state) 41Securing bolt, EExtrusion direction CLongitudinal movement of the cutter device MMovement direction of the knife αInclination angle of the knife to the direction of movement βInclination angle of the knife to the vertical bMovement section xIndex for characterizing the movement section, position and movement speed of the knife VVertical movement of the clamping frame HHorizontal movement of the intermediate plate

Claims

1. Method for separating profile sections in extrusion lines, in which, during the ongoing extrusion process, a carriage (2) is coupled in an upstream position to the calibrated profile strand (10) in order to move along with the profile strand (10), wherein, in the coupled state, a blade (11) arranged in a clamping frame (13, 33) is moved from an initial state (39) transversely to the extrusion direction into an end state (40) in order to sever a profile section from the profile strand (10), after which the blade (11) is moved back to the initial state (39), whereupon the carriage (2) is uncoupled from the profile strand (10) and the carriage (2) is moved back to the upstream state, characterised in that the movement of the blade (11) from the initial state (39) to the final state (40) is carried out controlled via a control device at speeds (v1 to v9) which differ from region to region, and in that the movement of the blade (11) is slower in movement sections (b1 to b7) in which fragile regions of the profile strand (10) are severed than in movement sections (b1 to b7) in which this is not the case.

2. Method according to claim 1, characterised in that the movement of the blade (11) is composed of a main movement and a transverse movement in different directions, in the plane of the blade and preferably at an angle of 90° to the main movement.

3. Method according to one of claims 1 or 2, characterised in that the blade (11) is mounted on a rotatable clamping frame (33), wherein the angle of inclination of the cutting edge can preferably be fixed mechanically when the cutter device is stationary or can be adjusted by means of an electronically controllable axis during operation of the cutter system.

4. Method according to one of claims 1 to 3, characterised in that a learning cycle is run through before the beginning of the extrusion process, in which the movement of the blade (11) from the initial state (39) to the final state (40) is simulated at a reduced speed, in order to be able to store the individual movement sections (b1 to bmax), the respective speeds (v1 to Vmax) and, optionally, movement directions (M) of the blade (11) in the machine control system.

5. Method according to one of claims 1 to 4, characterised in that the blade (11) is heated between each two cutting processes, wherein a temperature between 50°C and 300°C is preferably reached.

6. Method according to one of the claims 1 to 5, characterised in that the blade (11) is occasionally sprayed with a release agent between two cutting operations in order to reduce the friction and the cutting force, and / or in that the blade (11) is provided with a hard coating, preferably of TiN, in order to reduce wear.

7. Device for separating profile sections in extrusion lines, in which, during the ongoing extrusion process, the cutter device (2), which is displaceable in the extrusion direction, is temporarily coupled in an upstream position to the calibrated profile strand (10) in order to move together with the profile strand (10), having a blade (11) arranged in a displaceable clamping frame (13), characterised in that a control device is provided which is set up to control the movement of the blade (11) from the initial state (39) into the final state (40) in individual movement sections (b1 to bmax) at speeds (v1 to vmax) that differ from region to region, so that the movement of the blade (11) is slower in movement sections (b1 to b7) in which fragile regions of the profile strand (10) are severed than in movement sections (b1 to b7) in which this is not the case.

8. Device according to claim 7, characterised in that a first guide (14) is provided for the movement of the blade (11) in a main direction of movement and a further guide (28) is provided for a movement of the blade (11) transversely thereto, preferably at right angles to the first guide (5).

9. Device according to one of claims 7 or 8, characterised in that the blade (11) is arranged in a rotatable clamping frame (33), wherein the angle of inclination of the cutting edge is preferably fixed mechanically when the cutter device is stationary or can be adjusted with an electronically controllable axis during operation of the cutter system.

10. Device according to one of the claims 7 to 9, characterised in that the control device provides for the determination of multiple movement sections (b1 to bmax), each with predetermined speeds (v1 to vmax) and, optionally, directions of movement (M) of the blade (11), so that the blade performs the same movement in each cutting process.

11. Device according to one of claims 7 to 10, characterised in that the blade (11) has a cutting edge (12) which, with the direction of movement (7) of the blade (11) from the initial state (39) into the final state (40), encloses an angle (α) which is smaller than 60°, preferably smaller than 45°, particularly preferably smaller than 30°.

12. Device according to one of claims 7 to 11, characterised in that the blade (11) has a cutting edge (12) which forms a variable angle (α) with the direction of movement (7) of the blade (11) from the initial state (39) to the final state (40).

13. Device according to one of claims 7 to 12, characterised in that the blade (11) is pretensioned in the direction of the cutting edge (12).

14. Device according to one of claims 7 to 13, characterised in that two blades (11) are provided whose cutting edges (12) are arranged in a V-shaped concave manner.