US20140311204A1

US20140311204A1 - Spring winding machine with an adjustable cutting device

Info

Publication number: US20140311204A1
Application number: US14/251,898
Authority: US
Inventors: Andreas Sigg
Original assignee: Wafios AG
Current assignee: Wafios AG
Priority date: 2013-04-18
Filing date: 2014-04-14
Publication date: 2014-10-23
Also published as: BR102014009461A2; CN104107870A; CN104107870B; DE102013207028B3; EP2826572B1; EP2826572A1

Abstract

A spring winding machine that manufactures helical springs by spring winding includes a feed device that feeds wire to a shaping device, wherein the shaping device has a winding tool and a pitch die; a cutting device that separates a finished helical spring from the wire after termination of shaping, wherein the cutting device has a cutting tool which, by a drive system, can be moved along a predefinable closed trajectory; a control device that controls the feed device, the shaping device and the cutting device on the basis of an NC control program; and a programmable trajectory-setting system that sets the shape and/or position of the trajectory to be passed through by the cutting tool, wherein a trajectory which is mirror-symmetrical with respect to a plane of symmetry and has a predefinable ratio of height to width.

Description

TECHNICAL FIELD

This disclosure relates to spring winding machines that manufacture helical springs by spring winding.

BACKGROUND

Helical springs are machine elements required in numerous application areas in large numbers and different configurations. Helical springs, which are also referred to as wound torsion springs, are usually manufactured from spring wire and, depending on the load present during use, are configured as tension springs or compression springs. Compression springs, in particular bearing springs, are required, for example, in large quantities for automobile production.
Helical springs are usually manufactured nowadays by spring winding using numerically controlled spring winding machines. Thus, a wire (spring wire) is fed to a shaping device of the spring winding machine by a feed device under the control of an NC control program, and is shaped using tools of the shaping device to form a helical spring. The tools generally include one or more positionally adjustable winding pins to secure and, if appropriate, change the diameter of spring windings and one or more pitch dies by which the local pitch of the spring windings is determined in each phase of the fabrication process. After the termination of a shaping operation, a finished helical spring is separated from the fed wire by a cutting device under the control of the NC control program.
During the manufacture of springs, the type of cut is frequently of great significance since it also determines certain properties of the finished helical spring. Generally, three types of cutting methods are differentiated, specifically what is referred to as a “straight cut,” “rotational cut” and “torsional cut.” In the case of the straight cut, a cutting tool carries out a straight linear cutting movement during cutting of the wire. In the case of the rotational cut, the cutting edge of the cutting tool is guided along an essentially elliptical trajectory to cut the wire. In the case of the torsional cut, the wire is loaded mechanically such that it can be separated by torsional loading. A torsional cut can provide a burr-free cut. In the case of the other two types of cut, cutting burrs are generally produced at the cutting surface, and in some cases they have to be removed by brushing, blasting or grinding before further use of the helical springs.
EP 0 804 979 A1 describes components of a cutting device for a spring winding machine which permit the cutting device to be reset to optionally carry out a straight cut or a rotational cut, in which the cutting tool is guided along a droplet-shaped trajectory. The cutting tool is held in a carriage guided in a linearly movable fashion in a linear guide. The linear guide is mounted pivotably. A drive motor is coupled to the carriage via a drive shaft, an eccentric and a connecting rod and can as a result bring about the linear to-and-fro movement of the cutting tool. The pivoting movement of the linear guide can be brought about by a second drive shaft acting on the linear guide via an eccentric. The drive motor can optionally be disengaged from the second drive shaft or be engaged with the second drive shaft. If a drive connection is not set, the cutting device carries out a straight cut. During coupling of the second drive shaft to the drive motor, the linear guide carries out an oscillating pivoting movement, with the result that a droplet-shaped trajectory of the cutting tool is produced as a result of the superimposition of the straight linear movement and the pivoting movement.
U.S. Pat. No. 7,055,356 B2 describes components of a cutting device for a spring manufacturing machine which are constructed such that the cutting tool can be moved along an essentially elliptical trajectory. The shape of the trajectory can be changed by manually shifting the position of a sliding element along a linear guide.
JP 2001-293533 A shows components of a cutting device of a spring manufacturing machine. A carriage which is linearly movable in the vertical direction is provided to the front wall of the machine, it being possible to move the carriage up and down using a drive motor via a drive shaft, an eccentric and a connecting rod. The carriage supports on its front side a pivotable element which supports the cutting tool. A further drive motor generates a pivoting movement of this pivoting element via a drive shaft and a Cardan joint with axial length compensation about a pivoting axle mounted in the sliding element in the carriage. The position of the pivoting element on the carriage can be changed by a further shaft with a Cardan joint to change the position of the cutting tool in the spring axial direction.
It could therefore be helpful to provide a user-friendly spring winding machine which can be used in a flexible way and which can manufacture with a high level of productivity helical springs in terms of their cross section, position of the cutting burr and other spring parameters in accordance with their specification.

SUMMARY

I provide a spring winding machine that manufactures helical springs by spring winding including a feed device that feeds wire to a shaping device, wherein the shaping device has at least one winding tool and at least one pitch die; a cutting device that separates a finished helical spring from the fed wire after termination of a shaping operation, wherein the cutting device has a cutting tool which, by a cutting tool drive system, can be moved along a predefinable closed trajectory; a control device that controls the feed device, the shaping device and the cutting device on the basis of an NC control program; and a programmable trajectory-setting system that sets the shape and/or position of the trajectory to be passed through by the cutting tool, wherein a linear trajectory, an elliptical or egg-shaped trajectory, which is mirror-symmetrical with respect to a plane of symmetry and has a predefinable ratio of height to width, or an asymmetrical trajectory with a non-mirror-symmetrical profile which deviates from an elliptical shape or egg shape can optionally be set.
I also provide the spring winding machine wherein the cutting tool drive system has a first drive which can be actuated by the control device and generates a first movement of the cutting tool, and a second drive which can be activated by the control device independently of the first drive and generates a second movement of the cutting tool which is superimposed on the first movement.
I further provide a spring winding machine wherein the cutting tool drive system has a first drive which can be actuated by the control device and generates a first movement of the cutting tool, and a second drive which can be activated by the control device independently of the first drive and generates a second movement of the cutting tool which is superimposed on the first movement and wherein the first drive generates a linear to-and-fro first movement of the cutting tool in a first direction running in the longitudinal direction of the cutting tool, and the second drive is an actuating drive which, during the linear to-and-fro movement of the cutting took in the first direction, additionally generates a pivoting movement of the cutting tool, moved to and fro, about an axis running perpendicular to a working plane.
I further still provide a spring winding machine wherein the cutting tool drive system has a first drive which can be actuated by the control device and generates a first movement of the cutting tool, and a second drive which can be activated by the control device independently of the first drive and generates a second movement of the cutting tool which is superimposed on the first movement and wherein the cutting tool is attached to a carriage which can be moved linearly to and fro along a linear guide in a first direction, and the linear guide is attached to a pivoting element which can pivot about a pivoting axle running perpendicularly to the first direction, and the first drive is coupled to the carriage and the second drive is coupled to the pivoting element.
I further yet provide a spring winding machine that manufactures helical springs by spring winding including a feed device that feeds wire to a shaping device, wherein the shaping device has at least one winding tool and at least one pitch die; a cutting device that separates a finished helical spring from the fed wire after termination of a shaping operation, wherein the cutting device has a cutting tool which, by a cutting tool drive system, can be moved along a predefinable closed trajectory; a control device that controls the feed device, the shaping device and the cutting device on the basis of an NC control program; and a programmable trajectory-setting system that sets the shape and/or position of the trajectory to be passed through by the cutting tool, wherein a linear trajectory, an elliptical or egg-shaped trajectory, which is mirror-symmetrical with respect to a plane of symmetry and has a predefinable ratio of height to width, or an asymmetrical trajectory with a non-mirror-symmetrical profile which deviates from an elliptical shape or egg shape can optionally be set and wherein the control device is configured for teach-in programming.
I also further provide a spring winding machine that manufactures helical springs by spring winding including a feed device that feeds wire to a shaping device, wherein the shaping device has at least one winding tool and at least one pitch die; a cutting device that separates a finished helical spring from the fed wire after termination of a shaping operation, wherein the cutting device has a cutting tool which, by a cutting tool drive system, can be moved along a predefinable closed trajectory; a control device that controls the feed device, the shaping device and the cutting device on the basis of an NC control program; and a programmable trajectory-setting system that sets the shape and/or position of the trajectory to be passed through by the cutting tool, wherein a linear trajectory, an elliptical or egg-shaped trajectory, which is mirror-symmetrical with respect to a plane of symmetry and has a predefinable ratio of height to width, or an asymmetrical trajectory with a non-mirror-symmetrical profile which deviates from an elliptical shape or egg shape can optionally be set and wherein the control device is configured for teach-in programming and wherein the control device is configured such that in a programming configuration the cutting tool can be positioned manually at one or more positions in the region of a desired trajectory, coordinates of the positions can be stored in a memory of the control device, a trajectory can be calculated using the coordinates, and the cutting tool can be moved along the trajectory in an operating configuration under control of the control device.
I still further provide a spring winding machine that manufactures helical springs by spring winding including a feed device that feeds wire to a shaping device, wherein the shaping device has at least one winding tool and at least one pitch die; a cutting device that separates a finished helical spring from the fed wire after termination of a shaping operation, wherein the cutting device has a cutting tool which, by a cutting tool drive system, can be moved along a predefinable closed trajectory; a control device that controls the feed device, the shaping device and the cutting device on the basis of an NC control program; and a programmable trajectory-setting system that sets the shape and/or position of the trajectory to be passed through by the cutting tool, wherein a linear trajectory, an elliptical or egg-shaped trajectory, which is mirror-symmetrical with respect to a plane of symmetry and has a predefinable ratio of height to width, or an asymmetrical trajectory with a non-mirror-symmetrical profile which deviates from an elliptical shape or egg shape can optionally be set, wherein the trajectory-setting system is configured to permit at least three of the following settings independently of one another: (i) an ellipse width of the trajectory between a minimum value 0 for a straight cut and a maximum value relating to a maximum height of the ellipse; (ii) horizontal shifting of the entire trajectory between a minimum value and a maximum value; (iii) inclination of the trajectory between a value 0 for a vertically orientated trajectory, an inclination of the trajectory in the direction of the feed device and an inclination of the trajectory in the opposite direction; and (iv) shifting of the trajectory in its entirety in the vertical direction.
I also further provide the spring winding machine that manufactures helical springs by spring winding including a feed device that feeds wire to a shaping device, wherein the shaping device has at least one winding tool and at least one pitch die; a cutting device that separates a finished helical spring from the fed wire after termination of a shaping operation, wherein the cutting device has a cutting tool which, by a cutting tool drive system, can be moved along a predefinable closed trajectory; a control device that controls the feed device, the shaping device and the cutting device on the basis of an NC control program; and a programmable trajectory-setting system that sets the shape and/or position of the trajectory to be passed through by the cutting tool, wherein a linear trajectory, an elliptical or egg-shaped trajectory, which is mirror-symmetrical with respect to a plane of symmetry and has a predefinable ratio of height to width, or an asymmetrical trajectory with a non-mirror-symmetrical profile which deviates from an elliptical shape or egg shape can optionally be set, wherein the feed device is configured to continuously feed the wire, and the cutting device has a cutting tool which can be driven in rotation, and the spring winding machine is configured such that the finished helical spring is separated from the feed wire by a rotating flying cut.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic overview illustration of an example of a spring winding machine.

FIGS. 2 and 3 show enlarged views of components of the shaping device and various adjustable trajectories for the cutting tool.

FIGS. 4 to 6 show in schematic form various views of components of the cutting device from FIG. 1.

FIG. 7 shows a view of a graphic operator interface which assists the user in setting the trajectory.

FIG. 8 shows in 8A to 8E schematic views of various types of cut.

FIG. 9 shows a plan view of components of another example of a cutting device.

DETAILED DESCRIPTION

My spring winding machines have a programmable trajectory-setting system to set the shape and/or position of the trajectory to be passed through by the cutting tool. The trajectory-setting system makes it possible to set different types of cut in a flexible and simple way. In this context, a linear trajectory (for a straight cut), an elliptical or egg-shaped trajectory, which is mirror-symmetrical with respect to a plane of symmetry and has a predefinable ratio of height to width, or an asymmetrical, i.e., non-mirror-symmetrical, trajectory with a profile which deviates from an elliptical shape or egg shape can optionally be set. As a result of these setting options it is possible, depending on the application, to bring about, inter alia, expansion of the range of uses of the straight cut or of a rotational cut, control the output rate (machine output), control the cross section on the finished helical spring, control the position of the cutting burr on the finished helical spring and/or an increase in the service life of the cutting tools, in particular in the case of the straight cut.
I employ a programmable trajectory-setting system, as a result of which it is possible for an operator to predefine a large range of different trajectories for the cutting tool without manual interventions in the mechanical components of the cutting device and to program the trajectories solely by control interventions.
Preferably, the setting options are made possible by virtue of the fact that the cutting tool drive system has a first drive, which can be actuated by the control device and generates a first movement of the cutting tool, and a second drive, which can be activated by the control device independently of the first drive and generates a second movement of the cutting tool superimposed on the first movement. Different components of the cutting movement can thereby be set in almost any desired ratios with respect to one another.
The first movement is preferably a straight linear movement in a first direction, and the second movement is preferably a pivoting movement superimposed on the linear movement and is transverse with respect to the first direction. It would also be possible to superimpose two straight linear movements in directions which are perpendicular to one another.
The cutting tool may be attached to a carriage which can be moved linearly to and fro along a linear guide in a first direction, and the linear guide may be attached to a pivoting element which can pivot about a pivoting axle running substantially perpendicularly to the first direction, wherein the first drive is coupled to the carriage, and the second drive is coupled to the pivoting element. As a result, a particularly rigid arrangement is provided, which generates only relatively small tilting moments even in the case of large cutting forces. It is also possible to attach a pivoting element on a linearly moveable carriage.
The possibility of making the shape and/or position of the cutting path (trajectory of the cutting tool) exclusively by settings for the electric drives is used in one example of the spring winding machine during programming of the trajectory in a teaching process to approach manually one, two, three or more edge points or disrupting contours and, as a result, to position the trajectory in such that during later operation the trajectory remains within these disrupting contours and no collisions can occur, for example, with a winding tool or pitch die. For this purpose, the control device is configured for teach-in programming. The configuration is preferably such that in a programming configuration the cutting tool can be positioned manually at one or more positions in the region of a desired trajectory, the coordinates of the positions can be stored in a memory of the control device, a trajectory can be calculated using the coordinates, and the cutting tool can be moved along the trajectory in an operating configuration under the control of the control device. The approached positions are usually disrupting points defined as points which the trajectory must not overshoot.
The spring winding machine may be equipped with a camera system which with its image field captures the region of the shaping tools essentially from the front, i.e., parallel to the direction of the desired spring axle. From the images captured in this way it is possible to determine the position of the disrupting contours using an image processor. This determination can be made manually, semi-automatically or fully automatically. As a result, a virtual teaching process is possible in which the machine axes or the tools, in particular the cutting tool, do not have to be moved. In this case, the control device may also be configured for teach-in programming.
These and further features can arise not only from the appended claims but also from the description and the drawings, wherein the individual features are each implemented alone or together in the form of subcombinations in one example and in other fields, and can form advantageous examples which can be protected in themselves.
The schematic overview illustration in FIG. 1 shows a number of structural elements of a CNC spring winding machine 100 according to an example. FIGS. 2 to 6 show details.
The spring winding machine 100 has a feed device 110 equipped with feed rollers 112 and which can feed successive portions of a wire 115 which comes from a wire stock, is guided through a straightening device 114 and has a numerically controlled advancing speed profile in the horizontal direction into the region of a shaping device 120. Components of the shaping devices are shown in FIGS. 2 and 3. The wire is guided on the outlet side through a wire guide 116. The feed device can also be referred to as a pull-in device and, accordingly, the wire advance can also be referred to as a pulling in of the wire and the advancing speed as the pull-in speed.
The wire is shaped to form a helical spring with the aid of numerically controlled tools of the shaping device 120. The tools include two winding pins 122, 124 arranged offset at an angle of 90° and orientated in the radial direction with respect to the central axis 118 or with respect to the position of the desired spring axle and determine the diameter of the helical spring. The position of the winding pins can be changed for the basic setting of the spring diameter during set up in obliquely running directions as well as in the horizontal direction to set up the machine for different spring diameters. These movements can be performed using suitable electric drives under the control of the numeric controller.
A pitch die 130 has a tip orientated substantially perpendicularly to the spring axle and which engages next to the turns of the unwinding spring. The pitch die can be moved with the aid of a numerically controlled adjustment drive of the corresponding machine axle parallel to the axle 118 of the unwinding spring (i.e., perpendicular to the plane of the drawing). It is therefore also referred to as “pitch parallel.” The wire which is pushed forward during manufacture of the spring is pushed away in the direction parallel to the spring axle by the pitch die corresponding to the position of the pitch die, wherein the position of the pitch die determines the local pitch of the spring in the corresponding section. Changes in pitch are brought about by axis-parallel movement of the pitch die during manufacture of the spring.
The shaping device can have a further pitch die which can be moved in vertically from below and which has a wedge-shaped die tip inserted between adjacent windings when the pitch die is used. The adjustment movements of this pitch die run perpendicularly to the axle 118. This is therefore also referred to as “pitch perpendicular.” The pitch dies can be made to engage as required. In a specific spring winding process typically only one of the pitch dies is in engagement.
A numerically controllable cutting device 150 with a cutting tool 152 is provided above the spring axle, the cutting tool 152 separating, after termination of a shaping operation, the manufactured helical spring from the fed wire stock with a defined working movement. The cutting tool is for this purpose moved such that the cutting tool or its cutting edge 153 moves along a predefined, closed trajectory (cutting path) in a plane which lies perpendicular to the axle 118. FIGS. 2 and 3 show, for example, by dot-dash lines a number of possible trajectories BK1, BK3 which are also explained later in detail.
A mandrel 155 (trimming mandrel) serves as an opposing element for the cutting tool and is located in the interior of the unwinding spring and has an oblique cutting edge 156 which interacts with the cutting tool 152 during the separation process.
The cutting tool 152 is also referred to below as a cutting blade 152. The trajectory of the cutting tool, which is also referred to as a cutting curve, is defined here as that trajectory travelled along by the cutting edge 153 of the cutting tool in the working plane of the cutting tool which is perpendicular to the central axle 118.
The spring winding machine or the cutting device is configured such that the cutting path, that is to say the trajectory of the cutting tool during the cutting movement, within a structurally defined working range AB can be set to almost any desired profiles and changed. The settings do not require intervention by an operator in the mechanical components. Instead, the settings can be programmed by the operator control unit 104 of the spring winding machine using the control unit 102. The profile of the trajectory can therefore be adapted in an optimum way to different conditions during the manufacture of the spring.
With a freely programmable trajectory-setting system it is possible to predefine the shape and/or the position of the trajectory to be passed through by the cutting tool by programming the control unit 102. It is possible in this context to set, in addition to the cutting methods of the straight cut which can occasionally also be set in conventional spring winding machines (the cutting tool is moved to and fro along a linear trajectory) and the so-called rotational cut in which, to cut the wire, the cutting tool passes through an elliptical or egg-shaped trajectory which is mirror-symmetrical with respect to a plane of symmetry, also asymmetrical profiles of the trajectory which have a non-mirror-symmetrical profile which deviates from an elliptical shape or egg shape.
For this purpose, in an example, a cutting tool drive system comprises two electric drives 165, 175 which can be controlled independently of one another by the control unit 102 (cf. FIG. 6) and which are coupled to the cutting tool 152 to transmit tool movements. Both drives are electric servo drives. A first drive generates a linear to-and-fro first movement of the cutting tool in a first direction 154 which runs in the longitudinal direction of the cutting tool 152. The second drive generates a second movement of the cutting tool which is superimposed on the first movement, and the second drive functions in the exemplary case as an actuating drive which, during the linear to-and-fro movement of the cutting tool in the first direction, additionally generates a pivoting movement of the cutting tool, moved to and fro, about an axis running perpendicular to the working plane. As a result of the superimposition of the linear to-and-fro, essentially vertically extending movement on the pivoting movement it is possible to implement variable trajectories for the cutting tool.
As a result of the size and/or amplitude of the pivoting movement it is possible, for example, to set the width of an elliptical trajectory (measured perpendicularly to the first direction 154). If no pivoting movement is carried out so that only the linear movement remains, a straight cut can be carried out. As a result of the size and/or amplitude of the linear movement, in the case of a rotational cut, it is possible within the structurally predefined limits to set the height of the elliptical trajectory (measured parallel to the first direction), which corresponds to the stroke in the first direction 154 in the case of the straight cut. By predefining corresponding starting points of the drives it is additionally possible to change the position of the trajectory, for example, the position of an elliptical trajectory to be able to position the trajectory in an optimum way with respect to the trimming mandrel and the wire.
The first drive with its associated components should make available a certain centrifugal mass so that sufficient kinetic energy is made available for the cut. The second drive should have high dynamics to permit rapid changes in movement when necessary.
For the sake of further explanation, FIG. 2 illustrates the position of the rest of the cutting tool 152. FIG. 3 shows a situation in which the cutting edge 153 of the cutting tool is located precisely at the impact point 117 on the wire during the movement in the direction of the wire. The dot-dash lines represent a number of possible paths of the cutting edge of the cutting tool, that is to say the trajectories. Due to the mechanical conditions of the example, the cutting edge can theoretically travel through an approximately trapezoidal working range AB when the first and second drives each carry out their maximum strokes. Within this working range it is possible to map trajectories of almost any shape and position, wherein, of course, the necessary dynamics usually make certain trajectory profiles, for example, ones with corners or sharp bends, impractical during execution of the cutting movements. Within the working range it is, however, possible to generate narrow or wide ellipses, straight paths, oblique paths, shaped curves, laterally offset ellipses or other trajectories. As a result, the profile of the cutting path can be adapted in terms of control technology to the conditions.
A number of examples of particularly advantageous trajectories under different production conditions are explained in more detail below, for example, in relation to FIG. 8.
FIGS. 4 to 6 show various schematic views of components of the cutting device 150 from FIG. 1, which permit different trajectories to be flexibly set. An essentially rectangular pivoting plate 160 is rotatably mounted on a horizontal pivoting axle 161 on the vertical front wall 106 of the spring winding machine 100. The to-and-fro pivoting movement is implemented by a horizontally orientated pivoting shaft 162 which is driven by a second drive 165 which serves as a pivoting drive. The pivoting shaft 162 has at its front end an eccentric bolt 163 which bears a link 164 guided in a rectangular recess of the pivoting plate 160 to be movable in the longitudinal direction of the pivoting plate.
A linear guide 170 is provided on the front side of the pivoting plate 160 facing away from the pivoting axle 161 and is orientated in the longitudinal direction of the pivoting plate and bears a carriage 171 to which a tool holder 155 for the cutting tool 152 is attached. The cutting tool projects out of the tool holder at the lower end. At the upper end, a connecting rod 172 is provided in a pivotable fashion by a securing bolt, the connecting rod 172 being infinitely adjustable in terms of its length and being connected at its other end to an eccentric bolt 173 located on the end side of a cutting shaft 174. The latter is driven by the first drive 175.
The first and second drives, which are each formed by electric servo drives, are actuated in principle independently of one another, but in a coordinated fashion, by the control device 102. The “coupling” of the drives is not effected here in a mechanical fashion but rather instead exclusively by software, that is to say by the control program. This provides a high degree of flexibility during generation of working movements of the cutting tool.
The first drive 175 drives, via the cutting shaft 174, the essentially vertical linear cutting movement of the carriage 171 which bears the cutting tool 152. The pivoting shaft 162 which is driven by the second drive 165 functions, in contrast, merely as an actuating drive and is activated intermittently, that is to say generally does not carry out a 360° rotation. The cutting shaft 174 is, on the other hand, continuously operated in the same rotational direction and with a varying rotational speed to make available the necessary energy and speed for the separating process. However, it would also be possible to intermittently activate the cutting drive (first drive). This can be appropriate, for example, if the height of the trajectory in the upward direction is to be reduced compared to the maximum achievable height.
The first drive 175 (cutting drive) and the second drive 165 (pivoting drive) can be actuated independently of one another so that theoretically any desired superimpositions of the linear movement in the first direction 154 and of the pivoting movement superimposed thereon in the transverse direction are possible.
The pivoting element 160 can be secured in the vertical position by a locking device which can be moved into or out of engagement with the pivoting arm by machine commands, with the result that the carriage 171 is moved exclusively in the vertical direction. The locking device can have, for example, a bolt which can be activated electrically or pneumatically and which can be moved from behind (from the machine side) into a drilled hole on the rear side of the pivoting plate. By virtue of the locking, the arrangement becomes free of play in terms of the pivoting movement and reinforcement of the structure occurs for the vertical cut so that large cutting forces can be transmitted without excessive loading of the components of the cutting device.
The trajectory-setting system of the example is configured in a very user-friendly manner, and the complex settings for the correct trajectory can therefore be performed intuitively even by less experienced operators. FIG. 7 shows by way of example a view of the operator control unit with a graphic operator interface which assists the user during the setting operations. In the rectangular graphic representation shown on the left, a symbol 155′ for the currently used trimming mandrel, a symbol 130′ for the holder of the currently used pitch die and a symbol 115′ for the wire are represented at the lower edge of the image. The tools 155 and 130 form in the exemplary case the relevant disrupting contours which have to be taken into account during the configuration of the trajectory of the cutting blade. They are illustrated in the correct position and with the correct size ratio in the graphic generated by the control unit 102. The obliquely running dashed line in an extension of the oblique cutting edge (chamfer on the trimming mandrel) helps during the correct setting of the cutting gap. The cutting gap is defined here as the perpendicular distance between the cutting edge or the dashed line and a tangent, running parallel thereto, to the trajectory BK1 or BK4 at the impact point 117 on the wire. For excellent cutting results, this cutting gap should generally be 30 to 70° of the diameter of the wire.
At the operator interface, switching buttons to set trajectory parameters are made available to the operator to the right next to the graphical representation. With the upper switching button ELB it is possible to set the ellipse width between a minimum value (0) and a maximum value (90) by activating the arrow keys. These values respectively relate to a constant height of the ellipse. When the lower limiting value ELB=0 is set, a straight cut (linear to-and-fro movement of the cutting tool) is therefore carried out.
The switching button VH below brings about horizontal shifting of the entire closed trajectory between a minimum value VH=0 and a maximum value by activating the arrow keys. This horizontal displaceability of the trajectory makes it possible, inter alia, to use identical tools (mandrel, diameter) for different trajectories. If only the width of the ellipse were adjustable, the middle of the trajectory would remain unchanged and the impact point of the cutting tool on the wire would migrate away from the mandrel or in the direction of the mandrel. The cutting conditions would therefore generally worsen. Without lateral adjustability the cutting blade would theoretically have to have a somewhat different cutting geometry for each trajectory.
It is possible to provide that the adjustment of the ellipse width and the adjustment of the horizontal position of the trajectory are linked by software such that only parameter combinations which do not move the position of the impact point, or only do so slightly, so that an excellent cut remains possible can be set. If appropriate, a warning signal can be generated when parameters do not match one another sufficiently well.
The inclination of the trajectory can be set by the switching button N below. A value N=0 corresponds to a vertically orientated trajectory (long half axis vertical), and in the case of negative values the trajectory is tilted to the left, that is to say in the pull-in direction, and in the case of positive values to the right, in the direction of the winding pins. The switching button VV below brings about displacement of the trajectory in its entirety in the vertical direction. The value for the current wire diameter is input with the lower switching button D. Other configurations that in the end offer the same, equivalent or similar setting possibilities are possible.
The setting possibilities are given only by way of example. Individual setting possibilities can also be dispensed with completely in variants. Setting possibilities can be implemented in practice in different ways. Some or all of the parameters can, for example, be input directly into the control software, with the result that an operator interface with sliding controllers or the like is not necessary. The vertical adjustment of the trajectory is generally not programmed, but instead can be implemented by manual adjustment of the length of the connecting rod. It is also possible to store in a memory of the control device a number of predefined trajectory basic types which are controlled, for example, with respect to production speed or other parameters. These can then be retrieved by the operator and, if appropriate, then finely adjusted by changing individual parameters and adapted to the conditions of the spring winding process which is currently to be set up.
In the text which follows, a number of selected types of cut are explained with their specific application areas and properties with reference to FIG. 8. If appropriate, part of the cutting tool SW, part of the trimming mandrel DO, the end piece of the remaining wire DR with the cutting burr SG and the trajectory BK of the cutting edge of the cutting tool are shown schematically. The various elements are shown in an exploded view in the vertical direction for illustrative reasons.
The system can be set for a straight cut (FIG. 8A) in which the cutting tool is moved only vertically and a cutting tool and a trimming mandrel are each selected with a perpendicular cutting edge. The ellipse width and the inclination are for this purpose each set to zero. Advancing of the wire is stopped for the cut. With this type of cut a cutting burr SG is typically produced on the wire and is directed inward in the direction of the central axis of the spring.
The system can also be set to a rotational cut or a rotating elliptical cut (FIG. 8B). In this context, the cutting tool moves on an elliptical trajectory with a horizontal movement component and a vertical movement component, wherein a fixed height-width ratio is set. The cutting tool which is used and the trimming mandrel which is used may have an oblique cutting edge or chamfer in this case. With this type of cut, the cutting burr is generally directed in the winding direction of the wire, with the result that the internal diameter of the spring is not limited, or hardly limited. For this purpose, only the ellipse width ELB is set to the desired value.
The example permits these types of cut, which are also frequently made available with conventional spring winding machines, with a range which is increased compared to the prior art and with a simplified setting capability. The straight cut described above (vertical tool movement in conjunction with the blade and the trimming mandrel with a perpendicular cutting edge) can be modified to form a modified straight cut (FIG. 8C). In this context, a cutting tool and a trimming mandrel with a perpendicular cutting edge are also used. However, the cutting tool does not move exclusively vertically, but also has a slight horizontal movement component, with the result that a narrow elliptical shape (with an adjustable height-width ratio) is produced. A cutting burr mainly directed inwardly in the direction of the central axis of the spring is also produced. However, since, due to the slight elliptical shape, the upward movement of the cutting tool after the vertical cutting movement takes place at a small distance from the cutting edge and from the cutting surface on the wire, the cutting tool is no longer in contact with the cut-off wire during the return travel. As a result, the wear on the tool can be considerably reduced. Typical ratios between the height and the width of the essentially elliptical trajectory can be, for example, 5:1 to 30:1, in particular 12:1 to 25:1.
Furthermore, a large number of other variants of the rotational cut are available. In the case of the “variably rotating cut” type of cut (FIG. 8B), the pull-in of the wire for the cutting operation is stopped. A blade (cutting tool) and a trimming mandrel with oblique cutting edges are used. The cutting edge of the tool moves along an ellipse with a variably adjustable height-width ratio, typically in the case of relatively narrow to medium-width ellipses. In this case, it is possible to operate with “pitch perpendicular” or “pitch parallel”. A cutting burr is produced which is arranged essentially in the winding direction of the wire. The cutting burr is therefore within the inner and outer envelope curve of the spring, that is to say it does not project inwardly or outwardly beyond the spring.
In the case of the “flying rotating cut” type of cut (FIG. 8D), the spring winding machine operates with continuous advancing of the wire or pulling in of the wire in conjunction with a flying rotating cut. In this context, the cutting tool moves with a horizontal movement component and a vertical movement component on an elliptical trajectory with a relatively wide ellipse, that is to say relatively small height-width ratio. As a result, relatively high horizontal components of the movement during the cut are achieved. The cutting tool and trimming mandrel each have corresponding oblique cutting edges. Operations are carried out, for example, with a perpendicular pitch (lower pitch die). Depending on the design, the revolution can be elliptical or even circular. The revolving speed is normally non-uniform.
With this type of operation of the continuous advancing of the wire with a rotating flying cut, the wire is continuously advanced or pulled in with a constant or varying final advancing speed. Therefore, the wire feed does not come to a standstill during the production of a large number of successive helical springs. As a result, the output rate is increased. If the advancing of the wire runs constantly, the wire stock, which is, for example, kept on a reel, does not have to be continuously accelerated and braked. This also applies to the drives of the feed device and the tools. As a result, the energy requirement per spring is reduced compared to methods with a standing cut in which the advancing of the wire has to be stopped for the cutting process. In addition, there is no jerky pulling on the wire and no stick-slip effect, as a result of which the quality of the manufactured springs can be significantly increased compared to methods with a standing cut.
In the “flying cut” mode of operation there is automatic coordination of the movement speed of the cutting tool along the trajectory with the pull-in speed of the wire such that the shape of the trajectory is adapted to the revolving speed of the cutting tool such that in a time interval starting before the cutting edge penetrates into the wire until the cutting contact between the cutting tool and the wire is eliminated the movement speed of the cutting edge in the horizontal direction (essentially parallel to the wire advancing direction) is higher than the wire advancing speed. If that time interval in which the cutting tool is in engagement with the wire is referred to as the “wire collision region,” then the cutting tool should be accelerated such that its horizontal component (parallel to the wire advancing speed) is already larger before the start of the cut than that of the wire and does not drop below the speed of the wire again until after it moves out of the wire. For this reason, in this mode of operation flat elliptical trajectories with a relatively large width and correspondingly large horizontal component of the movement speed generally have to be set.
The elliptical paths of the cutting tool described here by way of example constitute only a number of special shapes of the theoretically possible trajectories. The curve BK3 in FIG. 2 constitutes one example of an asymmetrical, controlled trajectory shape with a finite height-width ratio. With this curve the same advantages are obtained during the cut as with an elliptical curved path BK1, but less space is required for the pitch die 130, with the result that such trajectory shapes can be useful particularly in the case of restricted conditions in the region of the shaping tools. A large number of other path shapes are possible, for example, even a flattened ellipse in the region of the chamfer on the trimming mandrel (FIG. 8E). The cutting path can, for example, be configured such that the flattened part runs parallel to the chamfer on the trimming mandrel with a largely linear profile. By suitable deformations, it is possible to set a large number of useful asymmetrical trajectory shapes on the basis of the basic shape of the ellipse or the egg shape.
Restrictions on the theoretically possible trajectories are, on the one hand, caused by disrupting edges or collision points with other tools such as winding fingers or pitch dies and, on the other hand, are conditioned by the limits of the dynamics or efficiency of the drive motors. These peripheral conditions can be taken into account, inter alia, in a method variant in which teach-in programming takes place. In this method variant, the potential collision points in the region of the shaping tools are approached manually with the cutting tool by the operator. When the cutting tool is positioned at a collision point, this position is transferred to the controller, that is to say communicated to the controller, by an input by the operator. By using these positions, the trajectory is then calculated automatically such that these collision regions are excluded from the curved path which is selected by the operator, or are not approached but are bypassed.
My machines and methods permit different technical problems to be addressed alternatively or cumulatively. On the one hand, the range of use is expanded compared to conventional systems with a straight cut and a rotating cut. Where possible, the output rate and/or the machine output can also be controlled. In many cases, the cross section at the cut wire is controlled. Furthermore, the position of the cutting burrs remaining on the wire can be controlled with respect to the intended use or further processing of the springs. Not least, suitable settings can increase the service life of the cutting tools, in particular in the case of the straight cut.
By setting the position and inclination of the trajectory or curved path during the cutting process, that is to say while the cutting tool is in contact with the wire, the inclination of the cutting edge on the wire can be determined. Furthermore, by these setting possibilities it is possible to determine the inclination or position of the remaining cutting burr. During the modified straight cut (narrow ellipse) the cutting edge is treated gently and chipping is prevented since the lateral moving away of the wire edge after completion of the cut relieves the cutting tool of lateral transverse forces caused by the wire.
Thanks to the possibility of programming the various trajectories, these advantages can be set much more easily, without mechanical intervention at the spring winding machine, than in conventional spring winding machines which had a possibility of setting different trajectories.
FIG. 9 shows a different structural example of components of the cutting device which likewise provides all the setting possibilities described above. The cutting tool 952 which is secured by a tool holder is also mounted on a carriage 971 guided in a linearly movable fashion by a linear guide 970. The linear guide is mounted on a plate-shaped pivoting element or a pivoting plate 960 rotatably mounted on a horizontal pivoting axle which is attached to the vertical front wall of the spring winding machine. Two separate drives which can be actuated independently of one another by the control device 902 are provided for the linear movement and the pivoting movement. A first drive 975 drives the horizontal cutting shaft 974, which has at its end side an eccentric bolt rotatably mounted in a link. The link is guided in a recess in the carriage 971 to be perpendicularly displaceable with respect to the longitudinal direction of the carriage. In this way, rotation of the cutting shaft brings about an up-and-down movement of the carriage 971 in the first direction 954, i.e., in the longitudinal direction of the pivoting element 960. The to-and-fro oscillating pivoting movement of the pivoting element is brought about by the second drive 965 which drives a pivoting shaft 962 in an intermittent fashion or to and fro. The pivoting shaft 962 has on its end side an eccentric bolt rotatably mounted in a link which is guided in a recess in the pivoting element 960 to be movable in the longitudinal direction thereof.
In this example, the pivoting shaft 962 is therefore arranged above the cutting shaft 974. In contrast to this, the arrangement in the example in FIGS. 4 to 6, where the cutting shaft is seated above the pivoting shaft, is reversed. These mechanical components of the cutting tool drive system can therefore be configured and arranged with respect to one another in different ways as a function of the available installation space and of other requirements.

Claims

1. A spring winding machine that manufactures helical springs by spring winding comprising:

a feed device that feeds wire to a shaping device, wherein the shaping device has at least one winding tool and at least one pitch die;

a cutting device that separates a finished helical spring from the fed wire after termination of a shaping operation, wherein the cutting device has a cutting tool which, by a cutting tool drive system, can be moved along a predefinable closed trajectory;

a control device that controls the feed device, the shaping device and the cutting device on the basis of an NC control program; and

a programmable trajectory-setting system that sets the shape and/or position of the trajectory to be passed through by the cutting tool, wherein a linear trajectory, an elliptical or egg-shaped trajectory, which is mirror-symmetrical with respect to a plane of symmetry and has a predefinable ratio of height to width, or an asymmetrical trajectory with a non-mirror-symmetrical profile which deviates from an elliptical shape or egg shape can optionally be set.

2. The spring winding machine according to claim 1, wherein the cutting tool drive system has a first drive which can be actuated by the control device and generates a first movement of the cutting tool, and a second drive which can be activated by the control device independently of the first drive and generates a second movement of the cutting tool which is superimposed on the first movement.

3. The spring winding machine according to claim 2, wherein the first drive generates a linear to-and-fro first movement of the cutting tool in a first direction running in the longitudinal direction of the cutting tool, and the second drive is an actuating drive which, during the linear to-and-fro movement of the cutting tool in the first direction, additionally generates a pivoting movement of the cutting tool, moved to and fro, about an axis running perpendicular to a working plane.

4. The spring winding machine according to claim 2, wherein the cutting tool is attached to a carriage which can be moved linearly to and fro along a linear guide in a first direction, and the linear guide is attached to a pivoting element which can pivot about a pivoting axle running perpendicularly to the first direction, and the first drive is coupled to the carriage and the second drive is coupled to the pivoting element.

5. The spring winding machine according to claim 1, wherein the control device is configured for teach-in programming.

6. The spring winding machine according to claim 5, wherein the control device is configured such that in a programming configuration, the cutting tool can be positioned manually at one or more positions in the region of a desired trajectory, coordinates of the positions can be stored in a memory of the control device, a trajectory can be calculated using the coordinates, and the cutting tool can be moved along the trajectory in an operating configuration under control of the control device.

7. The spring winding machine according to claim 1, wherein the trajectory-setting system is configured to permit at least three of the following settings independently of one another:

(i) an ellipse width of the trajectory between a minimum value 0 for a straight cut and a maximum value relating to a maximum height of the ellipse;

(ii) horizontal shifting of the entire trajectory between a minimum value and a maximum value;

(iii) inclination of the trajectory between a value 0 for a vertically orientated trajectory, an inclination of the trajectory in the direction of the feed device and an inclination of the trajectory in the opposite direction;

(iv) shifting of the trajectory in its entirety in the vertical direction.

8. The spring winding machine according to claim 1, wherein the feed device is configured to continuously feed the wire, and the cutting device has a cutting tool which can be driven in rotation, and the spring winding machine is configured such that the finished helical spring is separated from the feed wire by a rotating flying cut.

9. The spring winding machine according to claim 3, wherein the cutting tool is attached to a carriage which can be moved linearly to and fro along a linear guide in a first direction, and the linear guide is attached to a pivoting element which can pivot about a pivoting axle running perpendicularly to the first direction, and the first drive is coupled to the carriage and the second drive is coupled to the pivoting element.

10. The spring winding machine according to claim 2, wherein the control device is configured for teach-in programming.

11. The spring winding machine according to claim 3, wherein the control device is configured for teach-in programming.

12. The spring winding machine according to claim 4, wherein the control device is configured for teach-in programming.

13. The spring winding machine according to claim 2, wherein the trajectory-setting system is configured to permit at least three of the following settings independently of one another:

(iv) shifting of the trajectory in its entirety in the vertical direction.

14. The spring winding machine according to claim 3, wherein the trajectory-setting system is configured to permit at least three of the following settings independently of one another:

(iv) shifting of the trajectory in its entirety in the vertical direction.

15. The spring winding machine according to claim 4, wherein the trajectory-setting system is configured to permit at least three of the following settings independently of one another:

(iv) shifting of the trajectory in its entirety in the vertical direction.

16. The spring winding machine according to claim 5, wherein the trajectory-setting system is configured to permit at least three of the following settings independently of one another:

(iv) shifting of the trajectory in its entirety in the vertical direction.

17. The spring winding machine according to claim 6, wherein the trajectory-setting system is configured to permit at least three of the following settings independently of one another:

(iv) shifting of the trajectory in its entirety in the vertical direction.