Method for measuring a flatness deviation and / or the forming height of components and punching or forming machines

Abstract

The invention relates to a method for measuring a flatness deviation and / or the forming height of components in a punching or forming machine, comprising the steps: - measuring the distance (s0) between an upper starting position of an upper measuring tool (10) and the plane of a lower measuring tool (11); - placing a component to be measured (16) on the lower measuring tool (11); - moving the upper measuring tool (10) from its upper starting position until a force sensor (14) assigned to the upper or lower measuring tool indicates contact between the upper measuring tool (10) and the component (16) by an increase in the measured force, and measuring the distance s1 between the upper starting position of the upper measuring tool (10) and the contact plane between the upper measuring tool (10) and the component (16); - Determining the flatness deviation or forming height h of the component (16) from the equation: h = s0 - s1 - d, where s0 is the distance between the starting position of the upper measuring tool (10) and the lower measuring tool (11), s1 is the distance traveled by the upper measuring tool (10) from its upper starting position until it hits the component (16) and d is the starting thickness of the component (16).

Description

The invention relates to methods for measuring a variation in flatness and / or the forming height of components in a punching or forming machine.In the previously known methods, the quality of stamped or formed parts is controlled outside the stamping or forming machine in a quality control process downstream of the actual stamping or forming process. For this purpose, cameras, optical or tactile sensors are generally used in order to check, in particular, the dimensional accuracy of the components. If the quality control results in greater deviations from the flatness requirements of the component or the required forming height, the component must be post-processed or sorted out as scrap as far as possible. To avoid the production of further scrap parts, process parameters of the punching or forming machine are subsequently adjusted accordingly, usually manually.Due to the downstream quality control, however, these adaptations of the process parameters of the machine cannot take place promptly, so that relatively many parts have to be sorted out as scrap parts. Any subsequent processing of components can also only take place with a time delay.The invention is based on the object of enabling measurement of the flatness and the forming height of components already in the punching or forming machine.This object is achieved according to the invention by a method for measuring a flatness deviation and / or the forming height of components in a punching or forming machine, having the steps:measuring the distance between an upper starting position of an upper measuring tool and the plane of a lower measuring tool;placing a component to be measured on the lower measuring tool;moving the upper measuring tool from its upper starting position until a force sensor associated with the upper or lower measuring tool, in particular a force sensor integrated in the upper or lower measuring tool, indicates a contact between the upper measuring tool and the component by increasing the measured force, and measuring the distance s 1 between the upper starting position of the upper measuring tool and the contact plane between the upper measuring tool and the component;determining the flatness deviation or forming height h of the component from the equation: h = s 0- s 1- d,where s 0 is the distance between the starting position of the upper measuring tool and the lower measuring tool, s 1 is the distance travelled by the upper measuring tool from its upper starting position until it makes contact with the component, and d is the starting thickness of the component.The dependent claims relate to preferred embodiments of the method.The terms "flatness deviation" and "forming height" are defined here as the smallest distance between two ideal planes, wherein all points of the measured component surfaces must lie between these two planes. In a completely planar component, the flatness deviation h is therefore equal to zero. The initial thickness d of the component is its thickness before the punching or forming process, i.e. as a rule the thickness of the sheet metal from which the component is punched out or which is used as a blank for the forming process.The force sensor being "assigned" to the upper or lower measuring tool means, in the sense of the present invention, that the force sensor can be arranged integrally in the upper or lower measuring tool. Likewise, the force sensor can be arranged in a drive acting on the upper or lower measuring tool. A force measured by means of the force sensor can consequently be detected directly or indirectly.By means of the method according to the invention, components produced in a punching or forming machine can still be checked in the machine for a flatness deviation and / or a deviation from the required forming depth. The quality control is thus performed here close to the production process. A subsequent quality control and the devices required for this can be saved and the process chain for producing the components can thus be shortened. The method thus makes a contribution to a lasting and economical production of stamped and formed parts.In the case of a deviation of the ascertained value h for the flatness deviation from a tolerance value, process parameters of the punching or forming machine can be adapted for future punching work in such a way that the flatness deviation of the produced components remains below the tolerance value. In this way, the number of scrap parts can be significantly reduced. Impermissible deviations of the flatness of a component are immediately detected and an adaptation of the parameters can already take place before the production of the next component. The adaptation of the process parameters is also possible fully automatically in the machine by the quality control of the component. For this purpose, the measurement system can preferably be coupled to the machine controller.When carrying out the method for determining the forming height of a component, a post-processing of the component can be carried out in the punching or forming machine if the determined value h for the forming height deviates from a setpoint value. In addition, an adaptation of the process parameters of the machine can naturally also be carried out in this case. For the purpose of post-processing the component, it does not have to be fed to the machine again. The post-processing can therefore take place promptly and without manual intervention.The measurement of the distance between the upper starting position of the upper measuring tool and the plane of the lower measuring tool can be performed in absolute terms, i.e. an absolute value for this distance can be determined. Alternatively, the position of the upper and lower measurement tools may be referenced. For this purpose, in order to measure the distance between the upper starting position of the upper measuring tool and the plane of the lower measuring tool, the upper measuring tool can be moved from its upper starting position toward the lower measuring tool until the force sensor assigned to the upper or lower measuring tool, in particular the force sensor integrated in the upper or lower measuring tool, indicates an increase in force when the upper measuring tool hits the lower measuring tool, and the distance travelled by the upper measuring tool until the contact of the lower measuring tool is measured. This path corresponds to the distance between the upper starting position of the upper tool and the lower tool.To achieve reliable measurement results, upper and lower measurement tools can advantageously be used, which have planar horizontal surfaces. These surfaces should also be as large as possible and preferably should not be able to move past each other.The measuring tools can be separate tools used only for this purpose or punching or forming tools of the machine can also be used as measuring tools, wherein the upper punching or forming tool has a planar horizontal underside and the lower punching or forming tool is formed by a die with a planar bearing surface. By means of a tool changer of the machine, the measuring tools or the punching or forming tools suitable for the measurement can be changed in before the measurement is carried out.The distance or distance measurement signals and the signals of the force sensor can preferably be synchronized at close time in order to quickly obtain a reliable measurement result of the flatness deviation or the forming height.Advantageously, a force-path diagram can be created from the measurements. From this diagram, the flatness deviation or the forming depth can be read directly.The invention also relates to a punching or forming machine having a position measuring system for the movement of its tools, a replaceable upper measuring tool and a replaceable lower measuring tool, wherein a force sensor is assigned to the upper or lower measuring tool, in particular a force sensor is integrated in the upper or lower measuring tool, which force sensor is characterized in that it is configured to carry out a method according to one of the preceding claims.Further features and advantages of the invention are evident from the description, the claims and the drawing. According to the invention, the features mentioned above and those set out further below can each be used individually or together in any desired suitable combinations. The embodiments shown and described are not to be understood as a final enumeration, but rather have exemplary character for describing the invention.DETAILED DESCRIPTION OF THE INVENTION AND DRAWINGFIGS. 1 a, 1 b show a schematic representation of the starting phase of a method according to the invention and an associated force-path diagram; FIGS. 2 a, 2 b show a schematic representation of a reference measurement according to the method according to the invention and an associated force-path diagram; FIGS. 3 a, 3 b show a schematic representation of the first measurement phase of the method according to the invention and an associated force-path diagram; FIGS. 4 a, 4 b show a schematic representation of the final phase of the measurement according to the method according to the invention and an associated force-path diagram.FIG. 1 ashows in a schematic representation an upper measuring tool 10 and a lower measuring tool 11 of a punching or forming machine, not shown in any more detail. The upper measuring tool 10 is shown in its upper starting position. It can be moved by applying a force 12 in the direction of the lower measuring tool 11. The distance covered by the upper measuring tool 10 is detected by a distance measuring system 13. A force sensor 14 is also integrated into the upper measuring tool 10. Alternatively, a force sensor 14' could also be installed in the lower measuring tool. The signals of the force sensor 14 and of the position measuring system 13 are synchronized in a measurement amplifier 15. The measuring amplifier 15 can be a component of a machine control system, not shown. For the starting position of the measuring method shown in FIG. 1 a, the associated force-path diagram shown in FIG. 1 bindicates a path and a force of zero.FIG. 2 ashows the performance of a reference measurement. The upper measuring tool 10 was moved downward until it contacted the lower measuring tool 11. The associated force-path diagram in FIG. 2 b shows a sharp increase in the force measured by the force sensor 14 after a path s 0 has been traveled by the upper measuring tool 10. The path s 0 is the path that the upper measuring tool 10 has traveled until contact with the lower measuring tool 11. The value s 0 is stored as a reference value.Subsequently, the upper measuring tool 10 is moved back into its upper starting position and a component 16, here a curved sheet metal part, is placed on the lower measuring tool 11, as FIG. 3a illustrates. The associated force-path diagram in FIG. 3 bindicates a path and a force of zero.For measuring the flatness deviation h of the curved component 16, according to FIG. 4 a, the upper measuring tool 10 is moved downward from its upper starting position in the direction of arrow 12 until it strikes the component 16. The force-path diagram in FIG. 4 b also shows the reference value s 0. The flatness deviation can then be calculated from the two variables s 0 and s 1 according to the formula, where d is the initial thickness of the component 16.In an analogous manner, the forming height of a component 16 can also be measured, for example the depth of a depression made in the component 16 or the height of a formed-in tab (not shown).

Claims

Method for measuring a flatness deviation and / or a forming height of components (16) in a punching or forming machine, having the steps: - measuring the distance (s 0) between an upper starting position of an upper measuring tool (10) and the plane of a lower measuring tool (11); - placing a component (16) to be measured on the lower measuring tool (11); moving the upper measuring tool (10) from its upper starting position until a force sensor (14, 14') associated with the upper or lower measuring tool (10, 11) indicates a contact between the upper measuring tool (10) and the component (16) by increasing the measured force, and measuring the path (s 1) between the upper starting position of the upper measuring tool (10) and the contact plane between the upper measuring tool (10) and the component (16); determining the flatness deviation or forming height h of the component (16) from the equation: h = s 0- s 1- d, where s 0 is the distance between the starting position of the upper measuring tool (10) and the lower measuring tool (11), s 1 is the distance covered by the upper measuring tool (10) from its upper starting position until it makes contact with the component (16), and d is the starting thickness of the component (16).Method according to Claim 1, characterized in that, in the event of a deviation of the ascertained value h for the flatness deviation from a tolerance value, process parameters of the punching or forming machine are adapted for future punching work in such a way that the flatness deviation remains below the tolerance value.Method according to Claim 1 or 2, characterized in that, in the event of a deviation of the ascertained value h for the forming height from a setpoint value, a post-processing of the component (16) is carried out in the punching or forming machine.Method according to one of the preceding claims, characterized in that, in order to measure the distance (s 0) between the upper starting position of the upper measuring tool (10) and the plane of the lower measuring tool (11), the upper measuring tool (10) is moved from its upper starting position towards the lower measuring tool (11) until the force sensor (14, 14') assigned to the upper or lower measuring tool (10, 11) indicates an increase in force when the upper measuring tool (10) strikes the lower measuring tool (11), and the path (s 0) covered by the upper measuring tool (10) until the lower measuring tool (11) is touched is measured.Method according to one of the preceding claims, characterized in that upper and lower measuring tools (10, 11) are used which have planar horizontal surfaces.Method according to one of the preceding claims, characterized in that punching or forming tools are used as measuring tools (10, 11), wherein the upper punching or forming tool (10) has a planar horizontal underside and the lower punching or forming tool (11) is formed by a die with a planar bearing surface.Method according to one of the preceding claims, characterized in that the measuring tools (10, 11) are exchanged by a tool changer of the punching or forming machine.Method according to one of the preceding claims, characterized in that the distance measurement signals and the signals of the force sensor are synchronized.Method according to one of the preceding claims, characterized in that a force-path diagram is created from the measurements.Punching or forming machine having a position measuring system for the movement of its tools, an exchangeable upper measuring tool (10) and an exchangeable lower measuring tool (11), wherein a force sensor (14, 14') is assigned to the upper or lower measuring tool (10, 11), characterized in that it is designed to carry out a method according to one of the preceding claims.

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