Method for monitoring the operation of a press arrangement and monitoring device for a press arrangement

Abstract

Method for monitoring the operation of a press arrangement (80) with a press (82) having an interchangeable mold, wherein the mold serves to form a workpiece (98), and has several press elements, comprising: - a movable section for moving part of the shape, - a mechanical energy source, and - several energy transmission elements to transfer mechanical energy from the mechanical energy source to the moving part of the press, with the following steps: - Establishing a base vibration level for a first location on the press assembly (80) that defines a vibration upper limit above which press elements have a reduced service life; - Measuring the vibrations at the first location on the press assembly (80) during press operation; - Measuring the vibrations at a second location on the press assembly (80) during press operation; and - Correlating the vibrations measured at the first location with the vibrations measured at the second location, obtaining a vibration ratio; and inputting the measurement data and the basic vibration level into a processing unit (134) that can output signals to the press control.

Description

[0001] The invention relates to a method for monitoring the operation of a press arrangement and a monitoring device for a press arrangement.

[0002] DE 199 52 834 A1 relates to a method for monitoring the operation of a press with the following process steps: Operating the press over a multiple press run cycles;

[0003] Define a plurality of press operating events associated with the press's operation, each with a modifiable, associated control function. For each of these press operating events, a corresponding measurement of the vibration activity present in the press during each press run cycle is created, and a corresponding vibration measurement signal is generated. The corresponding vibration measurement signals assigned to each press operating event are processed to identify the presence of a vibration trend and to meet defined trend criteria. The corresponding control function of each press operating event is modified, as determined by the processing step associated with identifying the vibration trend.

[0004] DE 199 10 802 A1 relates to a method and a device for the dynamic, real-time monitoring of the operation of a press and the tool alignment during specific manufacturing operations, in order to evaluate the actual interaction between specific vibration activity occurring at multiple locations within the press geometry. A configuration of accelerometers is used to record measurement data indicative of the press's acceleration and tool alignment at multiple locations on the press. An integration device converts the acceleration data into displacement data, which represent the displacement activity of the press at the designated locations on the machine. Filtering the displacement data yields bending measurements, which represent the vibration activity occurring at the relevant location on the machine or the tooling.Measurements of the relative press movement activity between selected points on the machine provide an indication of the influence that the bending activity occurring at the respective points on the press machine has on each other.

[0005] A press drive with a condition monitoring device for detecting vibrations of the press drive is disclosed in DE 20 2005 015 402 U1, wherein the condition monitoring device comprises at least: - a memory for storing a vibration reference state, - at least one sensor device for detecting the current vibration state of the press drive, - a microprocessor device designed to compare a current vibration state of the press drive with the vibration reference state using an evaluation algorithm also stored in memory, wherein - the microprocessor device is further configured to activate at least one signaling means according to the degree of deviation between the vibration reference state and the currently measured vibration state.

[0006] Due to the high impact forces that occur during some stamping press operations, various mechanical elements of the press can fail prematurely. For example, if a press's expected lifespan is assumed to be 5 years based on certain production volumes of stamped parts, one or more of the press components will fail after only one or two years – premature failure. This can lead to considerable downtime and lost profits. Premature failure of press components can occur particularly when an older press is retrofitted to perform stamping operations with higher impact forces than those intended for the original die parameters.

[0007] Fig. Figure 1 shows an example of a double-acting press 10 of the type that was used by the stamping industry for many years. The press 10 comprises a head 12 and a press table 14, which are supported on a foundation 16. The press 10 is known as a double-action press because, in a first operating step, a workpiece holder slide 18 is moved downwards, pulling the upper section 20 of a workpiece holder 22 with it. The upper section 20 of the workpiece holder 22 holds a workpiece 24 between itself and the lower section 26 of the workpiece holder 22.

[0008] As in Fig. As shown in Figure 1, the lower section 26 of the workpiece holder 22 is rigidly connected to the press table 14, so that there is little impact when the upper section 20 engages with the workpiece 24. After the workpiece 24 is securely clamped between the upper and lower sections 20, 26 of the workpiece holder 22, a pull slide 28 is actuated and moved downwards, carrying with it a portion of the mold or upper table 30. The upper table 30 contacts the workpiece 24, pulling it into another section of the mold or the lower table 32. Again, the impact of this action is not very high, as the movement only involves the upper table 30, which pulls the already secured workpiece 24 into the lower table 32.

[0009] A toggle lever drive 34 consisting of flying wheels, gears and other elements is attached to the head piece 12, their reference numerals being in Fig. Figure 1 has been removed for clarity. A slide connecting rod 36 connects the toggle drive 34 to the slide 28. Similarly, a workpiece holder connecting rod 38 connects the toggle drive 34 to the workpiece holder slide 18. A phantom representation in Fig. The motor 40 shown can be used to supply mechanical energy to the toggle lever drive 34.

[0010] If the press 10 in Fig. When operated as a double-acting press, the elements of press 10 can each have a true service life that essentially coincides with their expected lifespan. A disadvantage of configuring press 10 is that the orientation of the workpiece 24 may be reversed for additional operating steps that need to be performed. Thus, as described in more detail below, double-acting presses like press 10 can be converted into single-acting presses with the workpiece orientation reversed.

[0011] Although this facilitates faster transfer and additional operating steps on the workpiece, it can also lead to greater impact and premature failure of press components.

[0012] Therefore, there is a need for a monitoring system and a procedure for monitoring press operation to provide information about the expected lifespan of the press components. This information can be used, for example, to modify press operation so that the press components have actual lifespans that generally coincide with their expected lifespans, or conversely, to enable a production manager to predict component failures and perform preventative maintenance according to a schedule, instead of repairing and replacing damaged components during an unexpected breakdown.

[0013] The object of the invention is therefore to enable monitoring of the press operation in order to predict premature failure of press components.

[0014] The problem is solved according to the invention by a method with the features of claim 1.

[0015] A method for monitoring the operation of a press arrangement with a press having an interchangeable mold, wherein the mold serves to form a workpiece, and has several press elements, is presented, comprising: - a movable section for moving part of the shape, - a mechanical energy source, and - several energy transmission elements to transfer mechanical energy from the mechanical energy source to the moving part of the press, with the following steps: - Establishing a baseline vibration level for a first location on the press assembly, which defines a vibration ceiling above which press elements have a reduced service life; - Measuring the vibrations at the first point on the press assembly during press operation; - Measuring the vibrations at a second location on the press assembly during press operation; and - Correlate the vibrations measured at the first location with the vibrations measured at the second location, while maintaining a vibration ratio; and

[0016] Input of the measurement data and the basic vibration level into a processing unit that can output signals to the press control.

[0017] However, the problem can also be solved with a monitoring device having the features of claim 12.

[0018] A monitoring device for a press arrangement with a press and an attached interchangeable mold is shown, wherein: the shape is configured to form a workpiece; the press has several press elements, comprising - a movable section to move part of the shape, - a mechanical energy source and - several energy transmission elements to mechanically transfer energy from the mechanical energy source to the movable section of the press, including: a sensor for measuring vibrations at a point on the press and; a control system connected to the sensor, which has a processing unit with a controller, wherein the controller is configured: Information that establishes a relationship between the vibrations measured at the sensor location and vibration data measured at a predetermined location on the mold, and to establish a baseline vibration level that defines a limit for vibrations beyond which one or more press elements have a reduced service life, wherein the baseline vibration level is established on the basis of vibrations measured at the predetermined location on the mold, wherein the control system with the processing unit is further configured to define a fault condition when a vibration measured by the sensor correlates with a vibration at the predetermined location on the form that exceeds the basic vibration level Beneficial further training courses result from the respective dependent requirements.

[0019] Embodiments of the invention offer advantages over known monitoring devices and methods that use stress gauges to monitor the operating steps of a stamping press and measure bending at various points on the press. Embodiments of the invention utilize vibration signatures to analyze the condition of various press components, such as the gear drive, the impeller, the coupling mechanisms, and the motor. The vibration signatures are acquired, and then parameters such as the root mean square (RMS), kurtosis, or other statistical parameters are applied to provide data trends over time and across frequency domains. For example, if the raw vibration data is collected over a period of time, a fast Fourier transform analysis is used to transform the data into a frequency domain as desired.The trend data can be automatically archived in the monitoring device's memory and accessed through analysis software, an operator interface, and an internet or intranet interface.

[0020] The monitoring device consists of various vibration sensors, such as accelerometers, positioned at different locations on the press head and press columns. These vibration sensors can be connected to a processing unit comprising one or more controllers and memory modules. The processing unit may also interface with a programmable logic controller (PLC) connected to the press to provide additional information, such as crankshaft angle, slide position, etc. The vibration sensors detect the vibrations of individual press components and transmit this information to the processing unit.

[0021] The processing unit can be pre-programmed to calculate various parameters in the time and frequency domains, such as minima, maxima, root mean square (RMS), and kurtosis. The processing unit can also apply statistical algorithms to data from a user-specified number of base cycles, which are used to set warning and alarm thresholds. In this way, embodiments of the monitoring device will provide a safeguard against catastrophic failure in addition to tracking trends and monitoring vibration signatures, thus facilitating efficient preventative maintenance. This enables more reliable press operation by allowing continuous, real-time monitoring of vibration signatures.

[0022] As mentioned above, a method for monitoring the operation of a press assembly is presented, which includes a press with an attached replaceable mold. The mold is configured to form a workpiece, and the press comprises several press elements, including a moving section to move part of the mold, a mechanical energy source, and several energy transfer elements to transfer mechanical energy from the mechanical energy source to the moving parts of the press. The method involves establishing a baseline vibration level for a first location on the press assembly. The baseline vibration level defines a limit for vibrations beyond which at least one of the press elements has a reduced service life.

[0023] Vibrations are measured at one location on the press assembly and also at a second location during press operation. The vibrations measured at the first location are correlated with those measured at the second location to establish a relationship between the vibrations at the first and second locations. For example, the baseline vibration level can be determined based on the vibrations measured at or near one of the dies. A second location for vibration measurement can also be selected at or near a press element on the press head.

[0024] Correlating the measurement times between the measured vibrations at both locations allows the vibrations to be adjusted so that a ratio can be determined. Since continuously measuring vibrations at or near the mold can be inefficient, the measurements can be interrupted once the ratio between the vibrations at both locations has been established. Thus, even after the baseline vibration level for vibrations at or near the mold has been determined, continuous monitoring of vibration levels during press operation can be justified for vibrations measured at locations far from the mold. This can offer advantages over continuously measuring vibrations at the mold, as molds are frequently changed during production runs, and placing vibration sensors on or near the molds necessitates frequent sensor replacement.

[0025] Embodiments of the invention also provide a method that is essentially similar to the one described above, wherein the baseline vibration level is determined by measuring vibrations at a predetermined location on the mold. Vibrations are then measured at this location on the mold during pressing operations simultaneously with vibration measurements at various other predetermined locations on the press. The vibrations measured at the predetermined location on the press are correlated with the vibrations measured at each of the corresponding predetermined locations on the press, thus establishing relationships between the vibrations at the predetermined location on the mold and at each of the predetermined locations on the press.

[0026] As mentioned above, a monitoring device for monitoring the operation of a press assembly of the type described above is also shown. The monitoring device comprises a sensor for measuring vibrations at a specific location on the press and a control system connected to the sensor, which includes at least one controller. The control system is configured with information that determines the relationship between the vibrations measured at the sensor location and vibration data measured at a predetermined location on the mold. The control system is also configured with a base vibration level that defines a limit for vibrations beyond which at least one of the press components has a reduced service life.

[0027] The base vibration level is determined based on vibrations measured at a predetermined location on the mold. The control system is further configured to generate an error message if a vibration measured by the sensor corresponds to a vibration at the predetermined location on the mold that exceeds the base vibration level. Because the various press components can withstand greater forces at certain positions, the base vibration level can be determined to provide an acceptable vibration level for a given position of the press during its stroke.

[0028] The invention will now be explained in more detail with reference to a preferred embodiment, to which it is by no means limited.

[0029] It shows: Fig. 1 a double-acting press with a two-part workpiece holder, one part of which is attached to a workpiece holder slide and the other part of which is attached to the press table; Fig. 2 a single-action press with a one-piece workpiece holder supported on nitrogen springs; Fig. 3 the seemingly simple press of the Fig. 2, wherein the carriage is in an upper position prior to punching a workpiece; Fig. 4 a double-acting press that has been converted to a single-acting press, with a one-piece workpiece holder mounted on nitrogen springs; Fig. 5 a curve of the relationship between the linear displacement and the crankshaft position for the in Fig. 4. Press shown and a vibration line for the press movement, measured at the location of the mold; and Fig. 6 a measured vibration line and a basic vibration level for the in Fig. 4 shown form.

[0030] In Fig. 1. Various current production processes dictate that the orientation of the workpiece in a stamping press is the opposite of that in Fig. The workpiece 24 shown in Figure 1 is shown. Furthermore, double-acting presses are on the decline compared to the more common single-acting presses, as shown in Figure 1. Fig. 2. Press arrangement 41 shown. The press arrangement 41 comprises a press 42 and a removable mold arrangement 43. The press 42 includes a single slide or draw slide 44. In contrast to the one shown in Fig. In the double-acting press 10 shown in Figure 1, there is no workpiece holder slide like the slide 18. Instead, the draw slide 44 is connected to a slide pull system 46 via two slide connecting rods 48, 50. As with press 10, a mechanical energy source is provided for press 42, which is shown in phantom representation in Fig. 2 is shown as motor 52. A press head 54 is connected to a press table 56 via the press columns 58, 60.

[0031] An upper table 62 of the forming assembly 43 is attached to the draw carriage 44. The upper table 62 is selected to fit together with another section of the forming assembly 43, in particular a draw die 64. The upper table 62 and the draw die 64 work together to form a workpiece 66 into a desired shape. As described above, the Fig. The press 10 shown in Figure 1 comprises a workpiece holder 22 with an upper section 20, which is attached to the workpiece holder slide 18, and a lower section 26, which is attached to the press table 14. In contrast, the press 42, in Fig. Figure 2 shows a one-piece workpiece holder 68, which is supported by nitrogen springs 70, 72. Additionally, the press 42 includes a hydraulic tension cushion arrangement 74, which is supported by the press foundation 76, which assists in absorbing impact forces during press operation 42.

[0032] Fig. Figure 3 shows the press 42 with the draw carriage 44 in a raised position with an unformed workpiece 78, supported by the workpiece holder 68 above the draw punch 64. Fig. Figure 3 shows that the nitrogen springs 70, 72 lift the workpiece holder 68 above the tip of the draw punch 64, so that the unformed workpiece 78 is supported by the workpiece holder 68. Although the configuration provides a suitable orientation for the workpiece, as shown in Figure 3, the workpiece holder 68 is supported by the nitrogen springs 70, 72. Fig. 2. The workpiece 66 shown in the diagram is subjected to much higher shocks by the press 42 than by the one in Fig. This will be explained in Figure 1 of the press 10 shown. This is partly due to the mass that must be accelerated from zero velocity to the velocity of the upper table 62 as the slide 44 moves downwards. In particular, the upper table 62 will exert an impact on the workpiece 78, clamping it between the upper table 62 and the workpiece holder 68, and then the workpiece 78 and workpiece holder 68 must be accelerated from zero to the velocity of the upper table 62 while all three components move downwards on the nitrogen cylinders 70, 72.

[0033] In contrast, the one in Fig. The press 10 shown does not have a floating workpiece holder, but instead a lower section 26 of the workpiece holder 22 that remains fixed to the press table 14, so that it never accelerates. Thus, when the upper table 30 comes into contact with the workpiece 24, the workpiece 24 is trapped between the upper and lower sections 20, 26 of the workpiece holder 22, which means that it does not move downwards except to be reshaped according to the shape of the upper and lower tables 30, 32. Thus, the Fig. The press shown in section 3 is exposed to much higher impact forces, and thus its elements can fail prematurely.

[0034] Although the in Fig. Since the double-acting press shown in Figure 1 should not be subjected to high impact forces due to its configuration, it is not uncommon, with older double-acting presses, to retrofit them similarly to single-acting presses, as in the Fig. 2 and Fig. 3 shown to reorient a workpiece to increase transfer speed and overall production speeds. Fig. Figure 4 shows a press arrangement 80 with a press 82 and a removable mold 84 attached to it. The press 82, originally configured as a double-acting press, has a workpiece holder slide 86 and a draw slide 88. In contrast to the workpiece holder slide 18, as shown in Fig. As shown in Figure 1, the workpiece holder slide 86 does not engage with the workpiece holder. Thus, although still connected to a slide drive system 90, it does not act on the workpiece holder. In fact, the press 82 includes a workpiece holder 92, which corresponds to the one shown in Figure 1. Fig. 2 and Fig. 3 workpiece holders 68 are similar.

[0035] The workpiece holder 92 is supported on nitrogen springs 94, 96, and when the draw slide 88 is raised, the nitrogen springs 94, 96 push the workpiece holder 62 upwards together with the workpiece 98. This is similar to the operation of the press 42. Fig. 2 and Fig. As shown in Figure 3, the press 82 is subjected to a large impact load when an upper table 100 of the mold assembly 84 moves downwards and impacts the workpiece 98 and the workpiece holder 92. Again, the workpiece 98 and workpiece holder 92 must accelerate from 0 to the speed of the upper table 100, which is dictated by the movements of the draw carriage 88. Operation of the draw carriage 88 is effected by a motor 102, shown in phantom form, via the power transmission elements of the carriage drive system 90.

[0036] To provide vibration data that can be used, for example, to modify the operating mode of a press or to predict when the press components need to be replaced, the invention provides several vibration sensors, which can be designed in the form of accelerometers. In one embodiment of the invention, a method is used to first establish a baseline vibration level for a press assembly, such as the one described in Fig. 4. Press arrangement 80 shown. To establish this base level, a vibration sensor 104 is positioned at a location on or near the mold arrangement 84, e.g. on the upper table 100, as shown in Figure 4. Fig. 4 shown.

[0037] To capture vibration peaks, a very high data collection rate is desired in order to obtain the vibration information from sensor 104.

[0038] For example, the raw signals from sensor 104 can be collected at a rate of 51,200 samples / sec, enabling the recording of signals with a maximum frequency of up to 10 kilohertz (kHz). One way to determine the baseline vibration level is to measure the vibrations over a long period during various operating modes, collect the vibration history, and correlate it with mechanical failure of press components. This allows a relationship between vibrations at the mold assembly 84 and the failure of press components to be determined.

[0039] In Fig. Figure 5 shows a curve 106 for the displacement of the slide 88 with the angular position of one of the slide connecting rods 108 or crankshaft. Fig. Figure 5 also shows a vibration curve 110, which corresponds to the crankshaft position on the abscissa. Fig. Figure 5 shows a correlation. Two points 112 and 114 on curve 106 correlate with peaks of the vibration curve 110. Positions 112 and 114 indicate the points of initial impact and recoil, respectively, between the upper table and the workpiece 98. In particular, point 112 denotes the position at which the upper table strikes the workpiece 98 and the workpiece holder 92 when they are positioned above the draw ram 116, similar to the position shown in Figure 5. Fig. 3 is shown. Point 114 denotes the point at which the sliding carriage 88, which is now moving upwards, releases the workpiece 98 and the workpiece holder 92, so that their speed quickly decreases to 0.

[0040] As described above, the correlation of vibration data, such as the data shown in vibration curve 110, with known failure of various press elements, such as press 82, makes it possible to create a basic vibration level. Fig. Figure 6 shows an RMS vibration curve 117 over a period of time and a base vibration level indicated by lines 118 and 119 at +20g. Lines 118 and 119 define a limit for vibrations measured at the upper table 100, beyond which one or more elements of the press 82 have a reduced service life; that is, one or more elements, such as the crankshaft or any of the other connecting elements, will fail long before their expected service life.

[0041] As in Fig. As shown in Figure 6, the points of initial impact and recoil exceed the baseline vibration level—as indicated by lines 118 and 119—while the remaining sections of each press cycle do not. Although the baseline vibration level in Fig. Since the basic vibration level is defined by two horizontal lines 118 and 119, it can also be defined as a curve, thus specifying a variable vibration level depending on where in the press cycle the vibration occurs. For example, it can be determined that higher vibrations are acceptable when the crankshaft position is 180°, i.e., when the draw slide 88 is in its lowest position. This is because the crankshaft 108 is essentially vertical at that point and, as such, acts as a two-force component. Thus, virtually no transverse load will occur when the crankshaft position is at 180° – therefore, the acceptable vibration level can be higher.

[0042] In Fig. In Figure 4, it is assumed that during operation of the press assembly 80, the mold assembly 84 will be frequently changed to enable the production of different products. Therefore, it may be inconvenient to monitor vibrations on the upper table 100 or on any part of the mold assembly 84. Thus, embodiments of the invention consider the use of one or more additional sensors, such as a sensor 120 next to the slide drive system 90, with sensor 122 being attached to the motor 102. During operation of the press assembly 80, vibrations can still be measured at sensor 104 and sensors 120 and 122. Vibration curves for a given period can be correlated to establish a relationship between the vibrations at the first location—i.e., at the location of sensor 104—and those measured at the second and third locations by sensors 120 and 122.

[0043] Typically, the vibrations measured by sensors 120 and 122 will be lower than those measured by sensor 104. Thus, the vibrations measured by both sensors 120 and 122 will probably never exceed the value in Fig. The basic vibration level shown in Figure 6 is exceeded. Therefore, in embodiments of the invention, establishing a ratio between the vibrations, e.g., those measured by sensor 104 and those measured by other sensors, is considered. In this way, the vibrations measured by sensors 120 and 122 can be appropriately adjusted based on this ratio, so that the adjusted vibration data can be used together with the basic vibration level indicated by lines 118 and 119.

[0044] Once the relationship between the measured vibrations of sensor 104 and sensors 120 and 122 has been determined, sensor 104 can be removed, leaving only the recently installed sensors 120 and 122. Vibration data can continue to be collected from sensors 120 and 122 and analyzed according to typical vibration analysis methods, such as using a time period or by transforming the raw data using a mathematical transformation, such as Fourier transform analysis, to create information in a frequency domain. The adjusted vibration data can also be analyzed taking into account the baseline vibration levels, as described, for example, in [reference to relevant section]. Fig. The 6 lines shown 118, 119. The specific ratio can indicate, for example, that the vibration measured at the upper table 100 by sensor 104 is approximately four times that measured by sensor 120 for any given press load. In such a case, the vibrations measured by the sensor can be increased by a factor of 4 and directly compared to the baseline vibration level indicated by lines 118, 119 in Fig. 6, can be compared.

[0045] Embodiments of the invention also consider using the ratio between the vibrations measured at a mold assembly, such as those measured by sensor 104, and the vibrations measured at other locations, such as those measured by sensors 120 and 122, to adjust the base vibration level. For example, instead of adjusting the measured vibration data as explained above, lines 118 and 119 can be adjusted accordingly to be applicable to the raw data measured by sensor 120 or sensor 122. Using the above example, the base vibration level can be reduced by a factor of 4, shifting lines 118 and 119 inwards to approximately +5g.

[0046] Embodiments of the invention include a monitoring device for a press operation, e.g. one at 124 in Fig. 3 Monitoring device shown. The monitoring device 124 comprises vibration sensors 126, 128, 130, each of which is connected to a control system 132. The control system 132 comprises a processing unit 134 with an electronic control unit and memory, and a PLC 136 connected to the processing unit 134. As described above, a base vibration level, which defines a limit for vibrations beyond which one or more of the elements of the presses 42 have a reduced service life, can be empirically determined by observing the press operation, correlated with information measured by a sensor, such as the sensor 126 on the upper table 62.

[0047] The baseline vibration level can be determined using a monitoring device, such as the monitoring device 124, or independently. The baseline vibration level information, as described in Fig.Figure 6 shows that the data can be stored in the processing unit 134, for example, in the form of a lookup table. The PLC 136 provides additional information to the processing unit 134 about the specific operating mode of the press 42, such as the position of the elements of the drive system 46 and the position of the draw carriage 44. The processing unit 134 also receives vibration data from the sensors 128 and 130 and can correlate this information with data measured by the sensor 126 on the upper table 62.

[0048] The processing unit 134 can employ one or more pre-programmed algorithms to establish a relationship between the vibration data measured by sensor 126 and the vibration data input from other sensors, such as sensors 128 and 130. Even after sensor 134 has been removed from the upper table 62, the processing unit 134 can continue to receive information from sensors 128 and 130 and compare this information with the predetermined baseline vibration level. If, at any time, the vibrations measured by sensors 128 and 130 exceed the baseline vibration level, the processing unit 134 can send an appropriate error signal to indicate to an operator or production manager that an adjustment needs to be made. For example,It may be desirable to adjust some operating parameters of the press to ensure that the vibration levels remain below the base vibration level, or it may be found that maintaining a vibration level above the base vibration level is acceptable, accepting that certain press elements will need to be replaced before they reach the end of their expected service life.

[0049] While the invention has been explained in detail with reference to a preferred embodiment, it is obvious to the person skilled in the art, to whom the invention is directed, that a wide variety of alternative embodiments and modifications for carrying out the invention as outlined in the claims are possible. Reference symbol list 10 Press 12 Headpiece 14 Press table 16 Foundation 18 workpiece holder slides 20 upper section 22 workpiece holders 24 workpieces 26 lower section 28 tow sleds 30 upper table 32 Under-table 34 Knee lever drive 36 Sled connecting rod 38 workpiece holder connecting rod 40 engine 41 Press arrangement 42 Press 43 Form arrangement 44 tow sleds 46 Drive system 48 Sliding connecting rod 50 sled connecting rod 52 Engine 54 Press head piece 56 press bed 58 press column 60 press columns 62 Upper table 64 train stamps 66 workpieces 68 workpiece holders 70 nitrogen spring 72 nitrogen spring 74 Traction cushion arrangement 76 Press foundation 78 workpiece 80 press arrangement 82 Press 84 Form arrangement 86 workpiece holder slides 88 tow sleds 90 Slide drive system 92 workpiece holders 94 Nitrogen spring 96 nitrogen spring 98 workpieces 100 upper table 102 engine 104 Sensor 106 Curve 108 Sled connecting rod 110 Vibration curve 112 points 114 points 116 train stamps 117 RMS vibration curve Line 118 Line 119 120 Sensor 122 Sensor 124 Monitoring device 126 Vibration sensor 128 Vibration sensor 130 vibration sensor 132 Tax system 134 processing units 136 PLC

Claims

[1] Method for monitoring the operation of a press arrangement (80) with a press (82) having an interchangeable mold, wherein the mold is used for forming a workpiece (98) and has several press elements, comprising: - a movable section for moving part of the shape, - a mechanical energy source, and - several energy transmission elements to transfer mechanical energy from the mechanical energy source to the moving part of the press, with the following steps: - Establishing a base vibration level for a first location on the press assembly (80) that defines a vibration upper limit above which press elements have a reduced service life; - Measuring the vibrations at the first location on the press assembly (80) during press operation; - Measuring the vibrations at a second location on the press assembly (80) during press operation; and - Correlating the vibrations measured at the first location with the vibrations measured at the second location, obtaining a vibration ratio; and inputting the measurement data and the basic vibration level into a processing unit (134) that can output signals to the press control. [2] Method according to claim 1, furthermore characterized by Interrupting the measurement of the vibrations at the first location after a ratio between the vibrations at the first and second locations has been established. [3] Method according to claim 2, furthermore characterized by Defining a faulty condition when the measured oscillation at the second location correlates with an oscillation at the first location that exceeds the basic oscillation level. [4] Method according to claim 1, wherein the step of establishing a base vibration level for the first location comprises measuring vibrations on a part of the mold during several operating modes of the press (82) and determining an acceptable vibration level for the mold for several positions of the movable sections of the press (82). [5] Method according to claim 4, characterized by , that the step of determining an acceptable vibration level includes determining a vibration level for the mold below which no press element will fail prematurely. [6] Method according to claim 1, wherein the second location is selected as the location with lower measured vibrations than the vibrations measured at the first location. [7] Method according to claim 1, wherein the second location is a location on the press (82). [8] Method according to claim 1, characterized by that the second location is a location near the energy transmission elements. [9] Method according to claim 1, furthermore characterized by Defining a basic vibration level for a second location based on a relationship established between the measured vibrations at the first location and the measured vibrations at the second location. [10] Method according to claim 9, furthermore characterized by Defining an error condition when a measured oscillation at the second location exceeds the baseline oscillation level for the second location. [11] Method according to claim 1, wherein the vibrations at the second location are measured using a sampling rate of over 5000 Hertz. [12] Monitoring device for a press arrangement (80) with a press (82) with an interchangeable mold attached thereto, wherein: the shape is configured to form a workpiece (98); the press (82) has several press elements, comprising - a movable section to move part of the shape, - a mechanical energy source and - several energy transmission elements to mechanically transfer energy from the mechanical energy source to the movable section of the press (82), comprising: a sensor (104,120,122,126,128) for measuring vibrations at a location of the press and; a control system (132) connected to the sensor (104,120,122,126,128), which has a processing unit (134) with a controller, wherein the controller is configured: Information that establishes a relationship between the vibrations measured at the sensor location and vibration data measured at a predetermined location on the mold, and to establish a baseline vibration level that defines a limit for vibrations beyond which one or more press elements have a reduced service life, wherein the baseline vibration level is established on the basis of vibrations measured at the predetermined location on the mold, wherein the control system (132) with the processing unit (134) is further configured to define a fault condition when a vibration measured by the sensor correlates with a vibration at the predetermined location on the shape that exceeds the basic vibration level. [13] Monitoring device according to claim 12, furthermore characterized bySensors (104, 120, 122, 126, 128) that measure vibrations at corresponding locations on the press (82), wherein the control system (132) with its processing unit (134) is further configured with information which creates a corresponding ratio between the vibrations measured at each sensor location and vibration data measured at the predetermined location on the mold.

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