CAN BODY MAKER AND METHOD FOR OPERATING A CAN BODY MAKER TO MITIGATE THE EFFECTS OF WEAR, DAMAGE AND / OR MISALIGNMENT OF TOOLS

Abstract

A can body forming machine for producing can bodies from cups. The can body forming machine comprises a ram configured to move alternately along an axis, a punch mounted on the ram, and a tooling set comprising a cradle and a plurality of tools located in the cradle for stretching and flattening a cup mounted on the punch during a forward stroke of the ram. The can body forming machine further comprises a support plate fixed to the can body forming machine, an adapter plate fixed to the support plate, and an extractor assembly fixed to the adapter plate for removing a can body from the punch during a return stroke of the ram, and a clamping mechanism for pressing the tools against a front face of the adapter plate.The can body making machine further comprises one or more load cells located on or above the adapter plate and configured to generate an output signal or signals indicative of an axial force exerted on the tools by the cup passing through them.

Description

The present invention relates to the monitoring of can body making machines. In particular, it relates to an apparatus and method for monitoring the forces acting on the components in a tool set of a can body making machine when the machine is being operated. BACKGROUND In can-body forming machines known for producing two-piece, thin-walled metal can bodies using a draw-and-iron (DWI) process, metal cups are fed into the body-former and conveyed by a punch at the end of a ram through a series of dies to produce a can body of the desired size and thickness. The die series may include a redrawing die to reduce the cup diameter and lengthen its side wall, and one or more ironing dies to flatten the cup wall into a can body. The area or cradle of the body-former frame within which the dies are located is known as the tooling set.The can body carried on the punch can then come into contact with a bottom forming or dome forming tool to create a shape such as a dome at the base of the can. An illustrative body forming tool is described in WO9934942. Can body forming machines typically operate for extended periods at high speed to produce more than 300 to 400 can bodies per minute. However, the quality of the can bodies produced can vary significantly over time due to changes in, for example: machine component alignment, coolant temperature and flow rate, machine lubrication, and / or the quality of the incoming cups (for example, due to variations in the quality of the metal coil from which the cups are made). During the DWI process, the metal is subjected to loads as the punch pushes it through the ironing dies. However, the magnitude and distribution of these loads change both during the stroke and from stroke to stroke, resulting in variations in the quality of the can bodies produced. For example, frictional forces and general wear will cause the ram alignment to vary slightly over time. In addition, a high-speed reciprocating ram is typically subject to at least some vibration, due to the impact of the ram on the can body and the varying camber of the ram as it moves to and from its fully extended position. As a further example, when the ram brings the can body into contact with the dome former, any misalignment can cause the end of the can body to break, particularly if the can body is made of aluminum. If the misalignment is slight, the break (sometimes known as a smile) may not be immediately visible to the naked eye, and the break can cause the can to explode once the can body has been filled. This may not occur until the can has been purchased already filled. Poor-quality can bodies can lead to material losses and downtime in can production. This can occur, for example, because the can body making machine itself needs to be realigned or repaired, or because other machines further down the production line are negatively impacted by the low quality of the cans being produced. Unfortunately, the high-speed, high-volume nature of the can manufacturing industry means that lost production time can be very costly for producers. ML / a / ZUZZ / U 14 1OU Traditionally, aligning and realigning can body formers is a complex and time-consuming process that must be painstakingly carried out by skilled operators (who are often scarce) only after serious problems have arisen. When a can body former is installed, the ram and its drive components are normally fixed in place on the body former frame. This aligns the ram shaft with the main shaft of the body former. The other components, including, for example, the redrawing and flattening dies and the dome former, are then aligned with the ram. SUMMARY According to a first aspect of the present invention, a can body maker is provided for producing can bodies from cups. The can body maker comprises a ram configured to move alternately along an axis, a punch mounted on the ram, and a tool set comprising a cradle and a plurality of tools located in the cradle for stretching and flattening a cup mounted on the punch during a forward stroke of the ram. The can body maker further comprises a support plate fixed to the can body maker, an adapter plate fixed to the support plate, an extractor assembly fixed to the adapter plate for removing a can body from the punch during a return stroke of the ram, and a clamping mechanism for pressing the tools against a front face of the adapter plate.The can body maker further comprises one or more load cells located on or above the adapter plate and configured to generate an output signal or signals indicative of an axial force exerted on the tools by the cup passing through them. The expression axial force means a force that has a component directed along the axis along which the ram alternately moves. The can body making machine may include an encoder configured to provide a measurement of the ram's position at one or more times during each reciprocating motion. The encoder may be a linear encoder. Alternatively, the encoder may be a rotary encoder configured to be rotated by a shaft used to drive the ram. The one or more load cells can be piezoelectric load cells. The one or more load cells may comprise more than one load cell, with the load cells being equally spaced angularly from each other around the axis. The can body manufacturer may include a processor configured to adjust one or more parameters 1 or» can body manufacturer operations, such as an alternating ram movement index, in response to the output signal(s). The adapter plate can be fixed to the support plate by means of one or more preload bolts, passing each preload bolt through a respective load cell to secure the load cell between the adapter plate and the support plate. The extractor assembly may include a radial deviation monitoring unit to detect misalignment of the ram and / or punch with respect to the shaft. The radial deviation monitoring unit may comprise an orifice configured to allow the punch and ram to pass through it and one or more separate eddy current sensors around the orifice. According to a second aspect of the present invention, an apparatus is provided for retrofitting a can body maker. The can body maker comprises: a ram configured to move alternately along an axis; a punch mounted on the ram; a tool set comprising a cradle and a plurality of tools located in the cradle for stretching and flattening a cup mounted on the punch during a forward stroke of the ram; a support plate fixed to the can body maker; an adapter plate fixed to the support plate; an extractor assembly for removing a can body from the punch during a return stroke of the ram; and a clamping mechanism for pressing said tools against a front face of the adapter plate.The apparatus comprises: a replacement adapter plate for attachment to the support plate in place of the adapter plate of the can body maker; and one or more load cells located on or above the replacement adapter plate and configurable to generate an output signal or signals indicative of an axial force exerted on the tools by the cup passing through them. The replacement adapter plate may include an extractor assembly comprising a radial deviation monitoring unit for detecting misalignment of the ram and / or punch with respect to the axis. The radial deviation monitoring unit may comprise a bore configured to allow passage of the punch and ram through it and one or more separate eddy current sensors around the bore. According to a third aspect of the present invention, a method is provided for calibrating the apparatus of the second aspect after it has been retrofitted to a can-body maker. The method comprises installing, in the cradle of the can-body maker, a calibration accessory comprising one or more reference load cells configured to generate an output signal or signals indicative of an axial force exerted on the tools located in the cradle. An axial force is applied to the tools and one or more reference load cells using the clamping mechanism of the can-body maker. The respective output signal or signals from the reference load cell(s) are used to determine a calibration factor or calibration function for estimating the force on the tool(s) from the output signals generated by the load cell(s) of the apparatus. According to a fourth aspect of the present invention, a method is provided for operating a can body forming machine to mitigate the effects of wear, damage, and / or misalignment of the tools during can body production. Each can body is formed by pushing a cup mounted on a ram punch that moves alternately along an axis through tools contained within a cradle of a tool set of the can body forming machine. The method comprises obtaining, from one or more load cells, output signals indicative of an axial force exerted on the tools by the cup as it passes through them, the load cell(s) being located on or in an adapter plate attached to a support plate fixed to the can body forming machine.The output signals are processed to obtain data indicating that one or more of the tools are worn, damaged, and / or misaligned with respect to the ram. One or more operating parameters of the can body maker, or of another component of a production line within which the can body maker is located, are adjusted based on this data to mitigate the effects of the tools being worn, damaged, and / or misaligned with respect to the ram. The one or more operating parameters may comprise one or more of: a can production index; an operating temperature of the tool set; an index or temperature at which coolant is supplied to the tool set; an index to which lubricant is supplied to the tool set; and a position of the dome former with respect to the ram shaft. The one or more operating parameters may comprise a parameter of a component of the production line upstream or downstream of the body maker, for example, a cup press. 1 o» The method may comprise removing the can body from the punch during a return stroke of the ram using an extractor attached to the adapter plate. The extractor can be provided in an extractor assembly comprising a radial deviation monitoring unit, and the method further comprises obtaining output signals indicative of a ram and / or punch position perpendicular to the axis using the radial deviation monitoring unit and adjusting said one or more operating parameters based on the data and output signals obtained from the radial deviation monitoring unit. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 schematically illustrates a perspective view of a can body manufacturer; Figure 2 is a schematic cross-sectional perspective view of a tool set from the can body maker of Figure 1; Figure 3 is another schematic cross-section perspective view of the can body maker of Figure 1; Figure 4 is a schematic perspective rear view of an adapter plate and extractor assembly; Figure 5 is a schematic cross-sectional side view of the adapter plate and extractor assembly of Figure 4; ινΐΛ / a / zuzz / u 14i oa Figure 6 is a schematic perspective front view of the adapter plate and extractor assembly of Figure 4; Figure 7 is a schematic cross-sectional side view of a load cell installed between the adapter plate and a tool set support plate; and Figure 8 is a flow diagram of a method for operating a can body maker to mitigate the effects of wear, damage and / or misalignment of the tools during can body production. DETAILED DESCRIPTION Figure 1 is a schematic perspective view of a modular body former 101 for manufacturing can bodies with drawn cups from sheet metal. The body former 101 comprises a base 102 supporting a machine bed 103 with a reference surface and a ram assembly 105. The ram assembly 105 comprises a reciprocating ram 106 with a punch (not shown) mounted at one end. During a feed stroke of the body former 101, the punch contacts a cup (not shown) held in the ram's path within a tool set 107 located on the reference surface. The punch pushes the cup through a redrawing die (not shown) contained within the tool set 107 to form an elongated can body.The can body is carried over the punch so that it comes into contact with a bottom forming tool 108 housed in a dome forming module 109 to form a shape such as a dome at the base of the can. On a return stroke of the body forming machine 101, an extractor (not shown) from the tool set 107 removes the can body from the punch. A can unloading turret 110 from a feed and unload module 111 located between the tool set 107 and the dome forming module 109 carries the can body away from the ram shaft. The tool set 107 also comprises a redraw sleeve module 112, located in front of the redraw die (not shown), for positioning the cup during the redraw process. The redraw sleeve module 112 comprises a bearing 113 with a cup locator (not shown) for receiving a cup from a feed mechanism 114 of the feed and unload module 111. The bearing 113 supports a reciprocating redraw sleeve 115 that is coaxially aligned with the ram and has a central bore allowing the punch to pass through it. A rear end of the redraw sleeve 115 is attached to a redraw carriage 116 that is driven with a reciprocating motion by a pair of push rods 117a, 117b located on opposite sides of the ram 106.Before the punch makes contact with the can, the redraw sleeve 115 enters through the open end of the cup and forces the cup into contact with the redraw die. The redraw sleeve 115 holds the cup firmly in place against the redraw die as the punch pushes the cup through an opening in the redraw die that has a smaller diameter than the cup. As the cup is drawn through the redraw die by the punch, its diameter is reduced and its sidewall is elongated. Tool set 107 may also contain one or more ironing dies or other tooling for forming the can body after the redraw die. The punch then carries the elongated cup away from the redraw sleeve module and through the tooling and the remaining ironing dies. Figures 2 and 3 are cross-sectional perspective views of the tool set 107, comprising a housing 219, within which a cradle 220 is provided, and an extractor assembly 221 attached to a support plate 223 by an adapter plate 225, the support plate 223 being attached to the housing 219 and providing a rear wall of the tool set 107. The axis along which the punch (not shown) moves is shown in Figure 2 by the dashed line AA'. The cradle 220 has a cylindrical inner surface and wear bars 229 that are used to support the ironing dies (not shown) and spacer rings (226A, B) within the housing 219. The redrawing die (not shown) is mounted on the front face of the housing 219 and forms an inlet to the housing 219 into which the punch moves on the ram's (106) advance stroke. The extractor assembly 221 comprises an extractor 233 mounted within an extractor housing 235 that is attached to the adapter plate 225. The extractor 233 comprises extraction legs that extend radially inwards, i.e., towards axis A-A'. During the forward stroke of the ram 106, the can body carried on the punch deflects the extraction legs as it moves through the extractor 233. On the return stroke, i.e., away from the bottom forming tool 108, the extraction legs prevent the can body from returning with the punch, and the can body is extracted from the punch and then removed from the body former 201 by the can discharge turret 210. In other embodiments not shown here, the can body can be removed from the body former 201 by compressed air (alternatively, compressed air can be used to assist in the removal of the can body by an extractor). The adapter plate 225 is located between the support plate 223 and the tool set housing 219. The adapter plate 225 comprises three load cells 237A-C (see Figures 4 to 6) spaced around axis AA' and each having an axis oriented along axis AA' towards the cradle 220 for measuring forces generated by the passage of the punch through the dies. In this example, the load cells 237A-C are piezoelectric load cells that each generate an electrical signal when compressed along their axis (the axis preferably being aligned parallel to axis AA'). Figure 4 shows the rear face of adapter plate 225 with the support plate 223 (and the remainder of tool kit 107) removed so that each of the three load cells 237A-C is visible. The annular body 301B of each load cell 237A-C is located in a recess formed in the edge and rear face of adapter plate 225 (i.e., the face of adapter plate 225 farthest from the tool kit cradle 220). In this example, each recess is shaped to accommodate a wired connection on the side of the annular body 301B. Load cell 237A also comprises a preload pin 301B that passes through adapter plate 225, through the center of the annular body 301, and into the support plate 223.The cylindrical body 301A protrudes from the recess so that it contacts the support plate 223 through a small gap between the adapter plate 225 and the support plate 223 (see Figure 7). The preload bolt 301B is used to press the adapter plate 225 toward the support plate 223 so that the annular body 301A is held in compression between them. Applying a force to the adapter plate 225 in the direction of the support plate 223 causes the annular body 301A to compress further (i.e., the preload 301B does not prevent the adapter plate 225 from moving toward the support plate 225). Figure 5 shows a vertical cross-section through adapter plate 225 and extractor assembly 221 along axis A-A'. Figure 6 shows a perspective view of the front face of adapter plate 225 (i.e., the face closest to tool set cradle 220). Figure 7 shows the adapter plate 225 bolted to the support plate 223 using the preload bolt 301B, which passes through the cylindrical body 301A of the load cell 237A. The cylindrical body 301A is held in compression between the rear face of the adapter plate 225 and the front face of the support plate 223. In the particular embodiment shown in Figures 4 to 7, the extractor housing 235 comprises four eddy current sensors 401A,B (although one or more of the four eddy current sensors can be used) spaced around the central hole through which the ram moves, to monitor the radial deflection of the punch / ram. The radial deflection data from the eddy current sensors can be correlated with the force data obtained from the load cells 237A-C. This correlation helps to identify the cause of radial misalignments between the ram / punch and the tool set components. For example, an abnormally large force arising from the passage of the punch through one of the dies could be caused by misalignment of the ram / punch or by misalignment of the die itself; these two possibilities can be distinguished from each other using the radial deflection data. Returning to Figures 2 and 3, as the punch moves through cradle 220 (i.e., from left to right in Figure 2), the can body is pushed through the redrawing die and the ironing dies, creating a longitudinal force that is transmitted through the dies and spacer rings to load cells 237AC. Therefore, the time-varying signals produced by load cells 237A-C provide measurements of the longitudinal forces acting on the dies when the can body's side walls are being drawn and / or ironed. The 237A-C load cells can be provided around the AA' axis in an equiangular arrangement to provide optimal sensitivity. A minimum of three 237A-C load cells is preferred to provide sufficient spatial detail, and the maximum number of 237AC load cells is limited only by cost and available space within the adapter plate 225. Other types of 237A-C load cells, such as capacitive load cells, can also be used instead of or in addition to piezoelectric load cells. The 225 adapter plate can be retrofitted to existing can body makers without modifications to the tooling set, for example, by replacing an existing adapter plate. Because the 237A-C load cells are located outside the 220 cradle, force measurements can be made without requiring any reconfiguration or replacement of the components (tooling) in the 220 cradle. For example, while in principle a fixture containing the 237AC load cells could be installed in place of one of the spacer rings, this would require the fixture to be manufactured to a high tolerance, and multiple versions of the fixture might be necessary depending on which dies are included in the tooling set. Such an arrangement could also negatively affect the cooling provided to the dies. Including the 237A-C load cells inside the 220 cradle can also be problematic because the installation and removal of components from the 220 cradle could potentially damage the 237A-C load cells. Although force measurements can be made with a single 237A load cell, it is preferable to have more than one transducer to obtain information about how the forces acting on the dies are distributed in space. For example, multiple 237A-C load cells can be used to determine if a correction to the relative alignment between the ram / punch and one or more of the dies is necessary. This can be done, for example, using an iterative procedure in which the forces measured by each of the 237A-C load cells are compared, and the alignment of the ram and / or dies is varied until the forces are balanced and / or until each of the measured forces is minimized.In practice, this procedure can be carried out using a computer device (not shown) comprising an analog-to-digital converter (ADC) to process the time-varying electrical signals generated by the 237A-C load cells and to generate an output reading or graphical display of the forces that can be viewed by an operator making the necessary adjustments. In some cases, the computer device can be configured to detect when forces exceed a threshold and / or if there is an imbalance in the measured forces (for example, one of the measured forces is greater than the others) that exceeds a threshold, and respond by generating a visual or audible alarm and / or stopping the operation of the can body maker 201. The computer device can also monitor one or more operating parameters of the can body maker 101 to ensure that it operates safely and efficiently. For example, the computer device can reduce the repeat rate of the can body maker 101 once a problem has begun to manifest. The time-varying measurements obtained from the 237A-C load cells can be recorded (e.g., stored in a database) so that gradual changes in alignment caused by wear and vibration can be monitored. The time resolution provided by the ADC is sufficient to resolve the time variation of the forces measured during a single stroke. This data can be correlated with longitudinal position data of the ram during each stroke (i.e., data indicative of the ram's movement along axis A-A'). This data can be obtained, for example, from a high-resolution rotary encoder that is rotated by the shaft used to drive the reciprocating ram, or from a high-resolution rotary encoder that measures the ram's longitudinal position. 1 or more directly. Correlating force measurements with position data allows particular characteristics in the force measurements to be attributed to the ram's passage through specific components of the tool set. This allows, for example, a particular die to be identified as poorly aligned or damaged, or the wear of each die to be estimated from the total force on each die, integrated over a large number of strokes. This analysis can be performed automatically by the computer, which can generate an alert or warning signal indicating that one or more dies need to be realigned or replaced.The number of runs can also be recorded in such a way that the measured strength data can be associated with a particular can or cans produced by the body manufacturer 201, for example, so that it can be certified that particular cans or batches of cans are likely to be free from defects, or otherwise prevented from being sent to customers. It is not essential to calibrate the 237A-C load cells because useful information can still be obtained from the relative forces measured by each individual 237A-C load cell (for example, to detect changes in the relative alignment of components over time). However, calibrating the 237A-C load cells can enable the creation of more accurate models of the forces acting on the dies, thereby allowing for more sophisticated measurement processing and earlier detection of potential problems. In this case, calibration refers to the conversion of the electrical signal produced by the 237A-C load cells to the actual longitudinal forces acting on the tooling components.This may involve determining a mathematical conversion function that takes the electrical signal(s) as an input and provides a corresponding force(s) as an output. In some cases, this function may consist of a multiplicative factor used to scale the electrical signal by multiplying it by a quantity. Calibration is generally necessary for accurate measurements because the proportion of force transmitted to the 237A-C load cells will vary depending on how the adapter plate 225 is mounted and / or because the transmission of forces from the dies can vary depending on how the tooling set is configured, for example, what preload is applied to the tooling set (see below). To calibrate the 237A-C load cells, an accessory comprising one or more reference load cells (not shown) can be installed in cradle 220 (for example, in place of one of the spacer rings or ironing dies). A load is then applied to the reference load cell(s) along axis AA', and the electrical signals produced by the 237A-C load cells and the reference load cell(s) are measured. The conversion function is then determined from the measured signals, for example, by fitting a piecewise differentiable or polynomial interpolation function to the reference signals plotted against the load cell signals.The load applied to the reference load cell(s) and load cell(s) 237A-C can be generated by the toolkit clamp 241 (see Figure 2), which provides a compressive load between the adapter plate 225 and a front wall 239 of the housing 219. A proportion of this load (referred to as preload) is applied when the body maker 101 is operated to secure the toolkit components firmly in place. Therefore, calibration of the load cells 237A-C can be used to account for (i.e., compensate for) variances in preload between can body makers. Calibration of the load cells 237AC also allows compensation for the proportion of longitudinal load that bypasses the load cells 237A-C via the preload bolt 301B. Force measurements obtained from the 237A-C load cells during can production can be analyzed using machine learning, analytics, and / or artificial intelligence techniques to determine how the can body maker's performance can be improved, for example, by adjusting one or more of its operating parameters. For instance, an evolutionary algorithm (or another type of optimization algorithm) can be used to modify the can body maker's operating parameters according to a fitness metric based on the measured forces. This metric could penalize measured forces that exceed a predefined threshold and / or forces measured by the 237A-C load cells that differ from each other by a predefined relative proportion or threshold. The operating parameters of the can body maker that are sent to the algorithm may include one or more of the following: the can production rate (the set speed of the can body maker), the operating temperature of the tool set, the rate at which coolant is supplied to the tool set, the rate at which lubricant is supplied to the tool set, and the position (alignment) of the cup former relative to the ram shaft. The algorithm may also take as input other types of data, such as the time elapsed since the can body maker was last serviced or reconfigured, the number of cans produced using the current set of dies, and / or a measurement of the quality of the raw material, such as the thickness or weight of the cups supplied to the body maker. Feedback control can also be used to adjust one or more of the can body maker's operating parameters to compensate for changes over time caused by wear or movement of components within the machine. For example, a proportional-integral-derivative (PID) controller can be used to vary one or more of the can body maker's operating parameters to minimize a specific error signal derived from measured forces. Figure 8 shows steps involved in a method for operating a can body forming machine to mitigate the effects of wear, damage, and / or misalignment of the tools during can body production, for example, using a can body forming machine as described above. The first step 801 comprises obtaining, from one or more load cells 237A-C, output signals indicative of an axial force exerted on the tools by the cup passing through them, the load cell(s) being located on or above an adopter plate 225 attached to a support plate 1 o» 223 of the can body maker. The output signals are then processed 802 to obtain data indicative that one or more of the tools are worn, damaged, and / or misaligned with respect to the ram 106. This may involve, for example, determining that the force exerted on the tools by the cup exceeds a threshold or that the difference or ratio of output signals obtained from two or more of the load cells exceeds a predetermined threshold. One or more operating parameters of the can body maker, or of another component of a production line within which the body maker is located, are adjusted 803 based on such data to mitigate the effects of one or more of the tools being worn, damaged, and / or misaligned with respect to the ram 106. This process can be repeated iteratively 804 in a feedback loop, as described above. Experts in the field will appreciate that various changes or modifications can be made to the realizations described above without departing from the scope of the ΜΛ / a / zuzz / u 14i ου invention.

Claims

1. A can body making machine for producing can bodies from cups and comprising: a ram configured to move alternately along an axis; a punch mounted on the ram; a tool set comprising a cradle and a plurality of tools located in the cradle for stretching and flattening a cup mounted on the punch during a forward stroke of the ram; a support plate fixed to the can body making machine; an adapter plate fixed to the support plate; an extractor assembly fixed to the adapter plate for removing a can body from the punch during a return stroke of the ram; a clamping mechanism for pressing said tools against a front face of the adapter plate;and one or more load cells located on or above the adapter plate and configured to generate an output signal or signals indicative of an axial force exerted on the tools by the cup passing through them.; 2. A can body maker according to claim 1 and comprising an encoder configured 28 to provide a measurement of the ram position at one or more times during each reciprocating motion.

3. A can body manufacturer according to claim 2, wherein the encoder is a linear encoder. 4 1 o» 4. A can body manufacturer according to claim 2, wherein the encoder is a rotary encoder configured to be rotated by a shaft used to drive the ram.

5. A can body manufacturer according to claim 1, wherein the one or more load cells are piezoelectric load cells.

6. A can body manufacturer according to claim 1, wherein the one or more load cells comprise more than one load cell, the load cells being equally spaced angularly from each other about axis e.

7. A can body maker according to claim 1 and comprising a processor configured to adjust one or more operating parameters of the can body maker, such as an alternate ram movement index 29, in response to the output signal(s).

8. A can body maker according to claim 1, wherein the adapter plate is fixed to the support plate by means of one or more preload bolts, each preload bolt passing through a respective of the load cells to secure the load cell between the adapter plate and the support plate.

9. A can body manufacturer according to claim 1, wherein the extractor assembly comprises a radial deviation monitoring unit for detecting misalignment of the ram and / or punch with respect to the axis.

10. A can body manufacturer according to claim 9, wherein the radial deviation monitoring unit comprises an orifice configured to allow passage of the punch and ram through it and one or more separate eddy current sensors around the orifice.

11. Apparatus for retrofitting to a can body maker, the can body maker comprising: IVIA / a / ZUZZ / U 141OU a ram configured to move alternately along an axis; a punch mounted on the ram; a tool set comprising a cradle and a plurality of tools located in the cradle for stretching and flattening a cup mounted on the punch during a forward stroke of the ram; a support plate fixed to the can body maker; an adapter plate fixed to the support plate; an extractor assembly for removing a can body from the punch during a return stroke of the ram; and a clamping mechanism for pressing said tools against a front face of the adapter plate; and the apparatus comprising: a replacement adapter plate for fixing to the support plate in place of the adapter plate of the can body maker;and one or more load cells located on or above the replacement adapter plate and configurable to generate an output signal or signals indicative of an axial force exerted on the tools by the cup passing through them.; 12. An apparatus according to claim 11, wherein the replacement adapter plate includes an extractor assembly comprising a radial deviation monitoring unit for detecting misalignment of the ram and / or punch with respect to the axis.

13. A can body manufacturer according to claim 12, wherein the radial deviation monitoring unit comprises an orifice configured to allow passage of the punch and ram through it and one or more separate eddy current sensors around the orifice.

14. A method for calibrating the apparatus of claim 11 after it has been retrofitted to a can body maker, the method comprising: installing, in the cradle of the can body maker, a calibration fixture comprising one or more reference load cells configured to generate an output signal or signals indicative of an axial force exerted on the tools located in the cradle; applying an axial force to the tools and one or more reference load cells using the clamping mechanism of the can body maker; and using the respective output signal or signals from the reference load cell(s) to determine a calibration factor or calibration function to estimate the force on the tool(s) from the output signals generated by the load cell(s) of the apparatus.

15. A method for operating a can body forming machine to mitigate the effects of wear, damage, and / or misalignment of the tools during the production of can bodies, each can body being formed by pushing a cup mounted on a punch of a ram that moves alternately along an axis through tools contained within a cradle of a tool set of the can body forming machine, the method comprising: obtaining, from one or more load cells, output signals indicative of an axial force exerted on the tools by the cup passing through them, the load cell(s) being located on or in an adapter plate attached to a support plate fixed to the can body forming machine; processing the output signals to obtain data indicative that one or more of the tools are worn, damaged, and / or misaligned with respect to the ram;Adjust one or more operating parameters of the can body maker or another component of a production line within which the body maker is located, based on such data to mitigate the effects of one or more of the tools being worn, damaged and / or misaligned with respect to the ram.

16. A method according to claim 15, wherein the one or more operating parameters comprise one or more of: a can production rate; an operating temperature of the tool set; a rate or temperature at which coolant is supplied to the tool set; a rate at which lubricant is supplied to the tool set; and a position of the dome former with respect to the ram axis.

17. A method according to claim 15, wherein the one or more operating parameters comprise a parameter of a component of the production line upstream or downstream of the body maker, for example, a cup press.

18. A method according to claim 15, comprising removing the can body from the punch during a return stroke of the ram using an extractor attached to the adapter plate.

19. A method according to claim 18, wherein the extractor is provided in an extractor assembly comprising a radial deviation monitoring unit, 5 and the method further comprises obtaining output signals indicative of a ram and / or punch position perpendicular to the axis using the radial deviation monitoring unit and adjusting said one or more operating parameters based on the data and output signals 10 obtained from the radial deviation monitoring unit.

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