Patent Application
20060000810
The present invention generally relates to power profile control for welding and in one arrangement, more particularly, to power profile control for welding inkjet printheads.
Generally, laser welding attaches a generally optically transparent or translucent material to a generally energy absorbing material using the standard constant power profile 300 illustrated in
In some arrangements, laser light is applied to the weld area in a contour welding method. Contour welding applies the beam of laser light on a single point of the weld area and welds the materials of the weld area point by point. For example, the laser beam can maneuver around the weld area, or the weld area can maneuver around the laser beam. In other arrangements, the laser light is applied to the weld area in a semi-simultaneous welding method or a simultaneous welding method. Semi-simultaneous welding method and simultaneous welding methods heat and weld multiple points of the weld area at the same time.
The laser energy is generally absorbed in a very thin portion of the absorbing material near the surface. Heat is conducted to the transparent material and also further conducted to the absorbing material from the surface in order to soften enough material to create a good joint. The laser power is normally ended by a preset timer or by the equipment sensing a preset collapse distance of the welded materials.
Various material combinations have been successfully attached using laser welding. However, one of the issues occurring when welding a semi-crystalline material is that the material has a very narrow sealing and softening temperature range. Accordingly, semi-crystalline materials are more prone to overheating and to developing imperfections (e.g., bubbles) in the weld joint.
Typically, the standard constant power profile being used during the simultaneous weld cycle for semi-crystalline materials produces bubbles in the weld area and effects the reliability of the weld joint. A dynamic power profile used during the weld cycle can, in some arrangements, allow the semi-crystalline material to quickly heat to a desired temperature and then maintain that temperature in a more controlled fashion to produce reliable weld joints.
In other arrangements, the dynamic power profile can reduce the welding time of non semi-crystalline materials.
In several embodiments, the invention provides a dynamic power profile for a laser weld cycle. The dynamic power profile can be used to weld a first portion to a second portion that includes a semi-crystalline material. For example, the dynamic power profile can be used to weld a printhead lid to a semi-crystalline printhead body.
In one embodiment, the invention provides a method of welding a first material of an apparatus to a second, semi-crystalline material of the apparatus. The method includes the acts of heating a weld area with a first power intensity for one time period and heating the weld area with a second power intensity (not equivalent to the first power intensity) for a second time period. The weld area is also not heated using a contour welding method.
In another embodiment, the invention provides a method of welding a first material of an apparatus to a second material of an apparatus. The method includes the acts of heating a weld area with a first power intensity for one time period, receiving feedback regarding the weld area during the one time period, and heating the weld area with a second power intensity for another time period based at least in part on the received feedback. The second power intensity is not equal to the first power intensity.
In still another embodiment, the invention provides a laser welding assembly for welding a first material of an apparatus to a second material of the apparatus during a weld cycle. The assembly includes a laser source for producing a light beam operable to heat at least a portion of the weld area. The light beam has a power intensity, and the laser source includes a source input terminal. The assembly also includes a controller having an input terminal operable to receive a first signal, and an output terminal coupled to the source input terminal and operable to transmit a second signal. The second signal includes a command to vary the power intensity of the light beam during a weld cycle, and the command is based at least in part on the first signal.
In still another embodiment, the invention provides a method of welding a first material of an apparatus to a second, semi-crystalline material of the apparatus. The method includes the acts of heating a weld area with a first power intensity for one time period and heating the weld area with a second power intensity (not equivalent to the first power intensity) for a second time period. The method also includes applying pressure to the weld area and producing a collapse distance within a portion of the weld area.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limited. The use of “including,” “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “mounted,” “connected” and “coupled” are used broadly and encompass both direct and indirect mounting, connecting and coupling. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
The body 15 can be constructed of a variety of materials including, without limitation, at least one of polymers, metals, ceramics, composites and the like. In the illustrated embodiments, the body 15 is constructed of at least one semi-crystalline material. For example, the body 15 can be constructed from glass-filled polybutylene terephthalate resin (available from G. E. Plastics of Huntersville, N.C. under the trade name VALOAX).
The printhead 10 further includes a lid 30 that is welded to the body 15 to cover the ink reservoir 25. When the lid 30 is welded to the housing 12, the lid 30 and housing 12 form a seal to prevent leakage of ink from the ink reservoir 25.
In the illustrated embodiments of
In another embodiment, such as the embodiment illustrated in
In some embodiments, such as the embodiment illustrated in
In the illustrated embodiment of
As shown in
In some embodiments, the controller 90 can accompany the laser source 70 in a single apparatus, or can be an external controller 90 from the laser 70, such as, for example, a personal computer. In the illustrated embodiment of
In some embodiments, the controller 90 can also include one or more input terminals 110 for receiving various inputs or signals. In some embodiments, such as the embodiment illustrated in
Also, in some embodiments, such as the embodiment illustrated in
In some embodiments, the feedback information and/or the secondary information 125 can be used during the weld cycle to vary the power intensity of the laser(s) 70. In some embodiments, the feedback information and/or the secondary information 125 can also be used during the weld cycle to terminate welding or to modify time periods throughout the weld cycle, as discussed below.
In some embodiments, the controller 90 can implement a dynamic power profile for each laser 70 during a weld cycle. The dynamic power profile includes at least one change in power intensity during the weld cycle. That is, the dynamic power profile varies the power intensity of the laser(s) 70 at least once between a first power intensity and a different, second power intensity.
For example, in a first general embodiment, the power of the laser(s) 70 is varied in a preset manner (e.g., set power intensities for set time periods). In this embodiment, the profile is not modified due to feedback during the weld cycle.
In a second general embodiment, the power of the laser(s) 70 is pulse width modulated in a preset manner. In this embodiment, the profile is not modified due to feedback during the weld cycle.
In a third general embodiment, the power of the laser(s) 70 is varied in a present manner. Power is modified or turned off due to input during the weld cycle, such as collapse distance. The input can include feedback from the weld area 65, stored information from previous weld cycles, an estimated or calculated value derived from other information, and the like.
In a fourth general embodiment, the power of the laser(s) 70 is partially or completely varied during the weld cycle due to a temperature input from the weld area 65.
In a fifth general embodiment, the power of the laser(s) 70 is varied as in the fourth general embodiment and/or with inputs of collapse distance, collapse velocity, rate of temperature change, uniformity of temperature, or the like, during the weld cycle.
In a sixth general embodiment, the power of the laser(s) 70 is varied as in the fifth general embodiment with inputs not from feedback during the weld cycle.
In a seventh general embodiment, the power of the laser(s) 70 is varied differently for different sections of the weld area 65.
In an exemplary implementation illustrated in
In this embodiment, the controller 70 receives temperature-based feedback (e.g., ) from the weld area 65 throughout the duration of the weld cycle, and compares the temperature data to certain thresholds. As illustrated in
The temperature of the weld area 65 is raised to a temperature (e.g., a starting temperature) over a first period of time T1. In some embodiments, the starting temperature includes a plurality of temperatures within a desired or set temperature range (e.g., the softening temperature range). In other embodiments, the starting temperature can include a specific temperature within the desired or set temperature range, such as, for example, the lower temperature limit or the higher temperature limit within the desired temperature range. In further embodiments, the starting temperature can include a desired or specific temperature point that may or may not be included in a desired temperature range. In this example, the starting temperature includes a plurality of temperatures within a desired or set temperature range, such as, for example, the softening temperature range. Also in this example, the temperature of the weld area 65 reaches the starting temperature (at point 230) at time t1.
As shown in
While the temperature is maintained at the starting temperature (e.g., at a temperature within the desired temperature range) (at point 245), the varied power intensity 220 has reached approximately zero, causing the weld cycle to be terminated at time t2. In some embodiments, the varied power intensity 220 in the second portion 210 can inversely correlate to the weld area temperature. When implementing this exemplary power profile 200, the temperature of the weld area 65 is less likely to exceed any thresholds (such as, for example, a melting or bubbling threshold, or a temperature that is greater than the desired temperature range) and overheat. The weld area 65 is less likely to overheat, because the rate of temperature change in the weld area 65 gradually lowers as the varied power intensity 220 is reduced (and the weld area temperature is maintained within the desired temperature range).
In some embodiments, the temperature of the weld area 65 can be raised to a starting temperature (i.e., a first set temperature point) over a first period of time T1. During the second time period, the temperature of the weld area 65 can be maintained at the starting temperature (i.e., the set temperature point) or can be gradually raised or lowered to an ending temperature (i.e., a second set temperature point). In one embodiment, for example, the second set temperature point can be greater than the first set temperature point, such that the weld area 65 is heated to a first temperature during the first time period T1, and then gradually heated to a higher second temperature during the second time period T2. In another embodiment, for example, the second set temperature point can be less than the first set temperature point, such that the weld area 65 is heated to a first temperature during the first time period T1, and then gradually reduces to a lower second temperature point during the second time period T2. In these embodiments, both the first set temperature point and the second set temperature point may be included within a softening temperature range.
As mentioned previously, in other embodiments, the weld area 65 can be heated to a starting temperature point (which may or may not include a range of temperatures) during the first time period T1, and then can be maintained within a desired range of temperatures during the second time period T2. In these embodiments, the temperature of the weld area 65 can be raised and/or lowered to one or more temperatures included in a range of temperatures during the second time period T2. In some embodiments, the starting temperature point can include a first range of temperatures, and the desired range of temperatures can include a second range of temperatures. The first range can differ from the second range or can include the same temperatures as the second range. Furthermore, the second range can differ from the first range or can include the same temperatures as the first range.
Also in the exemplary implementation, the controller 90 can also receive collapse-based feedback (e.g., collapse distance, maximum collapse distance, average collapse distance, collapse velocity, maximum collapse velocity, average collapse velocity, and the like) to control and modify the varied power intensity 220 of the second portion 205. For example, a manipulating element 80 can apply pressure to the weld area 65 during the first time period T1 and/or during the second time period T2 to produce a desired collapse distance D. In one embodiment, the desired collapse distance D is at least approximately 0.1 mm. The controller 90 can terminate the welding cycle when the controller 90 determines that the desired collapse distance D between the two materials has been achieved.
In other variations of the dynamic power profile 200, the first portion 205 can include a first varied power intensity having a first average power intensity. The second portion 210 can then include either a second constant power intensity that is less than the first average power intensity, or can include a second varied power intensity having a second average power intensity that is less than the first average power intensity.
Other examples of the dynamic power profiles (and multiple power settings) that the controller 90 can establish during a laser welding cycle are illustrated in
An operator can determine which dynamic power profile (e.g., the power vs. time control) to implement during the weld cycle based on several factors. In one embodiment, when welding a printhead lid 30 to a printhead body 15, a certain dynamic power profile is selected or is created in order to 1) raise the temperature of both materials (e.g., the lid 30 and the body 15) of the weld area 65 to a softening temperature as fast as possible, typically starting at full-power intensity (e.g., 100% intensity), 2) maintain the weld interface temperature in an allowing range (such as the softening temperature range), 3) maintain the weld area temperature so both materials (e.g., the lid 30 and the body 15) are not degraded by overheating, 4) maintain the weld area temperature so it is not overheated causing low viscosity melted material (e.g., the lid 30 or the body 15) to move out of the weld area 65, and 5) maintain the weld area temperature for enough time so that adequate cohesion or adhesion can occur in the weld area 65.
In this embodiment, the factors are dependent of the characteristics of the different material types being welded, such as, for example, the softening temperature threshold, the softening temperature range, an overheating threshold, the temperature at which the material heats to a low viscosity, and the like. When welding a translucent material to a semi-crystalline material, for example, temperature-based feedback control can aid in the dynamic power profile due to the fact that semi-crystalline materials have a narrow softening temperature range which can produce reliable weld joints in the material.
The various dynamic power profiles discussed above can also produce a more controlled collapse rate of the welded materials, as shown in
The embodiments described above and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims.
