9.5 Consideration
239 It was not suggested that any of the terms of the claims were technical terms, or anything other than ordinary English words. The construction of the terms is a matter for the Court: Airco Fasteners Pty Ltd v Illinois Tool Works Inc [2023] FCAFC 7 at [59].
240 The experts were in agreement as to how certain terms should be construed. Where that has occurred, I agree with and adopt the experts' construction of those terms as set out below.
241 The invention described in the specification and around which the claims are drawn is concerned with a particular arrangement of the sacrificial covers of a tooth construction for a mineral sizer, wherein the covers are welded to each other and to the support body indirectly, or are welded to the support body directly, so as to provide a robust tooth construction which will efficiently transmit the large forces generated during operation of the sizer by breaking particularly hard mineral, from the covers to the support body. Without the efficient transmission of the large forces generated, the covers may fall off the support body.
242 The invention is not a robust tooth construction however constructed. At times MMD's submissions and Mr de Vos' evidence in the joint session came very close to suggesting that any way of achieving a robust tooth construction would fall within the claims of the Patent. An example being the tooth construction depicted in diagram 3 which involved the transmission of force via weld between the very edges of the covers and (at best) the outer few millimetres of the front/rear face of the support body.
243 Both Dr Huggett and Mr de Vos agree that:
(a) The support body is a tooth shaped projection on the sizer ring that transmits the driving force from the support body through the shell connected to the support body to the actual ore. The shell is the outer covering that protects the support body. The tooth construction is the assembly of all those components together.
(b) A "plurality" of covers means more than one cover.
(c) The unitary construction requires the covers and support body to work together to act as one complete body rather than as individual components.
(d) The front cover is any cover that lies in front of the front face of the support body.
(e) A rear cover is a separate cover located at the rear face of the support body and protects the rear face of the support body.
(f) A "breaking tip member" is a component added to the front face of the tooth assembly for gripping the rocks and effecting the initial breakage of the rocks.
(g) The "juncture" is the location where the top and front walls of the top cover meet.
244 I consider that:
(a) the "shell" is composed of the covers covering the support body; and
(b) "tooth shaped" means that the support body is shaped like a tooth, in that it is symmetrical, smooth and rounded, without sharp corners.
245 The "separate" rear cover is separate from the front cover. If the rear cover is welded to the rest of the tooth construction shell, it does not become integral with the front cover. It remains a separate rear cover. However, if the rear cover is integral with the intermediate cover such that they are part of the same component, the rear cover will not be a separate rear cover. Mr de Vos agreed that a benefit of a separate rear cover was that it was easier to install the tooth construction and to position the front and rear faces as close as possible to the horn. The first cover can be placed on and then the separate rear cover can be placed on and pressed up against the horn. It is much harder to install a one piece tooth construction. That benefit is lost when the rear cover is an integral part of the intermediate cover, not a separate cover.
246 I do not consider that a rear cover which is an integral part of the intermediate cover can become a "separate" rear cover in the situation where a top cover is added over the intermediate cover, merely by being separate to the top cover, in particular the front face of the top cover.
247 Regarding the "unitary tooth construction" integer, I do not consider that welding the toe of one tooth construction to the heel of the next tooth construction around the circumference of the drum annulus results in the individual tooth constructions no longer being "unitary" tooth constructions. The plurality of covers come together to form the one complete tooth construction, that is not altered by that tooth construction being attached by a strip of weld to the next one situated on the annulus.
248 The major construction dispute between the parties arises in relation to two aspects of the following integer:
… a front cover which is weldingly secured to and seated in face to face contact with the front face of the support body …
249 For the reasons which I will explain shortly, I consider that the phrase "weldingly secured to and seated in face to face contact with the front face of the support body" requires that:
the front cover is:
(i) weldingly secured to; and
(ii) seated in face to face contact with the front face of;
the support body (Dr Huggett's Meaning B).
250 This construction also applies to the equivalent rear cover integer.
251 Meaning A may at first glance seem to be the more natural reading outside the context of the Patent, but to my mind Meaning B is consistent with the use of the phrases in the specification.
252 It is necessary to construe the phrases "weldingly secured" and "seated in face to face contact" within the context of the larger phrase.
253 Before continuing, I return to the ore fines issue that was introduced early in these reasons. The extensive recitation of Mr de Vos' evidence directed towards construction of the terms of the claims of the Patent demonstrates that the ingress and compression of ore fines (and corrosion) into the gaps and clearances in the tooth constructions was a significant element of Mr de Vos' reasoning processes in arriving at his preferred construction in his first affidavit, and was relied upon by MMD in its written opening submissions. As noted previously, considerable evidence was devoted to the issue of ore fines and corrosion.
254 The Court is left to attempt to reconcile MMD's case in closing absent the ore fines, with the evidence of Mr de Vos in which the ore fines play a significant part in his reasoning and consideration to reach the construction in his first affidavit, and to that extent cannot simply be set to one side. It was not practical or possible to just read out any reference to ore fines (and corrosion) from Mr de Vos' affidavits and leave his reasoning intact. Accordingly I cannot ignore the impact of ore fines on Mr de Vos' reasoning as set out in his five affidavits.
255 Equally, I cannot accept those of MMD's submissions which appear to have their origin in the ore fines infected reasoning, but which ignore the role of ore fines in the reasoning process. This is particularly applicable to MMD's submissions as to diagram 3. As I foreshadowed and will now explain, I do not consider that a tooth construction with the configuration depicted in diagram 3 falls within claim 1.
256 According to Mr de Vos the word "contact" imports into the claims the critical concept of the efficient transfer of forces. A robust tooth construction must be capable of efficiently and effectively transmitting forces from the covers to the support body.
257 As a result of the large forces that are imparted on the teeth, it is necessary for those forces to be efficiently transmitted to the support body and the shaft in order for the teeth to be sufficiently robust. Otherwise, the large forces that are imparted onto the teeth during operation (particularly in hard rock mining) can cause the means of securing the covers to fail if those forces are not efficiently transmitted to the support body. Failure of tooth covers in between scheduled maintenance breaks is very undesirable.
258 According to Mr de Vos, the most efficient way of transmitting force is a "compressive force", which involves "pushing into, or compressing, a component". In his first affidavit, Mr de Vos observed that "as compressive forces do not rely on a fastening medium unlike tensile and shear forces, it is preferable for the forces imparted on the covers during use to be transmitted to the support body through compressive forces".
259 In his first affidavit, Mr de Vos observed that the Patent emphasises the importance of the ability of the tooth construction to transmit forces from the covers to the support body to ensure that the welds securing the covers do not fail as a result of the forces imparted on them during use. I consider that the emphasis on the effective transmission of force is inconsistent with the welds being the means for the transmission of the majority of the force as shear force as per diagram 3. In the configuration as depicted in diagram 3, the majority of the forces are being transmitted through the welds, thereby placing the weld under stress which may cause them to crack and fail early. According to Mr de Vos weld will most commonly fail where large shear forces or tensile forces are repetitively imparted on the weld.
260 The person skilled in the art would be aware that mineral sizers undergo regular maintenance. The tooth construction must be robust enough to break the ore and remain intact for the duration of the maintenance period. The welds must secure the covers of the tooth construction for the entire maintenance period. As the tooth constructions are replaced at regular intervals, there is no need for the tooth constructions to be made to last as long as possible.
261 All of the words in the phrase "seated in face to face contact" have a role to play.
262 MMD focusses on the face of the support body as the face of interest. Its submissions speak of methods to ensure the requisite transmission of force "from the covers" to the support body not the faces of the covers or the faces of the support body (as the claims require). Diagram 3 depicts an arrangement where the "rear cover … does not directly touch the rear face of the support body". I consider that the words "face to face" contemplate the existence of two faces: the face of the front/rear cover, and the front/rear face of the support body, and that being in face to face contact requires the two faces to be in physical contact.
263 That face to face contact requires the physical contact of the two faces: the face of the front or rear cover and the corresponding face of the horn, is consistent with the usage of the phrases in the description of the two embodiments of the invention described in the specification. Each time the phrase "face to face contact" is used, it is in the context of a description of the placement of two faces: the front or rear cover, and the front or rear face of the horn. In contrast, the discussion of welding in the specification directs welding "to the horn", not to specifically the front or rear faces of the horn.
264 The phrase "face to face contact" first appears at page 5, line 11, in the description of the placement of the rear cover in the first embodiment. The rear cover is described as being seated in face to face contact with the rear face of the horn. There is no mention of how the rear cover is held in place until the next paragraph in which the rear cover is said to be preferably secured to "the horn", not the rear face of the horn, by welding. It is also noted that the rear cover may be "indirectly welded to the horn" by being welded to the side covers.
265 Later on page 5, line 30, the internal face of the top cover is said to be seated in "face to face contact" with the front face of the horn. The top cover is then said at page 6, line 18, to be "secured to the horn 12, preferably by welding". There is no reference to a particular face of the horn. The welding direction is to join the opposed faces between the top cover and the plate-like body of the side cover to one another.
266 I consider that "seated" in the phrase "seated in face to face contact" means positioned. The front cover is the front cover which is in physical contact with the front face of the horn.
267 The specification describes a method or sequence of the construction of the tooth construction - the cover is described as being "seated in face to face contact" with the relevant face of the horn, well before any discussion of how it is secured to the horn.
268 Sand casting is relatively imprecise. Components that are produced using sand casting have relatively rough surfaces. In practice, there will still be some clearances between (a) the face of the support body and (b) the front and/or rear covers due to the imprecision involved with sand casting. The front and/or rear covers will undulate across their surface, meaning part of the face of the covers will touch the support body and part will not.
269 I disagree that the two faces must be "flush" to the extent that "flush" requires intimate contact across all surface of the faces. Dr Huggett agreed in the joint session that he contemplated that the majority of the surfaces would be in contact, rather than a perfect 100%.
270 According to Mr de Vos the surface of the covers are unlikely to be smooth, even with the best manufacturing tolerances, as cast surface are likely to have undulations. Over a lifetime of use and refurbishment, including gouging off old welded-on covers, the surfaces of the horn are unlikely to be entirely smooth or identical to each other.
271 Thus a common sense construction of "face to face contact" in the context of front and rear covers which are likely to be sand cast, means physically touching across most of the faces of the cover and the support body (allowing for undulations inherent in the casting process). The same total force will be transmitted between two components, irrespective of whether they are "flush, in intimate contact across their surfaces, without any gaps" or there are some gaps between them.
272 Weld is discussed in the specification merely as the way to secure components, not as the primary conduit of force from the covers to the support body. In the method of construction outlined for the first embodiment, the side covers are said to be secured to the horn, preferably by welding. The specification states that preferably this is to be achieved by "welding along the front, upper and read edges" respectively to produce a welded seam. Similarly, the rear cover is secured to the horn and side covers preferably by welding. This is achieved "welding along the side edges" to produce "welded seams". There is no discussion in the specification of adjusting the weld to bear the transmission of the majority of the force as shear forces if there is no physical contact across the faces of the covers and the support body.
273 As I noted above, MMD's construction of claim 1 reached the point where it became almost a claim by result - anything which achieves the functionality of, or results in, a robust tooth construction falls within claim 1 - whether it be an embodiment of the kind in diagram 1 or at the other extreme with only point to point contact with the side cover such as diagram 3. This is illustrated by MMD's submission that a robust tooth construction can be created that is designed to transmit forces between the covers and the support body entirely through weld (diagram 3). I consider that such a construction ignores the references to face to face contact in the specification and gives "contact" no work to do. It also ignores the notion of efficient transmission of compressive force said by Mr de Vos to be imported by the word "contact".
274 I consider that a tooth construction of a kind depicted in diagram 2, in which the face of the rear cover is in physical face to face contact with the rear face of the support body, but which is welded to a part of the support body that is not the rear face (eg indirectly welded), is still a robust design within claim 1 of the Patent.
275 Provided that the rear cover is seated in face to face contact (touching across most of the two faces) with the rear of the support body, the forces imparted on those covers during use will be transmitted efficiently via compressive force to the support body. Even if, for instance, the rear cover is welded to the sides of the support body, most of the force will not be transmitted through those welds. The forces will predominantly be transmitted through the face to face contact between the rear cover and the rear face of the support body. In this configuration, the role of the weld is primarily to secure the rear cover to the support body.
276 Where there is a permanent gap between a cover and a support body, the cover or weld could break during use. Mr de Vos considered that the weld securing the cover to the support body may crack over time if there is a permanent gap between the cover and support body. In his experience, weld will most commonly fail where large shear forces or tensile forces are repetitively imparted on the weld.
277 In the tooth construction depicted in diagrams 1 and 2, the majority of force imparted at the rear of the tooth construction will be transmitted directly to the front face of the support body as a compression force transmitted via the physical contact of the faces of the rear cover and the support body. Mr de Vos agreed that where the rear cover and the rear face of the support body are "flush" (in contact across the majority of their faces), then the transfer of forces "would be much more effective", than when there is a gap such as that depicted in diagram 3.
278 MMD submits that diagram 3 shows that forces are transmitted from the rear cover to the peripheral sides of the rear face of the support body. Although forces may only be transmitted to the outer few millimetres of the rear face of the support body, they are still transmitted to the rear face of the support body and MMD submits that is sufficient for the claims of the Patent.
279 On MMD's case, the size of the weld is important, because (in the diagram 3 scenario) if the weld is only a few millimetres and is required to take a high amount of shear force, this renders it prone to cracking (or failure), with the consequence that the cover is likely to fall off during operation.
280 The Patent speaks of weld as a preferable way to secure the covers of the tooth construction. It says nothing about the transmission of forces through welds or the adjustment of the welds to bear transmission of the majority of the force as shear forces. If welds were contemplated by the inventor as components through which large forces were intended to be transmitted efficiently to the horn and thereby effect face to face contact, it would be expected the patentee would have said something about that topic, including on the importance and the nature of the welds required to effect the invention (including the size of the welds). Further, the sequence of construction described in the specification would not describe components as seated in face to face contact before welding had taken place; welding is said only to secure them after they are seated in face to face contact (page 5, line 10-16; page 5, line 29 to page 6, line 5; page 8, line 27 to page 9, line 4).