GB2549077A

GB2549077A - Generating control data for controlling an automated manufacturing process

Info

Publication number: GB2549077A
Application number: GB1605178.1A
Authority: GB
Inventors: Lionel Farmer Benjamin; Hawkins Andrew; Henry Ben Robarts-Arnold James; Edward Haythornthwaite Merlyn
Original assignee: Hieta Technologies Ltd
Current assignee: Hieta Technologies Ltd
Priority date: 2016-03-29
Filing date: 2016-03-29
Publication date: 2017-10-11
Also published as: GB201605178D0

Abstract

The design and manufacture of the bike frame is accomplished by a method of generating control data for controlling an automated manufacturing process, such as additive manufacturing, to generate the object (bike frame 2, figure 1) with a plurality of components. User specified parameters 8 indicative of overall dimensions of the objects are received; these are used to generate one or more component dimensional characteristics; an initial customised model 12, is generated based on the component characteristics and a reference model 14, this could be generated by CAD; a user specified loading parameters are provided; using loading parameter 14 and the initial model peak loads are determined for at least some of the said plurality of components; a modified customised model 16 is generated based on the peak loads, this model includes a modified component; this modified customised model is used to create the control data. The object created maybe a truss structure. The modified customised model may also take into account permitted stress, or other stress factors within the components. It may also take into account a cost parameter.

Description

GENERATING CONTROL DATA FOR CONTROLLING AN AUTOMATED

MANUFACTURING PROCESS

This disclosure relates to the field of generating control data for controlling an automated manufacturing process, such as, for example, control data for controlling an additive manufacturing process.

It is known to use automated manufacturing processes, such as additive manufacturing processes, to generate components which are then assembled into a desired object. The design of the components required to form the desired object is a skilled and time consuming task. The components are designed to fit together correctly and form the object having particular characteristics, such as strength, dimensions, dynamic or static performance and the like. An example of such an object is a bicycle frame. It would be desirable for a bicycle frame to be individually tailored to a given intended user, e.g. the arm reach of the user, the leg length of the user, the mass of the user etc. However, redesigning the components of a bicycle for individual users while maintaining the same margins would be undesirably burdensome. One approach would be to use margins which are too great for the normal case, but are sufficient to meet all requirements within a design range. However, such an approach typically leads to an inefficient design which is unnecessarily strong and accordingly unnecessarily heavy in the majority of cases.

At least some embodiments of the present disclosure provide a method of generating control data for controlling an automated manufacturing process to generate an object having a plurality of components, said method comprising: receiving one or more user specified parameters indicative of overall dimensional characteristics of said object; in dependence upon said one or more user specified parameters, generating one or more component dimensional characteristics of one or more of said plurality of components; in dependence upon said one or more component dimensional characteristics and a reference model of said object, generating an initial customised model of said object; receiving one or more user specified loading parameters indicative of a loading to be applied to said object in use; in dependence upon said initial customised model and said one or more user specified loading parameters, determining peak loads expected within at least some of said plurality of components; in dependence upon said peak loads, generating a modified customised model of said object with one or more modified components; and in dependence upon said modified customised model, generating said control data.

The present techniques break down the process of generating control data for controlling an automated manufacturing process into a sequence of steps for customising of a basic design in a manner which permits one or more user specified parameters to be achieved whilst not requiring excessive margining to be used to meet a required level of strength. More particularly, the user specified parameters are used to generate component dimensional characteristics of the components of an object with these component dimensional characteristics then being used with a reference model of the object to generate an initial customised model. A user specified load parameter or parameters may then be employed to determine peak loads expected in use with at least some of the components (e g. the strength limiting components). Such peak loads will be dependent upon the shapes and sizes of the customised components, which themselves have been changed in their shapes and sizes from those of the reference design based on the one or more user specified parameters indicative of the overall dimensional characteristics of the object. The peak load data which is generated may then be used to generate a modified customised model of the object in which the components are modified to take account of the expected peak loads such that they may have a form with a desired degree of margin in their strength. This modified customised model with the one or more modified components may then be used to generate the control data to control the automated manufacturing process. A further level of control and customization may be achieved by employing one or more user specified stress parameters which are indicative of permitted stresses within at least some of the components which form the object. Thus, the user can specify both the load to be carried by the object and the permitted stresses within the components such that they may effectively control the margin of strength to be provided. For example, a user might indicate a margin factor of two indicating that the maximum permitted stress which should occur within the modified components (which may have their shape, thickness, material etc. modified) is less than half the limiting stress characteristic of the component concerned. A user wishing to produce an object that is more durable will select a higher margin factor, but will accept that the object when manufactured may have other characteristics which are less desirable, e g. it may be heavier. Conversely, a different user might prioritise the ultimate level of performance over the durability (such as for one time competition use) and may select a margin factor less than a normal user and accept that the durability of the object would be less, but the other performance characteristics may be better, e g. the object may be lighter.

It will be appreciated that a range of automated manufacturing processes are known, such as computer driven machine tools. However, the present techniques are particularly well suited to use when one or more of the components is formed of consolidated material by additive manufacture. Additive manufacture gives a high degree of freedom over the form of the components in a way which may be exploited by the present techniques to provide characteristics of the components, and of the overall object, which are closely matched to the user specified parameters. Additive manufacture is also well suited to the manufacture of one-off customised designs as it involves less use of expensive tooling specific to a given design.

Whilst the present techniques may be used for generating the control data for controlling the automated manufacture of objects for a variety of different forms, they are particularly suited to generating the control data for controlling the automated manufacture of a truss structure. The design of a truss structure is typically highly correlated with the overall dimensional characteristics of the truss structure to be generated and the loads to be carried by that truss structure in a manner in which the present techniques are particularly useful. Within such truss structures, the truss structure nodes may be formed by consolidated material by additive manufacture. The truss struts may also have a degree of freedom in their form, but this may be more limited, such as by selection from a predetermined range of pre-manufactured truss struts (e.g. truss struts of different cross sections, wall thickness, materials etc.).

The generation of the one or more component dimensional characteristics of one or more of the plurality of components comprising the object may take the form of generating lengths of the truss struts and angles between the truss struts. The lengths of the truss struts selected to produce an object with an overall dimensional characteristic will have an influence upon the angles between the truss struts and also the way in which loads are carried by the truss structure. For this reason, the truss structure nodes may be modified as part of forming the modified customised model to have a desired strength necessary to support the “in use” load with a desired margin. The materials and section of the truss struts may also be changed and require modification within the truss structure nodes to provide appropriate joints.

As mentioned above, the truss structure nodes, or other components may be generated as part of forming the modified customised model and this may be done by morphing the truss nodes to reduce their mass under a constraint that the modelled maximum stress within the given component (which may or may not be the modelled truss structure node itself) matches a corresponding permitted strength (e.g. has an appropriate margin factor of strength).

The loading parameters for the object could take a variety of different forms depending upon the particular use of the object. However, one common form of a loading parameter may be a mass to be supported by the object, e g. the mass of a rider of a customised bicycle. Further customisation parameters may also be employed as part of the generation of the modified customised model. In particular, in some example embodiments, a user specified cost parameter may be received and at least one of generating the initial customised model and generating the modified customised model may be dependent upon this user specified cost parameter such that the object meets a cost constraint associated with the user specified cost parameter.

As an example, a cost constraint may indicate that a particular type of material should be used to form the structure and this can be indicated in the initial customised model before this is modified (in what is likely to be a way with relatively little impact upon the cost) when forming the modified customised model. Thus, for example, a particular cost constraint may indicate that a truss structure be formed of aluminium alloy tubes and aluminium alloy truss structure nodes. However, if the cost constraint is less severe, then superior performance may be achieved via the use of carbon reinforced polymer tubing and titanium alloy truss structure nodes. Different combinations of materials for the truss struts and the truss structure nodes may also be employed and may be a user specified parameter, which is directly specified rather than specified via a cost constrain parameter.

Cost constraint parameters may also be used to control manufacturing parameters of the object when additive manufacture is used. For example, if a longer build time is acceptable, with its associated higher cost, then it may be possible to generate components with a higher strength and a lower mass, using slower and more expensive, but higher resolution, additive manufacture.

While it will be appreciated that the one or more user specified parameters indicative of overall dimensional characteristics of the object could take a variety of different forms, they may, for example, take the form of biometric parameters of an intended user of the object which themselves control the overall dimensions of the objects, e.g. in the context of the frame of a bicycle, the arm reach of a user and the leg length of a user may control the desired size and geometry of a bicycle frame.

Other forms of the one or more user specified parameters indicative of the overall dimensional characteristics of the object may specify those characteristics as performance characteristics of the object. As an example, a user may specify a parameter indicative of the desired stability characteristics of a bicycle, or the suspension characteristics of a bicycle. These parameters then guide the modification of the component dimensions used to form the initial customised model, which is then further refined in dependence upon the required load carrying characteristics, cost constraints, or other parameters.

Other embodiments of the present disclosure provide a system comprising a user terminal and server a computer which together cooperate to perform the above described techniques. The user terminal may employ a web-based interface to collect various user specified parameters as discussed above. These parameters may then be sent to a remotely located server computer which performs the various modelling, determination and morphing steps which result in the control data for the automated manufacture. The control data for the automated manufacture may be sent back to the user, or may be forwarded to a manufacturing site, possibly at a further different location, where the desired object is then manufactured in accordance with that control data.

Example embodiments will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 schematically illustrates an object comprising a plurality of components which may be customised in dependence upon one or more user specified parameters as part of generating control data for controlling an automated manufacturing process;

Figure 2 is a flow diagram schematically illustrating how user requirements may be captured and then used to generate control data for controlling automated manufacture;

Figure 3 schematically illustrates how peak load in a component may vary with a dimensional or geometric parameter associated with that component or the model as a whole,

Figure 4 schematically illustrates margining; and

Figure 5 schematically illustrates an overall system incorporating user terminals, a server computer and a manufacturing site.

Figure 1 schematically illustrates an object 2 to be manufactured in the form of a bicycle frame 2. The bicycle frame 2 is a truss structure formed of a plurality of truss structure nodes 4 and a plurality of truss struts 6. The truss structure nodes 4 may be formed of consolidated material via an additive manufacturing process, such powder bed laser melting using titanium alloy or aluminium alloy. The truss struts 6 may be formed of tube material, such as aluminium alloy tube or carbon fibre reinforced polymer tube.

As illustrated in Figure 1, a user may specify a parameter indicative of the overall dimensional characteristics of the object such as by specifying the arm reach of the user. Many further parameters may be additionally or alternatively specified. The arm reach of the user should be matched to the lengths of the truss struts U and h such that the user’s hands fall comfortably upon the handlebars of the bicycle. Varying the lengths U and I2 in turn has an influence upon the required form of the truss structure node 4 at the head tube and varies, for example, the angle Θ. This is only one example of a user specified parameter which controls the overall dimensional characteristics of the object 2. Another example in the context of a bicycle frame would be the leg length of the user which may influence the truss strut lengths used in the rear portion of the bicycle frame 2 to achieve the desired spacing between the saddle and the bottom bracket carrying the bicycle pedal cranks.

The mass of the user may also be specified and used to control selection of some dimensional characteristics of the truss struts to be employed in terms of yielding a required strength and margin. The truss struts may be selected, for example, from a predetermined range of pre-manufactured truss struts with different cross sectional sizes and wall thicknesses. The appropriate truss strut may be selected based upon the loads calculated to be carried by that truss strut, which is in itself influenced both by the geometry of the frame (such as controlled by the specified arm reach) and the mass of the rider.

Further parameters which may be specified by the user include a required margin factor to be incorporated within the strength of the design to reflect a trade off between durability and mass of the object 2. A further user specified parameter may be a cost constraint to be applied to manufacture of the object 2. Such a cost constraint may limit the choice of materials to be employed. Furthermore, manufacturing parameters associated with additive manufacturing of some of the components may be varied dependent upon the cost constraint, such as whether or not a slow, but more expensive, additive manufacturing time is acceptable in order to provide higher strength/durability.

The biometric parameters of the user of the object, such as arm reach and leg length, may be collected via a web interface of a computer terminal as will be described further below. The user may at the same time, specify other performance characteristics they wish in the desired object. For example, the angle a of the head tube from the vertical as well as other characteristics, such as fork length and fork mass, will control the stability of the bicycle in use and may be specified by a user to suit their desired preferences or the desired use of the final object. Other performance controlling parameters relating to the handling of a bicycle when this is the object to be formed may include the bottom bracket height provided by the bicycle frame, the pivot positions in a suspension system, such as the rear suspension, and the chain stay length influencing the wheel base of the bicycle.

Figure 2 is a flow diagram schematically illustrating the steps in producing control data for controlling an automated manufacturing process to generate an object 2 having a plurality of components 4, 6 in dependence upon specified user parameters. At step 8 the user parameters are received, such as by being input to a web interface of a terminal computer. These parameters may include body dimensions of an intended user (biometric parameters, the weight of a user), the desired performance characteristics of the object (e g. stability, suspension characteristics etc.), the margin factor required (e g. the length of warranty a user wishes which correlates to the necessary durability to be built into the object), and possibly a cost constraint. Step 10 employs a geometry algorithm (such as may be provided by a spreadsheet-based model of the bicycle frame) to generate component dimensional characteristics of one or more of the components of the object 2, such as the truss strut lengths required to meet the body dimensions of the intended user. The strut angles may also be determined by the geometry algorithm 10 as these control the desired form of the truss structure nodes 4. At step 12 the determined truss strut lengths and angles between the truss struts together with a reference model of the object 14 are supplied to a computer program which generates an initial customised model of the object as a parametric solid model. Step 14 then uses the mass of the intended user (a user specified loading parameter) together with the initial customised model generated at step 12 to determine the peak loads expected within some or all of the components of the object 2. Step 16 is then able to use the peak load data generated at step 14 together with initial customised model to generate (e.g. by morphing) a modified customised model with one or more modified components (e.g. the wall thicknesses in the truss structure nodes 4 may be modified to have the required strength but not excessive strength). One or more user specified stress parameters (warranty/durability/stress allowable parameters) may also be used as an input to the morphing process which generates the modified customised model such that the desired degree of margin factor is achieved in the strength of the structure which is provided by the modified customised model. The re-meshing and local refinement which generates the modified customised model at step 16 may form component dimensions which are fed back into step 12 to ensure that the geometry is still met and make any consequential changes in other components. The modified customised model is then supplied to steps 18 and 20 where the control data for controlling an automated manufacturing process is generated using steps which may, for example, slice the model for layer-by-layer printing and generate appropriate support structure in dependence upon the selected automated manufacturing technique.

Figure 3 schematically illustrates how the peak load in a component as calculated at step 14 varies in dependence upon one or more variable geometry or dimensional parameters associated with that component. This diagram illustrates a one-dimensional variation, whereas it will be appreciated that in practice the geometry and dimensional characteristics provide N degrees of freedom in the design of the particular component with possibly each of these degrees of freedom influencing the peak load in the component. Step 14 is used to determine the peak load in dependence upon the geometry and dimensional characteristics which have already been set. This peak load can then be used to set other parameters, such as indicating the strength of the material to be used, and factors such as wall thicknesses, which will be required to carry the determined peak load with the required degree of margin.

Figure 4 schematically illustrates the use of a user specified margin. In this example, the stress within a truss node 4 in a particular direction is modelled and determined. The modelled maximum stress for a given load and a given loading scenario will vary with the morphing of the component at step 16. This morphing may be controlled such that the modelled maximum stress then matches a permitted stress. This match does not necessarily mean that the modelled maximum stress and permitted stress are equal, but may, for example, indicate that the permitted stress is double the maximum model stress if the user specifies a margin factor of 2 as appropriate for their desired warranty length.

Figure 5 schematically illustrates a system 22 utilising the above described techniques. User terminals 24 are used to collect user specified parameters, such as user body sizes, body mass, warranty/durability requirements, cost constraints and the like. These user specified parameters are supplied to a server computer 26 which uses a reference model 28 of the object to be built and employs a geometry algorithm, load determination software and morphing software to generate the modified customised model previously described. The server 26 further generates control data for controlling manufacture of the object in accordance with that modified customised model. The control data is sent to a manufacturing site 30 where the object is manufactured, such as by additive manufacture.

Claims

1. A method of generating control data for controlling an automated manufacturing process to generate an object having a plurality of components, said method comprising: receiving one or more user specified parameters indicative of overall dimensional characteristics of said object; in dependence upon said one or more user specified parameters, generating one or more component dimensional characteristics of one or more of said plurality of components; in dependence upon said one or more component dimensional characteristics and a reference model of said object, generating an initial customised model of said object; receiving one or more user specified loading parameters indicative of a loading to be applied to said object in use; in dependence upon said initial customised model and said one or more user specified loading parameters, determining peak loads expected within at least some of said plurality of components; in dependence upon said peak loads, generating a modified customised model of said object with one or more modified components; and in dependence upon said modified customised model, generating said control data.

2. A method as claimed in claim 1, comprising: receiving one or more user specified stress parameters indicative of a permitted stress within said at least some of said plurality of components; and wherein generation of said modified customised model is performed in dependence upon said peak loads and said one or more user specified stress parameters such that a modelled maximum stress within a given component matches a corresponding permitted stress.

3. A method as claimed in claim 1, wherein said one or more user specified stress parameters indicate a margin factor by which a limiting stress characteristic of said given component is to exceed said corresponding permitted stress in order that said modelled maximum stress matches said corresponding permitted stress.

4. A method as claimed in any one of claims 1, 2 and 3, wherein at least one of said plurality of components is formed of consolidated material by additive manufacture.

5. A method as claimed in any one of the preceding claims, wherein said object is a truss structure.

6. A method as claimed in claim 5, wherein said truss structure comprises: truss structure nodes formed of consolidated material by additive manufacture; and truss struts selected from a predetermined range of pre-manufactured truss struts.

7. A method as claimed in claim 6, wherein said step of generating one or more component dimensional characteristics of one or more of said plurality of components comprises generating lengths of at least some of said truss struts and angles between said truss struts.

8. A method as claimed in claim 2 and any one of claims 6 and 7, wherein said step of generating said modified customised model of said object comprises morphing said truss nodes to reduce mass of said truss nodes under a constraint that said modelled maximum stress within said given component matches said corresponding permitted stress.

9. A method as claimed in any one of the preceding claims, wherein said one or more user specified loading parameters are indicative of a mass to be supported by said object.

10. A method as claimed in any one of the preceding claims, further comprising receiving a user specified cost parameter for said object and at least one of generating said initial customised model and generating said modified customised model is dependent upon said user specified cost parameter such that said object meets a cost constraint corresponding to said user specified cost parameter.

11. A method as claimed in claim 4 and claim 10, wherein manufacturing parameters of said additive manufacture are controlled in dependence upon said user specified cost parameter.

12. A method as claimed in any one of the preceding claims, wherein said one or more user specified parameters indicative of overall dimensional characteristics of said object include one or more biometric parameters of an intended user of said object.

13. A method as claimed in any one of the preceding claims, wherein said one or more user specified parameters indicative of overall dimensional characteristics of said object are specified in terms of one or more performance characteristics of said object.

14. A method as claimed in any one of the preceding claims, wherein said object is a bicycle frame.

15. A system comprising: a user terminal computer and a server computer cooperating to perform a method as claimed in any one of claims 1 to 14.

16. A method substantially as herein before described with reference to the accompanying drawings.

17. A system substantially as herein before described with reference to the accompanying drawings.