GB2247929A

GB2247929A - Aligning of components

Info

Publication number: GB2247929A
Application number: GB9020172A
Authority: GB
Inventors: Michael Nawton Hoyle
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1990-09-14
Filing date: 1990-09-14
Publication date: 1992-03-18
Also published as: GB9020172D0

Abstract

Two components are aligned along mating surfaces 18, 20 by forming nominally aligned holes 22, 24 in the mating surfaces 18, 20, placing within the holes 22, 24 dowel pins 26 which are deformable, and applying pressure to force the mating surfaces 18, 20, into contact with one another, the pressure being sufficient to bring about equal deformation of the dowel pins 26, if the holes in the components are misaligned, so that any misalignment is shared, The pins 26 may be hollow or of star cross-section, and be formed of heat resistant plastics. <IMAGE>

Description

Title METHOD OF ALIGNING COMPONENTS Field of the invention The present invention relates to a method of aligning components which are to be secured to one another.

There are many occasions when separately manufactured components need to be mated to one another, one example being the fixing of a manifold to a cylinder head. In this case, the intake ducts in the manifold and the intake ports in the cylinder head need to be aligned with one another as accurately as possible before the two components are bolted to one another in order to ensure a smooth transition between the two.

However, because of manufacturing tolerances, the two components may not match identically and one must allow for such manufacturing tolerances by providing a range of positions in which the manifold can be bolted onto the cylinder head. For example, the holes in the manifold may be made larger than the bolts used for securing the manifold to the cylinder head.

Assuming in such a situation that the intake ducts in the manifold are a different distance apart from the distance between the intake ports in the cylinder head. It would be possible to align the manifold so that the passages at one end are perfectly aligned but those at the other are totally misaligned. However, it is preferred to align the manifold in such a manner that the dimensional errors are shared equally amongst the engine intake ducts, because the cylinders are better matched to one another and because the maximum misalignment error in any single passage is reduced.

Obiect of the invention The present invention is concerned with a method of aligning components prior to their being secured to one another which enables mismatch errors in the dimensioning of the components to be distributed over the mating surface between the components.

Summarv of the invention According to the present invention, there is provided a method of aligning two components along a mating surface, which comprises forming nominally aligned holes in the mating surfaces for receiving dowel pins, placing within the holes dowel pins which are deformable under pressure and applying a force to urge the mating surfaces into contact with one another, the force being sufficient to bring about any necessary deformation of the dowel pins, if the holes in the components are misaligned.

When the components are forced together, the forces tending to deform the dowel pins act against one another and with action and reaction being equal to one another, the dowel pins will deform equally and average out the error over the entire mating surface instead of the error being concentrated in one region. This averaging of misalignment errors is particularly advantageous in the mounting of an intake manifold on an engine with two banks of cylinders, such as a V6 or a V8 engine.

The invention also provides a dowel pin for aligning two components which is made of a deformable material and is shaped to enable it to collapse to fit into a hole of smaller diameter than the maximum diameter of the dowel pin.

Preferably, the dowel pin is tapered at least at one end to enable the pin to line up with holes in the two components when the holes are in slight misalignment.

Advantageously, the dowel pins are progressively deformable and the resistance to deformation increases with the amount of deformation.

The dowel pin may be made collapsible by virtue of being hollow. Alternatively, the pins may have a star shaped solid cross section, the points of the star being capable of being deformed inwards or sideways.

The dowel pin may be suitably formed of a plastics material, such as nylon or polyethylene. Though the dowels serve no useful purpose after the manifold has been firmly secured in place, it is preferred that they be made from a material capable of withstanding the manifold temperature during operation so that the dowels may readily be removed if the manifold is separated from the cylinder head.

Brief description of the drawing The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a section through a cylinder head and manifold during assembly, and Figure 2 is a section through a cylinder head and manifold after alignment by the deformable dowels of the invention.

Detailed description of the invention An intake manifold 10 having branches 10a and 10b, is being aligned in Figure 1 with a cylinder head 12 having intake ports 14 which must line up with ducts 16 in the manifold branches. The mating surfaces 18 and 20 of the manifold 10 and the cylinder head 12, respectively, are provided with nominally aligned holes 22 and 24 which receive deformable dowel pins 26, made of nylon.

The dowel pins 26 are tapered at one end so that they can be introduced into the holes 22 and 24 at the same time even if these holes are slightly misaligned. They are also either hollow or of non-circular circumference, so that they may on deformation fit into a hole smaller than their outer diameter.

To assemble the manifold 10, it is positioned against the cylinder head 12 as shown in Figure 1 then pushed until the two mating surfaces meet. In the process, the dowels 12 will, if necessary, deform because of misalignment of the holes 22 and 24 be deformed but if no net sideways force is applied, then the dowels 26 will be deformed equally and the misalignment between the intake ducts 16 and the intake ports 14 will be evenly distributed, as shown in Figure 2, and it will not be possible to align one intake duct perfectly while leaving the other to take up the full error caused by manufacturing tolerance.

After alignment by means of the dowel pins 26, the manifold 10 is secured to the cylinder head 12 by means of bolts which pass through holes (not shown) in the manifold. The holes in the manifold are of larger diameter than the bolts so as to allow for the tolerance in the positioning of the manifold relative to the cylinder head. Once the bolts have been secured, the dowel pins 26 serve no further purpose.

The use of deformable dowels allows tolerances to be taken up in more than one dimension making the invention of particular use in the fitting of manifolds to engines with two blocks.

Claims

1. A method of aligning two components along a mating surface, which comprises forming nominally aligned holes in the mating surfaces for receiving dowel pins, placing within the holes dowel pins which are deformable under pressure and applying a force to urge the mating surfaces into contact with one another, the force being sufficient to bring about any necessary deformation of the dowel pins, if the holes in the components are misaligned.

2. A dowel pin for use in performing the method of claim 1, wherein the dowel pin is made of a deformable material and is shaped to enable the pin to collapse to fit into a hole of smaller diameter than the maximum diameter of the dowel pin.

3. A dowel pin as claimed in claim 2, wherein the dowel pin is tapered at least at one end to enable the pin to line up with holes in two components when the holes are in slight misalignment.

4. A dowel pin as claimed in claim 2 or 3, wherein the dowel pin is made collapsible by virtue of being hollow.

5. A dowel pin as claimed in claim 2 or 3, wherein the pin has a non-circular solid cross section.

6. A dowel pin as claimed in claim 5, wherein the pin has a star shaped cross section, the points of the star being capable of being deformed inwards or sideways.

7. A dowel pin as claimed in any one of claims 2 to 6, wherein the dowel pin is formed of a plastics material, such as nylon or polyethylene.

8. A dowel pin as claimed in claim 7, wherein the plastics material is heat resistant.

9. A method of aligning two components along a mating surface, substantially as herein described with reference to and as illustrated in the accompanying drawings.